Method and apparatus for operating a wireless device

Abstract

This invention describes a method and apparatus for transmission reception point (TRP) selection comprising: transmitting, by a wireless device, at least one first message, to a first group of TRPs, receiving, by the wireless device, a second message from a second group of TRPs indicating at least a selected TRP, performing, by the wireless device, a data exchange and / or wireless sensing with and / or through at least a selected TRP in the second group of TRPs.

Description

[0001] Method and apparatus for operating a wireless device

[0002] FIELD OF THE INVENTION

[0003] This invention relates to a method, apparatus, and system for operating a wireless device such as a user equipment for enhanced coverage, reliability, and energy savings in a wireless system such as a cellular system, a Wi-Fi network or the like.

[0004] BACKGROUND OF THE INVENTION

[0005] In conventional cellular networks, a primary station serves a plurality of secondary stations located within a cell served by this primary station. Wireless communication from the primary station towards each secondary station is done on downlink channels. Conversely, wireless communication from each secondary towards the primary station is done on uplink channels. The wireless communication can include data traffic (sometimes referred to User Data), and control information (also referred sometimes as signalling). This control information typically comprises information to assist the primary station and / or the secondary station to exchange data traffic (e.g. resource allocation / requests, physical transmission parameters, information on the state of the respective stations).

[0006] In the context of cellular networks as standardized by 3GPP, the primary station is referred to a base station, or a gNodeB (or gNB) in 5G (NR) or an eNodeB (or eNB) in 4G (LTE). The eNB / gNB is part of the Radio Access Network RAN, which interfaces to functions in the Core Network (CN). In the same context, the secondary station corresponds to a mobile station, or a User Equipment (or a UE) in 4G / 5G, which is a wireless client device or a specific role played by such device. The term "node" is also used to denote either a UE or a gNB / eNB.

[0007] Additionally, for example, in the case of PC5 interface or Sidelink communication, it is possible to have Direct communication between secondary stations, here UEs. It is then also possible for UEs to operate as Relays to allow for example out of coverage UEs to get an inter-mediate (or indirect) connection to the eNB or gNB. To be able to work as a relay, a UE may use discovery messages to establish new connections with other UEs.

[0008] Current wireless systems have increased requirements in reliability and coverage and energy savings. For instance, to enable resilient communication and / or wireless sensing in non-terrestrial networks or ensure that the energy consumption is reduced in terrestrial networks, owever, existing cell selection procedures and / or mobility procedures are not fully suitable because of the inherent manner cells / primary stations / access devices are selected and / or mobility and / or signalling procedures work.

[0009] SUMMARY OF THE INVENTION

[0010] An aim of the invention is to address the above problems.

[0011] Another aim of the invention is to propose a wireless device (for) performing transmission reception point (TRP) selection to achieve increased coverage, reliability, and energy savings.

[0012] Another aim of the invention is to provide sufficient information to the network so that the network (e.g., access devices receiving such first messages) may determine the most suitable access device(s) for, e.g., complete the random-access procedure or to move to or to perform a wireless sensing procedure.

[0013] To this end, this disclosure proposes methods, apparatus and computer program product as defined in the appended claims.

[0014] More specifically, in a first aspect of the invention, it is proposed a method for transmission reception point (TRP) selection comprising:

[0015] transmitting, by a wireless device, at least one first message, to a first group of TRPs, receiving, by the wireless device, a second message from a second group of TRPs indicating at least a selected TRP,

[0016] performing, by the wireless device, a data exchange and / or wireless sensing with and / or through the at least a selected TRP in the second group of TRPs.

[0017] The inventors recognized that conventional cell- or TRP-centric access, mobility procedures, or wireless procedures, in general, bind a wireless device too early to a single transmission point (or access device) based on instantaneous or limited measurements, which is increasingly inefficient in dense, multi-TRP, beam-centric, and cell-free deployments. In particular, the inventors observed that a wireless device often has incomplete or outdated knowledgeof which TRP will actually provide the best communication or sensing performance at the time data exchange takes place, especially in scenarios involving mobility, directional transmission, non-terrestrial access, or network energy-saving operation. To address this, the inventors conceived a decoupled selection mechanism in which a wireless device first exposes its presence, context, or intent to a group of TRPs via a firstmessage, thereby enabling the network side to cooperatively evaluate reception conditions, load, capabilities, and predicted evolution of the radio environment. By allowing a possibly different group of TRPs to respond with an indication of at least one selected TRP, the selection decision can be made closer in time to actual data exchange (or wireless procedure) and can leverage distributed network knowledge rather than a single local measurement. This insight enables more reliable and adaptive TRP (or access device) selection, reduces unnecessary mobility events (e.g., handovers) and signaling, improves coverage and robustness, and allows energy-efficient operation by activating and / or relying on only those TRPs that are best suited for communication and / or wireless sensing. The resulting procedure is particularly advantageous for multi-TRP, beam-based, and predictive mobility scenarios, as well as for on-demand access and sensing, where flexibility in selecting the serving TRP directly translates into improved performance, reduced latency, and lower overall network and device energy consumption.

[0018] In a variant of the first aspect that may be combined with other variants, as suitable, the first group of TRPs comprises the second group of TRPs.

[0019] In a variant of the first aspect that may be combined with other variants, as suitable, which may be combined with the first variant, the second group of TRPs is not contained in the first group of TRPs or wherein the second group of TRPs is only partly contained in the first group of TRPs.

[0020] In another variant of the first aspect that may be combined with other variants, as suitable, the first message is one or more of:

[0021] - a wake-up signal,

[0022] - a wake-up signal to wake-up the wireless sensing functionality of an access device, - a random-access preamble,

[0023] - message 3 in the random-access procedure,

[0024] - the first message in a RACH-less handover,

[0025] - a reference signal,

[0026] - a MAC CE message.

[0027] In another variant of the first aspect that may be combined with other variants, as suitable, the second group of TRPs comprises a single TRP, and the single TRP is the selected TRP. Alternatively, the second group of TRPs comprises a first TRP in the first group of TRPs and the selected TRP.

[0028] In another variant of the first aspect that may be combined with other variants, as suitable, the method further comprises:

[0029] receiving, by the wireless device, a first configuration, said first configuration comprising parameters to(1) indicate the wireless device preferences for multi TRP selection in and / or (2) transmit the first message,

[0030] wherein the reception, by the wireless device, of the first configuration is prior to transmitting, by the wireless device, the at least one first message and

[0031] wherein the first configuration comprises one or more:

[0032] - parameters determining a transmission timing of the at least one first message, - parameters determining a transmission frequency of the at least one first message, - parameters determining a number of repetitions of the at least one first message, - parameters determining a transmission power of the at least one first message, - an (implicit or explicit) identifier used to indicate the multi TRP selection,

[0033] - parameters of the first message, the first message being used as a reference signal, wherein the reference signal is one of a channel-state reference signal, a sounding reference signal or a wireless sensing reference signal, and the first message used by the first group of access devices to estimate the communication channel with the wireless device.

[0034] In another variant of the first aspect that may be combined with other variants, as suitable, the method further comprises:

[0035] receiving, by the wireless device, a second configuration, said second configuration comprising a policy determining the wireless device preferences for multi TRP selection,

[0036] wherein the reception, by the wireless device, of the second configuration is prior to the transmitting, by the wireless device, the at least one first message and wherein the second configuration comprises one or more:

[0037] - energy consumption / saving requirements,

[0038] - quality of service requirements,

[0039] - service parameters / requirements.

[0040] Optionally, the first configuration and / or second configuration are received:

[0041] - in SIB1,

[0042] - in a SIB,

[0043] - in an RRC message,

[0044] - in a NAS message.

[0045] In another variant of the first aspect that may be combined with other variants, as suitable, wherein the first message indicates whether the wireless device desires to communicate through a specificTRP in the first group of TRPs orthrough a network-selected TRP in the second group of TRPs.

[0046] The first aspect may also include any of the following:- multi transmission reception point (TRP) selection is a multi-access device selection, - the first group of TRPs is a first group of access devices,

[0047] - the second group of TRPs is a second group of access devices,

[0048] - the one or more selected TRP are one or more selected access devices.

[0049] In another variant ofthe first aspect of its variants, the method is further characterized by any one of

[0050] - multi transmission reception point (TRP) selection is a multi-beam selection, - the first group of TRPs is a first group of beams,

[0051] - the second group of TRPs is a second group of beams, and

[0052] - the selected TRPs are selected beams.

[0053] In another variant of the first aspect that may be combined with other variants, as suitable, the first message is transmitted to trigger and / or perform one of:

[0054] -TRP selection,

[0055] -TRP re-selection,

[0056] -TRP handover.

[0057] In another variant of the first aspect that may be combined with other variants, as suitable, the method further comprises

[0058] determining, by the wireless device, assistance information to assist the first group of TRPs to determine the selected TRP,

[0059] transmitting, by the wireless device, the assistance information in the first message. In another variant, the method further comprises

[0060] receiving, by the wireless device, an AI / ML model for predicting the accuracy / confidence level of assistance information,

[0061] inferring, by the wireless device, the accuracy / confidence level of the assistance information by using the AI / ML model,

[0062] transmitting, by the wireless device, the inferred accuracy in the first message. In any of these 2 previous variants, wherein the assistance information may comprise one or more:

[0063] - assistance information for an "n hop handover" with n being at least two;

[0064] - the number of planned hops to perform a handover based on a configuration of the wireless device;

[0065] - the predicted confidence level of a successful handover towards target access device n hops away, with n greater than or equal to two;- the trajectory of and / or confidence in the trajectory confidence of the wireless device.

[0066] In another variant of the first aspect that may be combined with other variants, as suitable, the transmission of the first message triggers a conditional (LTM) handover.

[0067] In another variant of the first aspect that may be combined with other variants, as suitable, the first message is indicative of at least two potential target TRPs according to a first "n hop handover route".

[0068] In another variant, the second message is indicative of the one or more selected TRPs in connection order according to an "n hop handover route".

[0069] In another variant of the first aspect that may be combined with other variants, as suitable, the method comprises

[0070] deriving a root access stratum key by means of a key derivation function, wherein input information to the key derivation function comprises one or more identifiers of the TRPs in the first group of TRPs and / or the identity of the selected TRP in the second group of TRPs.

[0071] In another variant of the first aspect that may be combined with other variants, as suitable, the method comprises

[0072] performing, by the wireless device, a data exchange with and / or through at least the selected TRP in the second group of TRPs. Optionally, the method comprises, prior to the performing of the data exchange at least one of:

[0073] negotiating security algorithms and security levels of the lower layer communication and higher layer communication; and / or

[0074] disabling user plane security at a higher layer when lower layer security is enabled; and / or

[0075] enabling user plane security at a higher layer when lower layer security is set to null security.

[0076] Furthermore, the method may comprise, prior to the performing of the data exchange, deriving a lower layer key to protect a lower layer and deriving a higher layer key to protect a higher layer, and the deriving of the higher lay key may be conditioned to the selected TRP belonging to a cell different from the cell that the wireless device is connected to upon initiating the procedure.

[0077] Optionally, the input information to a key derivation function used to derive the lower layer key comprises one or more of (a) a root access stratum key, (b) at least a lower layer parameter and the at least lower layer parameter is one or more of the parameters in the TCI received from atleast a first TRP from the first group of TRPs and / or from the selected TRP from the second group of TRPs.

[0078] In a variant of the first aspect that may be combined with other variants, as suitable, the key derivation function used to derive the lower layer key is ASCON based.

[0079] In another variant of the first aspect that may be combined with other variants, as suitable, the lower layer key is used to protect a MAC CE.

[0080] In another variant of the first aspect that may be combined with other variants, as suitable, an algorithm used for integrity protection with the lower layer key is ASCON.

[0081] In another variant of the first aspect that may be combined with other variants, as suitable, the first message contains a secure envelope, and the secure envelope contains credentials to perform a mobility procedure towards the selected TRP.

[0082] In another variant of the first aspect that may be combined with other variants, as suitable, the keys and / or credentials and / or secure envelopes to perform a mobility procedure are characterized by a validity time, and upon expiration of the validity time, the keys and / or credentials and / or secure envelopes become invalid.

[0083] In another variant of the first aspect that may be combined with other variants, as suitable, the first message uses a network identifier, wherein this network identifier is provided in the first configuration, and wherein the network identifier belongs to a set of network identifiers shared between at least an TRP in the first group of TRPs and the selected TRP.

[0084] In another variant of the first aspect that may be combined with other variants, as suitable, transmitting, by the wireless device, at least one first message, to then first group of TRPs, comprises transmitting one or more first message bursts, each message burst comprising one or more first messages, and wherein:

[0085] - a first message is transmitted via an omnidirectional beam and another first message is transmitted via a directional beam; and / or

[0086] - message bursts are transmitted in an aperiodic manner; and / or

[0087] - two or more first messages transmitted via directional beams are time-multiplexed; - a first message includes an indication of the position in the first message burst; - a first message includes an indication of its first message burst.In another example of the first aspect that may be combined with other variants, as suitable, the data exchange and / or wireless sensing with two or more selected TRPs in the second group of TRPs is a joint and / or coherent transmission, and

[0088] the time and / or frequency and / or transmission power adjustments of the joint and / or coherent transmission are based on the transmitted first message.

[0089] In another variant of the first aspect that may be combined with other variants, as suitable, the wireless device performs a wireless sensing procedure with and / or through the at least a selected TRP in the second group of TRPs, and wherein the method is further adapted to:

[0090] transmitting, by the wireless device, information verifying or for verifying (to allow for the verification) that the wireless sensing procedure is performed with the wireless device.

[0091] In another variant of the first aspect that may be combined with other variants, as suitable, the wireless device adds (first) communication resources from the selected TRP, before releasing, by the wireless device, (second) communication resources from the first group of TRPs.

[0092] In another variant,

[0093] (a) the wireless device may be in IDLE / INACTIVE state, and

[0094] (b) the first message to the first group of TRPs may be a preamble for triggering the transmission of on-demand SIB1 and a random-access response indicating the selected access device, and

[0095] (c) prior to sending the first message and the second message, the wireless device may (cl) send a first first message for triggering the transmission of on-demand synchronization signals, and (c2) receive a first second message comprising on-demand synchronization signals from the first group of access devices.

[0096] In another variant, the wireless device is in CONNECTED state, and the first message to the first group of access device may indicate the selection of and / or preference to select two or more access devices,

[0097] In accordance with the second aspect of the invention, it is proposed a method for transmission reception point (TRP) selection comprising:

[0098] receiving, by a first group of TRPs, a first message from a wireless device,determining, by the first group of TRPs, a second group of TRPs comprising selected TRPs,

[0099] transmitting, by the first group of TRPs, an indication to the selected TRPs, causing:

[0100] at least one of the selected TRPs to transmit a second message indicating the selected TRPs,

[0101] and performing, by the selected TRPs, a data exchange and / or wireless sensing with the wireless device.

[0102] This method is advantageous because it allows the network to select a suitable access device to perform a wireless procedure with the wireless device, improving the performane of the wireless system.

[0103] In accordance with a third aspect of the invention, it is proposed an apparatus for transmission reception point selection comprising:

[0104] a processor,

[0105] a transceiver, and

[0106] a memory storing instructions which, when executed,

[0107] cause the apparatus to

[0108] transmit at least one first message, to a first group of TRPs,

[0109] receive a second message from a second group of TRPs indicating at least a selected TRP,

[0110] perform a data exchange and / or wireless sensing with and / or through at at least a selected TRP in the second group of TRPs.

[0111] In a fourth aspect of the invention, it is proposed an apparatus for transmission reception point selection comprising:

[0112] a processor,

[0113] a transceiver, and

[0114] a memory storing instructions which, when executed,

[0115] cause the apparatus to

[0116] receive a first message from a wireless device,

[0117] determine a second group of TRPs comprising selected TRPs,

[0118] transmit an indication to the selected TRPs, causing:

[0119] at least one of the selected TRPs to transmit a second message indicating the selected TRPs,and performing, by the selected TRPs, a data exchange and / or wireless sensing with the wireless device.

[0120] In accordance with a fifth aspect of the invention, it is proposed a computer program for transmission reception point selection comprising computer instructions to perform the steps in the methods of the first and second aspects and their variants.

[0121] It is to be noted that any variants of the first aspect may equally apply or be adapted to the other aspects, but are not repeated for the sake of conciseness.

[0122] It is to be noted that the wireless device (e.g., of the third aspect of the invention) and access device (e.g., of the fourth aspect of the invention) may form and / or operate as a system, e.g., a wireless system.

[0123] It shall be understood that a preferred embodiment of the invention can also be any combination of the dependent claims or above embodiments with the respective independent claim.

[0124] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0125] BRIEF DESCRIPTION OF THE DRAWINGS

[0126] In the following drawings:

[0127] Fig. 1 schematically represents the overall cellular system including UEs, RAN, and core network;

[0128] Fig. 2 provides a schematic representation of a UE and its components; and

[0129] Fig. 3 schematically represents different entities involved in a non-terrestrial network; Fig. 4 schematically represents a random-access procedure in a wireless network; Fig. 5 schematically represents a signalling procedure by an access device;

[0130] Fig. 6 schematically represents the periodic transmission of SSB bursts;

[0131] Fig. 7 schematically represents examples of wireless devices according to some embodiments;

[0132] Fig. 8 schematically represents an application scenario according to embodiments of the present disclosure;

[0133] Fig. 9a and Fig. 9b schematically represents message flows according to embodiments of the present disclosure;

[0134] Fig. 10 schematically represents an application scenario according to embodiments of the present disclosure;Fig. 11 schematically represents message flows according to embodiments of the present disclosure;

[0135] Fig. 12 schematically represents message flows according to embodiments of the present disclosure, e.g., related to conditional handover with reservation of a number of hops;

[0136] Fig. 13 schematically represents a deployment and operational scenario according to embodiments of the present disclosure; and

[0137] Fig. 14 schematically represents an application scenario according to embodiments of the present disclosure;

[0138] Fig. 15 schematically describes a communication procedure according to embodiments of the present disclosure;

[0139] Fig. 16 schematically describes a further communication procedure according to some embodiments of the present disclosure; and

[0140] Fig. 17 schematically describes a communication method for operating a wireless device, wherein the wireless device communicates while moving from a first TPR (or a first group of TRPs) to a second (or selected) TRP controlled by a common controller unit (CU); and

[0141] Fig. 18 is a block diagram illustrating an example processor.

[0142] DETAILED DESCRIPTION OF EMBODIMENTS

[0143] Embodiments of the present invention are now described based on a cellular communication network environment, such as 5G or 6G. However, the present invention may also be used in connection with other wireless technologies.

[0144] Throughout the present disclosure, the abbreviation "gNB" (5G terminology) or "BS" (base station) or the term "access device" is intended to mean a wireless access device such as a cellular base station or a Wi-Fi access point or a ultrawide band (UWB) personal area network (PAN) coordinator. The gNB may consist of a centralized control plane unit (gNB-CU-CP), multiple centralized user plane units (gNB-CU-UPs) and / or multiple distributed units (gNB-DUs). The gNB is part of a radio access network (RAN), which provides an interface to functions in the core network (CN). The RAN is part of a wireless communication network. It implements a radio access technology (RAT). Conceptually, it resides between a communication device such as a mobile phone, a computer, or any remotely controlled machine and provides connection with its CN. The CN is the communication network's core part, which offers numerous services to customers who are interconnected via the RAN. More specifically, it directs communication streams over the communication network and possibly other networks.Furthermore, the terms "base station" (BS) and "network" may be used as synonyms in this disclosure. This means for example that when it is written that the "network" performs a certain operation it may be performed by a CN function of a wireless communication network, or by one or more base stations that are part of such a wireless communication network, and vice versa. It can also mean that part of the functionality is performed by a CN function of the wireless communication network and part of the functionality by the base station.

[0145] It is further noted that throughout the present disclosure only those blocks, components and / or devices that are relevant are shown in the accompanying drawings. Other blocks have been omitted for reasons of brevity. Furthermore, blocks designated by same reference numbers are intended to have the same or at least a similar function, so that their function is not described again later.

[0146] A cellular system is a wireless communication system that consists of three main components: user equipment (UE), radio access network (RAN), and core network (CN). These components work together to provide voice and data services to mobile users over a large geographic area.

[0147] In conventional cellular networks, a primary station serves a plurality of secondary stations located within a cell served by this primary station. Wireless communication from the primary station towards each secondary station is done on downlink channels. Conversely, wireless communication from each secondary towards the primary station is done on uplink channels. The wireless communication can include data traffic (sometimes referred to User Data), and control information (also referred sometimes as signalling). This control information typically comprises information to assist the primary station and / or the secondary station to exchange data traffic (e.g. resource allocation / requests, physical transmission parameters, information on the state of the respective stations). In the context of cellular networks as standardized by 3GPP, the primary station is referred to a base station, or a gNodeB (or gNB) in 5G (NR) or an eNodeB (or eNB) in 4G (LTE). The eNB / gNB is part of the Radio Access Network RAN, which interfaces to functions in the Core Network (CN). In the same context, the secondary station corresponds to a mobile station, or a User Equipment (or a UE) in 4G / 5G, which is a wireless client device or a specific role played by such device. The term "node" is also used to denote either a UE or a gNB / eNB.

[0148] Additionally, for example, in the case of PC5 interface or Sidelink communication, it is possible to have Direct communication between secondary stations, here UEs. It is then also possible for UEs to operate as Relays to allow for example out of coverage UEs to get an inter-mediate (or indirect) connection to the eNB or gNB. To be able to work as a relay, a UE may use discovery messages to establish new connections with other UEs. Certain UEs may communicate with each other by usingdevice-to-device communication, also known as sidelink communication using the PC5 interface that may rely on physical sidelink (PS) broadcast channel, PS shared channel, PS control, etc. Furthermore, the role of a relay node has been introduced in 3GPP. This relay node is a wireless communication station that includes functionalities for relaying communication between a primary station, e.g. a gNB and a secondary station, e.g. a UE. This relay function for example allows to extend the coverage of a cell to an out-of-coverage (OoC) secondary station. This relay node may be a mobile station or could be a different type of device. In the specifications for 4G, the Proximity Services (ProSe) functions are defined inter alia in TS 23.303, and TS 24.334 to enable - amongst others -connectivity for the cellular User Equipment (UE) that is temporarily not in coverage of the cellular network base station (eNB) serving the cell. This particular function is called ProSe UE-to-network relay, or Relay UE for short. The Relay UE relays application and network traffic in two directions between the OoC UE and the eNB. The local communication between the Relay UE and the OoC UE is called device-to-device (D2D) communication or Sidelink (also known as PC5) communication in TS 23.303 and TS 24.334. Once the relaying relation is established, the OoC-UE is, e.g., IP-connected via the Relay UE and acts in a role of "Remote UE". This situation means the Remote UE has an indirect network connection to selected functions of the Core Network as opposed to a direct network connection to all Core Network functions that is the normal case. Furthermore, it has been introduced the role of a UE-to-UE relay node, i.e., a relay node re-laying the communication between two UE devices. The relay node relays the communications between UE devices. UEs may connect to the core network through a base station when in-coverage. In such relay scenarios, the relay devices may receive and store some information for some time before forwarding it towards the target device. This information that may be stored and forwarded may be discovery messages received from a source UE whereby the relay UE may release them at some point of time later. This information that may be stored and forwarded may be a SIB that may contain a timestamp.

[0149] User equipment (UE) is the device that a user uses to access the cellular system, such as a smartphone, a tablet, a laptop, loT device, or a wearable device. A UE typically may contain the following components:

[0150] - A universal integrated circuit card (UICC), which stores the user's identification and authentication information, such as the subscription permanent identifier (SUPI) or credentials.

[0151] - A transceiver, which converts the digital signals from the processor into analog signals for transmission and reception over the air interface. The transceiver also performs modulation, demodulation, coding, decoding, and other signal processing functions.- A processor, which controls the operation of the UE and executes the applications and services that the user requests. The processor also communicates with the RAN and the CN using various protocols.

[0152] - A display, which shows the user the information and feedback from the UE, such as the signal strength, the battery level, the call status, the messages, the contacts, the menu, etc.

[0153] - A microphone and a speaker, which enable the user to make and receive voice calls, as well as use other audio features, such as voice mail, voice recognition, etc.

[0154] - A keyboard and / or a touch screen, which allow the user to enter and select commands, text, numbers, etc.

[0155] - A camera and / or a video recorder, which enable the user to capture and send images and videos, as well as use other multimedia features, such as video calling, video streaming, etc.

[0156] - A memory, which stores the data and programs that the user needs, such as the phone book, the messages, the photos, the videos, the applications, etc as well as a computer program to perform the operations of the RAN and CN protocols.

[0157] - A battery, which provides the power supply for the UE.

[0158] Fig. 2 provides a schematic representation of a UE and its components, e.g., UICC (201), processor (202), transceiver (203), memory (204), input devices (205) such as camera, microphone, etc and output devices (206) such as display, speaker, etc. Fig. 7 schematically represents wireless devices that may include the capabilities of a UE and / or a STA. Fig. 7a) represents AR / VR glasses; Fig. 7b) represents a connected vehicle; and Fig. 7c) represents a mobile phone. In these devices, a reflective intelligent surface (RIS) may be embedded, e.g., by covering and / or under the whole a part of the UE surface. This may be used, e.g., to better deal with interferences or improve wireless sensing.

[0159] A UE may access the cellular network via the radio access network, as described below. Certain UEs may communicate with each other by using device-to-device communication, also known as sidelink communication using the PC5 interface that may rely on physical sidelink (PS) broadcast channel, PS shared channel, PS control channel, etc.

[0160] A UE may receive a configuration by means of different procedures:

[0161] Downlink control information (DCI) is a type of control information that is sent from the BS to the UE on the physical downlink control channel (PDCCH). DCI contains various parameters that instruct the UE how / when to decode and transmit data on the physical downlink shared channel (PDSCH) and the physical uplink shared channel (PUSCH), such as the resource allocation, the modulation and coding scheme. The UE needs to monitor the PDCCH in each subframe to detect and decode the DCI that is addressed to it.Uplink control information (UCI) is a type of control information that is sent from the UE to the BS on the physical uplink control channel (PUCCH) or the physical uplink shared channel (PUSCH). UCI contains various feedback signals that inform the BS about the status and quality of the downlink transmission, such as the HARQ. acknowledgments (ACKs), the channel state information (CSI ), and the scheduling requests (SRs). The UE needs to encode and transmit the UCI according to the configuration and timing indicated by the BS.

[0162] Sidelink control information (SCI) is a type of control information that is sent from the UE to another UE on the physical sidelink control channel (PSCCH) in device-to-device (D2D) communication scenarios. The main functions of SCI include resource allocation, synchronization, channel quality reporting, .

[0163] Medium access control (MAC) control element (MAC CE) is a type of control information that is sent from the BS to the UE or vice versa on the MAC layer. MAC CE contains various commands or indications that regulate the MAC layer functions, such as the buffer status report (BSR), the timing advance command (TAC), the discontinuous reception (DRX) command, etc. The UE needs to process the MAC CE according to the MAC protocol and the configuration provided by the BS.

[0164] Radio resource control (RRC) command is a type of control information that is exchanged between the BS and the UE on the RRC layer. RRC Command contains various messages that modify / configure RRC parameters and / or initiate, modify, or release the RRC connection or the radio bearers between the UE and the BS, such as the RRC connection setup, the RRC connection reconfiguration, the RRC connection release, the security mode command, the mobility from E-UTRA command, the handover from E-UTRA preparation request, etc. The UE needs to respond to the RRC Command according to the RRC protocol and the configuration provided by the BS.

[0165] Non-access stratum (NAS) messages are used for signalling between UE and core network (CN) on the non-access stratum (NAS) layer. NAS messages enable functionality such as registration, session establishment, security, and mobility management. The UE needs to respond to the NAS Command according to the NAS protocol and the configuration provided by the CN.

[0166] UE parameter update (UPU) is a procedure between the UE and the home network that enables the home network to update configuration parameters in mobile phones and / or USIM using the UDM control plane procedure (TS 23.502). The UE can receive Parameters Update Data from the UDM after the UE has registered in the 5G network.

[0167] Steering of Roaming (SoR) enables the home network to guide the user equipment (UE) when registering on a visited network. For detailed information about the interfaces and registration in the 5G System, refer to 3GPP TS.23.501 (Release 15) and 3GPP TS 24.501 (Release 15). The 5G CP-SOR is activated during or after registration to update the UE's "Operator Controlled PLMNSelector with Access Technology" list via secure NAS messages, as directed by the home PLMN based on specific operator policies, such as preferred networks or UE location.

[0168] UE configuration update (UCU) is used to update configuration parameters as per TS 23.502 that may include Access and Mobility Management related parameters decided and provided by the AMF, UE Policy provided by the PCF. When AMF wants to change the UE configuration for access and mobility management related parameters the AMF initiates the procedure defined in clause 4.2.4.2. When the PCF wants to change or provide new UE Policies in the UE, the PCF initiates the procedure defined in clause 4.2.4.3. If the UE Configuration Update procedure requires the UE to initiate a Registration procedure, the AMF indicates this to the UE explicitly. The procedure in clause 4.2.4.2 may be triggered also when the AAA Server that performed Network Slice-Specific Authentication and Authorization for an S-NSSAI revokes the authorization.

