Central unit, distributed unit and method

Abstract

A distributed access network is disclosed in which the central unit (CU) of the access network receives a first distributed unit (DU) of the access network a first notification indicating that a procedure has been initiated or will be initiated to switch the communication of user equipment (UE) from a first cell provided via a first DU to a second cell provided via a second DU of the access network. The CU sends a second notification to the second DU of the access network indicating that a procedure to switch the communication of the UE has been initiated or will be initiated.

Description

Technical Field

[0001] The present disclosure relates to a communication system.

Background Art

[0002] The present disclosure is particularly, but not limited to, related to a wireless communication system and its devices operating according to the 3rd Generation Partnership Project (3GPP (registered trademark)) standard or a standard equivalent thereto or a derivative standard thereof (including LTE-Advanced, next-generation or 5G networks, future generations, and thereafter). The present disclosure is particularly, but not necessarily limited to, related to inter-cell mobility triggered by L1 / L2 signaling.

[0003] The initial development of 3GPP standards was called Evolved Packet Core (EPC) Network Long-Term Evolution (LTE) and Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), and was commonly referred to as "4G." More recently, the terms "5G" and "new radio" (NR) have begun to be used to refer to evolving communication technologies expected to support a variety of applications and services. Various details of 5G networks are described in the "NGMN 5G White Paper" V1.0 by the Next Generation Mobile Network (NGMN) Alliance, which can be obtained, for example, from https: / / www.ngmn.org / 5g-white-paper.html. 3GPP intends to support 5G through the so-called 3GPP Next Generation (NextGen) Radio Access Network (RAN) and 3GPP NextGen Core Network.

[0004] Under the 3GPP standard, a NodeB (or eNB in ​​LTE, and gNB in ​​5G) is a radio access network (RAN) node (or simply an “access node,” “access network node,” or “base station”) through which communication devices (user equipment or “UE”) connect to the core network and communicate with other communication devices or remote servers. For simplicity, this application uses the terms access network node, (R)AN node, RAN equipment, or base station to refer to any such access node.

[0005] For simplicity, this application uses the terms mobile device, user device, or UE to refer to any communication device that can connect to a core network via one or more base stations. While this application may refer to mobile devices in its description, it will be understood that the described technology can be implemented on any (mobile and / or generally fixed) communication device that can connect to a communication network to transmit / receive data, whether such communication device is controlled by human input or by software instructions stored in memory.

[0006] In current 5G architectures, the structure of a gNB can be divided into two or more parts. In some RAN implementations, there are two parts, sometimes called a “control unit” (Central Unit: CU or gNB-CU) and known as a “distributed unit” (DU or gNB-DU), connected by an F1 interface. This makes it possible to use a “split” architecture. Typically, a “split” architecture separates a “higher” CU layer (such as the Packet Data Convergence Protocol (PDCP) layer and the Radio Resource Control (RRC) layer, but not limited to these) and a “lower” DU layer (such as the Radio Link Control (RLC) layer, the Media Access Control (MAC) layer, and the Physical (PHY) layer, but not limited to these) from a specific CU and one or more DUs connected to and controlled by that CU via an F1 interface. Therefore, for example, the upper-layer CU functions of several gNBs can be centrally implemented (for example, by a single processing unit, or in a cloud-based or virtualized system) while each gNB maintains its own separate lower-layer DU functions locally. [Preliminary Technology Documents] [Non-licensed literature]

[0007] [Non-licensed Document 1] "NGMN 5G White Paper" V1.0, available from Next Generation Mobile Networks (NGMN) Alliance, https: / / www.ngmn.org / 5g-white-paper.html. [Non-licensed Document 2] "LTM procedure descriptions and stage 2 aspects", 3GPP DRAFT TYPE DISCUSSION, vol 3GPP RAN 2, DAVID LECOMPTE ET AL, https: / / www.3gpp.org / ftp / TSG_RAN / WG2_RL2 / TSGR2_121 / Docs / R2-2301358.zip It is possible to get it. [Non-licensed Document 3] "(TP for LlL2 Mob BLCR for TS 38.401) Discussion about the open issues for LlL2 mobility", 3GPP DRAFT TYPE DISCUSSION, vol 3GPP RAN 3, 2022, JIAYING SUN ET AL, https: / / www.3gpp.org / ftp / TSG_RAN / WG3_RL3 / TSGR3_119 / Docs / R3-230890.zip is available. [Non-licensed Document 4] "(TP for LlL2MobBLCR for TS 38.401):Ll / L2 Mobility", 3GPP DRAFT, TYPE DISCUSSION, vol 3GPP RAN 3, 2023, HONGZHUO ZHANG ET AL, https: / / www.3gpp.org / ftp / TSG_RAN / WG3_RL3 / TSGR3_119 / Docs / R3-230580.zip is available. [Non-licensed Document 5] "Rapporteur Update to TS 38.401", 3GPP DRAFT, vol RAN WG3, 2022, NEC(38 401 RAPPORTUER) [Overview of the project] [Problems that the invention aims to solve]

[0008] Historically, mobility between different cells in cellular communications has been based on higher-layer communications such as Layer 3 (e.g., L3 or radio resource control (RRC) layer) signaling. More recently, with the aim of providing enhanced mobility, there has been consideration to develop and provide support for Layer 1 (e.g., L1 or physical (PHY) layer) and / or Layer 2 (e.g., L2 or media access control (MAC) layer)-centric (also called L1 / L2-centric mobility) mobility rather than higher-layer (e.g., RRC layer) mobility. Such L1 / L2-centric mobility (also called L1 / L2 triggered mobility or "LTM") is expected to improve the mobility of devices operating in both sub-7GHz and mmWave bands by supporting, for example, lower handover latency and improved robustness.