[0169] Radio access network (RAN) is the part of the cellular system that connects the UEs to the CN via the air interface. The RAN consists of base stations (BSs). A base station (BS) is a fixed or mobile transceiver that covers a certain geographic area, called a cell. In 5G, a BS is also called a gNB (next generation node B). A BS can serve multiple UEs simultaneously within its cell, by using different frequencies, time slots, codes, or beams. A BS also performs functions such as power control, handover control, channel allocation, interference management, etc. A base station can be divided into two units: a central unit (CU) and a distributed unit (DU). The CU performs the higher layer functions, such as RLC, PDCP, RRC, etc. The DU performs the lower layer functions, such as PHY and MAC. The CU and the DU can be co-located or separated, depending on the network architecture and deployment. In cellular systems, a base station may be denoted, based on context, as a cell, or gNB.

[0170] The cell may also refer to the coverage area of a base station. A BS may have different coverage areas such as a macro cell (e.g. several kilometres wide), a pico cell (e.g., for a given location such as a stadium) or a femto cell for a small location (e.g., a home or part of it).

[0171] A base station may communicate with the core network. Since there can be base stations for different cellular systems, different interfaces are required. For instance, a base station, eNB, in a 4G Long Term Evolution (LTE) system (also known as Evolved Universal Mobile Telecommunications Systems (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the 4G CN known as EPC through the corresponding interface. For instance, a base station, gNB, in a 5G system (i.e., 5G New Radio or Next Generation RAN) may communicate with the 5GC through a different interface. 4G and 5G base stations may communicate with each other directly or through their corresponding core networks.

[0172] The main protocols used between the UEs and the RAN are:- The physical layer (PHY), which defines the characteristics of the air interface, such as the frequency bands, the modulation schemes, the coding rates, the frame structure, the synchronization, etc.

[0173] - The medium access control (MAC) layer, which regulates the access of the UEs to the shared radio channel, by using techniques such as orthogonal frequency division multiple access (OFDMA), time division duplex (TDD), frequency division duplex (FDD), etc.

[0174] - The radio link control (RLC) layer, which provides reliable data transmission over the radio channel, by using techniques such as segmentation, reassembly, error detection, error correction, retransmission, etc.

[0175] - The packet data convergence protocol (PDCP) layer, which compresses and decompresses the headers of the data packets, encrypts and decrypts the data, and performs data integrity protection.

[0176] - The radio resource control (RRC) layer, which establishes, maintains, and releases the radio bearers between the UEs and the RAN, as well as exchanges the signalling messages for functions such as connection setup, handover, measurement reporting, security activation, etc.

[0177] A transmission / reception communication unit or transceiver may be used by BS and UE to transmit / receive data. Control data may be required for a physical broadcast channel, physical downlink control channel, etc. Data may be for the physical downlink shared channel.

[0178] Data may be encoded by the UE and / or BS to obtain data symbols and / or control symbols that may be exchanged over the wireless interface. The conversion from digital data into analog symbols may be done by the transmission / reception communication unit

[0179] A medium access control control-element (MAC-CE) is a MAC layer communication element that is used to control the communication between wireless devices. A MAC-CE may be exchanged in a shared channel, e.g., the physical downlink / uplink / sidelink shared channel.

[0180] The communication between a UE and a base station or the communication between UEs (when sidelink is used) may involve the exchange of reference signals. Reference signals may include primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel demodulation reference signal (DMRS), a channel state information reference signal (CSI-RS). Core network (CN) is the part of the cellular system that connects the RAN to other networks, such as the Internet, or other cellular systems. The CN consists of two main (control / user) domains. The control domain is responsible for providing signalling and control functions for the UEs, such as authentication, authorization, mobility management, session management, etc. The control plane consists of several network functions (NFs), such as the access and mobility management function (AMF), the session management function (SMF), the unified data management (UDM), thepolicy control function (PCF), the network exposure function (NEF), and the authentication server function (AUSF). The access and mobility management function (AMF) is a NF that handles the registration, deregistration, connection management, and mobility management for the UEs. The session management function (SMF) is a NF that handles the establishment, modification, and release of the sessions for the UEs. The SMF also communicates with the user plane devices to perform functions such as IP address allocation, tunnelling, QoS, etc. The unified data management (UDM) is a NF that stores and manages the user data, such as the SUPI, the service profile, the subscription status, etc. The policy control function (PCF) is a NF that provides the policy rules and charging information for the UEs, such as the access type, the service level, the data rate, the quota, etc. The network exposure function (NEF) is a NF that exposes the network capabilities and services to external applications and devices, such as the IMS, the Internet of Things (loT), etc. The authentication server function (AUSF) is a NF that performs the primary authentication with the by using credentials and the SUPI. The user domain is responsible for providing data and multimedia services to the UEs, by using packets and IP addresses. The user plane consists of two main functions: the user plane function (UPF) and the data network (DN). The user plane function (UPF) is a device that forwards the data packets between the UEs and the DNs, as well as performs functions such as tunnelling, firewall, QoS, charging, etc. The data network (DN) is a network that provides access to the services and applications that the UEs request, such as the Internet, the IMS, etc.

[0181] A residential gateway (RG) is a device that connects a home network to an external network, such as the Internet or a cellular system. An RG typically provides functions such as routing, switching, firewall, NAT, DHCP, DNS, VPN, etc. An RG can also support various types of interfaces, such as Ethernet, Wi-Fi, Bluetooth, USB, etc. A cellular-capable RG is an RG that has a cellular interface, such as a UICC slot, a cellular modem, or an antenna, that enables it to access the cellular system as a backup or an alternative to the wired or wireless broadband connection. A cellular-capable RG can provide benefits such as: (1) Enhanced reliability, by switching to the cellular connection in case of a failure or a degradation of the broadband connection; (2) Increased bandwidth, by aggregating the cellular connection and the broadband connection to achieve higher data rates or QoS.

[0182] A multi-SIM subscription is a subscription that allows a user to have multiple SIMs (or eSIMs) that are linked to the same account and service profile. A user can use the multi-SIM subscription to access the cellular system from different devices, such as a smartphone, a tablet, a laptop, or a wearable device, without having to switch the SIM card or the device.

[0183] Overall system: Fig. 1 provides an overall description of a wireless system wherein devices 100, 102, and 128 can play the role of UEs. Device 102 is part of a cellular-capable RG providingconnectivity to a home network 129 e.g., by means of a local area network and / or wireless local area network. Device 102 is served by base station 104.

[0184] The RAN 127 comprises base station 103 and serves UE 128. UE 128 may also be a UE to Network relay given access to remote UE 136 that is out of coverage of base station 103. UEs 134 and 136 also communicate with each other via a UE-to-UE relay 135. UE to UE communication via relays is enabled by means of sidelink communication / PC5 interface.

[0185] Within the RAN, the range of base station 103 is extended via smart repeater 137 and reflective intelligent surface (RIS) 138. Smart repeater 137 and RIS 138 give access to UE 142.

[0186] The RAN 143 includes base station 104 tand serves as wireless access infrastructure for the home network. Base station 104 also serves a mobile access device and / or UE as a UAV 139. UAV 139 may provide connectivity to remote UE 136.

[0187] Furthermore, a satellite gateway 141 is shown that connects to satellite 140 and may provide connectivity services to remote UE 136 or UE 100.

[0188] In Fig. 1, the 5G core network 133 may include one or more an AMF 121, SMF 123, UPF 122, AUSF 124, UDM 125, PCF 131, NEF 132 and allows the connection to a data network 130.

[0189] In Fig. 1, a second core network 142, e.g., a legacy core network as a 4G core network, is also shown that may interface with the 5G core network 133, interface with base stations denoted eNB in 4G, and provide a connection to the data network 130. The legacy 4G core network is denoted EPC and may include one or more mobility management entities (MME), a serving gateway, a multimedia broadcast multicast service gateway, a broadcast multicast service center, a packet data network gateway, etc. The mobility management entity may handle the signalling between UE and the 4G CN and may interact with the home subscriber server (HSS) in charge of the storage and management of subscriber data and secrets. The MME may provide connection management, similar to the AMF in 5G. The serving gateway may be used to exchange user internet protocol messages whereby the serving gateway may interact with the packet data network gateway that is connected to IP services. Multiple protocols in 4G and 5G have similar features. For example, the 5G network registration and 4G attach registration message are initially sent by the UE to establish a connection between the UE and the CN, which involves sending an initial request from the UE with its identity and capabilities, receiving an authentication request from the CN with a challenge, sending an authentication response from the UE with a response, receiving an authentication result from the CN with an indication of success or failure, and sending a security mode command from the CN with the selected security algorithms. As a result of this connection establishment procedure, NAS and AS keys are derived from the K_AMF (5G) and K_ASME (4G) where K_AMF is managed by the AMF and K_ASME is managed by the MME. A UE may connect to a serving network or serving Public Land Mobile Network(PLMN). A UE may have a subscription with a home PLMN, and during the registration procedure, the (AM F of the) serving PLMN may forward the registration request to the (AUSF of the) home PLMN that may perform an initial authentication procedure between home PLMN and UE. If the authentication procedure is successful, keys are derived and the home PLMN may share derived credentials with the serving PLMN, including K_SEAF, that may be used to derive K_AMF, from which NAS keys and AS keys are derived. The registration request sent by the UE includes an identifier that can be used by the home PLMN to identify the UE. To prevent privacy vulnerabilities, the long-term subscriber's identifier known as Subscriber Permanent Identifier (SUPI) may not be exchanged in the clear, but instead, either a Subscription Concealed Identifier (SUCI) or a pseudonym known as GUTI are exchanged with the AMF of the serving PLMN. The AMF of the PLMN may then forward the SUCI to the home PLMN so that the home PLMN decrypts / verifies it.

[0190] Satellite access: Fig. 1 depicts satellite 140 providing access to one or more UEs. Satellite access can be performed by means of non-terrestrial devices at different altitudes such as Low Earth Orbit (LEO), Medium Earth Orbit (MEO) or Geosynchronous Equatorial Orbit (GEO) satellites. Other types of non-terrestrial devices may include high-altitude platform station (HAPS) or unmanned aerial vehicle (UAVs) that may comprise a base station. Fig. 3 illustrates different elements including a GEO satellite 302, a MEO satellite 303, LEO satellites 304 and 304', a UAV 305, all of them potential non-terrestrial mobile access devices giving coverage to wireless device (e.g., a UE) 301. GEO satellite 302 remains static over a given earth position while MEO and LEO satellites move. MEO satellite 303 has a slower moving vector 306 in relation to the earth compared with LEO satellites 304 / 304' that have a faster moving vector 307 / 307'. A non-terrestrial gateway 308 is included that provides connectivity to the mobile access device via a feeder link 310. A mobile access device provides service to the wireless device via a service link 311. Two mobile access devices in the same orbit may communicate with each other via an intra-orbit-satellite link 312 while two mobile access devices in different orbits may communicate with each other via an inter-orbit-satellite link 313. Fig. 3 finally also includes a terrestrial access device 309 that may also provide connectivity to wireless device 301. The terrestrial access device 309, the wireless device 301, and non-terrestrial gateway are on the earth surface 314.

[0191] Non-terrestrial devices such as satellites distribute system information in specific SIBs, in particular, SIB31 in 4G and SIB19 in 5G. SIB19 information element as defined in TS 38.331 18.2.0. — ASN1START

[0192] — TAG-SIB19-START

[0193] SIB19-rl7 SEQUENCE {tn- Co f ig-r 17 NTN-Conf ig-rl7

[0194] OPTIONAL, — Need R

[0195] t-Service-rl7 INTEGER ( 0. .549755813887 ) OPTIONAL, — Need R

[0196] ref erenceLocation-rl7 Ref erenceLocation-rl7 OPTIONAL, — Need R

[0197] distanceThresh-rl7 INTEGER ( 0 . . 65525 ) OPTIONAL, — Need R

[0198] ntn-NeighCellConf igList-rl7 NTN-NeighCellConf igList-r!7 OPTIONAL, — Need R

[0199] lateNonCriticalExtension OCTET STRING

[0200] OPTIONAL,

[0201] [ [

[0202] ntn-NeighCellConf igListExt-vl720 NTN-NeighCellConf igList-r!7 OPTIONAL — Need R

[0203] ] ] ,

[0204] [ [

[0205] movingRef erenceLocation-rl8 Ref erenceLocation-rl7 OPTIONAL, — Need R

[0206] ntnCovEnh-rl8 NTN-CovEnh-rl8

[0207] OPTIONAL, — Need R

[0208] satSwitchWithReSync-rl8 SatSwitchWithReSync-rl8 OPTIONAL — Need R

[0209] ] ]

[0210] }

[0211] NTN-NeighCellConf igList-rl7 : : = SEQUENCE (SIZE ( 1 . . maxCellNTN-rl7 ) ) OF NTN-NeighCellConf ig-rl7

[0212] NTN-NeighCellConf ig-rl7 : : = SEQUENCE {

[0213] ntn- Conf ig-r 17 NTN-Conf ig-r 17

[0214] OPTIONAL, — Need R

[0215] carrierFreq-rl7 ARFCN-ValueNR

[0216] OPTIONAL, — Need R

[0217] physCell!d-rl7 PhysCellld

[0218] OPTIONAL — Need R

[0219] }

[0220] NTN-CovEnh-rl8 : : = SEQUENCE {

[0221] numberOfMsg4HARQ-ACK-Repetitions-rl8 BIT STRING (SIZE ( 4 ) ) , rsrp-ThresholdMsg4HARQ-ACK-rl8 RSRP-Range

[0222] OPTIONAL — Need R

[0223] }

[0224] SatSwitchWithReSync-rl8 : : = SEQUENCE {

[0225] ntn- Conf ig-r 18 NTN-Conf ig-r 17 ,

[0226] t-ServiceStart-rl8 INTEGER ( 0. .549755813887 ) OPTIONAL, — Need R

[0227] ssb-TimeOf f set-rl8 INTEGER ( 0. . 159 )

[0228] OPTIONAL — Need R

[0229] }

[0230] TAG-SIB19-STOP

[0231] ASN1STOP

[0232]

[0233]

[0234]

[0235]

[0236] A UE in a cellular system performs an initial random-access procedure to connect an access device. The 5G random access procedure is illustrated by means of Fig. 4 wherein 401 represents a user equipment and 402 represents an access device. The access device distributes signals 402. Signals 402 can be distributed periodically or on demand. Signals 402 may comprise the Master Information Block (MIB) transmitted together with / in the physical broadcast channel (PBCH) and the synchronization signals. The MIB comprises:

[0237] MIB ::= SEQUENCE {

[0238] systemFrameNumber BIT STRING (SIZE (6)), subCarrierSpacingCommon ENUMERATED {scsl5or60, scs30orl20}, ssb-SubcarrierOffset INTEGER (0..15),

[0239] dmrs-TypeA-Position ENUMERATED {pos2, pos3},

[0240] pdcch-ConfigSIBl INTEGER (0..255),

[0241] cellBarred ENUMERATED {barred, notBarred}, intraFreqReselection ENUMERATED {allowed, notAllowed}, spare BIT STRING (SIZE (1))

[0242] }

[0243] MIB and PBCH are transmitted as part of a Synchronization Signal Block, and the access device may transmit multiple SSBs through different beams, allowing the user equipment to determine the preferred beam, and once the preferred beam is obtained, retrieve the MIB, and use the information in the MIB to attempt to retrieve System Information Block 1 (SIB1) that may also be distributed periodically. The UE can use the information in SIB1 to perform the random-access procedure selecting a preamble to indicate its intention to access the cell by means of message 404, e.g., preamble transmission. This message may be used to derive a random-access radio network temporary identifier (RA-RNTI). Upon reception of message 404, access device 402 replies with message 405, e.g., a random access response. This message may include a time advance field to adapt the transmission timing, a value matching the preamble used by wireless device 401, and a grant (communication resources) for the wireless device. The access device also assigns a temporary cell radio network temporary identifier (TC-RNTI). Prior to this message 405, the access device may send a PDCCH DCI message assigning resources (a communication grant). This message may be addressed using the RA-RNTI. Upon reception of message 405, wireless device uses the initial grant received in the previous message and the RA-RNTI to transmit a subsequent message 406, e.g, an RRCSetupRequest or PHY layer. This message may include a Contention Resolution Identifier (CRI). This message may be sent in the PUSCH. As a response, access device replies with message 407, e.g., RRCSetup, that includes / repeats the received CRI confirming that the access device has identified the access device. This message includesa Cell RNTI (C-RNTI). Next, wireless device replies with message 408, e.g., an RRCSetupComplete that includes the RegistrationRequest message, and UE capabilities.

[0244] MIB and PBCH are transmitted as part of a Synchronization Signal Block, and the access device may transmit multiple SSBs through different beams. Multiple SSBs transmitted through multiple beams form an SSB burst. The multiple SSBs in an SSB burst are transmitted sequentially in the first part of a frame. SSB bursts are transmitted periodically, typically every 20 ms, or more.

[0245] Fig. 5 schematically illustrates an access device 500 transmitting four beams, each of them transmitting an SSB, namely 501, 502, 503, and 504. A wireless device 505 can measure the signal strength, i.e., RSRP (Reference Signal Received Power), of the beams. This is illustrated by means of the graph in Fig. 5 where 501', 502', 503', and 504' represent the RSRP of beams 501, 502, 503, and 504, respectively, as measured by wireless device 505. Wireless device 505 can use this information to determine which one of the beams is the preferred beam for further communication, e.g., to perform the random access procedure.

[0246] Fig. 6 further schematically illustrates SSB bursts transmitted periodically. In this case, each SSB burst comprises four SSBs transmitted in the first part / half of every second frame. In this figure, frames are denoted as f, f+1, f+2, f+3,...A frame has a typical duration of 10 ms.

[0247] Resource grid: in a cellular network, such as a 5G network, the resource grid is a structured framework used to allocate and manage communication resources efficiently. It is characterized by a time-frequency matrix where each element, known as a resource element, is defined by its position in both time and frequency domains. The vertical axis represents frequency, segmented into subcarriers, which are spaced at intervals. The subcarrier spacing can vary depending on the deployment scenario, with common spacings being 15 kHz, 30 kHz, 60 kHz, 120 kHz, 240 kHz, and 480 kHz (corresponding to mu equal to 0, 1, 2, 3, 4, and 5, respectively). The horizontal axis of the grid represents time and is divided into frames, subframes, and slots, each frame has a duration of 10 ms and each subframe has a duration of 1 millisecond. Within these subframes, the time is further divided into slots. For mu, there are 2Amu slotsper subframe. Each slot typically spans 14 OFDM symbols. Each resource element in the grid, defined by the intersection of a time symbol and a frequency subcarrier, can carry a small portion of data, control information, or reference signals. These resource elements are grouped into larger units called Resource Blocks (RBs), which span 12 subcarriers in frequency and one slot in time. The allocation of these RBs is dynamically managed.Reflective intelligent surfaces (RIS): may be used as part of the wireless infrastructure or as part of the wireless devices. RIS, often referred to as metasurfaces, are advanced materials engineered with sub-wavelength structures that can manipulate electromagnetic waves in a controlled manner. These surfaces consist of an array of unit cells, each capable of adjusting its electromagnetic response through electronic control, thus enabling dynamic alteration of the wavefront of the incident signal. The wireless device can utilize the RIS to fine-tune the reflection properties of the wireless sensing signal, such as phase, amplitude, and polarization. By dynamically adjusting these parameters, the RIS can enhance signal strength, directivity, and overall signal quality. For instance, the RIS can focus the reflected signal towards the transmitter, significantly improving signal reception. This capability is particularly advantageous in urban environments where obstacles and interference are prevalent. Technical details of the RIS involve the implementation of tunable elements, such as varactor diodes or microelectromechanical systems (MEMS), in each unit cell. These elements allow real-time reconfiguration of the surface's electromagnetic properties in response to control signals from the wireless device. The control signals can be generated based on real-time analysis of the received signal's quality and contextual parameters, ensuring optimal reflection under varying conditions. The RIS can operate in various frequency bands, including sub-6 GHz and millimeter-wave (mmWave) frequencies, making it versatile for different wireless applications. Additionally, the RIS can incorporate sensing capabilities to monitor the environment and further refine the reflection parameters. For example, integrated sensors can detect changes in temperature, humidity, or the presence of obstacles, and adjust the reflection properties accordingly to maintain high signal quality.

[0248] Quality of Service: a wireless system may be used to transport data belonging to different types of applications such as Machine Type Communication (MTC), Critical Machine Type Communication (CMTC), Enhanced Mobile Broadband (EMB), or Fixed Wireless Access (FWA). MTC (e.g., smart meters, tracking,...) requires low bandwidth and non-latency critical, CMTC (e.g., industrial applications) has strict throughput, latency, and availability needs, EMB (VR / AR, 4K UDH, ...) and FWA (e.g., in the home) require high data rate, with low latency, and low end-to-end response time. In wireless network such as 5G the Quality of Service has to accommodate different applications such as EMB, MTC, ultra-reliable low latency communications. QoS is influenced by the entities involved in the communication, UE, RAN, UPF, and DN. Data exchanges between UE and DN are mapped to QoS flows, and each QoS flow is mapped to a 5G QoS Identifier (5QI) in TS 23.501 (Table 5.7.4-1) that describes resource types, priority, packet delay budget, packet error rate, maximum data burst volume. Network is configured to configure RAN and core network interfaces to achieve the requirements of a 5QI. QoSis applied to a data stream from the wireless physical layer to the core network. Between RAN and UPF, QoS is applied in terms of a QoS flow. QoS in the RAN is managed by means of Data Radio Bearers (DRB). A QoS flow on core network side is created by means of a PDU session establishment accept. The mapping between a QoS flow and a DRB is done by means of SDAP configuration in an RRC message (RRCSetup or RRCReconfiguration) The indication or identifier that connects the whole QoS pipe is called QoS flow identifier. Downlink traffic requires mapping IP messages and the QoS pipe, and this is done by the UPF. For each IP message or packet, the UPF checks (by means of a packet QoS assignment / detection rule) the packet information (source / destination / protocol / type of service / ...) and directs the IP packet to a QoS flow. The packet QoS assignment / detection rule is provided by SMF interacting with PCF. In the uplink, the UE performs a similar task by applying QoS rules provided in NAS messages (e.g., PDU session establishment) by the SMF or are pre-configured / derived by the UE.

[0249] Discontinuous reception (DRX) in cellular networks such as 5G is in two types, Idle mode DRX and Connected mode DRX. In Idle mode DRX, the UE wakes up to monitor for paging messages. If no paging message is detected, it sleeps further. In Connected DRX mode, the UE enters in sleep mode periodically and during the sleep period the UE is not required to monitor the Physical Download Control Channel. The access device configures the UE device with C-DRX parameters. Connected DRX approach reduces energy consumption of the device because it does not require monitoring the PDCCH periodically and it also reduces the transmissions of CSI or SRS signals, that also has a positive effect in the network / access devices load. There are two types of DRX cycles, long and short. A long DRX cycle consists of an on period and an off period. The on duration is in terms of milliseconds. The long DRC cycle may be configured or the long DRX cycle and short DRX cycles may be configured. The access device can configure the time (drx-onDurationTimer) during which the UE is awake and goes back to sleep if there is no PDCCH received. The access device can also configure a given drx-LongCycleStartOffiset to start to awake period at a subframe boundary and / or drx-SlotOffset relative to the subframe boundary. If there is activity in an awake period, the UE may remain awake some more time determined by the drx-lnactivityTimer. Furthermore, the access device can configure long DRX cycle together with additional DRX cycle which is shorter than long DRX cycle. Configurable parameters include the drx-ShortCycle (duration of the short cycle) and drx-ShortCycleTImer that determines how many short cycles before the device should apply.

[0250] Data scheduling in a cellular network such as a 5G cellular network may be performed by means of a scheduler wherein the scheduler takes as input information such as measurements of UE / network, buffer status report, QoS requirements, associated radio bearers, or a schedulingrequest. In the downlink, data scheduling may be performed by means of dynamic scheduling and semi persistent scheduling (SPS). In dynamic scheduling, every data exchange in the Physical Downlink Shared Channel (PDSCH) is scheduled by means of a downlink control information (DCI) message in the Physical Downlink Control Channel (PDCCH). In SPS, the scheduling is done by means of an RRC message. In the uplink, scheduling can be performed by means of dynamic scheduling and configured scheduling (CS). In dynamic scheduling each Physical Uplink Shared Channel (PUSCH) is scheduled over DCI. In CS, the PUSCH transmission is scheduled via RRC message. Furthermore, a Scheduling Request message may be sent over the PUCCH (Physical Uplink Control Channel) or in an Uplink Control Information (UCI) in the PUSCH (Physical Uplink Shared Channel). An SR may be sent by a UE device when it has data to transmit. Upon reception, the access device can allocate resources (Uplink Grant by means of the Physical Downlink Control Channel. Upon resource allocation, the UE device can transmit data in the Physical Uplink Shared Channel.

[0251] Wireless sensing and integrated wireless sensing and communication: wireless systems are evolving to include wireless sensing capabilities. These wireless sensing capabilities may be implemented e.g. by a radar functionality in wireless communication involving one or more access devices (e.g., base stations (BS)) and / or one or more terminal devices (e.g., UEs). As an example, Frequency Modulated Continuous Wave (FMCW) mmWave radar systems can measure range, velocity, and angle of arrival (if two receivers are available) of objects in the scene which reflect radio waves. Such radar systems emit a chirp signal, e.g., a sine wave that increases in frequency over time. The chirp signal (e.g., a continuous wave pulse) has a bandwidth and a frequency increase rate. Generally, a continuous series of such chirps are emitted. The transmitted and received analogue chirp signals are mixed to generate an intermediate frequency (IF) signal which corresponds to the difference in frequencies of the two signals (outbound and inbound) and whose output phase corresponds to the difference in the phases of the two signals. Each surface of a scene or environment will therefore produce a constant frequency IF signal whose frequency relates to the distance to the surface (i.e., a first distance from the transmitter of the chirp signal to the surface plus a second distance from the surface to the receiver of the chirp signal). To resolve two surfaces at different distances, the two IF signals can be frequency resolved. A longer time window of the IF signal results in greater resolution. As the chirp time is related to its bandwidth (with constant chirp frequency change) the resolution of the radar is related to the chirp bandwidth. The IF signal may then be band pass filtered (to remove signals below some minimal range and frequencies above the maximum frequency for a subsequent analogue-to-digital converter (ADC)) and digitized prior to further processing. The upper frequency sensing range of the bandpass filter and ADC sets the maximum range that can be detected (i.e., IF frequencies increase with range). To detect vibrations,the phase of the IF signal is important, since the phase (i.e., the difference in phases of the transmitted and received chirp signals) is a sensitive measure of small changes in the distance of a surface. Small distance changes can be detected in the phase signal but may be indiscernible in the frequency signal. Moreover, phase difference measures between two consecutive chirp signals can be used to determine the velocity of the surface. As an example, a fast Fourier transform (FFT) processing can be performed across multiple chirp signals to enable separation of objects with the same range but moving at different velocities. A Fourier transform converts a signal from a space or time domain into the frequency domain. In the frequency domain the signal is represented by a weighted sum of sine and cosine waves. A discrete digital signal with N samples can be represented exactly by a sum of N waves. FFT provides a faster way of computing a discrete Fourier transform by using the symmetry and repetition of waves to combine samples and reuse partial results. This method can save a huge amount of processing time, especially with real-world signals that can have many thousands or even millions of samples. As a further example, angle estimation can be performed by using the phase difference between the received chirp signal at two separated receivers.

[0252] As another option, a channel state information (CSI) can be used, which is a measure of the phases and amplitudes of many frequencies detected at a receiver, thereby forming a complex 'map' of the radio environment, including effects of objects within that environment. CSI characterizes how wireless signals propagate from the transmitter to the receiver at certain carrier frequencies. CSI amplitude and phase are impacted by multi-path effects including amplitude attenuation and phase shift, e.g., by the displacements and movements of the transmitter, receiver, and surrounding objects and humans. In other words, CSI captures the wireless characteristics of the nearby environment. These characteristics, assisted by mathematical modeling or machine learning algorithms, can be used for different sensing applications. A radio channel may be divided into multiple subcarriers, as is done e.g. in 5G communication systems (using e.g. orthogonal frequency division multiplexing (OFDM)). To measure CSI, the transmitter may send long training symbols (LTFs), which contain pre-defined symbols for each subcarrier, e.g., in a packet preamble. When those LTFs are received, the receiver can estimate a CSI matrix using the received signals and the original LTFs. For each subcarrier, the channel can be modeled by y = Hx + n, where y is the received signal, x is the transmitted signal, H is the CSI matrix, and n is the noise vector. The receiver estimates the CSI matrix H using a pre-defined signal x and the received signal y after signal processing such as removing cyclic prefix, de-mapping and demodulation. The estimated CSI is then a three-dimensional matrix of complex values and this matrix represents an 'image' of the radio environment at that time. By processing a time series of such 'images' information on movements, locations and vibrations of objects can be extracted. Such aprocessing of a CSI matrix can be used for vital signs monitoring, presence detection, and human movement recognition. As an example, neural network like recognition techniques can be used to process the CSI matrix to perform such kinds of recognition.

[0253] It is noted that systems using channel state information (CSI) are somehow related to systems with FMCW mmWave radar. In a CSI-based system, the input signal X may be defined and the receiver may use the received signal Y to obtain H, i.e., as H = (Y - N) / X . In a FMCW mmWave radar, the transmitted signal Chirp X may also be predefined, and the receiver may uses the received signal Y to obtain a transfer function as H = Y / X . This last step is in fact somehow related to multiplying the locally computed chirp signal and the received chirp signal and applying a bandpass filter. According to various embodiments in this invention, the above-described wireless sensing techniques are implemented in a mobile communication system (e.g. 5G or 6G or other cellular or WiFi communication systems), while the functional coexistence of radar and communication operating in the same frequency bands is configured to avoid interference bandwidths. Thereby, radio sensing can be integrated into large-scale mobile networks to create perceptive mobile networks.

[0254] As another example, the sensing signal may consist of a number of pulses sent, e.g., at specific frequencies and timing (sensing signal parameter information) by a sensing transmitter. The sensing receiver may include a number of bandpass filters that allow identifying the sensing signal parameter information, e.g., timing and frequency of the received pulses. In particular, if the transmitter determines a given pseudo-random sequence of frequency / timing pulses and beams it, e.g., by means of beamforming, in a specific direction, and if the transmitter communicates to the receiver the timing / frequency, in general, the sensing signal parameter information, of the transmitted sensing signal, the receiver can use its bandpass filters to identify the reception of the same transmitted pulses, i.e., sensing signal, based on the received sensing signal parameter information.

[0255] The wireless sensing signal may be part of the synchronization signal block. For instance, the wireless sensing signal may be a reference signal included in the primary synchronization signal or in the secondary synchronization signal. It may consist of a number of reference signals and / or it may be a wide band signal. This wireless sensing signal can allow the access devices to determine the presence of a wireless device. The wireless device may also use this wireless sensing signal to determine the access device that is more suitable to (re-)select.

[0256] Wireless local area network technologies such as Wi-Fi allow devices to connect to the Internet or to each other without using cables. Wi-Fi is based on radio waves that are transmitted and received by a device called a wireless access point (AP). The AP acts as a hub that connects Wi-Fi enabled devices, such as laptops, smartphones, tablets, smart TVs, etc., to a wired network, such as a local area network (LAN) or the Internet.

[0257] The term Wi-Fi is a trademark of the Wi-Fi Alliance, an industry association that certifies products that comply with the IEEE 802.11 standards for wireless local area networks (WLANs). These standards define the physical and data link layers of the communication protocol, such as the frequency bands, modulation schemes, encryption methods, authentication mechanisms, and data rates used by Wi-Fi devices. The most common Wi-Fi standards are 802.11a, 802.11b, 802.11g, 802. lln, 802.11ac, and 802.11ax, which operate in different frequency bands (2.4 GHz, 5 GHz, or both) and offer different levels of performance and compatibility.

[0258] To use Wi-Fi, a device needs to have a wireless network interface card (NIC) that can send and receive radio signals. The NIC scans the available wireless channels and detects the presence of nearby APs. The device then selects an AP to connect to, based on factors such as signal strength, security settings, and network name (SSID). The device and the AP exchange information, such as the MAC address, IP address, encryption key, and password, to establish a connection. This process is called association. After the connection is established, the device can communicate with the AP and other devices on the same network, or access the Internet through the AP.

[0259] IEEE 802. lln (Wi-Fi 4) provided new features such as MIMO and frame aggregation to increase throughput. IEEE 802.11ac (Wi-Fi 5) introduced wider bandwidth and MU-MIMO. IEEE 802.11 ax (Wi-Fi-6) included OFDMA and BSS color or spatial reuse to use spectrum resources more efficiently. IEEE 802.11 ah introduced target wake time (TWT) to support low power loT applications by allowing STAs to go into sleep when not in a wake period after negotiation with AP. IEEE 802.11be (Wi-Fi 7) aims at improving throughput and latency operating in unlicensed bands between 1GHz and 7.125 GHz. Wi-Fi 7 increases bandwidths up to 320 MHz, 4096 QAM modulation, and supporting up to 16 spatial streams in MU-MIMO with an improved sounding procedure. Wi-FI 7 also enables multiple resource units to be assigned to a single device. Furthermore, it includes an enhanced preamble with a universal SIG filed indicating the PHY version. It also extends the negotiated ack buffer size to 1024 bits.lt also enables multilink operation (MLO) enabling multiple links between a station and an access point, for instance an AP can have two radios 2.4 and 5 GHz and use both of them for simultaneous transmission and / or reception with a multi-link capable device (MLD) capable station. Wi-Fi 7 also includes a restricted TWT providing predictable latency by assigning STAs to different rTWT types and making sure that other STAs do not transmit if they do not belong to a given rTWT type. Wi-Fi 7 also include multi-AP coordination performing, e.g., coordinated transmission, beamforming, or joint transmission.For instance, in references to Fig. 1, devices 100, 101 and 102 can be Wi-FI access points and device 106 can be a wireless station. Station 106 and access point 101 are MLD and communicate with two links 126. Device 102 is a cellular capable residential gateway.

[0260] Section: this invention

[0261] Embodiments of this invention are illustrated in the context of a procedure to access the network and / or move through the network. In particular, a procedure used by a wireless device to select a cell, or trigger the selection of a cell, or perform cell re-selection, or trigger cell re-selection, or move to another cell and further perform or receive some wireless services such as communication and / or wireless sensing, e.g., in an integrated communication and sensing (ISAC).

[0262] In the following a legacy example illustrating the problems of existing procedures is provided. This example focuses on the cell selection procedure in 5G involves a series of steps designed to ensure that a user equipment (UE) connects to the most suitable cell within the 5G network. Initially, the UE may scan available frequencies to detect potential cells by measuring the received signal power and quality of the synchronization signals. This process includes both primary synchronization signal (PSS) and secondary synchronization signal (SSS) detection, allowing the UE to determine the physical cell identity (PCI). Subsequently, the UE reads the master information block (MIB) and system information blocks (SIBs) from the broadcast channel (BCH), which provide essential information such as the system frame number (SFN), subcarrier spacing, and network configuration. The UE then evaluates the candidate cells based on criteria such as the received signal strength indicator (RSSI), reference signal received power (RSRP), and reference signal received quality (RSRQ). It prioritizes cells, typically starting with the ones on its home public land mobile network (HPLMN) or equivalent public land mobile network (EPLMN), but also considers cells from visited public land mobile networks (VPLMNs) if necessary. The UE employs the cell selection criteria defined in 3GPP TS 38.304, which include S-criteria (signal level threshold) and Q-criteria (signal quality threshold), ensuring that the chosen cell satisfies the minimum signal strength and quality requirements. If the UE identifies multiple suitable cells, it selects the one with the highest RSRP or RSRQ. The UE also considers non-standalone (NSA) and standalone (SA) deployment scenarios, where NSA involves cooperation with an LTE anchor cell, requiring additional measurements and decisions. After selecting a suitable cell, the UE performs random access procedures (RACH) to establish initial access and synchronize uplink timing, which includes sending a random-access preamble and receiving a randomaccess response (RAR) from the base station. If the connection is successful, the UE transitions to connected mode (RRC_CONNECTED) and begins regular communication. In cases where the cellselection fails or the UE loses connection, it reverts to cell (re-)selection processes, periodically monitoring the signal environment to find a better cell. The main problem of this process is that each cell has to distribute synchronization signals. The UE (i.e., wireless device) selects a cell based on them, and performs the random-access procedure with the selected cell. This is a problem because the cell that is selected at an initial time may not be the best cell sometime later, e.g., when the wireless device is moving. This is illustrated by means of Fig. 10 wherein devices 100-1 and 100-2 represent two access devices, e.g., two base stations, device 101 represents a wireless device such as a user equipment and 102 represents the movement direction of the wireless device. If the wireless device performs a cell selection procedure as currently specified in 5G, the wireless device may be likely to select access device 100-1 since it is the closest one at the time of the selection, and thus, the received signal strength is the highest one. However, at a later point of time, access device 100-2 may be the best one because wireless device 101 is moving towards it. Thus, it may be advantageous to not select 100-1 but 100-2.

[0263] In some scenarios, a UE may send a signal, e.g., a reference signal that may be detected by an access device and may trigger the transmission of pilot signals such as SSBs. This signal may be indicative of the request for a pilot signal. A UE may transmit this signal when it is trying to or wishes to access the network. Communication resources, e.g., a frequency band (e.g., certain frequency resources) may be reserved for the transmission of this signal, e.g., a frequency band that is reserved for this purpose. Access devices may monitor these communication resources. The signal may be a common signal, e.g., including a well-known preamble and an identifier indicative of the request for on-demand pilot signals. It may also include UE specific fields such as e.g. a random identifier RID randomly generated by the UE with the purpose to identify itself in this initial communication or an ID indicative of its capabilities or the type of device (e.g. eMBB, XR, industrial loT, massive loT etc.), or a specific random access related information proposed to the access device for contention free random access. Multiple access devices may receive the UE signal, and may coordinate with each other to determine which of the access devices is best located to provide access to the device. This may be determined based on, e.g., the time of arrival and measured signal strength of the received UE signal at those multiple access devices since the time of arrival / measured signal strength allow the multiple access device to determine the rough location of the UE, and from there, determine which of the multiple access devices may have the best connection, or the type of device (e.g. eMBB, XR, industrial loT, massive loT etc.) to determine the most suitable access device for the specific UE device type, or the UE history information (UHI) and the access device may predict the next mostly likely cell according to AI / ML. The multiple access device may interact with each other via acommunication interface (e.g., Xn interface) or via the core network, exchanging, e.g., the direction from which the signal was received and / or received power or time of arrival. The access device(s) may also be able to determine the (rough) location of the UE based on said signal so that an on-demand pilot signal may be better directed towards the location of the UE. Once they have determined the most suitable access device, one or more selected access devices may transmit the on-demand pilot signal towards the UE. This may be done using one or a few SSBs covering the rough location of the UE. The on-demand pilot signal may be generic or may include some fields included in the UE transmitted signal such as RID so that the UE can discern the pilot signals to be used to select the right beam / access device, e.g., a UE should only use pilot signals including its previously transmitted RID.

[0264] Section: proposed concept

[0265] Access device selection, re-selection, and mobility procedures in modern cellular systems are becoming increasingly complex due to dense deployments, multi-beam operation, distributed architectures, and cell-free or multi-TRP configurations. Conventional approaches typically bind a wireless device to a single cell or access point based on limited measurements, which can result in sub-optimal connectivity, unnecessary handovers, increased signaling overhead, and inefficient energy usage at both the device and network sides. These limitations are exacerbated when access devices comprise multiple functional entities, such as TRPs, beams, or distributed units, where the notion of a "best cell" is no longer sufficient. The embodiments described herein address this problem by introducing a flexible access-device selection concept in which a wireless device transmits a first message to a group of access devices and receives, in response, an indication of one or more selected access devices best suited to provide service. The technical effect is improved connectivity quality, more reliable and adaptive mobility, reduced energy consumption, and enhanced system-level efficiency by enabling informed, distributed, and context-aware selection of access devices for communication and / or sensing.

[0266] In general, this invention proposes embodiments that facilitate a cell selection, cell reselection, mobility between access device, etc. in such a way that the access device a wireless device connects to provides the best possible connection while ensuring the overall system reliability and energy consumption is reduced.

[0267] In accordance with a definition of this invention, a wireless device may select an access device e.g. a base station or access device or access point. However, this may also refer to a transmission reception point (TRP), or a communication beam, or a distributed unit in a cell. Forinstance, a TRP may be used for transmission or reception and a cell may comprise multiple TRPs, for instance, in the context of a so called cell-free system or a single cell multiple carrier cell. In this example, it is needed to identify the best TRP(s) for communication. Similarly, a cell may use multiple beams for communication, e.g., covering different areas, and in this example, it is also needed to identify the best beam(s) for communication. Similarly, an access device may comprise a central unit (CU) and one or more distributed units (DUs), wherein the DUs implement the lowest protocol layers (e.g., RLC, MAC, and PHY) of an access device and the CU implements the highest protocol layers of an access device (e.g., RRC, PDCP layer). In this example, it is needed to identify / use the best DUs for communication.

[0268] In an embodiment of the invention that may be combined with other embodiments or used independently, it is proposed a method for access device selection comprising:

[0269] transmitting, by a wireless device, at least one first message, to a first group of access devices,

[0270] receiving, by the wireless device, a second message from a second group of access devices indicating at least a selected access device,

[0271] performing, by the wireless device, a data exchange and / or wireless sensing with and / or through at least a selected access device in the second group of access devices.

[0272] The first group of access device(s) (that may comprise a single access device, or two or more access devices) may interact with each other and / or access devices in the second group of access devices may interact with each other and / or perform measurements to determine the selected access devices.

[0273] In an example, the first group of access devices comprises the second group of access devices. This may be the case when all devices receiving the first message may provide an answer. The second group of access devices may be the devices that are most suitable to provide service (e.g., communication or sensing) to the wireless device. For instance, in the first group G1 we may have access devices with identifiers {1, 2, 3}. In this first case, the access devices in the second group may be access devices with identifiers, e.g., {1, 2}.

[0274] In an example, the second group of access devices is not contained in the first group of access devices. This is the case when devices providing the answer belong to a different type of access devices. For instance, in the first group G1 we may have access devices with identifiers {1, 2, 3}, and in the second group G2 we may have access devices with identifiers, e.g., {2, 4}. In this case, G2 is partly contained in Gl. In another case, the second group G2 we may have access devices with identifiers, e.g., {4, 5}. In this case, G2 is not contained in Gl.In an example, the second message from the second group of access devices may indicate at least a selected access device and may be transmitted by one of selected access device, or by any other device in the second group of access devices.

[0275] In an example, the wireless device may transmit a first message (e.g., a preamble) to a first access device, the wireless device may receive the second message (e.g., a random-access response) from a second access device, and the wireless device may perform the data exchange (e.g., transmit message 3 in the random access procedure) through the selected access device.

[0276] In an example, the first message may be one of:

[0277] - a wireless sensing signal transmitted by the wireless device,

[0278] - a random-access preamble, e.g. used as wake-up signal to trigger the transmission of on-demand SSBs or an on-demand SIB1 or to trigger a random access procedure,

[0279] - message 3 in the random access procedure,

[0280] - the first message in a RACH-less handover,

[0281] - the first message sent by a wireless device when performing a handover towards a target access device.

[0282] In an example, the second group of access devices may comprise a single access device, and the single access device is the selected access device.

[0283] In an example, the second group of access devices may comprise a first access device in the first group of access devices and a selected access device.

[0284] This proposed concept provides a communication procedure that allows selecting a suitable (selected) access device, e.g., during initial access.

[0285] Section: exemplary procedures when the wireless device, in particular, is in IDLE / INACTIVE state Initial access and mobility support in IDLE or INACTIVE states are particularly challenging in dense cellular deployments with multiple access devices or TRPs, where continuously broadcasting synchronization signals and system information leads to excessive energy consumption and signaling overhead. Conventional procedures rely on periodic transmission of SSBs and SIB1, forcing wireless devices to perform repeated scanning and delaying access, while networks expend resources even when no devices require service. These inefficiencies are exacerbated when a wireless device must evaluate multiple candidate access devices before initiating random access. The embodiments described herein address this problem by introducing request-driven, multi-step access procedures in which a wireless device explicitly triggers the transmission of on-demand synchronization signals, system information, and random-access responses using differentiated first messages while in IDLE or INACTIVE state. The technical effect is reduced access latency, lower energyconsumption at both the network and device sides, and more efficient access-device selection, by ensuring that signaling is generated only when needed and only by relevant access devices, while still enabling robust initial access in multi-TRP environments.

[0286] In some cases, there can be multiple first messages, e.g., a first first message, and a second first message, and a third first message. For clarity, the first messages may considered in this embodiment as request. For instance, a first first message (or first request) may be a preamble (wakeup signal) reserved to trigger on demand SSBs (OD SSBs). For instance, a second first message (or second request) may be a preamble (wake-up signal) reserved to trigger the transmission of on demand SI Bl. For instance, a third first message (third request) may be a message (preamble) reserved to perform the random access. There can be a first configuration for multiple first messages / requests, or multiple first configurations, each for a first message / corresponding request.

[0287] For instance, a random-access procedure may be as follows comprising three message exchanges.

[0288] First message / Request Second message / Response

[0289] First first message: Preamble / wake-up signal First second message: On-demand SSB Second first message: Preamble / wake-up signal Second second message: On-demand SI Bl Third first message: Preamble / wake-up signal Third second message: RAR

[0290] The first request may be used to trigger the distribution of on-demand SSBs by a first second set of access devices, e.g., the access devices addressed and / or receiving the first request. Once the on-demand SSBs are received, the wireless device may send a second request to a second second set of access devices, e.g., a preamble / wake-up signal to trigger the on-demand distribution of SIB1 by one or more access devices. Finally, the wireless device may select an access device, and send the third request, e.g., a preamble to access an access device. It is to be noted that the first request may be used to address a single access device, or multiple access devices. Similarly, for the second request. It may be, e.g., devices in a certain area.

[0291] For instance, a random-access procedure may be comprising two message exchanges in which on-demand SIB1 and RAR are combined in a single message. Combining on-demand SIB1 and RAR messages can be useful to reduce the latency of the connection setup in the random-access procedure. It can be useful, in particular, if SIB1 is not distributed in a periodic manner, or very infrequently. It is to be noted that the first request, e.g., to the first group of access devices, below may trigger one or multiple access devices, in the second group of access devices, to transmit on-demand SSBs so that the wireless device may be able to assess its best options (i.e., the best access devices). Similarly, the second request may be addressed to one or more access devices (e.g., in a second first group of access devices) so that one or more access devices (e.g., in a second second group of access devices) may be able to transmit SIB1 / RAR messages, e.g., depending on the network choices.

[0292]

[0293] It is to be noted that the transmission of the requests may be towards (a first) access device(s) in a first group of access device, and the second messages / responses may be from a second group of access devices. In different steps of above procedures containing several first messages (or requests) and several second messages (responses), the corresponding receiving (first group of access devices) and transmitting (second group of access devices) access devices may be different.

[0294] For instance, wireless device may transmit the "first first message" to a "first first group" of access devices. A "first second group" of access device may reply with a "first second message", e.g., on-demand SSBs to facilitate its synchronization. The wireless device may then transmit the "second first message" to the "second first group" of access device. The wireless device receive the "second second message" from the "second second group" of access devices

[0295] These proposed procedures describe how a wireless device can trigger the transmission of on-demand SSBs / on-demand SIB1 / RAN, e.g., during initial access in a cellular system comprising multiple TRPs when in IDLE / INACTIVE state.

[0296] Section: burst of first messages in directional manner

[0297] Initial access and access-device selection in directional and beam-based wireless systems present significant challenges, particularly in dense deployments where multiple access devices and beams coexist and where rapid and reliable discovery is required. Conventional procedures often rely on either omnidirectional transmissions, which are robust but inefficient and provide limited beam information, or purely directional transmissions, which may miss candidate access devices due to misalignment or blockage. This trade-off can lead to delayed access, sub-optimal access-device selection, increased signaling overhead, and inefficient use of radio resources, especially in multi-TRP or cell-free scenarios. The embodiments described herein address these issues by introducing burst-based transmission of first messages using a combination of omnidirectional anddirectional beams, potentially with varying beam widths and controlled repetition patterns. By enabling nearby access devices to evaluate reception quality across multiple directions within a structured first-message burst, the network can more accurately identify suitable access devices and beam pairs. The technical effect is faster and more reliable access-device selection, improved beam alignment, reduced access latency, and enhanced overall system efficiency.

[0298] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may transmit some or all of the first messages (e.g., a preamble, wake up signal) in an omnidirectional manner, and / or in a directional manner.

[0299] In an example, a wireless device may transmit X first messages in directional manner by using multiple beams.

[0300] In an example, a wireless device may transmit in a first message burst a first message in an omnidirectional manner and a first message in a directional manner.

[0301] In an example, a wireless device may transmit in a first message burst a first message in a directional manner by using a beam of a first width and another first message in a directional manner using a beam of a second width, e.g., the first width may be wider than the first width.

[0302] In an example, a set of first messages transmitted in different directions by using multiple beams may be denoted as a first message burst. Each first message in a first message burst may include an indication of the number X of first messages that are included in the first message burst. Each first message may include an identifier indicating the position of the first message in the first message burst. The first messages in a first message burst may be time-multiplexed, i.e., the first first message is sent first through a first beam, the second first message is sent afterwards through a second beam, the third first message is sent afterwards through a third beam, and so on.

[0303] In an example, multiple first message bursts may be transmitted. This may be done in a periodic or aperiodic manner. Transmission parameters may be indicated in the first message(s), implicitly or explicitly. For example, the periodicity may be indicated, or the next (last) time (or times) the first message burst was transmitted. This may allow a receiving access device to monitor multiple repetitions of the first message burst. Periodic transmission may make the reception simpler. Aperiodic transmission may make the transmission / reception more robust, against, to interferences and / or collisions.

[0304] In an example, the transmission parameters of the first message burst, e.g., which type of beams, how many beams, how many first messages, may be determined by means of a configuration, e.g., the first configuration. This may be useful so that access devices monitoring the first messages transmitted by the wireless device can better determine how to communicate with the wireless device.In an example, the choice to transmit omnidirectional first message or directional first messages may be based on the requirements / context of the wireless device. For instance, if the wireless device needs to setup a communication faster, directional first messages in a first message burst may be preferred since it allows the access devices to acquire beamforming information about the wireless device.

[0305] In an example, the transmission of the first message burst may be part of a random access procedure towards a specific access device. In an example, the transmission of the first message burst may be part of a (random) access procedure towards the network so that one or more selected access devices can be determined.

[0306] In an example, access devices around (i.e., close to) the wireless device may monitor the first messages in the first message burst. Each of the access devices may determine which one(s) of the first messages is(are) received how well / best, e.g., in terms of signal strength. This information may be used by the network (e.g., access devices in a distributed manner or an entity managing the access devices) to select one or more selected access devices to perform a wireless procedure, e.g., further communication / data transfer / wireless sensing.

[0307] For instance, Fig. 14 depicts a wireless device 1400 and multiple access devices 1400-1, 1400-2, 1400-3. Wireless device 1400 transmits a first message burst comprising, in this example, four first messages 1405-1, 1405-2, 1405-3, and 1405-4 that may be transmitted time-multiplexed. The first messages may be, e.g., preambles. Access devices receiving the first message burst may determine which of the beams used by the wireless device may be most suitable for further communication. For instance, access device 1400-1 may determine that the best received first message is the one transmitted through beam 1405-1 (and received through 1401-1-1), while access device 1400-2 may determine that the best first message is the one transmitted through beam 1405-2 (and received through 1401-2-1). Access device 1400-3 may receive both first messages transmitted through beams 1405-1 and 1405-2 equally well, but worse than the other access devices. Fig. 14 also includes entity 1402 that may act as a controller of access devices 1400-1, 1400-2, and 1400-3, e.g., as in a cell-free cellular system.

[0308] The usage of a burst of first messages in this embodiment allows for an improved selection of the selected access device.

[0309] Section: network energy savings (NES) in 5G NR R19 or 6G

[0310] Network Energy Savings (NES) mechanisms in 5G NR Release 19 and future 6G systems aim to significantly reduce infrastructure energy consumption by minimizing always-on signaling, such as periodic transmission of SSBs and system information, particularly in low-traffic or idle scenarios.However, the introduction of wake-up signals (WUS) and on-demand SIB1 distribution creates new challenges when multiple NES cells share common configurations, frequencies, or identifiers. In such cases, a wireless device may need to efficiently trigger system information from one or more candidate access devices while avoiding ambiguity in cell identification, unnecessary signaling, or unintended activation of network resources. The embodiments described herein address these challenges by enabling flexible, multi-cell-aware WUS transmission, selective addressing of access devices, and robust mechanisms for unambiguous association between received on-demand system information and the corresponding NES cell. The technical effect includes reduced network energy consumption, faster and more reliable initial access or handover decisions, improved scalability of NES deployments, and enhanced robustness against cell misidentification, while preserving compatibility with shared configurations and dense multi-cell scenarios.

[0311] In a particular scenario related to Network Energy Savings, e.g., in 5G NR R19 or 6G, a wake-up signal (WUS) configuration (that may be part of the first configuration) for on-demand SIB1 distribution can be associated with a list of NES cells if the whole WUS configuration is the same. In this scenario, a wireless device may monitor the SSBs of one or more access devices (denoted in this embodiment as NES cells), the wireless device may select the most suitable access device (e.g., based on the SSB RSRP) and may trigger the distribution of the OD-SIB1 from that selected cell by using the common WUS configuration (i.e., sending the WUS towards the access device selected by the wireless device). As illustrated by embodiments in this invention, it would be advantageous if the wireless device can send the WUS towards two or more access devices, and the access devices reply with the second message through the most suitable access device (the selected access device). The wireless device may have received the first configuration (e.g., common WUS configuration) via a SIB message, e.g., broadcasted by an anchor cell, e.g., an anchor cell that may be covering multiple NES cells or an access device in charge of managing (the access to) other access devices.

[0312] In a related embodiment of the invention that may be combined with other embodiments or used independently, the first configuration may contain a (WUS) configuration common for multiple access devices (e.g., NES cells). This first configuration may contain a common PRACH configuration index (the PRACH transmission time / frequency), in other words, prach-Configurationlndex provides a pointer to a table (e.g., defined by RANI) on the time / frequency resources for sending Msgl / preambles (also known as PRACH), in other words, the available set of PRACH occasions for the transmission of the Random Access Preamble for Msgl. These are applicable to the MSGA PRACH if the PRACH occasions are shared between 2-step and 4-step RA types.

[0313] In another embodiment of the invention that may be combined with other embodiments or used independently, each access device (NES cell) may have a different PRACHconfiguration index (which implies different RACH Occasions and PRACH channels, so that the access devices do not have overlapping PRACH channels.

[0314] In an embodiment of the invention that may be combined with other embodiments or used independently, two or more access devices in a second group of access devices each may reply with one or more second messages, and the wireless device may select one of the two or more access devices for further communication after the reception of the plurality of second messages. For instance, in above NES scenario, two NES cells receiving the WUS may each respond with an OD-SIB1 message. This can be understood as there are two possible selected access devices. The wireless device may then decide at this point of time which of the access devices, in this case, which NES cell, it selects.

[0315] In an embodiment of the invention that may be combined with other embodiments or used independently, when the wireless device sends the first message and this first message may be addressed up to N access devices (in a first group of access devices) but the wireless device only wants to address a subset of them, the wireless device may select the first message in such a way that it indicates the addressed access devices. For instance, in above NES scenario, 4 access devices (e.g., #0, #1, #2, #3) may share a common WUS configuration and the wireless device may have determined based on SSB RSRP measurements that two access devices (e.g., #1, #3) are potentially good candidates. Then, in an example, the first message may, e.g., include an identifier, e.g., a bitmask (0101), indicating the addressed access devices requiring the distribution of the second message. In an example, the preamble selected may indicate the addressed access devices. For instance, the WUS configuration may include a number of preambles (e.g., can also be related to a different PRACH configuration index), each preamble may indicate the target access devices, e.g.,

[0316] preamble #0 may indicate only access device #0

[0317] preamble #1 may indicate only access device #1

[0318] preamble #4 may indicate access devices #0, and #1

[0319] Preamble #5 may indicate access devices #0, and #2

[0320] Then the preamble selected by the wireless device may indicate the access devices required (to evaluate whether) to transmit the second message (in above NES scenario), the on-demand (OD-) SIB1.In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may send multiple first messages, each corresponding to the SSB pattern of one NES serving cell. The wireless device may determine which SSB patterns are relevant to its communication needs and send separate first messages accordingly. This approach may allow the wireless device to target specific cells that have the most suitable SSB configurations for efficient communication.

[0321] In an embodiment of the invention that may be combined with other embodiments or used independently, the resources for monitoring may be common for all cells (access devices). The cells may have pre-agreed MIB configurations or identical SSB patterns to facilitate the use of this functionality. The wireless device may transmit the first message using these common resources, ensuring that all cells can monitor and respond appropriately. This standardized approach may simplify the communication process and improve coordination among the cells.

[0322] In an embodiment of the invention that may be combined with other embodiments or used independently, the first message may be digitally beamformed to be received by more than one access device using different precoders. The wireless device may employ advanced beamforming techniques to direct the first message toward multiple access devices, optimizing the signal quality and reliability of the communication. This method may increase the likelihood of successful reception and response from the access devices, enhancing overall network performance.

[0323] In wireless communication systems, the transmission of WUS (Wake-Up Signal) allows the identification of NES Cells during, e.g., initial access or handover, by incorporating the PhysCell ID (Physical Cell Identifier) or using a WUS configuration that is specific to a given cell or several cells. Conversely, OD-SIB1 (On-Demand System Information Block Type 1) (transmitted after reception of the WUS) contains Cell Identity, a globally unique identifier for a cell, but it omits the PhyCelllD information. This discrepancy presents a challenge when the wireless devices (user equipment (UE)) receives OD-SIB1 from multiple NES Cells, as it cannot associate the received OD-SIB1 with the correct NES Cell without the PhysCell ID. This may happen when multiple NES cells share the same frequency. This may also happen when multiple NES cells in different frequencies share the same WUS configuration, and the same WUS configuration is used with NES cells that share the same PCI (e.g., since the PCI is a relatively short identifier or the access devices are part of a single cell-free system). To address this issue, there are different potential solutions which may be employed to ensure correct cell association.