[0009] Therefore, there is a need to develop communication devices (such as base stations and / or UEs) that support efficient / flexible mechanisms for LTM. [Means for solving the problem]

[0010] This disclosure aims to provide one or more devices and / or one or more related methods that at least partially address the above needs.

[0011] In one embodiment, a method is provided which is performed by a central unit (CU) of an access network, the method including receiving a first notification from a first DU of the access network indicating that a procedure has been initiated or will be initiated to switch the communication of user equipment (UE) from a first cell provided via a first distributed unit (DU) to a second cell provided via a second DU of the access network, and sending a second notification to the second DU of the access network indicating that a procedure to switch the communication of UE has been initiated or will be initiated.

[0012] A first notification may be received to initiate the procedure for switching the UE's communication, and a second notification may be sent before the message is sent from the first DU to the UE. The first notification may contain first information, and the second notification may contain second information different from the first information. The procedure for switching the UE's communication may be part of a layer 1 / layer 2 triggered mobility (LTM) procedure.

[0013] In another embodiment, a method is provided which is performed by a second distributed unit (DU) of the access network, the method including receiving a notification from the central unit (CU) of the access network indicating that a procedure has been initiated or will be initiated to switch the communication of user equipment (UE) from a first cell provided through a first DU of the access network to a second cell provided through a second DU, and receiving at least one uplink message from the UE based on the notification.

[0014] Receiving based on a notification may include dynamically scheduling at least one resource for uplink communication based on the notification, and receiving at least one uplink message from the UE using at least one resource. The method may further include pre-configuring at least one resource for uplink communication prior to receiving the notification, and receiving based on the notification may include decoding at least one uplink message received from the UE using at least one resource based on the notification.

[0015] In another embodiment, a method is provided which is performed by a first distributed unit (DU) of the access network, which includes determining that a procedure is initiated to switch the communications of user equipment (UE) from a first cell provided through the first DU to a second cell provided through a second DU of the access network, sending a notification to the central unit (CU) of the access network indicating that the procedure for switching the communications of the UE has been initiated or will be initiated, and sending a message to the UE to initiate the procedure for switching the communications of the UE, wherein the notification is sent prior to the message to initiate the procedure for switching the communications of the UE.

[0016] A notification may be sent when it is determined that the procedure for switching the UE's communications has been initiated. A notification may be sent when a message is sent to initiate the procedure for switching the UE's communications.

[0017] In another embodiment, a method is provided which is performed by an access network node, and which includes sending information about triggers for a group procedure to each user equipment (UE) in the UE group in order for each UE in the UE group to switch communication from a first cell to a second cell provided by the access network node.

[0018] Trigger information may be transmitted in a common message to be received by each UE in the UE group. Trigger information may include an indication that the first cell has switched to network energy saving mode. Trigger information may include a paging message. A paging message may include fields for triggering a group procedure. Trigger information may include system information or paging information, including a command for triggering a group procedure. Trigger information may be provided using downlink control information (DCI) to trigger a group procedure. Trigger information may be provided using at least one media access control (MAC) signal to trigger a group procedure. At least one MAC signal may be a MAC control element (MAC CE) or a MAC service data unit (MAC SDU). Trigger information may be provided using a transport block (TB) that carries the respective MAC signal for each UE in the UE group to trigger a UE and switch communications. At least one MAC signal may include the respective command for each UE in the UE group to trigger that UE and switch communications. Trigger information may include at least one UE group identifier to identify a UE group. Trigger information may include a list of UE group identifiers. Trigger information may include a list of identifiers for each UE to which a group procedure is triggered. Trigger information may be configured to be received using a shared radio network temporary identifier. Trigger information may be configured to be received using a shared radio network temporary identifier by both any UE in a first cell that is a member of a UE group and any UE in a first cell that is not a member of a UE group.Trigger information may be configured to be received by any UE in a first cell that is a member of the UE group, but not by any UE in a first cell that is not a member of the UE group, using a shared radio network temporary identifier. Trigger information may include Layer 2 (L2) protocol processing information. Trigger information may include information for identifying at least one target cell of the group procedure. The group procedure may be part of a Layer 1 / Layer 2 triggered mobility (LTM) procedure. The group procedure may be part of a conditional handover procedure.