[0324] In an embodiment of the invention that may be combined with other embodiments or used independently, a solution to the problem involves adding an identifier, such as a PhysCell ID information in the Random Access Response (RAR) or directly within the OD-SIB1 itself. By includingan identifier such as the PhyCelllD in OD-SIB1, the UE may be able to accurately determine the corresponding NES Cell, thus resolving the ambiguity. This method may enhance the reliability of the cell identification process, ensuring seamless handover and access procedures. Moreover, incorporating PhysCelllD in the OD-SIB1 may provide a straightforward approach to align the identification mechanisms between WUS and OD-SIB1. Other identifiers could be considered, i.e., may be applied.

[0325] In an embodiment of the invention that may be combined with other embodiments or used independently, another potential solution lies in ensuring that no two NES Cells sharing the same WUS configuration have the same Physical Cell Identifier (PCI). By assigning unique PCIs to NES Cells with identical WUS configurations, the UE may be able to distinguish between the cells even when the PhysCelllD is missing in the OD-SIB1. This approach may involve a careful coordination mechanism to guarantee PCI uniqueness across the network, potentially simplifying the cell association process for the UE. Consequently, the avoidance of duplicate PCIs within the same WUS configuration may eliminate the issue of misidentification.

[0326] In an embodiment of the invention that may be combined with other embodiments or used independently, a third solution may involve including an identifier such as a Cell Identity in the WUS next to the PCI, effectively combining both identifiers within the same signal (and for completeness, next to the ARFCN-ValueNR value). The inclusion of Cel I Identity in the WUS may enable the UE to accurately associate the received OD-SIB1 with the correct NES Cell by cross-referencing the Cellldentity and PCI information. This method may offer an enhanced level of precision in cell identification, thereby improving the efficiency of network operations. Integrating Cellldentity in the WUS may provide a robust framework for facilitating UE access and handover procedures while maintaining consistency across communication signals.

[0327] In an embodiment of the invention that may be combined with other embodiments or used independently, a fourth solution may involve allocating different frequencies to NES Cells that share the same WUS configuration and PCI. This may require a technical specification requiring that any two cells sharing the same WUS configuration and having the same PhysCelllD have a different frequency (a different ARFCN-ValueNR value). By ensuring that cells with identical WUS configurations and PCIs operate on separate frequencies, the UE may be able to distinguish between the cells during the identification process. This method may mitigate the issue of misidentification, as the frequency differentiation provides an additional layer of distinction between cells. This approach may require careful frequency planning and coordination within the network but can significantly enhance the reliability of cell association procedures.Section: contents of the first message

[0328] The content and structure of initial access signaling play a critical role in enabling efficient access-device selection and random-access procedures in dense, distributed, and mobility-aware cellular networks. Conventional systems typically treat the initial access message as a simple trigger for a single target access device, with limited capability to convey context, address multiple candidates, or support cooperative decision-making among access devices. This can lead to sub-optimal access-device selection, increased latency, unnecessary signaling, and inefficient energy usage, particularly when a wireless device is in IDLE or INACTIVE state and only loosely synchronized. The embodiments described herein address these limitations by enriching the contents of a first message transmitted by the wireless device, allowing it to implicitly or explicitly address groups of access devices, trigger on-demand synchronization signaling, and convey assistance information such as mobility context, service requirements, and quality-of-service constraints. The technical effect is a more informed, cooperative, and context-aware access procedure that enables the network to identify suitable access devices before initiating random access, resulting in faster access, improved mobility robustness, better alignment with service needs, and reduced signaling and energy consumption.

[0329] In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may send the first message to one or more first access devices. Upon reception of the first message by the first access device, in general, the one or more first access device(s), may consider the first message as an indication (implicitly or explicitly) to request on-demand SSBs and start to transmit SSBs at one or more frequencies (implicitly indicated by the first message or explicitly indicated in the first message) for a period of time. After sending the first message, the wireless device may start to detect the SSBs at the implicitly or explicitly indicated frequenc(ies) and time locations.

[0330] The first message may be a preamble, e.g., a preamble out of a few preambles reserved to trigger on demand SSBs (OD SSBs) and / or on-demand SIB1. This set of preambles may be used when the wireless device is in IDLE / INACTIVE state. Another set of preambles may be used when the wireless device is in CONNECTED state. The resources used to transmit this first message may also be different of communication resources when the wireless device is already in CONNECTED state. The reason is that the wireless device in IDLE / INACTIVE state may only be loosely synchronized, so that slots for the transmission / reception may be wider, e.g., have a longer guard time.In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may send the first message to one or more first access devices. For instance, the first message may be addressed to two access devices at different locations that may monitor certain features of the received first message. The one or more first access devices may then interact with each other, e.g., exchange measurements of the received first message. Measurements may include signal strength, signal quality, frequency shift, estimated location (e.g., based on the received first message and / or wireless sensing), etc. The one or more access devices may determine based on said measurements which of them, as well other access devices, is or are most suitable for further communication. The selected access device(s) may then respond with a second message, e.g., a random-access response.

[0331] In an embodiment of the invention that may be combined with other embodiments or used independently, by or upon receiving the second message from a selected access device, a wireless device may start and / or perform a random-access procedure through the selected access device.

[0332] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may indicate implicitly or explicitly which access devices (or TRPs, DUs, beams, etc.) are addressed by the first message. For instance, this may be done by transmitting the first message in time / frequency resources that are monitored by a certain group of access devices in an area. This type of addressing is implicit. For instance, the first message may include an explicit identifier indicating the group of access devices addressed. For instance, the first message may include an area (geo-fencing) so that only the access devices within that area are addressed.

[0333] In an embodiment of the invention that may be combined with other embodiments or used independently, a first group of access devices (e.g., a first access device) may distribute the schedule used for monitoring certain resources, e.g., location / beam by the first group of access devices and a second group of access devices. This may be advantageous because the wireless device may then transmit the first message in those resources to make sure that both the first group of access devices and second group of access devices can monitor it, and use the measurements / reception of the first message to determine which of the access devices are most suitable to perform further communication.

[0334] In an embodiment of the invention that may be combined with other embodiments or used independently, a first group of access devices (e.g., a first access device) may distribute the schedule used for monitoring certain resources, e.g., location / beam by the first group of access devices. A second group of access devices may be available but may not be actively monitoring. This may be advantageous because the wireless device may then transmit the first message in thoseresources to make sure that the first group of access devices can monitor it, and use the measurements / reception of the first message to determine which of the access devices in both the first group of access devices and second group of access devices are most suitable to perform further communication. If the first group of access devices determines that one or more of the access devices in the second group of access devices should be selected, the first group of access devices may then indicate this to the selected access devices, that may then respond with a second message.

[0335] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may include assistance information in the first message that may assist the network / access device in determining the best access devices to provide access / connection to the wireless device. For instance, the wireless device may include its speed, direction, acceleration,... so that the network can determine which access device may be suitable. For instance, the wireless device may indicate whether it requires immediate access for communication or not. If it requires access, it may need to determine the best access device once the connection is established. For instance, the wireless device may indicate what type of communication is required. For instance, if it is a high volume data transfer, the network may rather select a second access device that is further away but that will be close soon (e.g., based on the mobility pattern of the wireless device) because the second access device is more suitable for a high volume data transfer (e.g., supports high frequency bands, supports more antenna elements, etc.). For instance, the wireless device may indicate the required QoS.

[0336] In an embodiment of the invention that may be combined with other embodiments or used independently, when a wireless device provides assistance information, e.g., about its trajectory / movement pattern, the network and / or wireless device may determine whether the trajectory / movement pattern (in general other information in the assistance information) is determinable and how accurately it can be determined.

[0337] Section: usage of an AI / ML model and inclusion in the first configuration

[0338] The increasing use of mobility prediction, context-aware access selection, and multi-hop handover in dense and heterogeneous cellular networks raises challenges in how reliably a wireless device and the network can anticipate future connectivity conditions. Conventional mobility procedures typically rely on network-side estimation or static thresholds, without explicit awareness of how accurate device-reported assistance information— such as trajectory, speed, or movement patterns— actually is. This can lead to overly conservative decisions with unnecessary signaling, oroverly aggressive decisions that increase the risk of radio link failure when predictions are inaccurate. The embodiments described herein address this problem by integrating AI / ML- based confidence estimation into the wireless device and exposing the resulting confidence levels through configuration and signaling. By enabling the wireless device to locally infer the accuracy of its own assistance information and report this to the network, mobility decisions such as access-device selection, hop prediction, and handover scheduling can be adapted to the reliability of the prediction. The technical effect includes more robust and energy-efficient mobility management, reduced signaling overhead, improved privacy through local inference, and adaptive scheduling of sensing, measurement, and handover procedures that balances performance and risk based on quantified confidence levels.

[0339] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may be configured with a function, e.g., an AI / ML model, that may provide a prediction on how accurate (i.e., regarding the confidence level) the provided trajectory and / or other assistance information parameter is. For instance, the AI / ML model may be provided by the network and may be in charge of inferring such prediction. This is advantageous because it may offload the network from performing predictions for each wireless device, reducing network energy consumption. Furthermore, it keeps data locally at the wireless device reducing privacy risks. The inferred value (e.g., accuracy of / confidence in the predicted trajectory, or accuracy of other assistance information parameter) may then be provided, by the wireless device, to the network, e.g., access devices, e.g., in the first message or in another message. This information may then be used by the wireless device / network for, e.g., better selection of preferred access devices for further communication or optimize other communication / sensing services. For instance, if the user is on a highway, the movement pattern is fairly determinable, same when in a train, so that multiple hops / access devices may be selected. But if the user is in a city, it is harder to determine how the user may move, and thus, to determine two or more hops. UE historic mobility patterns could be used by the network to estimate trajectory e.g., someone going to work everyday, it is fair to assume they take the same route.

[0340] The AI / ML model may allow determining how many hops can be predicted with a certain confidence level. A configuration may determine a certain threshold (confidence) to go for a single hop, two hops, and so on. In this way, the network can instruct a wireless device to take a route by itself while keeping the risk of, e.g., a radio link failure (RLF) low.

[0341] Next to this information, the wireless device may also provide other measurements related to certain (mobility) events and / or other predicted events.

[0342] The usage of the confidence level with regard to some of the parameters (e.g., trajectory) may also allow the network to better assess / take decisions on the (predicted) mobilityevents, e.g., determining a selected access device. An AI / ML model mentioned before may also be used for such a purpose. For these scenarios where the trajectory is determinable, the handovers, cell (re)selections can be scheduled by the network and / or selected by the wireless device (in case of handover or cell selection) far in advance and minimize signalling as much as possible, and default to wireless device triggered signalling-based selection / HO when mobility patterns are broken. The prediction of the accuracy of the trajectory (or assistance information parameters) by the AI / ML model may be supplemented by location information fed by the wireless device to the AI / ML model at a configured, and / or self determined frequency e.g., based on a determinacy metric, for instance the highest the likelihood that the UE is following the predicted trajectory (e.g., when the user is on a train or in the highway) the less the frequency of location information acquisition), while a trajectory branching where two or more candidate trajectories are foreseen (e.g., a highway exit) may increase the frequency of location information acquisition and / or introduce an out-of-schedule location information acquisition action e.g., trigger a timer based on the velocity of the wireless device, such that the wireless device acquires the location information right after the trajectory branching point thus ensuring an accurate selection of the continuation of the trajectory, and subsequently the candidate target access devices the wireless device will be handed over to.

[0343] In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may provide certain parameters (e.g., assistance information) as in other embodiments. The network may verify the received information. For instance, the trajectory of a wireless device / user may be verified by means of wireless sensing (e.g., radar). The amount of measurements may be adapted based on the accuracy of the measurement, e.g., when the measurement matches the reported value, the frequency of the measurement may decrease. The frequency of the measurements may also increase if the reported accuracy of the assistance information decreases.

[0344] Section: determining the type of access (legacy access or new)

[0345] Access-device selection procedures must increasingly accommodate heterogeneous deployments in which legacy access mechanisms coexist with newer, more flexible network-assisted selection techniques. Conventional systems typically assume a fixed selection paradigm— either the wireless device autonomously selects a serving cell based on measured reference signals, or the network unilaterally determines the serving access device— without allowing dynamic adaptation between these modes. This rigid separation can lead to sub-optimal performance, reduced interoperability, and inefficient operation when deployment conditions, device capabilities, or radioenvironments change over time, such as in fixed wireless access scenarios or during migration from legacy systems (e.g., 5G) to newer systems (e.g., 6G). The embodiments described herein address this problem by enabling a wireless device to explicitly indicate, via a first message and associated policy, whether it prefers a legacy device-controlled access procedure or a network-assisted selection procedure, and to dynamically switch between these modes based on configured conditions and measurements. The technical effect includes improved interoperability between legacy and new access technologies, more robust access-device selection under changing conditions, and enhanced flexibility that allows combining proven legacy behavior with advanced network-optimized selection mechanisms.

[0346] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may include in the first message whether it prefers to (1) select a specific access device (e.g., perform a legacy cell selection procedure in which the wireless device does select the cell, e.g., based on measurements of the synchronization signals), or (2) relies on the network to determine the most suitable access device(s). This embodiment is advantageous because it allows combining a legacy behavior in which the wireless device is in control with other embodiments of this invention (in which the network / access devices figure out the best access devices).

[0347] This embodiment may be applicable to some scenarios, e.g., in fixed wireless access, in which the wireless device is aware of the best selected access device. Even in these scenarios, the environment may change, and thus, the best selected access device may change over time. Thus, in an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may comprise a policy (e.g., provided in the first configuration) that may determine the conditions under which the wireless device may need to change the selection mode, i.e., whether it selects the access device or whether the network selects the selected access device. For instance, even if the wireless device is of a type in which a "fixed" access device may be used, the wireless device may have a policy in which if the communication parameters (e.g., RSRP / RSRP of reference signals (e.g., SSBs) are below a threshold, the wireless device change the operation mode.

[0348] This embodiment may be applicable to scenarios in which a wireless device needs to operate with legacy access devices (e.g., 5G) or newer access devices (e.g., 6G). This may allow guiding the selection procedure and it may allow ensuring interoperability. For instance, if a 6G access device can support both legacy 5G wireless devices and 6G wireless devices, a 5G device may try and still be able to connect through a 6G access device (supporting some of the embodiments in this invention).In this case, the 6G access device will understand that the 5G device needs to access through the specific 6G access device. However, the 6G wireless device may be guided to a different access device.

[0349] Section: reliability / how to transmit the first message

[0350] Achieving reliable and resilient initial access and access-device selection is increasingly challenging in heterogeneous networks that integrate multiple access technologies, directional beams, and diverse service requirements. Conventional access procedures often rely on a single transmission of a simple access message toward one access device, which may be insufficient in scenarios requiring high reliability, rapid beam determination, or seamless operation across terrestrial and non-terrestrial networks. Such limitations can result in access failures, sub-optimal beam selection, increased signaling, or delayed service establishment, particularly in coverage-limited areas or highly dynamic environments. The embodiments described herein address these challenges by enhancing how the first message is transmitted and processed, including repetition, power adaptation, beam-aware reception, and the use of richer reference signals. By allowing the first message to be received by multiple access devices, processed through multiple beams, and optionally combined with channel estimation or sensing information, the network can more robustly determine suitable access devices and transmission parameters. The technical effect includes improved access reliability, enhanced beam and access-device selection accuracy, reduced retransmissions and signaling overhead, and increased resilience through multi-RAT and multi-access-device support, while maintaining efficient use of radio and energy resources.

[0351] In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device and / or the access device may request and / or determine that more than a single access device is selected. For instance, the wireless device may require a highly reliable and resilient communication, and the wireless device may request access to both a terrestrial access device and a non-terrestrial access device. This may be required, e.g., when the wireless device is about entering an area of poor (terrestrial) coverage. In this case, the first message may be sent to a terrestrial access device, and the terrestrial access device may determine the most suitable terrestrial access device (e.g., another terrestrial access device located somewhere on the route of the wireless device) and a non-terrestrial access device, e.g., a LEO satellite. One, a subset, or all selected access devices may respond with a second message, e.g., a random-access response. The second message(s) may include an indication of the selected device(s). This also means that the firstmessage may need to indicate which radio access technologies may be used when receiving a second message, e.g., only terrestrial network RAT or also non-terrestrial network (RAT).

[0352] In an embodiment that may be combined with other embodiments or used independently, next generation of cellular systems, 6G, will integrate terrestrial and non-terrestrial networks to enhance coverage and resilience. In some cases, a wireless device that is trying to gain access may send a first message that may address only terrestrial access devices that may be able to identify the most suitable access devices to provide service. In case that no terrestrial access device is available, the wireless device may revert to the usage of a non-terrestrial access device.

[0353] In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device and access device may wish to determine the preferred beam for further communication with an access device while sending a single message. The access device may use multiple beams when distributing synchronization signals. In this embodiment, multiple beams may share common resources (i.e., resources that are monitored in multiple beams simultaneously) so that the wireless device can send a single first message (e.g., a single preamble) and the access device can receive the same first message through two or more beams simultaneously. This may allow the access device to determine which of the beams is preferred, e.g., because the received message is received best (e.g., with the highest signal strength, or quality) and reduce transmission requirements by the wireless device.

[0354] Additionally or alternatively, the wireless device may send multiple repetitions of the same first message. This may allow, e.g., an access device using multiple beams, to process each of the repetitions through each of the beams to obtain an estimation of which beam is the most suitable one.

[0355] In an embodiment that may be combined with other embodiments or used independently, the first message may be a preamble transmitted to perform a random-access procedure. The preamble in this case may be transmitted via communication resources (e.g., random access occasions, transmission occasions, ...) that may be monitored by multiple access devices in a first group of access devices.

[0356] In an embodiment that may be combined with other embodiments or used independently, the first message may be a more complex signal that may allow the access devices toestimate the channel between access devices and the wireless device. For instance, the first message may be an uplink channel state information reference signal or a sounding reference signal or a sensing reference signal. The wireless device may also transmit one or more first messages. This embodiment allows reducing the communication overhead, since the access devices can determine the channel state information when receiving and processing the reference signals, reducing the communication overhead and allowing for better communication in further communication.

[0357] In a related embodiment that may be combined with other embodiments or used independently, if the wireless device transmits a first message, e.g., reference signal, such as a channel state reference signal, the receiving (first) access devices may be able to determine the channel between wireless device and access device. This allows selecting a selected access device in an improved manner.

[0358] In a related embodiment that may be combined with other embodiments or used independently, if a wireless device may send a first message, e.g., wireless sensing signal, the wireless device may be able to determine the location of the TRPs, e.g., if the TRPs insert, e.g., an identifier in the reflected wireless sensing signal. This can allow the wireless device to not only determine the location of the wireless access devices, but also to locate itself with respect to the wireless access devices. This can be done, e.g., if the wireless device is informed (e.g., through the first configuration) about the location of the access devices and the identifier that each of the access devices may include in the reflected wireless sensing signal.

[0359] In a related embodiment that may be combined with other embodiments or used independently, one or more access devices may indicate through a first configuration (in a SIB (e.g., SI Bl) or RRC message, or MAC CE, etc) the type of first message, e.g., type of reference signal, that is required for a suitable channel estimation, e.g., the periodicity, frequency band, beamforming, etc, or select an index for the desired reference signal from a set or codebook of reference signals The selected parameters may also depend on the hardware / capabilities of the wireless device, e.g., the number of antennas of the wireless device. The first configuration may include the context (area, time, purpose) in which the first configuration is valid and may be used, it may include information about other access devices in the area, it may include also which type of first message / reference signal the wireless device needs to transmit depending on its capabilities and / or requirements. It may also include how the first message (reference signal) is to be transmitted (as explained in other embodiments below).In a related embodiment that may be combined with other embodiments or used independently, the operation of the wireless device when transmitting one or more first messages may be iterative. In a first step, the wireless device may not be aware of the location of the access devices (device may not be CONNECTED yet, i.e., not in CONNECTED state yet), so that the first first message / first reference signal may be transmitted in omnidirectional mode. In an example, the wireless device may perform beam sweeping meaning that multiple (e.g., N) first first messages may be transmitted in different directions according to a predefined timing between the N first first messages. The first first message / first reference signal may be of a first type, e.g., a preamble. In a subsequent step, once one or more access devices are aware of the presence / approximate location of the wireless device based on the reception of the one or more first first messages, and the wireless device may have synchronized with the network (and be in CONNECTED state) and / or get allocation of communication resources, the wireless device may transmit one or more second first messages / second reference signals, e.g., a channel state reference signal, e.g., transmitted towards the one or more access devices.

[0360] In a related embodiment that may be combined with other embodiments or used independently, the wireless device may distribute one or more first messages, e.g., a reference signal, e.g., as described in other embodiments, according to the received parameters, e.g., via SIB1 or RRC or MAC CE.

[0361] In a related embodiment that may be combined with other embodiments or used independently, the reference signal may also include the type of access devices that the wireless device requires. For instance, if the wireless device may need and / or allow the usage of wireless sensing services, or communication services only, or both wireless sensing and communication services, or other services (e.g., computing services). The network may then determine the most suitable access devices out of a second group of access devices. This may be based on, e.g., distance to the wireless device, quality of received messages (e.g., first message), etc. In general, it is based on a function of KPIs such as distance, signal strength, signal quality,..., device needs (e.g., only sensing, low bandwidth communication service, high bandwidth communication service, etc). This selection may then be indicated to the wireless device through a control message, ensuring that the wireless device is aware of the selected access devices and can establish communication accordingly.

[0362] In a related embodiment that may be combined with other embodiments or used independently, whether the wireless device may send the first message (reference signal) and / or the wireless device receives a reference signal from one or more access devices may depend on, e.g., the number of wireless devices in an area. For instance, when estimating the channel, if there is a singlewireless device, it may be more efficient if the wireless device transmits a channel state reference signal; but if there are many wireless devices, it may be more efficient if the access devices transmit the channel state reference signals. One or more access devices may monitor the number of wireless devices, and determine whether to require the wireless devices to transmit reference signals and / or receive reference signals. This may be indicated to the wireless device, e.g., via a configuration message, which may be sent periodically, and / or on request of a wireless device, and / or if the indication needs to be changed.

[0363] In a related embodiment that may be combined with other embodiments or used independently, the reference signal may include the type of services that the wireless device requires (e.g., low power communication, broadband communication, wireless sensing, computing as a service, etc). Based on this information, the network may select the most suitable access devices for the device to connect to and be served. The selection procedure can vary depending on the type of access devices and their purposes. For instance, the system may have different types of access devices such as terrestrial access devices for high-speed broadband communication, non-terrestrial access devices like LEO satellites for wide-area coverage, or specialized access devices for specific services such as low latency or high reliability. Depending on the required service, more or fewer access devices may need to be selected to meet the performance criteria. The network determines the most appropriate access devices based on the service request and the current network conditions. This selection is then indicated to the wireless device through a control message, ensuring that the wireless device is aware of the selected access devices and can establish communication accordingly. This procedure ensures that the wireless device is always connected to the optimal access devices for its current needs, enhancing the overall efficiency and performance of the network. The procedure may be applied periodically and / or if there is a change in required service and / or in network conditions.

[0364] In an embodiment that may be combined with other embodiments or used independently, the first message may be repeated multiple times, each time with an increasing signal strength. This may allow that more or less access devices receive more or less first message repetitions. This may allow determining which of the access devices is closer or further. This may allow adjusting the transmission power to transmit a second message, e.g., according to an adjustment rate so that each repetition of the first message is transmitted with an increased transmission power according to the adjustment rate. This may also allow determining the selected access devices for the transmission of the second message. For instance, the first message may be transmitted 4 times with transmission power X, 2X, 4X and 8X, (in this case, X is an initial transmission power, and the transmission power is doubled every repetition, i.e., the adjustment rate equals two) a first access device may receive all four transmissions, and a second access device may only receive the last twotransmissions. The access devices may determine that the wireless device may connect through the second access device since the wireless device is detected (e.g., via wireless sensing, measurement of frequency shift) to be moving towards the second access device. In the example, the second access device detects the two last times because the transmission power then is high enough. With transmit powers X,2X,4X,8X, if the two last transmissions are received successfully, we could conclude that the wireless is moving towards the second access device. If initially, there is no correct reception, and later on, there is correct reception, we can conclude that the wireless device is moving towards the second access device.

[0365] In some examples, the adjustment rate may be configurable (e.g., provided by an access device), and may depend, e.g., on the deployment of access devices.

[0366] In an embodiment that may be combined with other embodiments or used independently, the first message may be repeated multiple times, each time with a slightly different transmission configuration (e.g., frequency band, modulation, ...) so that the receiving access devices can determine which of the first message repetitions can be received properly and which ones cannot. This can be used to better assess the channel and better determine communication parameters.

[0367] Section: security embodiments

[0368] Advanced access-device selection and low-latency mobility procedures, particularly those triggered at lower protocol layers or involving multiple candidate access devices, introduce new security challenges that are not adequately addressed by conventional cell-centric key hierarchies. When a wireless device exchanges initial messages with one set of access devices and subsequently establishes communication with a different selected access device, there is a risk that security contexts, keys, and trust relationships become misaligned, leading to potential exposure to impersonation, replay, or man-in-the-middle attacks. These risks are amplified in scenarios such as Ll / L2-triggered mobility, multi-TRP operation, predictive multi-hop handover, and pre-activation of target resources. The embodiments described herein address this problem by binding security key derivation and update procedures to the identities, physical-layer characteristics, and contextual parameters of the access devices involved in selection and mobility. By enabling layer-specific key hierarchies, TCI- or physical-parameter-dependent keys, advance distribution of protected key material, and secure envelopes for rapid target access, the proposed techniques ensure continuity of trust while minimizing latency. The technical effect is enhanced security assurance during access andmobility, reduced handover delay, and robust protection of control and user planes across heterogeneous and predictive mobility scenarios.

[0369] Security procedures need to be secured. In particular, the NAS / AS keys of a wireless device may need to be updated as a wireless device selects an access device to connect to, and / or moves between access devices. This is a problem when a wireless device in the case that a wireless device sends a message to a first (group of) access device(s), and receives a second message from a second (group of) access device(s) indicating a selected access device, in particular, when this refers to a mobility procedure performed at lower layers. Thus, it is an aim to provide embodiments that improve security in such deployments.

[0370] In an embodiment that may be combined with other embodiments or used independently, when a wireless device accesses the network, e.g., performing a cell selection procedure as in other embodiments, the identities of the access devices involved may be used in the derivation of the key hierarchy, for instance, the identities of the first group of access devices (TRPs), the identities of the second group of access devices (TRP) and / or the identity of the selected access device (TRP). For instance, the identities of the first group of access devices and / or selected access device may be sent in a registration request message (similar to 5G registration request). The contents may be used in the derivation of the key hierarchy (e.g., a root key, NAS keys, and / or AS keys). This may be advantageous because the wireless device receives guarantees about the devices involved in, e.g., the random access.

[0371] In an embodiment that may be combined with other embodiments or used independently, when a wireless device performs a mobility procedure, e.g.:

[0372] - accesses the network by means of one of the procedures above, i.e., sends a first message to a first access device (e.g., preamble) and receives a second message (e.g., RAR) through a second (selected) access device,

[0373] - performs a handover from a first (source) access device to a second (target) access device (out of multiple access devices),

[0374] the security key update, if any, and / or hierarchy is such that it reflects both first and second (selected) access devices. In particular, an access device key similar to 5G K_gNB, or a key derived therefrom, may depend on an identifier of both the first access device and / or the second access device and / or communication parameters, including context information (e.g., location and / or timing information) of both the first access device and / or the second access device. This procedure ensures that the wireless device can verify (access devices) involved in the selection of the second (selected) access device that leads to further communication between wireless device and selected access device.In a related embodiment that may be combined with other embodiments or used independently, the key derivation algorithm used to derive the access device key or a key used to protect the control plane at a given layer may use as input a transmission configuration indication (TCI) that may include the quasi co-located properties of the reference signals of both access devices (e.g., doppler shift, doppler spread, average delay, delay spread, spatial RX parameter).

[0375] This may be beneficial to ensure that the properties of the second (selected / target) access device can be implicitly verified. This may be in particular when using an L1 / L2 triggered mobility procedure (LTM).

[0376] In general, lower layer parameters (beyond / in addition to TCI) may be used as input when deriving such lower layer key so that the lower layer key depends on the specific access device / TRP / DU / beam used.

[0377] This TCI-dependent key / lower layer parameter dependent key may also be a key used at a lower layer, e.g., MAC layer, and may be used to protect updated fields and / or update messages in MAC messages, e.g., when performing an LTM handover.

[0378] In a related embodiment that may be combined with other embodiments or used independently, the AS (access stratum) key hierarchy may be:

[0379] K_access device --> key higher layer -->key(s) user plane

[0380] --> key(s) control plane

[0381] --> key lower layer --> key(s) MAC_CE

[0382] -> keys(s) MAC SDUs

[0383] In the context of a lower layer being the MAC layer, Keys MAC_CE may be used to protect MAC control elements (CEs). Keys MAC SDU may be used to protect traffic from upper layers (e.g., RLC). This may allow protecting only control traffic at MAC layer (e.g., MAC CEs) and non-control traffic at MAC layer depending on the keys that are configured / required.

[0384] An access device may have a root key, e.g., derived during primary authentication, e.g., an access stratum root key. From it, a root key for a higher layer protocol (PDCP) and a root key for a lower layer protocol may be derived. The key for the lower layer protocol may be updated during mobility events affecting the lower layer (e.g., change of beam, TRP, DU), while the updates for the access device / keys higher layer may only be required when changing cell.In a related embodiment that may be combined with other embodiments or used independently, the update frequency of lower layer (e.g., L2) and higher layer (e.g., PDCP) keys may be different, e.g., it may determined by a configuration. In particular, higher layer keys may only be updated when the wireless device changes the cell, e.g., similar to 5G, while lower layer keys (e.g., L2) may need to be updated every time the wireless device changes the beam / DU / TRP (part of a cell). The central entity in the access device (e.g., DU) may push / configure the lower layer key to the TRPs / DUs. This may be done in advance (to reduce delays), e.g., based on a predicted / indicated "n hop handover route" as described in other embodiment.

[0385] In a related embodiment that may be combined with other embodiments or used independently, an access device key may be used to derive keys for different protocol layers, e.g., PDCP layer and MAC layer. For instance, keys for the PDCP layer may be derived using a key derivation function such as a HMAC based SHA256 as in 5G (or other key derivation function, e.g., SHA-3 based) and the derived key(s) may be used in the user plane and control plane. Different keys may be negotiated, e.g., different keys for integrity and confidentiality protection, or a single key to be used in AEAD (Authenticated Encryption with Associated Data) algorithm. The keys at a higher protocol layer may be 256 bit long or 128 bit long. For lower protocol layers, performance may be more important, and the usage of lightweight algorithms such as ASCON may be advantageous despite only being able to achieve 128 bit security. This may require the negotiation of algorithms for a high layer protocol and low layer protocol, e.g., during an initial primary authentication procedure, e.g., between the wireless device and the core network and / or between the wireless device and the access devices. Agreed security algorithms may be selected in the wireless devices, and may be used when performing handover operations. Enabling of a lower layer security may imply, e.g., disabling of a higher layer security (e.g., user plane security). Setting null security at a lower layer may require enabling a higher layer security. In general, it could also be a matter of network policy / configuration. In another example, the wireless device maintains, e.g., higher layer security, until after wireless device starts exchanging data with selected TRP using, e.g., lower layer security. This may be done by setting up a timer, or waiting till a confirmation message is received. Conditionally, user plane security in higher layers could be disabled / enabled e.g., for QoS purposes (e.g., lower latency), redundant security need / avoidance, type of traffic / use.

[0386] In some scenarios related to Inter-CU LTM Execution Phase, during Inter-CU LTM execution phase, the Source-DU signals the NCC to the UE within the Cell Switch Command. Further, the Candidate-CU (which becomes the new Source-CU after LTM mobility) initiates, after reception of the RRCReconfigurationComplete message, a path switch procedure toward the AMF. The AMF will in place include the incremented NCC and a new NH to the new Source-CU in the Security Context IEwithin the PATH SWITCH REQUEST ACKNOWLEDGE message. The new Source-CU generates a fresh Key NG-RAN Star IE for all inter-CU LTM configured candidates, and signals within the LTM CONFIGURATION UPDATE message. The Candidate-CU(s) update the earlier stored Key NG-RAN Star with the newly received one and use it to generate the AS keys. Similarly, the new Source-CU shares the NCC with the new Source-DU, as it will be required for Cell Switch Command toward the UE during subsequent LTM. In this scenario, Key NG-RAN star plays the role of K_access device in above table.

[0387] As a matter of clarification, this scenario shows the advantage of "The central entity in the access device (e.g., DU) may push / configure the lower layer key to the TRPs / Dus (in general, access device). This may be done in advance (to reduce delays), e.g., based on a predicted / indicated "n hop handover route" as described in other embodiment. In above scenario, "the new Source-CU generates a fresh Key NG-RAN Star IE for all inter-CU LTM configured candidates, and signals within the LTM CONFIGURATION UPDATE message." This indicates that the new source-CU prepares for a subsequent handover procedure.

[0388] In an embodiment of the invention that may be combined with other embodiments or used independently, the freshly generated Key NG-RAN Star IE for all inter-CU LTM configured candidates may be different keys for each of the potential inter-CU LTM configured candidates. This makes sure that communication cannot be eavesdropped / modified by different devices. Key NG-RAN Star may be different by using the access device cell identity, and / or other identification information such as location, frequency used, etc.

[0389] In an embodiment of the invention that may be combined with other embodiments or used independently, the configured Key NG-RAN Star should not be valid for an unlimited period of time. Thus, the keys may be derived taking as input a timer, or an expiration time / date. The entities (e.g., UE / access devices) using them should make use of the timer / expiration time / date / etc to generate them, and validate that the current time / date is valid when using them. Additionally, or alternatively, the fresh Key NG-RAN Star may have a validity period, and the distributed key NG-RAN Star may be distributed with metadata including the validity period. This is advantageous to make sure that an access device does not need to store the key forever. The wireless device may also be aware of the timer / expiration time / date, so that they are aware that the key may need to be refreshed. Additionally, or alternatively, this timer / expiration time / date only applies when the handover has not been performed. If the handover is performed and the key NG-RAN start is in use, the timer / expiration time / date loses its validity.

[0390] A challenge in LTM mobility procedures is latency. Security may introduce additional latency because during handover the target access device needs to be configured with one or multiple keys, e.g., as per above key hierarchy. The configuration may involve, depending on the type ofhandover, interaction between cells (as in 5G Xn handover), or even interaction with the core networks (as in 5G N2 handover). This may involve signalling back and forth between the access devices and / or access and mobility functions (e.g., 5G AMF).

[0391] In order to reduce this latency, in an embodiment that may be combined with other embodiments or used independently, an access device, e.g., a target access device, is associated with certain keying materials, e.g., a public key, or an identity-based public key. These keying materials may be provided by the source access device to the wireless device (e.g., source beam / TRP / DU and target beam / TRP / DU). Thus, when a wireless device desires to move to the target access device, the wireless device may prepare a protected message, e.g., an encrypted and / or integrity protected message and send it to the target access device. The target access device may receive this message, e.g., an encrypted message, e.g., with the keying materials of the target access device. This message may protect information associated with the keying materials (e.g., K_Access device, or Key lower layer) to be used by the target access device. For instance, keying materials as in above table. The keying materials associated with an access device may be certified by a trusted third party (e.g., the core network, home PLMN, serving PLMN) so that the wireless device can verify them. The certificate may include metadata such as access device capabilities, identity, location, physical layer parameters, etc so that the wireless device can verify the target access device.

[0392] In a related embodiment that may be combined with other embodiments or used independently, the wireless device may receive and / or compute a secure envelope containing the keys to be used with the target access device. The secure envelope may protect the keys to be used with the target access device. The secure envelope may be received from higher layers or a central management entity, e.g., a central unit. For instance, the wireless device may receive one or more secure envelopes for a few potential target access devices, and when a target access device is selected, the wireless device may share the secure envelope with the selected target access device. This embodiment may reduce signalling in the higher layers and may also reduce latency.

[0393] In a related embodiment that may be combined with other embodiments or used independently, the source / first access device creates the secure envelope by protecting Key NG-RAN start with key K_env. The cellular system / first / source access device may distribute the K_env to all candidate target access devices. The first / source access device may provide the secure envelop to UE, which would then forward it to the second / target access devices, and the latter use K_env to decrypt / verify the secure envelop and retrieve the contents, e.g., a Key_Access device, e.g., key NG RAN star (K-NGRAN*)). An identifier, e.g., K_env, or secure envelope identifier may also be provided by the wireless device to target access device to identify the key, in case there were several.In a related embodiment that may be combined with other embodiments or used independently, other handover parameters such as NH or NCC may also be exchanged in a secure manner in a similar manner, e.g., by exchanging them in a secure manner through the wireless device, e.g., in a secure envelope.

[0394] In a further related embodiment that may be combined with other embodiments or used independently, the keys of the lower layers (e.g., MAC layer, e.g., lower layer key) may be derived by means of physical layer security key derivation techniques. For instance, the source access device may inform the wireless access device about the communication parameters (frequency band, timing, beam forming, modulation, etc) to be used when joining the target access device. The wireless device may then engage in a communication establishment with said target access device using the indicated communication parameters. When performing the communication establishment, the wireless device and target access device may derive a shared secret. This shared secret may be used, e.g., as lower layer key, and / or as key to derive the lower layer key, and / or to protect / securely exchange other keys (as in other secure envelope embodiments). This shared secret may also be used to securely exchange with the target access device other keys, e.g., keys of a key hierarchy as in other embodiments and / or procedures (e.g., RRC connection establishment) between the wireless device and the target access device.

[0395] It is to be noted, that in the context of a mobility procedure such as a handover, the first message as defined in some of the embodiments may correspond to a message sent from the wireless device to the target access device, e.g., a message containing the secure envelope. The first configuration may be a message received by the wireless device from a / the source access device, e.g., with secure envelopes. The second message may be a message received from the target device, e.g., a confirmation message or a message as reply to the first message.

[0396] Section: mobility in IDLE / INACTIVE states

[0397] Mobility handling in IDLE and INACTIVE states presents distinct challenges compared to CONNECTED-mode mobility, particularly in dense deployments where multiple access devices may be available to serve a wireless device. Conventional procedures largely rely on cell-centric scanning and selection based on individual synchronization signals or system information, offering limited insight into whether an access device can facilitate coordinated selection among multiple candidate access devices. As a result, a wireless device may initiate access through a sub-optimal entry point, experience increased access latency, or contribute to load imbalance and unnecessary signaling, especially during initial access or re-selection. The embodiments described herein address theselimitations by enabling a wireless device, while in IDLE or INACTIVE state, to identify access devices that act as gateways to multiple candidate access devices and to obtain configuration, policy, or condition information through synchronization signals or SIB1. By allowing the network to guide selection based on load, coverage, or device characteristics, and by enabling the wireless device to indicate its type or preferences, access and mobility decisions can be optimized early. The technical effect includes faster and more reliable initial access, improved load balancing, reduced signaling overhead, and more efficient mobility behavior before connection establishment.

[0398] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may monitor the synchronization signals of one or more first access devices. The synchronization signals may indicate (e.g., in SIB1) that it is a first access device giving access to multiple access devices (in other words, the network / first access device will determine the most suitable access device for the connection, e.g., to perform the random-access procedure). The wireless device may use this information to determine whether this is suitable (first) access device or not. For instance, the wireless device may discard an access device that does not give access to multiple access devices if it is seeking such an access.

[0399] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may acquire SIB1 distributed by a first access device and SIB1 may indicate that the first access device gives access to multiple access devices (in other words, the network / first access device will determine the most suitable access device for the connection, e.g., to perform the random-access procedure. This SIB1 message may be received when the wireless device seeks network access for first time (.i.e., initial network access) . The wireless device may use this information to determine whether the (first) access device is suitable or not to perform initial access to the network. For instance, the wireless device may discard an access device that does not give access to multiple access devices if it is seeking such an access. The wireless device may obtain from SIB1 specific parameters that may be required to transmit the first message according to the needs of the wireless device. For example, if the wireless device wants to select the first access device, the wireless device may use parameters (e.g., determining a preamble) that are specific for the first access device, while if the wireless device wishes the network to indicate the most suitable access device in a given area (e.g., within a radius of 200 m), the wireless device may use different parameters (e.g., determining a different preamble).

[0400] In a related embodiment that may be combined with other embodiments or used independently, a first access device (e.g., a perch cell as described in some scenarios) may broadcast or distribute conditions / configuration / policy to wireless devices.These conditions / configuration / policy may be used by the wireless device to select / determine a preferred access device (e.g., to perform anchor cell selection as described in some scenarios). For instance, conditions may indicate / reflect network conditions, e.g., if a certain cell is nearing congestion, number of active cells, required transmission powers, type of allowed devices, etc. The first access device may, e.g., indicate stronger signal characteristics requirements / conditions to limit access to certain access devices only to wireless devices with very high RSSI, RSRP, RSRQs, etc. This embodiment is advantageous because it allows indicating conditions / configurations and provides some means to perform load balancing.

[0401] In an embodiment that may be combined with other embodiments or used independently, the wireless device may indicate implicitly / explicitly its type in the first message. This information may be used by the network to determine / select the most suitable access device for further communication.

[0402] Section: Mobility in CONNECTED state / conditional (LTM) handover selecting several hops

[0403] Mobility management in cellular networks, particularly in the CONNECTED state, faces increasing challenges as network densification, beam-level mobility, long-term mobility (LTM), and heterogeneous access deployments lead to frequent and tightly time-constrained handovers. Conventional handover and conditional handover mechanisms typically rely on the selection of a single target access device based on instantaneous measurements or predefined conditions, which may be sub-optimal for scenarios where the wireless device follows a predictable trajectory, where multiple access devices are viable candidates, or where successive handovers are likely to occur within a short time interval. This can result in excessive signaling, increased handover failure risk, service interruption, and inefficient use of network resources. The embodiments described herein address these limitations by enabling multi-hop aware mobility in which a wireless device can predict, evaluate, and signal multiple potential target access devices and handover routes, optionally with associated confidence levels. The technical effect includes improved handover robustness, reduced signaling overhead, better anticipation of successive mobility events, and more reliable and efficient mobility execution across beams, cells, and access devices.

[0404] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may receive an RRC message containing parameters to use when sending the first message. This RRC message may be received when the wireless device is inCONNECTED state and requires a handover and is seeking the most suitable target access device. In contrast with a standard handover in which the SOURCE access device determines the TARGET access device in advance or in contrast with a conditional handover in which the wireless device determines the TARGET access device based on a set of conditions, this embodiment describes a handover in which the wireless device may determine two or more potential TARGET access devices, and transmits a first message towards one or more of the potential TARGET access devices. The potential TARGET access devices may then determine the best TARGET access device(s) and indicate this back to the wireless device. Additionally or alternatively, the two or more TARGET access devices send parameters back to the wireless device that allow the wireless device to determine the best TARGET access device. In this way, no coordination or communication between access devices is required. It is to be noted that this embodiment (as in other embodiments) access device may also represent a DU, beam, TRP, etc.

[0405] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may need to perform a handover operation and the wireless device may prefer to enhance the mobility procedure by identifying two or more possible subsequent hops, e.g., in an LTM based mobility procedure, where a subsequent hop means a subsequent beam (L1 / L2 mobility) or access device (L3 mobility) to connect to. The wireless device may have determined parameters triggering mobility procedures, e.g., its trajectory and / or signal strength, etc., and the wireless device may have inferred whether those parameters (e.g., its trajectory) are determined with high / low accuracy / confidence, e.g., as per other embodiments, e.g., using an AI / ML model. The wireless device may have also been configured with a configuration for conditional handover identifying a number of potential subsequent hops, e.g., identifying a first hop (e.g., a first target cell or a first target beam) and identifying a second hop (e.g., a second target cell or a second target beam after the current first target cell or first target beam). This may be based on current measurements and / or historical data that may be kept by the wireless device. For instance, if a wireless device moves every day along the same route, the wireless device may keep track of the best access devices, and the wireless device may keep informing the network (access devices) which route / target access devices it expects to connect to. When sending the first message that may indicate the potential target access device(s) the wireless device may wish to move to, the wireless device may also use when selecting the contents of the first message (e.g., preferred access device) the inferred accuracy / confidence and / or indicate the inferred accuracy / confidence of the information in the first message.

[0406] In another embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may include an AI / ML model and / or anAI / ML configuration that may be used to predict the subsequent hops. The AI / ML can be used to determine how many hops can be predicted in advance. For instance, the AI / ML model may take as input the current location of the wireless device, the time of the day, the date, state of the wireless device (e.g., CONNECTED or INACTIVE) orthe activity of the user (e.g., making a call), and it may predict / infer whether it is possible predict and / or it should predict 1 hop, 2 hops, ... N hops. In an option, it may also predict and / or determine how many Y candidate access devices are considered X hop away, e.g., it may determine that up to Y=3 access devices may be predicted / inferred when the access devices are X=1 hop away. In a further option, it may be possible to predict and / or determine how many N hop routes can be predicted / determined shared.

[0407] In another embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may have an AI / ML model and / or configuration that may be used to predict and / or determine the most probable N next hops. For instance, the AI / ML model may take as input measurements (e.g., RSRP) of different access devices, the current location of the wireless device, the time of the day, the date, state of the wireless device (e.g., CONNECTED or INACTIVE) or the activity of the user (e.g., making a call), and / or the movement direction, and it may predict / infer the most likely 1 hop, 2 hops, ... N hops.

[0408] In a (related) embodiment of the invention that may be combined with other embodiments or used independently, each predicted next hop may be associated to

[0409] (1) a likelihood of being a suitable next hop,

[0410] (2) one or more possible subsequent next hops,

[0411] (3) expected conditions (time, location, context, etc) to become the next hop. For instance:

[0412] Next hop: ID1 Likelihood: 60%

[0413] Subsequent next hops: ID3, ID4

[0414] Conditions: Time, Location,

[0415] Number of hops away: 1

[0416] Route: direct

[0417] Next hop: ID2 Likelihood: 30%

[0418] Subsequent next hops: I D3, ID5

[0419] Conditions: Time, Location,

[0420] Number of hops away: 1

[0421] Route: direct

[0422] Next hop: ID3 Likelihood: 60%

[0423] Subsequent next hops: ID6, ID7

[0424] Conditions: Time, Location,Number of hops away: 2

[0425] Route: ID1, ID2

[0426] Next hop: ID4 Likelihood: 20%

[0427] Subsequent next hops: I D6, ID7

[0428] Conditions: Time, Location,

[0429] Number of hops away: 2

[0430] Route: ID1

[0431] Next hop: ID5 Likelihood: 20%

[0432] Subsequent next hops: ID6, ID7

[0433] Conditions: Time, Location,

[0434] Number of hops away: 2

[0435] Route: ID2

[0436] Based on the above examples, the most likely two-hop route is I DI, ID3, the next likely two-hop route is ID2, ID3, the next likely two-hop route is ID1, ID4, and the least likely two hop route is ID1, ID5. The wireless device may have been configured to share up to, e.g., 3 two hop routes. This means that the wireless device may then share the data of ID1, ID2, ID3, and ID4 and / or the combined information, e.g., whatever is smaller.

[0437] In an embodiment of the invention that may be combined with other embodiments or used independently, the first message may trigger a conditional (LTM) handover, and / or the first message may indicate at least one or more (e.g., two) potential target access devices, and each potential target access devices may be associated to a predicted preference and / or an accuracy of the prediction. This information may be used by the access devices receiving the first message to determine whether a single preferred "hop" (preferred access device) in the conditional handover can be determined, or more than one preferred "hop" can be determined (e.g., the next hop and the next next hop) as well as the identities of the hops, i.e., the identities of the target access devices that wireless device should connect to. Furthermore, the conditions to connect, e.g., timing, may also be determined. This information may be indicated by means of the second message, wherein the second message may include the one or more selected access devices in connection order and / or conditions to connect (e.g., time or location). Furthermore, an accuracy level may be included in the second message that may also help the wireless device to determine whether the determined hops (one hop, or two hops, etc) have been determined in a very accurate manner (so that the wireless device does not require further signaling, but just changing the access devices when required), or further signaling may be required, e.g., a subsequent transmission of a first message.In an embodiment of the invention that may be combined with other embodiments or used independently, the access device may broadcast in the system information or unicast in the dedicated RRC message the location and coverage information of cells of itself and other cells of other access devices nearby. It may also broadcast more granular information such as the area of the cell that has high / medium / low coverage. The wireless device may obtain the location and coverage information of the cells through acquisition of the system information or dedicated RRC message or MAC CE. The wireless device may check the real-time location of itself as it moves in the coverage area of the cell. The location may also be provided by the access device, e.g., based on wireless sensing indicating not only the location, but the specific connectivity properties associated to the specific location of the wireless device. The wireless device / network may determine the next mostly likely cell or cells according to its current location and next possible location which may be obtained from the upper layer (e.g. navigation application) or the moving pattern of the wireless device or the predicted UE location by the AI / ML model on the device side based on UE's moving pattern, then send a message (first message) to the access device (or access devices) of the candidate cell (or cells) for handover. The access device may send messages to the other access devices of the candidate cells and request the other access devices to prepare the resources for handover. It may determine how many hops can be determined in advance with which accuracy and / or reliability. The other access devices may admit the request and return the configuration to the access device. The access device then sends back the configuration to the wireless device either in the RRC message or MAC CE, so that wireless device is appropriately configured for the handover. Upon the condition of handover is met, e.g. the wireless device moves into the coverage area of the other access device, the wireless device may perform condition handover to the other access device using either RACH-based or RACH-less handover.

[0438] In cellular networks, measurement events determine when / whether the conditions of a cell, or a close cell are better than the current one, and may trigger mobility procedures, e.g., handover. Types of events include:

[0439] Same RAT Events (Al to A6), e.g., Al: Serving cell becomes better than threshold; A2: Serving cell becomes worse than threshold; A3: Neighbor cell becomes offset better than serving cell; A4: Neighbor cell becomes better than threshold; A5: Serving cell becomes worse than thresholdl, and neighbor cell becomes better than threshold2. A6: Neighbor cell becomes offset better than secondary cell (for carrier aggregation, Release 10 in LTE).

[0440] Inter-RAT Events (Bl, B2): Bl: Inter-RAT neighbor becomes better than threshold; B2: Serving cell becomes worse than thresholdl, and inter-RAT neighbor becomes better than threshold2.Additional Events in NR / LTE: Include Cl, C2 (CSI-RS based), W1-W3 (WLAN), V1-V2 (channel busy ratio), H1-H2 (Aerial UE height), as seen in LTE documentation, though less common for pure mobility.

[0441] In an embodiment of the invention (related to the previous ones) that may be combined with other embodiments or used independently, in the context of a multi access device selection and conditional handover, one or multiple new types of "n hop" measurement events can be defined in which the wireless device is configured with certain thresholds, e.g., related to conditions to determine a first hop (e.g., next target access device), a second hop (e.g., next next target access device), ..., an nth hop (e.g., a next next (n times) next access device. These new types of measurement events could be considered as the combination / concatenation of multiple measurement events as above.

[0442] The thresholds for such "n hop" measurement events may be, e.g., an extension of a given measurement event type, e.g., A3 measurement events. In the case of being related to A3 measurement events, the thresholds may be A3 related thresholds for the first hop (i.e., the neighbor cell), and for the second hop (i.e., the neighbor neighbor cell), and so on. Thus, the thresholds may be used in predictions of the expected A3 measurement events over a number of hops.

[0443] An n hop event may be triggered and communicated (based on configuration / policy) when at least n hops are determined to be feasible with a certain confidentiality level.

[0444] The wireless device may have a functionality (e.g., through an AI / ML model) to determine an event with n hops (e.g., n hop event), predict whether the first hop is reliable enough (confidence level), and whether the second hop will be reliable enough (confidence level), and transmit a first message including these and other exemplary parameters.

[0445] The next target device may then receive this message and may inform and / or interact with, e.g., the next next target device whether the handover is to be performed in the indicated manner by the wireless device, and / or introduce certain modifications, e.g., taking into account the state of the access devices.

[0446] In an example, a wireless device may be configured with a "handover route" and / or receive feedback about the "handover route" comprising a set of hops (next hop, next next hop, and so on until n hops) and keep re-evaluating its feasibility / confidence in the handover route (e.g., locally, e.g., by means of measurements and / or AI / ML model). This may be provided in the second message or first configuration (as in other embodiments. This "handover route" can be also called "n hop handover route".

[0447] In an example, a wireless device may determine and / or provide feedback about a handover route", e.g., through the first message.A wireless device and / or network may determine multiple potential "handover routes". The wireless device and / or network may be able to select among several of them. Selection may be done by using a function that minimizes, e.g., the number of hops in a given time / area, and / or energy and / or signalling and / or downtime, etc. The function may be as simple as taking the "handover route" out of multiple possible "handover routes" such that has the highest confidence level in the first hop and the second hop up to a threshold. The function may also be based on an AI / ML model that may return the preferred "handover route".

[0448] Such a mobility scenario and mobility events may be applicable, e.g., to non-terrestrial networks wherein satellites (mobile access devices) follow well defined trajectories, e.g., when a wireless device is in certain conditions, e.g., open space, good weather, etc. In these cases, the wireless device may be able to determine by itself or based on configuration several subsequent hops (an n hop handover) and may then perform handover procedures in an automated manner.

[0449] Such a mobility scenario and mobility events may be applicable, e.g., to terrestrial networks when a wireless device follows a well defined / known trajectory and it is aware of multiple access devices in its trajectory (e.g., based on historical data that may have been provided by the network and / or collected by the device). The wireless device may then infer an n hop handover and communicate it to the network (e.g., through the first next hop access device).

[0450] Section: allocation of a set of identifiers of a second access device to the first access device

[0451] In the 3GPP R19 inter-CU LTM, the UE may switch from a source access device (also target gNB / gNB-CU) to a target access device (gNB / gNB-CU). It has been agreed to use Xn-based handover as the baseline at RAN2#125 meeting. SA3 also agreed to use the MAC CE to transfer the NCC to the UE to avoid the latency caused by the legacy RRC-based signalling for transferring the security parameters. In order to operate appropriately in the target access device, UE needs to acquire an identifier, e.g., a C-RNTI. This identifier may be allocated by the target access device for the RRC connection management. In the legacy L3 RRC-based handover, i.e. reconfigurationWithSync may contain such identifier, in this case, C-RNTI, allocated by the target access device for the UE to use if RACH-less handover or Contention Free Random Access is used; if such C-RNTI is not configured, the UE may perform the legacy Contention Based Random Access to acquire a C-RNTI allocated by the target access device. In the inter-CU LTM, UE may also need the C-RNTI allocated by the target access device in different cases. However, it is challenging to determine the best possible way of allocating such identifier while keeping the latency low. In some situations, the target access device may includea newly allocated identifier, e.g., C-RNTI, for the UE in a first message, e.g., the Handovercommand message contained in XnAP HANDOVER REQUEST ACKNOWLEDGE message, and may send the first message to the source access device. In some situations, the RRCReconfiguration message may include the new identifier, e.g., C-RNTI value in the rrcReconfigurationWithSync IE, or it may include the new identifier, e.g., C-RNTI value, in the Itm-Config IE, or another dedicated field. After the source access device received the first message, e.g., Handovercommand, from the target access device, it may apply the configuration, e.g., RRCReconfiguration, to the UE, so that the UE will have the new identifier, e.g., C-RNTI, allocated by the target access device for interaction with the target access device. In some situations, the target access device may include the new identifier, e.g., C-RNTI value, for the UE in a new field in XnAP HANDOVER REQUEST ACKNOWLEDGE message, and send the message to the source access device. Once receiving the message, the source access device may transmit the new identifier, e.g., C-RNTI value, allocated by the target access device using either an existing MAC CE or a newly defined MAC CE. In one embodiment, the new identifier, C-RNTI, may be a new field in the LTM Cell Switch Command MAC CE, or a field in the new MAC CE for the NCC transfer.

[0452] In previous scenarios / situations, the target access device (gNB) provides the source access device (gNB) with an identifier for the wireless device (UE). The source access device needs to configure this identifier in the wireless device. This identifier is then used by the wireless device when connecting to the target access device. These embodiments require, therefore, signalling between target and source access devices. In the mobility situations described in this invention, where a wireless device sends a first message towards a first group of access devices, this may require the allocation of multiple potential identifiers. These identifiers may be used in a handover procedure but also when performing a cell (re-)selection procedure.

[0453] An approach to reduce that signalling is described by means of the following embodiment that may be combined with other embodiments or used independently, a first (e.g., source) access device may be configured with / have a set of identifiers by / of one or more potential second (e.g., target) access devices. This set of identifiers, e.g., C-RNTIs, may be allocated to a wireless device that is going to perform the mobility procedure, e.g., LTM handover. A pair of first (e.g., source) access device and second (e.g., target) access device may share a set of identifiers specific for that pair of access devices.

[0454] In an example, when the wireless device is configured by the first (e.g., source) access device to perform the mobility (e.g., handover) to the second (e.g., target) access device, the first access device allocates an identifier in the set of identifiers to the wireless device. In this manner, explicit signalling is not required between first and second access devices.In an example, the wireless device uses the allocated identifier to communicate with the second access device, e.g., in a RACH-less access. Upon initial access, the second access device may allocate a different identifier, e.g., a different RNTI.

[0455] In an example, when the first access device allocates an identifier in the set of identifiers to a wireless device, the allocated identifier may be used by the wireless device for a maximum amount of time determined by a timer (maximum time) that may also be configured / agreed by the first access device and / or second access device.

[0456] In an example, first and second device may exchange the set of identifiers, e.g., the number of identifies that may be available at a given point of time, the identities, the maximum time for their usage, etc.

[0457] Section: first configuration distributed by the access device

[0458] Initial access and access device selection in dense and heterogeneous cellular networks present increasing challenges, particularly when multiple access devices, transmission points, or beams are available in a given area and when the wireless device is mobile. Conventional random access and initial connection procedures typically assume that a wireless device targets a single access device selected implicitly by coverage or signal strength, without awareness of nearby alternatives, device trajectory, or future connectivity requirements. This may lead to sub-optimal access decisions, unnecessary signaling, repeated access attempts, or inefficient mobility handling when the wireless device moves across coverage areas or subareas served by different sets of access devices. The embodiments described herein address these issues by introducing a first configuration distributed by the access device that provides the wireless device with information about surrounding access devices, their locations, preferred service areas, and transmission parameters for an initial access message. The technical effect is to enable informed, flexible, and trajectory-aware access device selection, reduce access failures and signaling overhead, support seamless mobility across overlapping and non-overlapping subareas, and improve overall network efficiency and user experience during initial access and subsequent mobility procedures.

[0459] In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may obtain a configuration that can be used to send a first message such as a preamble to a first access device. This first message will / may indicate to the first access device that the wireless device is seeking access to the network, but it is seeking access not necessarily through the first access device, but through the most suitable access device, e.g., in a givenarea. The first access device may interact with other access devices, e.g., as indicated in the first message. The first access device may also monitor the wireless device, e.g., whether it is moving or is static. Based on such interactions, monitoring, and / or information obtained from the wireless device via the first message, the first access device (in general, network) may determine the most suitable access device. The first access device and / or the selected access device may reply with a second message, e.g., a random-access response.

[0460] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may receive a (first) configuration (e.g., via an RRC message or SIB message or SIB1 message) indicating the location of the surrounding (e.g., M) access devices in a given area. This information may then be used by the wireless device to determine, e.g., which access devices it wishes to address when sending its first message, and / or which access devices may be potential candidates to be determined as selected access devices. This may allow the wireless device to determine, e.g., a suitable trajectory (e.g., when moving) and / or to plan a data exchange procedure. For instance, if a user is downloading a movie and the user (with the UE) is moving, and the UE is informed about the locations of the access devices, the UE may determine when the data transfers should occur. For instance and referring to Fig. 8, wireless device 803 may be aware of access devices 800-1, 800-2, and 800-3, and may indicate in the first message that operations it may prefer to do with some of the devices, e.g., may inform 800-1 via its first message that it wishes to access the network, it may indicate that it may prefer to use 800-3 to access the network (e.g., perform the random access procedure) and that it may require a high capacity afterwards (e.g., use 800-2). Similarly, the network may also determine which (e.g., a second group of M) access devices may be able to serve the wireless devices, e.g., based on the indication of the wireless device.

[0461] In an embodiment of the invention that may be combined with other embodiments or used independently, the first configuration may include a list of access devices and their locations and / or areas in which one or more access device is preferred (e.g., for a given purpose). The reception of the first configuration may also allow the wireless device to determine its own location. Additionally or alternatively, the wireless device may determine its own location by other means, e.g., GNSS. For instance, the first configuration may be transmitted in a message that may also be used for positioning purposes. The wireless device may determine the contents of the first message based on the reception of this first configuration and the determination of its own location. The wireless device may select (and / or indicate a preferred) access device based on the list and its own location, ensuring optimal connectivity and network performance. In general, the information received in the synchronization signals, or SIB, or SIB1, or RRC as per embodiments in this invention, e.g., previous embodiments, may represent a first configuration comprising parametersthat may indicate, e.g., (1) the wireless device preferences for access device selection and / or (2) how to transmit the first message. For instance, the first configuration may comprise one or more:

[0462] - parameters determining the transmission timing of the at least one first message, - parameters determining the transmission frequency of the at least one first message, - parameters determining the number of repetitions of the at least one first message, - parameters determining the transmission power of the at least one first message, - an (implicit or explicit) identifier used to indicate the multi TRP selection.

[0463] It is to be noted that if a wireless device moves (e.g., to a very different area), the M initially available devices that may have been received in a first first configuration may not be available anymore. In this case, the wireless device may receive some synchronization signals and / or a second first configuration, e.g., via SIB1 from another first access device in another first group of access devices (e.g., M' access devices). It is to be noted that only a few first access devices may distribute such a first configuration, e.g., via a SI Bl. The overall area may then be divided into overlapping or non-overlapping subareas i. Each subarea containing MJ access devices. When the subareas are nonoverlapping, a wireless device may be forced to do a "hard" handover from one subarea to another subarea. When the subareas are overlapping, a "hard" handover is not required , because if a wireless device moves from subarea i to subarea i1, there is an overlap between the MJ access devices in subarea i and the MJ1access devices in subarea i1. The wireless device can the acquire in a progressive manner the new set of access devices. Based on this observation, in an embodiment of the invention that may be combined with other embodiments or used independently, the first configuration may contain information about access devices in overlapping or non-overlapping subareas. The first configuration may also indicate adjacent subareas, and whether they are overlapping or not overlapping. Based on this information, the wireless device may be able to move (perform a mobility procedure) by adding / removing access devices (e.g., TRPs as in MIMO), or by performing a hard handover procedure between the access devices in non-overlapping subareas.

[0464] Section: second configuration

[0465] Access device selection and connection procedures in modern cellular networks must increasingly balance competing requirements related to energy efficiency, quality of service, and service-specific capabilities, particularly in dense deployments with multiple candidate access devices. Conventional access and mobility mechanisms typically apply uniform procedures that do not sufficiently account for dynamic policy constraints, subscription-dependent requirements, or service-aware trade-offs, which may result in inefficient energy usage, unnecessary latency, orsub-optimal service provisioning. The embodiments described herein address this problem by introducing a second configuration or policy that governs how a wireless device applies advanced access and selection procedures. By allowing energy consumption targets, quality-of-service constraints, and service requirements to influence how and whether enhanced access mechanisms are used, the wireless device can adapt its behavior to current policies and network objectives. The technical effect is a policy-aware and context-sensitive access procedure that improves alignment between device behavior and network or subscription constraints, enables more efficient selection of suitable access devices, and enhances overall system efficiency, service reliability, and user experience.

[0466] In an embodiment of the invention that may be combined with other embodiments or used independent, a wireless device may receive a second configuration and / or policy determining how the wireless device may use some of the embodiments of the present disclosure. For instance, the policy may comprise one or more:

[0467] - required energy consumption, these parameters may determine whether the wireless device uses, e.g., a traditional cell selection procedure that may be more efficient for the network instead of a procedure as in some of the embodiments in this invention that may involve more signaling between the access devices. Similarly, depending on the energy consumption parameters or goals, the wireless device may determine which access devices should receive the first message (e.g., 903 in Fig. 9a) and / or which devices may provide service (i.e., may be selected).

[0468] - required quality of service, these parameters may determine the type of procedure that may be performed. For instance, if the wireless device cannot support any latency, using some embodiments in this invention (e.g., wherein the wireless device is offered an access device that is further away) may not be suitable because this may incur higher delay. However, if the device does not handle time-sensitive traffic, the network may be allowed to choose certain access devices that may be more suitable, e.g., energy wise despite the higher latency.

[0469] - required service parameters, these parameters may determine the type of services required by the wireless device, e.g., computing services, wireless sensing services, a certain bandwidth, etc. These parameters may be used by the wireless device to determine which access devices may be suitable and indicate this accordingly.

[0470] In some cases, such required parameters are determined / provided by the core network, e.g., by a policy control function and / or according to the subscription of the user. Thus, such a second configuration / policy may be provided via NAS signaling or in form of URSP rules.

[0471] In some examples, such required parameters may be used by the wireless device to determine the contents of the first message. For instance, include an implicit or explicit identifieridentifying the requirements as per the second configuration / policy so that the network (e.g., access device receiving the first message) can select accordingly the preferred access device(s).

[0472] Section: continuous operation

[0473] Wireless sensing and communication in dense and heterogeneous deployments increasingly involve multiple access devices capable of jointly serving a moving wireless device. Conventional systems typically activate a fixed or overly broad set of access devices and apply static transmission periodicities and parameters, regardless of the device's mobility, service type, or operational state. This can lead to unnecessary energy consumption, excessive signaling, and inefficient use of sensing and communication resources, particularly when continuous operation, multi-device coordination, or service-dependent behavior is required. The embodiments described herein address this problem by enabling the dynamic assignment and management of a subset of access devices that are active toward a given wireless device over defined time intervals, positions, or conditions. Furthermore, transmission frequencies and other communication parameters are adapted based on device state, service requirements, and sensing versus communication needs. The technical effect is a more energy-efficient, adaptive, and context-aware operation in which sensing and communication resources are selectively activated, transmission periodicities are optimized, and performance targets such as quality of service and positioning accuracy are achieved with reduced overhead and improved system efficiency.

[0474] In an embodiment that may be combined with other embodiments or used independently, a wireless device moving in a given deployment area covered by a number of access devices may be assigned and / or select a subset of the access devices to perform the wireless sensing and / or communication tasks.

[0475] In an example, the wireless device may be assigned one or more selected access devices in a second message.

[0476] In an example, in case of continuous operation, the second message (and / or first configuration and / or second configuration) may include conditions indicating how long the one or more selected devices are "selected", i.e., can be used. For instance, four selected access devices may be assigned that will be active:

[0477] Access device 0: [to --> tl]

[0478] Access device 1: [to --> t2]

[0479] Access device 2: [t3 --> t4]

[0480] Access device 3: [tS --> t6]with t0< t3 < tl < t5 < t2 < t4 < t6. t i ->t j indicates that the access device is active from t i to t j.

[0481] This configuration would ensure that at least two selected devices are active simultaneously as long a t < t4. Other conditions may include, e.g., position. The number of active devices may also depend on the state (e.g., CONNECTED or IDLE) and / or operation (type of communication being performed) of the wireless device and / or required service (e.g., communication and / or sensing). Here, "active" means active towards a given wireless device.

[0482] In an example, the wireless device may be required to keep sending a first message (e.g., a reference signal) that may allow the cellular system to determine the best access devices to serve the wireless device depending on its current communication and / or sensing needs.

[0483] In an example, the wireless device may be required to keep sending / send a first message with first, second, or third frequency (i.e. periodicity) when the wireless system is performing wireless sensing, wireless communication, or wireless sensing and communication, respectively. In other words, the frequency of the transmission of the first message may depend on the service that is required.

[0484] In an example, the wireless device may be required to keep sending a first message with a given frequency, depending on the communication state (e.g., data exchange of higher or lower QoS requirements) and / or state of the wireless device (e.g., IDLE or CONNECTED).

[0485] In an example, to save energy, an access device may distribute certain signals, e.g., wireless sensing signals, with a fourth frequency when it is not actively performing sensing or communication.

[0486] In an example, to save energy, an access device may distribute certain signals, e.g., wireless sensing signals, with a fifth, sixth, or seventh frequency when it is actively performing sensing, communication, or sensing & communication respectively.

[0487] In an example, the distribution frequencies as well as other communication parameters (e.g., transmission signal strength, bandwidth, etc) are selected to minimize energy consumption while achieving certain performance goals (e.g., sufficient positioning accuracy, sufficient QoS, etc).

[0488] In an example, the transmission or communication parameters (e.g., the one or more transmission frequencies) may be assigned by means of the first configuration.

[0489] In an example, the transmission or communication parameters may be subject to conditional activation, deactivation, or adaptation. For instance, depending on the speed of the wireless device, or the state of the wireless device, the parameters may be activated or deactivated or adapted. For instance, when the wireless device is in IDLE or INACTIVE state, sensing may be performed with a lower frequency.This allows for more efficient and adaptive operation.

[0490] Section: wireless sensing and integrated sensing and communication

[0491] Wireless sensing and integrated sensing and communication (ISAC) introduce new challenges in cellular systems, particularly with respect to how sensing and communication resources are activated, coordinated, and adapted in response to device mobility, service demands, and network energy constraints. Conventional systems typically treat sensing and communication as largely separate functions and rely on static configurations, leading to inefficient energy usage, delayed mobility decisions, and limited situational awareness, especially in dense deployments or during handover-critical situations. Moreover, existing mobility procedures depend primarily on communication measurements and may not fully exploit sensing capabilities to anticipate or refine handover decisions. The embodiments described herein address these limitations by enabling flexible use of wireless sensing signals transmitted by wireless devices and access devices, optionally integrated with communication signaling, to dynamically support positioning, mobility prediction, and access device selection. By activating sensing functionality selectively, adapting sensing frequency in critical areas, and using sensing-aware first messages to wake up or configure network elements, the proposed techniques improve the accuracy and timeliness of mobility decisions while reducing unnecessary sensing activity. The technical effect includes enhanced handover robustness, improved positioning and trajectory awareness, tighter integration of sensing and communication, and significantly improved energy efficiency at both the network and device levels.

[0492] In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless system may rely on wireless sensing signals transmitted by one or more access devices, e.g., to provide wireless sensing services and / or to facilitate communication procedures (in the context of integrated sensing and communication). How the wireless sensing signals are transmitted may be determined, e.g., by input of the wireless devices.

[0493] In an example, the location of a user / wireless device may be at least partially determined by means of wireless sensing. This location information may be useful to determine specific access devices to be used for wireless communication with said user / wireless device.

[0494] In an example, wireless sensing may be performed (e.g., more frequently) by an access device when the wireless device reaches an area that is critical, e.g., to perform a handover, e.g., in the area between two different cells and / or two access devices. This is called: a critical area. This (determining that the wireless device is in a critical area) may allow the cellular system to better determine when to perform the communication handover from a first access device to a second accessdevice. The critical area may be determined based on wireless sensing measurements. The critical area may also be indicated by the wireless device.

[0495] An A3 measurement event is triggered in LTE / 5G networks when a neighboring cell's signal becomes better than the serving cell's signal by a defined offsetl. The conditions include: (a) Signal Strength Threshold: The serving cell's Reference Signal Received Power (RSRP) or Reference Signal Received Quality (RSRQ) drops below a configured threshold; (b) Hysteresis and Offset: The neighboring cell's signal exceeds the serving cell's by a specified offset, accounting for hysteresis to avoid frequent handovers; (c)Time-to-Trigger (TTT): The conditions persist for a predefined duration; (d) Mobility State: Triggering depends on UE mobility, configured for stationary, medium, or highspeed scenarios.

[0496] In an example, a wireless device may determine and / or predict by means of a prediction function, e.g., an AI / ML model, a mobility event, e.g., an A3 measurement event. A wireless device may be configured with a condition, e.g., an offset2 (e.g., offset2 < offsetl) such that when the neighboring cell's signal becomes better than the serving cell's signal by this defined offset2, the wireless device indicates the access device of neighboring cell to increase / adapt the ratio at which wireless sensing is performed. This command may be performed including a timer so that the adapted wireless sensing is performed during the time specified in the timer. In other words, the wireless device may adapt a change in the frequency of the transmitted wireless sensing signals and / or measurements based on the measurements of certain reference signals. This can allow saving energy in the infrastructure, and can also allow for more accurate mobility procedure in which an access device may indicate a selected access device to the wireless device.

[0497] In a related example, to save energy (of the network infrastructure), frequent wireless sensing should only be performed in designated areas, e.g., areas between cells / access devices or critical areas. Outside of the designated areas, wireless sensing may be performed less frequently, or even not at all. The network / a central controller may send indications to access devices on how frequently they should perform sensing operations. A wireless device may request more frequent wireless sensing and / or a higher accuracy when performing certain tasks. The measurements of wireless devices, e.g., measurement events triggering mobility, e.g., A3 measurement events may be used to determine the designated areas. A wireless device may also be requested to perform certain measurements to establish the designed areas. For instance, a wireless device may be requested to indicate when the signal strength / quality of certain reference signals, e.g., synchronization signals, is in a given range (e.g., higher than a first threshold, or lower than a second threshold, or differ more than a third threshold).In an embodiment that may be combined with other embodiments or used independently, a target (e.g., a subject carrying a wireless device) may wish to receive communication / sensing services. In this case, the wireless device may transmit a first message, e.g., a pilot signal, a preamble, wake up signal, and / or a sounding reference signal and / or wireless sensing signal. For instance, the first message may be a combination of them, e.g., a preamble followed by or embedded in or preceded by a wider band sensing signal. In an example, the transmission of a preamble or wake up signal can be considered as a signal waking up the wireless sensing functionality, e.g., in transmission mode. In general, a wireless device may be provided / configured with different information (e.g., different preambles) depending on the functionality (e.g., communication and / or sensing) that needs to be used / is required from an access device.

[0498] In 5G, the transmission of a preamble for the Random Access Channel (RACH) or to wake up a NES cell depends on the PRACH configuration and deployment scenario. The preamble occupies specific time durations, ranging from fractions of a slot (e.g., 0.125 slots for short preamble formats) to up to 3 slots for long formats. It is transmitted over a subset of subcarriers within the PRACH frequency allocation, with subcarrier spacing options of 1.25 kHz, 5 kHz, 15 kHz, 30 kHz, or 60 kHz, depending on the scenario. Typically, the preamble uses between 12 and 144 subcarriers, ensuring flexibility for various deployment needs, including terrestrial and satellite networks. The preamble may be transmitted prior (i.e., preceding) a wide band signal, e.g., OFDM based or an impulse radio signal, such as those used in Ultra-Wideband (UWB) systems, generated by creating very short-duration pulses with extremely wide bandwidth. Other type of wireless sensing signal may be (based on) a frequency modulated continuous wave sensing signal (FMCW). The pulses are modulated to encode information. Common modulation schemes for UWB include Pulse Position Modulation (PPM), Binary Phase Shift Keying (BPSK), or On-Off Keying (OOK).

[0499] In an example, transmitting a wireless sensing signal as a first message may be advantageous because the access devices may be in IDLE mode, and may only be receiving wireless sensing signals. The reception of a wireless sensing signal transmitted by the wireless device may allow the access devices to locate the wireless device, determine its moving direction, etc.

[0500] In an example, transmitting such a first message (e.g. preamble and sensing signal) may be advantageous because it may allow access devices that may initially operate as communication receiver (i.e., no active transmission, no sensing) to wake-up, e.g., the wireless sensing receiver, e.g., if a suitable preamble (e.g., an access device specific preamble used to wake up the wireless sensing receiver) is received.

[0501] In an example, once the wireless sensing receiver is active, the access device may determine the location of the subject / wireless device by means of the received wireless sensing signal.In an example, once the access device receives a preamble, the access device may indicate the wireless device that it may start transmitting wireless sensing signals. Furthermore, the access device may turn on the wireless sensing receiver. The access device may provide the wireless device with communication resources (e.g., time / frequency) to transmit the wireless sensing signal. The access device may also determine other access devices that may need to receive the wireless sensing signal, and it may request them to switch on the wireless sensing receiver and monitor wireless sensing signals in the previously mentioned communication resources.

[0502] In an example, the reception of such a first message (e.g., a preamble received through the communication receiver) may also trigger the access device to switch on the transmitter (e.g., wireless sensing transmitter) and / or may also trigger the network to switch on the transmitter (e.g., wireless sensing transmitter) of some of them so that the network / access device can start performing active wireless sensing on the wireless device / target / subject. This allows adjusting the energy consumption of the different devices.

[0503] In an example, the reception of such a first message triggers some measurements, e.g., signal strength, by one or more access devices. The access devices may exchange the measurements with each other, or with a central unit, and one or more of the access devices may be assigned to perform wireless sensing on the wireless device / target / subject. In an example, the timing values for the measurements taken by the access devices can vary depending on the specific application and requirements. For instance, the access devices may perform measurements at intervals ranging from milliseconds to seconds. Furthermore, access devices may have a predetermined active period during which they remain in monitoring mode after receiving a first message. The frequency of data exchange between access devices may be adjusted based on network requirements and the movement of the wireless device. In highly dynamic environments, such as urban settings with fast-moving users, data exchange might occur more frequently, e.g., several times per second. Conversely, in more static environments, this frequency could be reduced to once every few seconds or longer. Access devices may utilize advanced algorithms to optimize the timing and frequency of these exchanges, balancing energy consumption and network performance.

[0504] In some cases, the type of first message (e.g., the type of preamble transmitted) may be used to, e.g., switch on the wireless sensing receiver or switch the wireless transmitter or switch on the wireless sensing receiver / wireless transmitter. The type of first message that the wireless device transmits may depend on the service needs (sensing and / or communication) and may be used to wake-up different type of functionality (sensing / communication, transmitter / receiver). This information may be part of the first configuration.In an example, a preamble may be transmitted by the wireless device and the first access devices may receive and measure the preamble to determine which of the wireless access devices should be activated to perform wireless sensing. The wireless device may transmit (by itself, or on request of at least one wireless access device) sounding reference signals. This may require at least one wireless access device to allocate communication resources for the transmission of the sounding reference signal. The wireless access devices may then measure the sounding reference signal to determine the communication channel between wireless access devices and wireless device, and perform beamforming.

[0505] Section: (time) synchronization aspects & joint / coherent transmission / sensing

[0506] Wireless sensing and integrated sensing and communication (ISAC) introduce new challenges in cellular systems, particularly with respect to how sensing and communication resources are activated, coordinated, and adapted in response to device mobility, service demands, and network energy constraints. Conventional systems typically treat sensing and communication as largely separate functions and rely on static configurations, leading to inefficient energy usage, delayed mobility decisions, and limited situational awareness, especially in dense deployments or during handover-critical situations. Moreover, existing mobility procedures depend primarily on communication measurements and may not fully exploit sensing capabilities to anticipate or refine handover decisions. The embodiments described herein address these limitations by enabling flexible use of wireless sensing signals transmitted by wireless devices and access devices, optionally integrated with communication signaling, to dynamically support positioning, mobility prediction, and access device selection. By activating sensing functionality selectively, adapting sensing frequency in critical areas, and using sensing-aware first messages to wake up or configure network elements, the proposed techniques improve the accuracy and timeliness of mobility decisions while reducing unnecessary sensing activity. The technical effect includes enhanced handover robustness, improved positioning and trajectory awareness, tighter integration of sensing and communication, and significantly improved energy efficiency at both the network and device levels.

[0507] In an embodiment, the wireless device may send a signal (first message). This signal may include a token to identify the signal and / or a timestamp, indicating when the signal was sent. One or more access devices may measure the received signal, e.g., signal strength and / or note the time of arrival of the signal, and / or the received frequency, and may infer / derive other parameters based on said measurements. For instance, they may infer the propagation delay from the wireless device to the access device as the difference between the time of arrival and the time of sending. Forinstance, they may infer the difference of propagation delays as the difference of the times of arrival. For instance, they may infer the frequency difference of the received signal (first message). The network may select one or more selected access devices in a second group of access devices. The network may now configure multiple access devices to perform a wireless procedure, e.g., a joint / coherent transmission by sending data to the wireless device in a coherent manner, by adapting, e.g., delaying or adapting the transmission frequency, their transmissions in accordance with the propagation delays / frequency differences such that the data sent by each access device arrives simultaneously at the wireless device and in a coherent manner.

[0508] In an embodiment of the invention that may be combined with other embodiments or used independently, the wireless device transmits a first message, e.g., a preamble, that is received by a first access device in a first group of access devices at time tl and a second access device in the first group of access devices at time t2. The first and second access devices may measure other parameters such as the received frequency (e.g., fl and f2) and / or signal strength. The first and second access devices are synchronized, e.g., in time and / or frequency. The first and second access devices may determine the difference of the propagation times from wireless device to access devices as tl -t2, or the difference in the received frequencies as fl - f2. One of the access devices (e.g., the first access device) may act as master and use a reference transmission / frequency. The second access device may adapt its timing / frequency accordingly. Additionally or alternatively, there may be a coordinating entity in that may coordinate one or more (selected) access devices and may assign frequencies.

[0509] These measurements and / or correction factors may also be required when performing a subsequent wireless procedure, e.g., wireless sensing.

[0510] In an embodiment of the invention that may be combined with other embodiments or used independently, in bistatic wireless sensing, knowing the frequency offset fl-f2 can allow correcting a position error.

[0511] For instance, the wireless device may transmit a first message, and the one or more access devices in the first group of access device may determine the reception time, for instance, three access devices may determine as reception times tl, t2, and t3. Pairs of access devices may obtain the difference of the arrival times tl-t2, t2-t3, and t3-tl allowing the first group of access devices to determine the (rough) location of the wireless device since those time differences are related to the difference of the distances from the access devices to the wireless device, e.g., if dl and d2 are the distances from the first and second access devices to the wireless device, then tl-t2 = (dl-d2) / c.

[0512] In an embodiment of the invention that may be combined with other embodiments or used independently, if the location of the wireless device is determined based on the first messagetransmitted by the wireless device, the one or more access devices in the first group of access devices may determine the timing advance parameter applicable to the communication with the wireless device with and / or through one or more selected access devices in a second group of access devices. For instance, if it is determined that a given access device is the best one to handle the required service, and the position of the given access device is known, and the position of the wireless device is known, the timing advance value can be provided to the wireless device, e.g., by the given (selected) access device. This embodiment enables precise synchronization and optimized resource allocation among access devices, resulting in improved sensing accuracy and reduced energy consumption.

[0513] In an embodiment of the invention that may be combined with other embodiments or used independently, given the location of the wireless device, at least a selected (or one or more selected) access device(s) in a second group of access devices may be selected. These one or more selected access devices in the second group of access devices may perform wireless sensing, e.g., to perform tracking of the wireless device and / or subject carrying it. The knowledge of the location of the one or more access device and the (rough) location of the wireless device based on the initial first message transmission can be useful, e.g., to obtain a rough estimate of when a reflected wireless sensing signal will arrive. For instance, consider a setting with two access devices and the rough distance estimation from the first access device to the wireless device is dl and the rough distance estimation from the second access device to the wireless device is d2, then in the case of monostatic sensing, the first (or second) access device knows that the reflected sensing signal will arrive roughly 2*dl / c (or 2*d2 / c) after the transmission of the sensing signal. In the case of bistatic sensing, if the first access device acts as transmitter, then the second access device knows that the reflected sensing signal will arrive roughly (dl+d2 / c) after the sensing signal is transmitted. This embodiment enables accurate synchronization and efficient allocation of communication and sensing resources, thereby improving overall system performance and reducing energy consumption.

[0514] In an embodiment of the invention that may be combined with other embodiments or used independently, the timing of the certain operations may be synchronized and / or optimized based on the rough / known location of the target wireless device. For instance, one or more selected access devices in a second group of access devices may be used to perform a certain wireless procedure, e.g., a wireless sensing procedure. These one or more selected access devices may be access devices 800-1, 800-2 and 800-3 as per Fig. 8 and may be used to perform wireless sensing of wireless device 803, e.g., a car, to track its position. There are multiple ways of performing such a wireless procedure:All three access devices may be active and determine the position since the distances from access device to wireless devices are known;

[0515] Only one access device may be active and determine the position since the distance from the access device to wireless device is known, and angle can be determined via beam sweeping; Monostatic / multi-static sensing can be used.

[0516] How many selected access devices are in the second group of access devices, which ones are the selected access devices, and what their roles and configuration need to be determined, and this is a matter of optimization, e.g. to reduce energy consumption or resource (e.g., bandwidth) consumption. In an example, a central controller (e.g., 802 in Fig. 8) in the RAN or in the core network may determine the most suitable configuration. The central controller may receive measurements (e.g., of an initial first message transmitted by the wireless device as received by the access devices), and the central controller may distribute a suitable configuration. Next, some examples of suitable configurations are illustrated.

[0517] In an example, the beam sweeping schedules of two access devices (ADI, e.g., 800-1 in Fig. 8 and AD2, e.g., 800-3 in Fig. 8) acting as transmitters are synchronized to reduce interference and / or energy consumption, e.g., at the receiving access device(s) (e.g., AD3, e.g., 800-2 in Fig. 8). For instance, consider that the distances from AD1 / AD2 / AD3 to wireless device are dl / d2 / d3 and consider that dl + d3 = d2 + d3. To avoid interference at the receiving access device (AD3) and reduce energy consumption,

[0518] ADI may need to start transmission (dl + d3) / c time units (or a number related or proportional to it) before the required reception time slot by AD3;

[0519] AD2 may need to start transmission once ADI has finished (if the same bandwidth part is used) plus a guard time.

[0520] This allows adapting the transmission time to avoid interferences at reception while reducing the awake time of AD3 to receive the sensing signals.

[0521] In an example, two access devices (ADI and AD2) act as transmitters towards an access device AD3 acting as receiver. ADI and AD2 may be able to start transmission simultaneously if ADI and AD2 use different bandwidth parts (in other words, the wireless sensing signals are frequency multiplexed), and AD3 is capable of processing both incoming wireless sensing signals simultaneously. This allows reducing the transmission time and synchronized reception.

[0522] In an example, two access devices (ADI and AD2) act as transmitters towards an access device AD3 acting as receiver. Beam sweeping of ADI and AD2 may be time / frequency multiplexed, e.g., ADI may transmit a first sensing signal via a first beam (e.g., 801-1-1) at time t (e.g., dl+d3 / c time units before the reception time slot by AD3), then (after a time guard) AD2 may transmita second sensing signal via another beam (e.g., 801-2-1), then (after a time guard) ADI may transmit a further sensing signal via a another beam (e.g., 801-1-2), etc. The beam sweeping procedure may stop once enough measurements are collected.

[0523] In an example, wireless sensing may be performed by increasing the bandwidth of the wireless sensing signal in subsequent repetitions of the wireless sensing procedure. This allows increasing the resolution (e.g., position accuracy) until a certain resolution is achieved. This configuration is suitable when a low QoS is required, e.g., when low / medium accurate positioning is required and certain latency is tolerable.

[0524] In an example, wireless sensing may be performed by decreasing the bandwidth of the wireless sensing signal in subsequent repetitions of the wireless sensing procedure. This allows achieving a high resolution (e.g., position accuracy) very fast (at the price of higher resources). This configuration is suitable when a high QoS is required, e.g., when highly accurate positioning is required with no latency.

[0525] In an example, the configuration that is selected may depend on the QoS requirements of the wireless sensing procedure.

[0526] In an example, which access devices are selected may depend on the selected configuration, so that the selected access devices may perform the wireless sensing procedure according to said configuration.

[0527] In an example, the configuration may include the number of beams, and / or angles of the beams when performing beam sweeping, e.g., a first access device (e.g., ADI, e.g., 800-1 in Fig. 8) may transmit sensing signals through one or more N beams forming a first angle alpha, and a second access device (e.g., AD2, e.g., 800-3) may transmit one or more M beams forming a second angle beta. This allows setting N different from M, e.g., N = 3 and M = 1. This allows setting alpha different from beta, e.g., alpha is greater than beta. This may allow adjusting the resolution that is feasible by different access devices. For instance, if an access device is close to the wireless device, it may be useful to use multiple beams with a greater angle between them, while if an access device is far from the wireless device, it may be sufficient to use a single beam.

[0528] In an example, a wireless device may act as transmitter and an access device may act as receiver. The sensed object may be at a distance dl from the wireless device and at a distance d2 from the access device. In order to avoid interferences at the receiver, the wireless device may need to transmit the wireless sensing signal (dl+d2) / c time units (or a time proportional to it, and / or with a certain guard time) before the expected / allocated reception slot. This value (or similar values in other examples) can be denoted as a timing advance parameter of the reflected wireless sensing signal.In an example, the timing advance parameter of the reflected wireless sensing signal may be unknown or approximate. For instance, in previous example, (dl+d2)c may be based on a previous measurement or position estimate. However, if the sensed object moves, this value may not be correct. Thus, the transmitted sensing signal may be transmitted Th time units later than expected. In previous example, this would be: (dl+d2) / c - Th. In this way, even if the sensed object moves closer to the access devices, the reflected wireless sensing signal will not interfere in a negative manner. Th is a guard time that may be configurable and may depend on the properties of the sensed object (e.g., speed), quality of service of the sensing procedure, accuracy of the sensing procedure, etc.

[0529] Section: mobility and seamless cell-free MIMO between TRPs in a cell-free system

[0530] Mobility in cell-free and multi-TRP deployments raises a distinct set of challenges compared to conventional single-cell handover, because a moving wireless device may be served by multiple transmission reception points (TRPs) under coordination of a common controller while resources, beams, carriers, and even control channels are dynamically re-assigned. In such environments, "break-before-make" transitions and uncoordinated additions / releases can cause user-plane interruption, control-plane discontinuities, collisions (e.g., between control and shared channels), and degraded MIMO / coherent combining performance, particularly when different TRPs operate on different carriers or numerologies. The embodiments described herein address these issues by enabling a coordinated "make-before-break" mobility procedure in which communication resources from a second (selected) TRP— such as beams, antenna elements, and / or carrier resources— are added and stabilized (including, in some examples, establishing a second control channel) before releasing corresponding resources at the first TRP, under centralized timing / frequency / beam coordination. The technical effect is seamless service continuity with improved robustness and throughput during movement, while reducing interruption risk and coordination overhead.

[0531] Fig. 14 describes an embodiment of the invention that may be combined with other embodiments or used independently, this figure may schematically illustrate a cell-free cellular system with three TRPs 1400-1, 1400-2, and 1400-3 controlled by a central unit 1402. The wireless device 1403 moves from an initial location (Location 1) to a second location (Location 2) to a final location (Location 3). At location 1, wireless device 1403 connects to the first TRP 1400-1. At location 2, wireless device is connected to both the first and second TRPs 1400-1 and 1400-2. At location 3, wireless device is connected to the second TRP and third TPR 1400-2 and 1400-3. The connection via the TRPs the wireless device is connected to may be based on (single-TRP) MIMO (e.g., at location 1) or via multi-TRP MIMO (e.g., at locations 2 and 3). When moving between locations, new beams / antennas are enabled (from the newTRPs that are within communication range) before disabling beams / antennas (from TRPs that are not within communication range anymore).

[0532] Fig. 15 describes an embodiment of the invention that may be combined with other embodiments or used independently, this figure schematically illustrates a mobility procedure for a wireless device 1403 in a cell-free cellular system comprising three TRPs (1400-1, 1400-2, 1400-3) controlled by a central unit 1402, as in Fig. 14. The procedure enables seamless communication as the wireless device moves between locations, by dynamically aggregating and releasing communication resources from different TRPs. Fig. 15 describes a procedure that may comprise multiple steps. The steps in the figure are described below. It is to be noted that not all of the steps may be required:

[0533] Step 1500 (Synchronization signals from TRP 1400-1):

[0534] At Location 1, the wireless device 1403 may receive synchronization signals from the first TRP 1400-1 and / or transmit reference signals to TRPs. These signals enable the wireless device and / or TRPs to synchronize, determine the best TRPs, and prepare for initial access. These signals may also be used to estimate channel state information for the first uplink transmission of the initial access.

[0535] Step 1501 (Random Access Channel (RACH) procedure with TRP 1400-1): The wireless device 1403 may perform a random access procedure with the first TRP 1400-1 to establish a connection and obtain initial communication resources.

[0536] Step 1502 (Channel State Reference Signals (CS-RS) from TRP 1400-1): The wireless device may receive channel state reference signals from the first TRP 1400-1, which are used for channel estimation and link adaptation. These reference signals, e.g,. channel state reference signals, may be commonly configured in the access device, e.g., serving cell, for all UEs in the cell, or dedicated configuration for individual UEs.

[0537] Step 1503 (MIMO Data with TRP 1400-1): The wireless device may exchange MIMO data with the first TRP 1400-1 using the allocated resources.

[0538] Step 1504 (Synchronization signals from TRP 1400-2): nAs the wireless device may move towards Location 2, it begins to receive synchronization signals from the second TRP 1400-2, in addition to those from the first TRP. Additionally, or alternatively, it may transmit first signals (e.g., preamble, SRS, etc) that may allow the TRPs to determine which TRPs should be involved in further communication.

[0539] Step 1505 (Channel State Reference Signals (CS-RS) from TRP 1400-2): The wireless device may receive channel state reference signals from the second TRP 1400-2, enablingit to estimate the channel and prepare for resource aggregation. These channel state reference signals may be commonly configured in the serving cell for all UEs.

[0540] Step 1506 (Multi-TRP MIMO Data with TRP 1400-1 and TRP 1400-2): The system may perform carrier aggregation, e.g., by adding communication resources from the second TRP 1400-2 before releasing resources from the first TRP 1400-1. The wireless device may communicate using multi-TRP MIMO, leveraging resources from both TRPs under the coordination of the central unit 1402.

[0541] Step 1507 (Synchronization signals from TRP 1400-3): As the wireless device moves towards Location 3, it may receive synchronization signals from the third TRP 1400-3, in addition to those from the second TRP. Additionally, or alternatively, it may transmit first signals (e.g., preamble, SRS, etc) that may allow the TRPs to determine which TRPs should be involved in further communication.

[0542] Step 1508 (Channel State Reference Signals (CS-RS) from TRP 1400-3): The wireless device may receive channel state reference signals from the third TRP 1400-3, enabling further channel estimation and preparation for resource aggregation.

[0543] Step 1509 (Multi-TRP MIMO Data with TRP 1400-2 and TRP 1400-3): The system may add communication resources from the third TRP 1400-3 before releasing resources from the second TRP 1400-2. The wireless device may communicate using carrier aggregation / multi-TRP MIMO with both the second and third TRPs, ensuring uninterrupted service.

[0544] Throughout this procedure, the addition of new communication resources from a target TRP (steps 1506, 1509) is always performed prior to the release of resources from the source TRP, thereby ensuring uninterrupted service and robust mobility support. The communication resources may comprise one or more of: a first beam from the first TRP, a second beam from the second TRP, first frequency resources in a first frequency band allocated by the first TRP, and second frequency resources in a second frequency band allocated by the second TRP. The coordination of resource aggregation and release is managed by the central unit 1402, which controls all TRPs.

[0545] This procedure provides a method for communicating with a wireless device in a cell-free system, wherein the wireless device is adapted to communicate while moving from a first TRP to a second TRP, and wherein carrier aggregation is performed by adding communication resources from the second TRP before releasing communication resources from the first TRP. The described method is applicable when the first TRP and the second TRP are controlled by a common central unit, asillustrated in Fig. 15. Carrier aggregation means that different TRPs may be in charge of different carriers, all in the same cell.

[0546] In a related embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may report measurements of a received reference signals (e.g., of synchronization signals, SSBs, CS-RS) received from a second access device / second TRP to a first access device / first TRP. The first access device / first TRP may then coordinate with the second access device / second TRP to trigger, e.g., the transmission of other reference signals (e.g., CS-RS) and / or start communication with the wireless device. For instance, if the first access device / TRP (or a central unit controlling it) determines that the wireless device is approaching the second access device / TRP, the central unit may request the second access device / TRP to transmit certain reference signals, e.g., synchronization signals and / or channel-state reference signals.

[0547] In a related embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may send a measurement report that may indicate that a second access device (e.g, 1400-2) may be a suitable candidate. This measurement report may be sent to the first access device. The transmission of the measurement report with such condition may also trigger the transmission by the wireless device of a first message, e.g., a preamble and / or sounding reference signal so that one or more second access device evaluate the mobility conditions, e.g., indicate a suitable (selected / second) access device to connect to.

[0548] In a related embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may use a fixed number of resources, e.g., a number of beams, a given bandwidth size, a number of antenna elements, etc. These communication resources may be shared with one, two, ...., up to Z access devices according to a first configuration. For instance, in an NxM MIMO configuration in which the wireless device has N antenna elements and the TRPs can have up to M antenna elements, if the wireless device performs MIMO with a single TRP, the wireless device can use up to N x M antennas. In an example, if the wireless device performs MIMO with two TRPs, the network (e.g., a central unit controlling the TRPs) may determine that the wireless device uses e.g., N1 antennas with the first TRP and N2 antennas (e.g., N2=N-N1) with the second TRP, and the first TRP uses up to Ml antenna elements and the second TRP uses up to M2 antenna elements, e.g., M2=M-M1.In an embodiment of the invention that may be combined with other embodiments or used independently, the adding and / or releasing of communication resources may be triggered by measurement conditions, e.g., a measurement performed at LI, e.g., an indication that a second access device (TRP) may be better than the first access device (TRP). The activation / deactivation of resources may be confirmed by sending (or receiving) a LI / L2 message (e.g., DCI message, UCI message, or MAC CE). The activation / deactivation may also be conditional to a time-to-trigger, a location, or a measurement.

[0549] In an embodiment of the invention that may be combined with other embodiments or used independently, the "first frequency resources" and "second frequency resources" (i.e., the resources used by two different access devices (e.g., TRPs) or for two different transmissions) are configured with different numerologies. For example, one TRP might use 15 kHz subcarrier spacing, while another uses 60 kHz. Because different numerologies may have different symbol durations and slot timings, their transmissions can overlap or "collide" in time if not properly coordinated. The Central Unit (CU) or controller (e.g., 1402 in Fig. 14) is responsible for coordinating the timing between these different numerologies. It ensures that transmissions from different TRPs (using different numerologies) do not interfere with each other."

[0550] In an embodiment of the invention that may be combined with other embodiments or used independently, the first and second access devices(TRPs), e.g., 1400-1 and 1400-2 may provide connectivity to wireless device 1403 in Fig. 14. The beams from both access devices, e.g., 1401-1-2 and 1401-2-1, and / or the beams of wireless device (e.g., 1405-1 and 1405-2) may be configured with a wider angle than a threshold to improve reliability when / while wireless device moves, e.g., while / when gets connected to the second access device 1400-2. For instance, when a wireless device is connected to a single access device, e.g., 1400-1, the beam angle may be narrow(er), while during the addition and removal of resources the beam angles may need to be larger than a threshold. The central controller may control multiple configuration parameters and configure them in the wireless device (e.g., 1403), e.g., the beam widths, timing to make them wider or narrower.

[0551] In a related embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may be connected / communicate through two or more access devices / TRPs, e.g., at location 2, wireless device 1403 communicates via 1400-1 and 1400-2. In this case, wireless device may perform multi-TRP MIMO and demodulation reference signals (DM-RS) signals from both access devices may be aligned to maintain coherent demodulation.This allows estimating the channel from both access devices / TRPs and combine the signals coherently.

[0552] In a related embodiment of the invention that may be combined with other embodiments or used independently, the central unit (e.g., 1402 in Fig. 14) may transmit a configured grant (e.g., via RRC signaling) scheduling resources (e.g., periodic resources) for one or more access devices (e.g., first and / or second access devices) wherein some of the second scheduled resources for one or more second access devices may be scheduled later in time that the first scheduled resources for one or more first access devices. For instance, wireless device may receive a configuration to communicate at time to, tl=tO*k,...,tn=tO+n*k with a first access device (e.g., 1400-1) and at times t3 = t0+3k, ..., tn=tO+n*k,..., tm= t0+m*k with a second access device (e.g., 1400-2). This allows orchestrating the communication with different TRPs. The configuration grant may be exchanged in an efficient manner, e.g., by including the configurations in the same message, and / or providing a configuration for a second access device that is a delta configuration with respect to the configuration with the first access device.

[0553] In a related embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may add communication resource from a second access device / TRP (e.g., 1400-2 in Fig. 14) while still communicating with a first access device / TRP (e.g., 1400-1 in Fig. 14) while moving. For instance, the second access device may be assigned a second frequency band (a range of frequencies, e.g., a first bandwidth part, e.g., a first carrier), and the second access TRP may enable the communication using the second frequency band, e.g., a second bandwidth part, e.g., a second carrier. This approach allows for seamless mobility of the wireless device.

[0554] In a related embodiment of the invention that may be combined with other embodiments or used independently, the control messages (e.g., RRC messages, MAC CE messages, DCI / UCI messages) controlling the operation of the wireless device may be transmitted via a single access device / TRP even if the wireless device is connected to two or more access devices / TRPs. For instance, at Location 2 in Fig. 14, RRC messages may be exchanged via access device 1400-1 (that is the source access device). This is because all those devices belong logically to the same cell and are centrally coordinated.In a mobility event, once the user data starts being transmitted from the second access device / TRP, the entity handling control messages (e.g., RRC, MAC CE, ... messages) will change, e.g., from the first access device / TRP (e.g., 1400-1 in Fig. 14) to the second access device / TRP (e.g., 1400-2 in Fig. 14).

[0555] This and other embodiments may be illustrated by means of Fig. 16. This figure schematically illustrates a mobility procedure for a wireless device 1403 in a cell-free cellular system comprising three TRPs (1400-1, 1400-2, 1400-3) controlled by a central unit 1402. The procedure enables seamless communication as the wireless device moves between locations, by dynamically relocation the data and control planes.

[0556] For instance, while at location 1, wireless device 1403 performs data transmission 1600 and control channel 1601 via 1400-1.

[0557] For instance, when wireless device moves to location 2, wireless device may add data links 1603 via 1400-2, add control 1604 via 1400-2, and only then release control 1605 from 1400-1, and data 1606 from 1400-1.

[0558] For instance, when wireless device moves to location 3, wireless device may add data links 1607 via 1400-3, add control 1608 via 1400-3, and only then release control 1609 from 1400-2.

[0559] In an example, the control channel at a higher protocol layer, e.g., RRC, remains stable, and the addition / removal of control (e.g., 1604 and 1605) may refer to layer 1 / layer 2 control channels.

[0560] In an example, a central controller (e.g., 1402) may enforce / configure a minimum overlap time between active control planes / channels.

[0561] For instance, a physical downlink control channel (PDCCH) may be added in step 1604 to exchange DCI messages from 1400-2, and a PDCCH may be removed in step 1605 so that no more DCI messages can be received from 1400-1.

[0562] For instance, MAC CEs that are control messages may be transported via a physical control channel.

[0563] For instance, in Step 1603 a physical downlink shared channel may be established. This even may have been indicated via the control channel in 1601.

[0564] At some point of time (in step 1604), it may be indicated (e.g., via RRC or L2 or LI signalling) via 1601 that the same PDSCH of step 1603 may be used to receive control messages, e.g., MAC-CEs, from 1400-2.

[0565] In Step 1605, it may be indicated that no further control messages (e.g., MAC CEs exchanged, e.g., via a PDCCH) will be received from 1400-1. This may be indicated via a control message from 1400-1 and / or 1400-2.In a related embodiment of the invention that may be combined with other embodiments or used independently, a second PDCCH (e.g., between second access device and the wireless device) may be established prior to the release of the first PDCCH by configuring a search space set and CORESET associated with the second TRP.

[0566] In some examples, DCI for user-plane scheduling / data transmission is exchanged on the second PDCCH while RRC and / or MAC CE signaling continues on the first PDCCH for a transition interval.

[0567] In a related embodiment of the invention that may be combined with other embodiments or used independently, the split of data channels between wireless device (e.g., 1403) and first and second access devices / TRPs, may be determined by the measurements of reference signals (e.g., LI measurements) and / or the QoS of the communication links between wireless device and access devices / TRPs.

[0568] In a related embodiment of the invention that may be combined with other embodiments or used independently, control information associated to a second access device / TRP (e.g., 1400-2) may be piggy-backed in an existing channel (e.g., PDSCH) instead of setting up a new channel (e.g., PDCCH). In some cases, piggy-backing in an existing channel may be performed for an interval of time after the establishment of the new channel (e.g., PDCCH).

[0569] In a related embodiment of the invention that may be combined with other embodiments or used independently, the second PDCCH may be configured in a second frequency band (e.g., a second bandwidth part / second carrier) than the first PDCCH. Similarly, in some cases, the second PDCCH may be configured in a different frequency band than the first PDCCH, and the wireless device may apply a beam switch according to TCI information provided by the first TRP.

[0570] In a related embodiment of the invention that may be combined with other embodiments or used independently, messages (e.g., MAC-CEs) associated with the second TRP may be carried on PDSCH of the first TRP during the transition.

[0571] In a further example, the CU may select non-overlapping CORESETs and may enforce inter-TRP mute patterns to avoid PDCCH-PDSCH collisions, i.e., periods of time in which some channels are muted to avoid collisions.In some examples, adding communication resources may use a different subcarrier spacing at the second TRP and / or the device may apply timing-advance compensation configured by the central controller.

[0572] In a related embodiment of the invention that may be combined with other embodiments or used independently, a source access device (TRP, e.g., TRP 1400-1 in Fig. 14) to which the wireless device is connected to / communicating through may send TCI information related to other access devices / TRPs, e.g., upcoming beam from TRP 1400-2, to the wireless device so that wireless device may adjust the receiver to receive a beam directly from the access device.

[0573] In a related embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may detect the SSBs from the other access device (TRP, e.g. TRP 1400-2 in Fig. 14), and the SSBs may encode the same PCI as the source access device (TRP, e.g. TRP 1400-1 in Fig. 14). The wireless device may determine the two access devices may belong to the same serving cell and / or carrier, or the wireless device may not be aware the other access device, i.e. TRP 1400-2 is different from the source access device, i.e. TRP 1400-1. The wireless device may apply the beam management procedure to tune the transmission and reception beam towards the beams of the other access device, i.e. TRP 1400-2. By doing this, the wireless device can seamlessly switch from the source access device (TRP 1400-1) to the target access device (TRP 1400-2).

[0574] In an example, in 5G NR, an access device may broadcast SSBs with a PCI, and there may be up to 64 beams. In a cell-free scenario, 64 beams (beam indexes) for all TRPs in an area may not be sufficient. Thus, multiple PCIs may be associated (e.g., associated PCIs may be distributed in a SIB, e.g., SIB1) may comprise a cell-free cell. In an example, beam indexes may be reused in different areas.

[0575] In a related embodiment of the invention that may be combined with other embodiments or used independently, the wireless device may detect the SSBs from the other access device (TRP, e.g. TRP 1400-2 in Fig. 14), and the SSBs may encode the different PCI as the source access device (TRP, e.g. TRP 1400-1 in Fig. 14). The wireless device may determine the two access devices may belong to the different serving cells and / or carriers. The wireless device may be configured by the network to operate in a cell-free operation mode and may have a configuration of a list of PCIs of the serving cells which can be considered for the wireless device to belong to for the cell-free operation.The wireless device may select an access device whose SSBs encode a PCI that is in its cell-free configuration.

[0576] In one embodiment, the wireless device may report the measurements to the source access device of Ll-RSRP of beams of both the source access device and the other access device. The source access device (or the central controller (e.g., 1402 in Fig. 14) may then determine the wireless device is leaving from the coverage of the source access device (as Ll-RSRP of the beams of the source access device is getting smaller) and is moving into the coverage of the other access device (as Ll-RSRP of the beams of the other access device is getting bigger). The source access device may start the cell-free beam management procedure, and communicate (directly or indirectly) with the other access device about the best beams and pre-allocated resources for the wireless device to use for the first initial uplink transmission of the wireless device to the other access device. Then the source access device may send a cell-free beam change command to the wireless device to instruct the wireless device to switch to the beams of the other access device with the pre-allocated resources for the first initial uplink transmission to the other access device. The source access device may also ask the other access device to configure a set of SSBs and / or CSI-RS for the wireless device to use to acquire the channel state information.

[0577] In another embodiment, the wireless device may be configured with the configuration for the access to the other access device (TRP 1400-2). The wireless device may measure the Ll-RSRP of beams from both the source access device (TRP 1400-1) and the other access device (TRP 1400-2), and may determine the Ll-RSRP of the source access device's beams is getting smaller and the Ll-RSRP of the other access device's beams is getting bigger. The wireless device may be configured with some conditions and the some condition may be triggered so that the wireless device may start the wireless device initiated cell-free switch procedure to switch to the other access device by tuning the beams to the best beam towards the other access device. The wireless device may use the preconfigured resources of the other access device (e.g. configured grants) and / or random access procedure if no pre-configured resource is available for access to the other access device. In the cell-free operation mode, the wireless device may be configured with an option to reuse the security credentials with the source access device. Or a security credentials may be configured on the wireless device specifically for the cell-free operation, so that the security credentials do not need to change when the wireless device moves across the TRPs which may belong to the different serving cell / carrier but configured for the cell-free operation, i.e. those TRPs may comprise of a "virtual" cell from the logical perspective.In a related embodiment of the invention that may be combined with other embodiments or used independently, the position of a wireless device may be tracked passively, e.g, via wireless sensing signals. This may allow a first access device (e.g., 1400-1 in Fig. 14) to determine that the wireless device is moving towards a second access device (e.g., 1400-2 in Fig. 14). This may allow the first access device to configure wireless device with, e.g., TCI information about the second access device.

[0578] In general, in a first clause, it is described a method that is schematically illustrated by means of Fig. 17, the method for operating a wireless device, wherein the wireless device communicates while moving from a first TPR (or a first group of TRPs) to a second (or selected) TRP controlled by a common or shared controller unit (CU), wherein the method comprises:

[0579] adding (second) communication resources from the second (or selected) TRP (1700); before releasing (first) communication resources from the first TRP (1701) (or first group of TRPs). In general, in a second clause, it is proposed the method of Clause 1, wherein the communication resources comprise one or more of:

[0580] a first beam from the first TRP;

[0581] one or more antenna elements from the first TRP;

[0582] a second beam from the second TRP;

[0583] one or more antenna elements from the second TRP;

[0584] first frequency resources in a first frequency band allocated by the first TRP; second frequency resources in a second frequency band allocated by the second TRP. In general, in a third clause, it is proposed the method of any of the preceding clauses, wherein the wireless device communicates by performing one or more of:

[0585] - MIMO from the first TRP before adding communication resources from the second TRP;

[0586] - multi-TPR MIMO from the first and second TRPs before releasing communication resources from the first TRP;

[0587] - carrier aggregation via the first and second TRPs before releasing communication resources from the first TRP. In general, in a fourth clause, it is proposed the method of any of the preceding clauses, wherein the wireless device communicates by establishing a second physical downlink control channel with the second TRP before releasing a first physical downlink control channel with the first TRP. In general, in a fifth clause, it is proposed the method of Clause 1, wherein the first and second TRPs are controlled by a common or shared central unit (CU) that coordinates timing, frequency, and beam assignments to the wireless device. In general, in a sixth clause, it isproposed the method of Clause 1, wherein adding communication resources from the second TRP comprises activating a beam of the second TRP before deactivating a beam of the first TRP. In general, in a seventh clause, it is proposed the method of Clause 1, wherein adding communication resources from the second TRP comprises allocating downlink shared channel resources (PDSCH) and uplink shared channel resources (PUSCH) from the second TRP while maintaining ongoing PDSCH and / or PUSCH at the first TRP. In general, in a eighth clause, it is proposed the method of Clause 1, wherein the adding and releasing are ordered by layer such that data-plane resources are added first, followed by control-plane resources, prior to any release at the first TRP. In general, in a ninth clause, it is proposed the method of Clause 1, wherein the wireless device transmits an uplink reference signal (e.g., preamble, or SRS) that is used by the first and / pr second TRPs to determine channel state for multi-TRP operation during the addition. In general, in a tenth clause, it is proposed the method of Clause 1, wherein the adding comprises configuring a multi-TRP coherent transmission and applying per-TRP timing and / or frequency corrections derived from the received uplink reference signal. In general, in a eleventh clause, it is proposed the method of Clause 1, wherein the adding comprises allocating frequency resources in a second frequency band distinct from a first frequency band allocated by the first TRP, and the releasing comprises de-allocating the first frequency band only after user-plane traffic has migrated to the second frequency band. In general, in a twelfth clause, it is proposed the method of Clause 1, wherein the wireless device provides measurement reports of synchronization signals and / or CSI-RS received from the second TRP to the first TRP, and the CU triggers the adding based on those reports. In general, in a thirteenth clause, it is proposed the method of Clause 1, wherein the adding is conditionally triggered when a measurement condition is met, the measurement condition comprising a second TRP better than first TRP criterion and / or a time-to-trigger. In general, in a fourteenth clause, it is proposed the method of Clause 1, wherein wireless sensing by one or more TRPs is used to estimate the device trajectory and the adding is scheduled in advance according to the estimated trajectory. In general, in a fifteenth clause, it is proposed the method of Clause 1, wherein the wireless device maintains at least one active data path through one of the TRPs at all times during movement between locations. In general, in a sixteenth clause, it is proposed the method of Clause 2, wherein the number of antenna elements used by the second TRP is selected such that M2 = M - Ml, where Ml is the number of antenna elements used at the first TRP and M is a maximum number of antenna elements supported by the TRPs when communicating with the wireless device. In general, in a 17th clause, it is proposed the method of Clause 2, wherein the wireless device with N antennas is configured to use N1 antennas towards the first TRP and N2 = N - N1 antennas towards the second TRP. In general, in a 18th clause, it is proposed the method of Clause 2, wherein the second TRP is assigned a beamforming codebook index (TCI state)and the first TRP indicates said index to the wireless device prior to the adding. In general, in a 19th clause, it is proposed the method of Clause 2, wherein the first frequency resources and the second frequency resources are located in different numerologies and the CU configures inter-numerology timing to avoid inter-TRP collision. In general, in a 20th clause, it is proposed the method of Clause 2, wherein the first beam and the second beam are selected to produce angular diversity exceeding a threshold to improve link reliability during mobility. In general, in a 21st clause, it is proposed the method of Clause 3, wherein the wireless device transitions from single-TRP MIMO at the first TRP to multi-TRP MIMO across the first and second TRPs, and subsequently to single-TRP MIMO at the second TRP, without interrupting user-plane data. In general, in a 22nd clause, it is proposed the method of Clause 3, wherein carrier aggregation uses the first TRP as a PCell and the second TRP as a SCell until a reconfiguration indicates the second TRP as the PCell. In general, in a 23rd clause, it is proposed the method of Clause 3, wherein during multi-TRP MIMO the wireless device receives co-scheduled PDSCH from both TRPs with aligned DM-RS mapping types to maintain coherent demodulation. In general, in a 24th clause, it is proposed the method of Clause 3, wherein an uplink configured grant is used to sustain uplink transmissions while downlink carrier aggregation is established with the second TRP. In general, in a 25th clause, it is proposed the method of Clause 4, wherein the second PDCCH is established by configuring a search space set and CORESET associated with the second TRP prior to release of the first PDCCH. In general, in a 26th clause, it is proposed the method of Clause 4, wherein DCI for user-plane scheduling is received on the second PDCCH while RRC and / or MAC CE signaling continues on the first PDCCH for a transition interval. In general, in a 27th clause, it is proposed the method of Clause 4, wherein the wireless device is instructed to stop monitoring the first PDCCH via a MAC control element or RRC message after confirmation that the second PDCCH is operational. In general, in a 28th clause, it is proposed the method of Clause 4, wherein at least part of the control information (MAC CEs) destined for the second TRP is piggy-backed on PDSCH addressed by the second TRP after establishment of the second PDCCH. In general, in a 29th clause, it is proposed the method of Clause 4, wherein the second PDCCH is configured in a different frequency band than the first PDCCH, and the wireless device applies a beam switch according to TCI information provided by the first TRP. In general, in a 30th clause, it is proposed the method of any of Clauses 1-4, wherein the first TRP sends TCI information corresponding to an upcoming beam of the second TRP, enabling the wireless device to pre-align reception for the second TRP. In general, in a 31st clause, it is proposed the method of any of Clauses 1-4, wherein uplink SRS-based beam selection by the second TRP is initiated responsive to a measurement report sent to the first TRP. In general, in a 32nd clause, it is proposed the method of any of Clauses 1-4, wherein data-plane addition at the second TRP precedes control-plane addition, and control-plane release at the first TRP precedes data-plane release at thefirst TRP. In general, in a 33rd clause, it is proposed the method of any of Clauses 1-4, wherein a minimum overlap time between active control planes at the first and second TRPs is enforced by the CU. In general, in a 34th clause, it is proposed the method of any of Clauses 1-4, wherein the wireless device is configured with a fixed resource budget comprising at least one of: number of device beams, bandwidth, and number of device antenna elements, and the CU splits said budget between the first and second TRPs during the adding. In general, in a 35th clause, it is proposed the method of any of Clauses 1-4, wherein the split is adaptively re-balanced according to a mobility metric or QoS metric. In general, in a 36th clause, it is proposed the method of any of Clauses 1-4, wherein wireless sensing performed by one or more TRPs determines that the wireless device is moving toward the second TRP, and the adding is pre-scheduled accordingly. In general, in a 37th clause, it is proposed the method of any of Clauses 1-4, wherein the wireless device reports an AI / ML-derived confidence score for its trajectory and the CU adjusts the overlap between first and second TRP resources based on the score. In general, in a 38th clause, it is proposed the method of any of Clauses 1-4, further comprising deriving a lower-layer (L1 / L2) key bound to at least one TCI parameter of the second TRP prior to control-plane relocation. In general, in a 39th clause, it is proposed the method of any of Clauses 1-4, wherein a secure envelope containing mobility credentials for the second TRP is delivered to and forwarded by the device during the adding. In general, in a 40th clause, it is proposed the method of any of clause 39, wherein the validity time of the mobility credentials is checked by the wireless device before activating resources of the second TRP. In general, in a 41st clause, it is proposed the method of any of Clauses 1-4, wherein MAC-CEs associated with the second TRP are carried on PDSCH of the first TRP during the transition. In general, in a 42nd clause, it is proposed the method of any of Clauses 1-4, wherein the adding is triggered by a wake-up signal that causes the second TRP to transmit on-demand synchronization and / or CSI-RS. In general, in a 43rd clause, it is proposed the method of any of Clauses 1-4, wherein the CU pre-computes a two-hop TRP route and a second message indicates the connection order of the next two TRPs. In general, in a 44th clause, it is proposed the method of Clause 43, wherein the second message includes a confidence indicator for the connection order. In general, in a 45th clause, it is proposed the method of any of Clauses 1-4, wherein during adding the CU selects non-overlapping CORESETs and enforces inter-TRP mute patterns to avoid PDCCH-PDSCH collisions. In general, in a 46th clause, it is proposed the method of any of Clauses 1-4, wherein the adding uses a different subcarrier spacing at the second TRP and the device applies timing-advance compensation configured by the central controller.

[0588] Section: verification by the sensed wireless deviceIn some scenarios, a wireless device may wish to receive certain services, e.g., a wireless sensing service. The wireless device may transmit a first message requesting the service. And one or more selected devices in a second group of access devices may be selected to provide said sensing service. A problem arising in this situation is how to verify that the sensed wireless device is the same wireless device that requested the service. This may be applicable, in particular, when wireless devices are deployed in close proximity. It is an aim of the invention to address this problem.

[0589] In an embodiment of the invention that may be combined with other embodiments or used independently, the one or more selected access devices may require the requested wireless device to provide feedback about the subsequent wireless sensing procedure.

[0590] For instance, feedback may consist in providing a confirmation and / or information related to the subsequent wireless sensing procedure so that the one or more selected access device can verify it.

[0591] For instance, the sensing signal may include a code (e.g., in a narrow band signal embedded in the sensing signal), and the wireless device may retrieve the code, and send it to the one or more selected access devices as a confirmation.

[0592] For instance, the sensing signal may follow and / or use randomized parameters, e.g., timing of the sensing signal, frequency band, etc and the wireless device may monitor and / or measure, and report those parameters. Those reported parameters may serve as a confirmation that the right wireless device is monitored / sensed.

[0593] For instance, the wireless device may receive a code from one or more of the (selected) access devices and / or in a first configuration and / or generate a code locally and share it with one or more of the (selected) access devices. The wireless device may transmit said code in (part of) the received wireless sensing signal and / or before / after the received wireless sensing signal. For instance, the code may be transmitted by backscattering the code in the received wireless sensing signal and / or a carrier wave part of the wireless sensing signal. For instance, the code may be actively transmitted after the reception of the wireless sensing signal.

[0594] For instance, the wireless device may indicate, e.g., in the first message, the type of wireless device it is, and / or the type of object / subject that is carrying the wireless device. For instance, if it is a car, it may indicate (explicitly or implicitly) the form factor, material, etc. For instance, if it is carried by a human, it may indicate his height, weight, clothes, etc. This information may be used by one or more selected access devices to verify the identity (type) of sensed object because the form, material, etc affects how a wireless sensing signal is reflected.

[0595] Section: Figure descriptionsFig. 8 schematically illustrates some embodiments of the present disclosure and represents a wireless device 803 moving in direction indicated by arrow 804. Wireless device 803 is surrounded by a number of access devices 800-1, 802-2, and 800-3, some of them distributing synchronization signals through beams 800-1-1, 800-1-2, 800-1-3, 801-3-1, 801-3-2, and 801-3-3. Wireless device 803 may receive a configuration, e.g., via SIB1 from 800-1 indicating that several access devices may be available. Wireless device 803 may send a first message to 800-1 indicating that it is seeking the best access device close to its final destination, e.g., building 805. The network may then determine that, e.g., access device 800-3 is the most suitable one. The network may also determine that beam 801-3-3 is also the most suitable one to perform the random-access procedure and that beam 801-3-1 is the most suitable one for later communication. The selected access device, 800-3 may provide wireless device 803 with a second message (e.g., random access response) indicating, e.g., this information.

[0596] In an embodiment of the invention that may be combined with other embodiments or used independently, a wireless device may transmit a first message indicating its request to the network to identify a preferred access device for further communication. The wireless device may have sent this message to the first access device from which it received some synchronization signals, e.g., wireless device 803 in Fig. 8 may send the first message to access device 800-1 via beam 801-1-1. Access device may then interact with other access devices to determine the most suitable access device, e.g., 800-2 using on-demand SSB / beam 801-2-1. Wireless device 803 may monitor potential responses (a second message) in all directions (i.e., without beamforming). In order to assist the wireless device with determining the best beamforming towards the selected access device, the second message may include assistance information for beamforming towards access device 800-2 via beam 801-2-1. For instance, since wireless device 803 is aware of beam 801-1-2, the assistance beamforming information may relate the relative directions of both beams, i.e., the beam used to transmit the first message and the beam used to receive the second message (and further communication). This can allow the wireless device to adjust beamforming parameters after.

[0597] Fig. 9a schematically illustrates some embodiments of the present disclosure and represents a cell selection procedure wherein 900 represents a wireless device, and 901-1 and 901-2 represent two access devices. The first access device, namely 901-1, may transmit reference signals 902 in a periodic or on demand manner. The reference signals may comprise, e.g., synchronization signals and / or SI Bl. Wireless device 900 may send a first message 903 towards access devices 901-1 and 901-2. Upon reception, access devices interact with each other via signaling 904, e.g., exchangingmeasurements and determining the preferred access device. This preferred access device may be 901-1, that may then send a second message (e.g., random access response) to wireless device 900.

[0598] Fig. 9b schematically illustrates some embodiments of the present disclosure and represents a similar scenario, with the main difference that the first message 903 that is transmitted only reaches access device 901-1. This may happen to prevent access device 901-2 from keeping monitoring resources / transmissions. Once the first access device 901-1 receives a transmission (e.g., the first transmission) of the first message, first access device 901-1 may inform access device 901-2, e.g., via an interface between access devices, to trigger the monitoring of the first message 903, e.g., during a time window.

[0599] Fig. 11 schematically illustrates some embodiments of the present disclosure and represents a mobility scenario in which wireless device 1100, currently connected to access device 1101-1, evaluates a handover to potential target access devices 1101-2 and 1101-3. In step 1102, the SOURCE access device 1101-1 may send a message including a first configuration that may determine, e.g., potential target devices 1101-2, 1101-3, and others. It may also include conditions to perform the handover. Upon evaluation of this configuration, wireless device 1100 may determine a first message and may transmit such a first message. This first message may be, e.g., a preamble or Msg3 in a random-access procedure, or the initial message in a RACH-less procedure, etc. This first message may be addressed to potential target access devices 1101-2 and 1102-3 since at this stage it may not be fully clear for wireless device 1100 which of the potential target access devices is the preferred one. Both potential target devices may perform a communication exchange, e.g., 1104, e.g., exchanging measurements of the received message 1103 and may determine which of them should take over the communication with wireless device 1100. In this exemplary figure, only access device 1101-2 takes over, so that access device 1101-2 sends a second message 1105 indicating that further communication will happen through / with it.

[0600] Fig. 12 schematically illustrates some embodiments of the present disclosure and represents a mobility scenario in which wireless device 1200, currently connected to access device 1201-1, evaluates a handover, e.g., an LTM handover, to potential target access devices 1201-2 and 1201-3. Entity 1202 represents an access device and / or the radio access network, and / or the core network.

[0601] In step 1203, wireless device 1200 may be configured with an AI / ML model that may be used by the wireless device to infer the accuracy of a prediction and / or a choice. In an example, it refers to an indication transmitted by the wireless device wherein the indication indicates which are the preferred target access devices. In an example, it refers to the accuracy of assistance information provided by the wireless device to help determining the preferred target access device.In step 1204, wireless device may receive a configuration from current source access device 1201-1. This configuration may include conditions to perform a conditional handover, e.g., a conditional LTM handover in which the configuration may include information about potential target beams and conditions to select certain target beams.

[0602] Upon reception of the configuration, wireless device 1200 may keep evaluating the handover conditions. Wireless device may also keep evaluating how accurate the assistance information is, e.g., how accurate the predicted trajectory (part of the assistance information) is.

[0603] In step 1205, wireless device 1200 may transmit a first message indicating the need to perform a handover. Wireless device may determine one, two, or more potential target access devices for the next hop, and / or the next next hop. Message 1205 may reach, e.g., access devices 1201-2 and 1201-3 directly. Message 1205 may reach, e.g., access device 1201-2 and access device 1201-2 may forward this first message 1205' to access device 1201-3. This first message 1205 / 1205' may include the preferred target access devices, and an indication on how accurate the prediction of the preferred access device and / or assistance information is.

[0604] In step 1206, access devices 1201-2 and 1201-3 may interact to determine the preferred access device that should act as the next target access device, and potentially the next next access device.

[0605] In step 1207, the preferred access device 1201-2 may respond to the wireless device with a second message.

[0606] Fig. 13 schematically describes a deployment scenario used to illustrate some embodiments of the present disclosure. In Fig. 13, 1300 represents a wireless device at three times / locations, namely (time, position): (tO,pO), (tl,pl), and (t2,p2). Devices 1301-1, 1301-2, 1301-3, 1301-4 represent access devices that may distribute a first configuration. Devices 1302-k with k from 1 to 11 represent access devices that may provide different services, e.g., communication, sensing, etc.The total area is divided into three subareas 1303-1, 1303-2, and 1303-3. The first two subareas are overlapping and share some access devices (1301-2, 1302-4, and 1302-3). The third subarea is not overlapping. Finally, Fig. 13 shows that wireless device 1300 has established different links / exchanges data / signals with different access devices at different times / positions:

[0607] (to, pO): wireless device 1300 interacts with access device 1302-4 via link 1304-1, i.e., access device 1302-4 is the selected access device of a second group of access devices.

[0608] (tl, pl): wireless device 1300 interacts with access devices 1302-4, 1302-5, and 1302-7 via links 1304-2, 1304-4, and 1304-3, respectively. In this case, access devices 1302-4, 1304-5, and 1304-7 are the selected access devices in a second group of access devices.

[0609] (t2, p2): wireless device 1300 interacts with access device 1302-11 via link 1304-5.Finally, all access devices may be coordinated by a central unit or a network function in the core network, not shown in the figure.

[0610] When wireless device 1300 is at (tO,pO), wireless device may receive a first configuration (e.g., SIB1) via 1301-1. This first configuration may be used by wireless device 1300 to send a first message in subarea 1303-1 to determine the best access device. The first message may be received by one or more of the access devices in the subarea and the network may then determine that the best access device is 1302-4. This access device may then reply with a second message indicating it is the selected device.

[0611] When wireless device 1300 is at (tl,pl), wireless device may receive a first configuration (e.g., RRC) via 1302-4 or SIB1 via 1301-1. Wireless device 1300 may require additional services, e.g., positioning services. Wireless device may send an additional first message indicating, e.g., the need of wireless sensing-based positioning service, and as response two additional access devices 1302-5 and 1302-7 may provide wireless sensing services to locate wireless device 1300. Simultaneously, wireless device may further receive communication services.

[0612] It is observed that because of the overlap in the access devices between subareas 1303-1 and 1303-2, a link can remain active at any point of time, so that this represents a mobility scenario in which handovers are done in a very soft manner. Such a soft handover may be a type of L1 / L2 triggered mobility procedure, with the additional feature that a communication path (through an access device) always remains active reducing the chances of severe interruption.

[0613] When wireless device 1300 wishes to move to (t2,p2), a harder handover may be required, e.g., because the transition from one subarea (and its access devices) to the adjacent subarea (and its access devices) is less coordinated / does not share common access devices, so that all connections in access devices in subarea 1303-2 need to be moved to the access devices in subarea 1303-3. This type of harder handover may be a type of 5G LTM handover, or Xn / N2 handover procedures.

[0614] Section: Application to certain scenarios

[0615] In some scenarios, it is envisioned a "Perch / Anchor / Data" architecture. Perch cells handle the behavior / resources for searching the cellular network (e.g., initial access on sync raster), anchor cells define the behavior / resources for idle state (e.g., RACH, paging, C-plane, etc on P-Cell), and data cells handle resources for the connected state.

[0616] In the context of such a scenario, a "Perch cell" may correspond to an access device in this invention receiving the first message. The "Perch cell" may then identify the best "Anchor cell" to handle further communication process, e.g., the remaining random-access procedure, wherein, e.g.,a selected anchor cell may then send a second message (e.g., as in other embodiments of the present disclosure). In some cases, the "Anchor cell" may send the second message indicating one or more selected access devices, and the selected access devise may be "Data cells".

[0617] In the context of such a scenario, a first "data cell" may correspond to an access device in this invention providing a first configuration to a wireless device. The wireless device may send a first message towards one or multiple other TARGET "data cells" to further determine the selected "TARGET cell" in a mobility procedure.

[0618] In an embodiment that may be combined with other embodiments or used independently, a wireless device may have already accessed the network and be in an IDLE or INACTIVE state. In this state, the device may determine that its last (anchor) cell is not suitable, and it may prefer to perform a re-selection process. In this case, the wireless device may perform the reselection process by transmitting a new first message towards a first access device. This first message may include an indication (e.g., one time term identifier similar to l-RNTI) that may allow the first access device receiving it to identify the context of the access device. The wireless device may also indicate the cause for performing the re-selection procedure so that the network can take this information into account.

[0619] In an exemplary embodiment of this invention, a wireless device may transmit a reference signal so that the access devices assess the channel may be used in a cell-free cellular system. In a cell-free cellular system, multiple access devices (e.g., TRPs) may coordinate themselves to perform MIMO for wireless sensing and / or integrated sensing and communication. The transmitted reference signal may allow for a more efficient approach of determining the channel for beamforming purposes than requiring the wireless device to receive several reference signals from the access devices, measuring the CSI, and transferring it. In this scenario, the sensing target (UE) may be required to transmit a reference signal. Based on the received reference signal, the multiple TRPs can determine the channel and perform (wireless sensing) beamforming towards the target to determine its location (or other parameters), and use this information, e.g., to assist in a mobility procedure, e.g., a communication handover or select the most suitable access device. The network may, e.g., request the selected access device to transmit on demand pilot signals.

[0620] In a related example, which may be applicable to a situation in which a wireless device requires positioning services, e.g., via wireless sensing, the wireless device may move through an area in which multiple (e.g., M) access devices are available, but only a subset (e.g. S) of access devices is required to provide the required service, e.g., communication or sensing services. The wireless device may receive some synchronization signals and / or first configuration, e.g., via SIB1 from a first access device in a first group of access devices (e.g., the M access devices). The wireless device may send afirst message to one or more devices in the first group of access devices, and may receive a second message from a second group of access devices (e.g., a first subset S). The second group of access devices may distribute reference signals so that the wireless device can determine the channel state information with the second group of access devices. Additionally or alternatively, the wireless device may send a(n additional) first message that is also a reference signal so that the second group of access devices can determine the channel state information, access devices may use the determined channel state information to perform beamforming to determine the position of the wireless device. If the wireless device is mobile, the cellular system may keep performing mobility procedures and / or perform continuous operation to reselect and / or require the wireless device to reselect subsequent second groups of access devices. It is to be noted that if the wireless device moves (e.g., to a very different area), the M initially available devices may not be available anymore. In this case, the wireless device may receive some synchronization signals and / or another first configuration, e.g., via SIB1 from another first access device in another first group of access devices (e.g., M' access devices). The wireless device may then repeat the operations.

[0621] In a related example / application of the invention, the first configuration may be a configuration of a wake-up signal, e.g., a configuration to wake-up one or more access devices. The first message may be the transmission of the wake-up signal according to the first configuration. The reception of the (first message) wake-up signal may trigger one or more access devices to transmit on-demand SSBs or an on demand SIB1.

[0622] In general, embodiments of this invention may allow the deployment of a "cell-free" cellular system wherein some access devices, e.g., long range access devices distribute some synchronization signals, and the wireless devices use them to access the cellular system by sending an initial first message / reference signal, e.g., a preamble. The cellular system will then determine the best access devices to, e.g., take over the random-access procedure of the wireless device. The selected device may then reply to the wireless device with a second message, e.g., a random-access response.

[0623] In general, the access devices receiving the first messages may be well-known macro access devices, e.g., access devices that are well-known and whose function is to enable access. They may be, e.g., non-terrestrial access devices that are at a well known location, e.g., GEO satellites that are globally accessible, or, e.g., a UAV hovering at a specific location / altitude over a geographical area. Their function would then be to receive the first messages, and determine the best selected devices to further proceed with, e.g., the network access procedure, e.g., random access procedure.Section: miscellaneous

[0624] This invention can be applied to various types of UEs or terminal devices, such as mobile phone, vital signs monitoring / telemetry devices, smartwatches, detectors, vehicles (for vehicle-to-vehicle (V2V) communication or more general vehicle-to-everything (V2X) communication), V2X devices, Internet of Things (loT) hubs, loT devices, including low-power medical sensors for health monitoring, medical (emergency) diagnosis and treatment devices, for hospital use or first-responder use, virtual reality (VR) headsets, etc.

[0625] Fig. 18 is a block diagram illustrating an example processor X00 for use in embodiments of the invention. Processor X00 may be used to implement one or more processors described herein, for example, processor 202 shown in Fig. 2. Processor X00 may include any suitable processor type including, but not limited to, a microprocessor, a microcontroller, a digital signal processor (DSP), a field programmable array (FPGA) where the FPGA has been programmed to form a processor, a graphical processing unit (GPU), an application specific circuit (ASIC) where the ASIC has been designed to form a processor, or a combination thereof.

[0626] The processor X00 may include one or more cores X02. The core X02 may include one or more arithmetic logic units (ALU) X04. In some embodiments, the...

Claims

1. Claims1. A method for transmission reception point (TRP) selection comprising: transmitting, by a wireless device, at least one first message, to a first group of TRPs, receiving, by the wireless device, a second message from a second group of TRPs indicating at least a selected TRP,performing, by the wireless device, a data exchange and / or wireless sensing with and / or through the at least a selected TRP in the second group of TRPs.

2. The method of claim 1, wherein the first group of TRPs comprises the second group of TRPs.

3. The method of claim 1, wherein the second group of TRPs is not contained in the first group of TRPs or wherein the second group of TRPs is only partly contained in the first group of TRPs.

4. The method of claim 1, wherein the first message is one or more of:- a wake-up signal,- a wake-up signal to wake-up the wireless sensing functionality of an access device, - a random-access preamble,- message 3 in the random access procedure,- the first message in a RACH-less handover,- a reference signal,- a MAC CE message.

5. The method of claims 1, 3, or 4, wherein:- the second group of TRPs comprises a single TRP, and the single TRP is the selected TRP, or- the second group of TRPs comprises a first TRP in the first group of TRPs and the selected TRP.

6. The method of any previous claims, further comprising:receiving, by the wireless device, a first configuration, said first configuration comprising parameters to(1) indicate the wireless device preferences for multi TRP selection and / or(2) transmit the first message,wherein the reception, by the wireless device, of the first configuration is prior to transmitting, by the wireless device, the at least one first message andwherein the first configuration comprises one or more:- parameters determining a transmission timing of the at least one first message, - parameters determining a transmission frequency of the at least one first message, - parameters determining a number of repetitions of the at least one first message, - parameters determining a transmission power of the at least one first message, - an (implicit or explicit) identifier used to indicate the multi TRP selection,- parameters of the first message, the first message being used as a reference signal, wherein the reference signal is one of a channel-state reference signal, a sounding reference signal or a wireless sensing reference signal, and the first message is used by the first group of access devices to estimate the communication channel with the wireless device.

7. The method of any previous claims, further comprising:receiving, by the wireless device, a second configuration, said second configuration comprising a policy determining the wireless device preferences for multi TRP selection,wherein the reception, by the wireless device, of the second configuration is prior to the transmitting, by the wireless device, the at least one first message and wherein the second configuration comprises one or more:- energy consumption / saving requirements,- quality of service requirements, and- service parameters / requirements.

8. The method of claims 6 or 7, wherein the first configuration and / or second configuration are received:- in SIB1,- in a SIB,- in an RRC message,- in a NAS message.

9. The method of any previous claims, wherein the first message indicates whether the wireless device desires to communicate through a specific TRP in the first group of TRPs or through a network-selected TRP in the second group of TRPs.

10. The method of any previous claims, wherein:- multi transmission reception point (TRP) selection is a multi-access device selection, - the first group of TRPs is a first group of access devices,- the second group of TRPs is a second group of access devices,- the one or more selected TRP are one or more selected access devices.

11. The method of any previous claims, wherein:- multi transmission reception point (TRP) selection is a multi-beam selection, - the first group of TRPs is a first group of beams,- the second group of TRPs is a second group of beams, and- the selected TRPs are selected beams.

12. The method of any previous claims, wherein the first message is transmitted to trigger and / or perform one of:-TRP selection,-TRP re-selection,-TRP handover.

13. The method of any previous claims, further comprising:determining, by the wireless device, assistance information to assist the first group of TRPs to determine the selected TRP,transmitting, by the wireless device, the assistance information in the first message.

14. The method of any previous claims, further comprising:receiving, by the wireless device, an AI / ML model for predicting the accuracy / confidence level of assistance information,inferring, by the wireless device, the accuracy / confidence level of the assistance information by using the AI / ML model,transmitting, by the wireless device, the inferred accuracy in the first message.

15. The method of claims 13 or 14, wherein the assistance information comprises one or more:- assistance information for an "n hop handover" with n being at least two;- the number of planned hops to perform a handover based on a configuration of the wireless device;- the predicted confidence level of a successful handover towards target access device n hops away, with n greater than or equal to two;- the trajectory of and / or confidence in the trajectory confidence of the wireless device.

16. The method of any of the previous claims, wherein:- the transmission of the first message triggers a conditional (LTM) handover.

17. The method of any of the previous claims, wherein the first message is indicative of at least two potential target TRPs according to a first "n hop handover route".

18. The method of any of the previous claims, wherein the second message is indicative of the one or more selected TRPs in connection order according to an "n hop handover route".

19. The method of any previous claims, comprisingderiving a root access stratum key by means of a key derivation function, wherein input information to the key derivation function comprises one or more identifiers of the TRPs in the first group of TRPs and / or the identity of the selected TRP in the second group of TRPs.

20. The method of any previous claims, comprisingperforming, by the wireless device, a data exchange with and / or through at least the selected TRP in the second group of TRPs.

21. The method of claim 20, comprising prior to the performing of the data exchange at least one of:negotiating security algorithms and security levels of the lower layer communication and higher layer communication; and / ordisabling user plane security at a higher layer when lower layer security is enabled; and / orenabling user plane security at a higher layer when lower layer security is set to null security.

22. The method of claim 20 or 21, comprising, prior to the performing of the data exchange, deriving a lower layer key to protect a lower layer and deriving a higher layer key to protect a higher layer,wherein the deriving of the higher layer key is conditional on the selected TRP belonging to a cell different from the cell that the wireless device is connected to upon initiating the procedure.

23. The method of claim 22, wherein the input information to a key derivation function used to derive the lower layer key comprises one or more of (a) a root access stratum key, (b) at least a lower layer parameter that is one or more of the parameters in the TCI received from at least a first TRP from the first group of TRPs and / or from the selected TRP from the second group of TRPs.

24. The method of claim 22 or 23, wherein the key derivation function used to derive the lower layer key is ASCON based.

25. The method of any of claims 22 to 24, wherein the lower layer key is used to protect one or more MAC CE.

26. The method of any of claims 22 to 25, wherein an algorithm used for integrity protection with the lower layer key is ASCON.

27. The method of any previous claims, wherein the first message contains a secure envelope, and the secure envelope contains credentials to perform a mobility procedure towards the selected TRP.

28. The method of any previous claims, wherein the keys and / or credentials and / or secure envelopes to perform a mobility procedure are characterized by a validity time, and upon expiration of the validity time, the keys and / or credentials and / or secure envelopes become invalid.

29. The method of any previous claims, wherein the first message uses a network identifier, wherein this network identifier is provided in the first configuration, and wherein the network identifier belongs to a set of network identifiers shared between at least an TRP in the first group of TRPs and the selected TRP.

30. The method of any previous claims, wherein the transmitting, by the wireless device, at least one first message, to the first group of TRPs, comprises the wireless device transmitting one or more message bursts, each message burst comprising one or more corresponding first messages, and wherein:- a first message burst is transmitted via an omnidirectional beam and a second message burst is transmitted via a directional beam; and / or- the message bursts are transmitted in an aperiodic manner; and / or - two or more of the message bursts transmitted via directional beams are time-multiplexed;- in case of a plurality of first messages in the message burst, a first message of the plurality of first message includes an indication of its position in the message burst;- a corresponding first message includes an indication of its first message burst.

31. The method of any previous claims,wherein the data exchange and / or wireless sensing with two or more selected TRPs in the second group of TRPs is a joint and / or coherent transmission, andwherein the time and / or frequency and / or transmission power adjustments of the joint and / or coherent transmission are based on the transmitted first message.

32. The method of any previous claims, comprisingperforming by the wireless device a wireless sensing procedure with and / or through the at least a selected TRP in the second group of TRPs, andtransmitting, by the wireless device, information verifying or for verifying that the wireless sensing procedure is performed with the wireless device.

33. The method of any of previous claims, comprising:adding, by the wireless device, first communication resources from the selected TRP, before releasing, by the wireless device, second communication resources from the first group of TRPs.

34. The method of claim 1,wherein the wireless device is in IDLE / INACTIVE state, andwherein the first message to the first group of TRPs is a preamble for triggering the transmission of on-demand SIB1 and a random-access response indicating the selected access device, andwherein prior to sending the first message and the second message, the method further comprises:sending, by the wireless device, a first first message for triggering the transmission of on-demand synchronization signals, andreceiving, by the wireless device, a first second message comprising on-demand synchronization signals from the first group of access devices.35: The method of claim 1,wherein the wireless device is in CONNECTED state, andWherein the first message to the first group of access device indicates the selection of two or more access devices.

36. A method for transmission reception point (TRP) selection comprising: receiving, by a first group of TRPs, a first message from a wireless device, determining, by the first group of TRPs, a second group of TRPs comprising selected TRPs,transmitting, by the first group of TRPs, an indication to the selected TRPs, causing:at least one of the selected TRPs to transmit a second message indicating the selected TRPs,and performing, by the selected TRPs, a data exchange and / or wireless sensing with the wireless device.

37. An apparatus for transmission reception point selection comprising: a processor,a transceiver, anda memory storing instructions which, when executed,cause the apparatus totransmit at least one first message, to a first group of TRPs,receive a second message from a second group of TRPs indicating at least a selected TRP,perform a data exchange and / or wireless sensing with and / or through at least a selected TRP in the second group of TRPs.

38. An apparatus for transmission reception point selection comprising:a processor,a transceiver, anda memory storing instructions which, when executed,cause the apparatus toreceive a first message from a wireless device,determine a second group of TRPs comprising selected TRPs,transmit an indication to the selected TRPs, causing:at least one of the selected TRPs to transmit a second message indicating the selected TRPs,and performing, by the selected TRPs, a data exchange and / or wireless sensing with the wireless device.

39. A computer program for transmission reception point selection comprising computer instructions to perform the steps in the methods of any of claims 1 to 36.

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