[0019] In another embodiment, a method is provided which is performed by user equipment (UE), the method including, in each UE in a group of UEs, receiving information from an access network node regarding a trigger for a group procedure in order to switch communication from a first cell to a second cell provided by the access network node, respectively, and initiating a procedure to switch communication from the first cell to the second cell provided by the access network node, based on the trigger information.

[0020] In another embodiment, a method is provided which is performed by user equipment (UE), the method including monitoring at least one group trigger condition for triggering a group procedure to switch communication from a first cell to a second cell, in each UE of a UE group of which the UE is a member, and initiating a procedure to switch communication from the first cell to the second cell when at least one group trigger condition is met.

[0021] The group trigger condition may be satisfied when a predetermined time is reached. The predetermined time may be based on the time when the non-terrestrial network (NTN) cell is scheduled to stop providing services to the area where the UE is located, or may be based on the time when network energy saving is scheduled to be activated for the first cell.

[0022] In another aspect, a method executed by a central unit (CU) of an access network is provided. The method includes determining to start a procedure for pre-configuring a user equipment (UE) to switch communication from a serving cell provided via a serving distributed unit (DU) of the access network to a target cell of a target DU of the access network; sending a request for configuring at least one candidate cell that is a candidate for the target DU to at least one candidate DU of the access network that provides at least one candidate cell; receiving configuration information of at least one approved candidate cell that is a candidate for the target cell from at least one candidate DU; sending second configuration information for configuring the UE to switch to at least one approved candidate cell to the serving DU based on communication with at least one candidate DU; and sending information for identifying each approved candidate cell of at least one approved candidate cell to at least one candidate DU.

[0023] The information for identifying each approved candidate cell may be sent to the candidate DU that was the target DU of the switched communication after the UE has switched the communication. The information for identifying each approved candidate cell may be sent to each candidate DU that is at least one candidate DU after the UE receives a notification from the serving DU indicating that the application of the second configuration information was successful.

[0024] In another aspect, a method executed by a candidate distributed unit (DU) of an access network is provided. The method includes receiving, from a central unit (CU) of the access network, a configuration request for at least one candidate cell that is a candidate for the target DU as part of a procedure for pre-configuring a user equipment (UE) to switch communication from a serving cell provided via a serving DU of the access network to a target cell of the target DU of the access network; transmitting, to the CU, configuration information of at least one approved candidate cell that is a candidate for the target cell; and receiving, from the CU, information for identifying at least one approved candidate cell provided by at least one additional candidate DU.

[0025] After the UE switches communication and after the candidate DU that was the target DU of the switched communication, information for identifying each approved candidate cell can be received. The information for identifying each approved candidate cell can be received at the UE before the switching of communication to the target cell is initiated.

[0026] In another aspect, a central unit (CU) for an access network is provided. The CU includes means for receiving, from a first distributed unit (DU) of the access network, a first notification indicating that a procedure for switching communication of a user equipment (UE) from a first cell provided via the first DU to a second cell provided via a second DU of the access network has been started or is to be started; and means for transmitting, to the second DU of the access network, a second notification indicating that a procedure for switching communication of the UE has been started or is to be started.

[0027] In another embodiment, a second distributed unit (DU) for the access network is provided, the second DU includes means for receiving a notification from the central unit (CU) of the access network indicating that a procedure has been initiated or will be initiated to switch the communication of user equipment (UE) from a first cell provided through the first DU of the access network to a second cell provided through the second DU, and means for receiving at least one uplink message from the UE based on the notification.

[0028] In another embodiment, a first distributed unit (DU) is provided for the access network, and the first DU includes determining that a procedure is initiated to switch the communication of user equipment (UE) from a first cell provided through the first DU to a second cell provided through a second DU of the access network, sending a notification to the central unit (CU) of the access network indicating that the procedure for switching the communication of the UE has been initiated or will be initiated, and sending a message to the UE to initiate the procedure for switching the communication of the UE, wherein the notification is sent prior to the message to initiate the procedure for switching the communication of the UE.

[0029] In another embodiment, an access network node is provided, which includes means for transmitting information regarding triggers for group procedures to each user equipment (UE) in the UE group in order for each UE in the UE group to switch communication from a first cell to a second cell provided by the access network node.

[0030] In another embodiment, user equipment (UE) is provided, and each UE in a group of UEs includes means for receiving information from an access network node regarding triggers for group procedures in order to switch communication from a first cell to a second cell provided by the access network node, respectively, and means for initiating a procedure to switch communication from the first cell to the second cell provided by the access network node, based on the information regarding the triggers.

[0031] In another embodiment, user equipment (UE) is provided, which includes means for monitoring at least one group trigger condition for triggering a group procedure to switch communication from a first cell to a second cell in each UE of a group of UEs of which the UE is a member, and means for initiating a procedure to switch communication from the first cell to the second cell when at least one group trigger condition is met.

[0032] In another embodiment, a central unit (CU) for an access network is provided, and the CU includes means for deciding to initiate a procedure to preconfigure user equipment (UE) to switch communication from a serving cell provided via a distributed unit (DU) of the access network to a target cell of a target DU of the access network; means for transmitting a request to at least one candidate DU of an access network that provides at least one candidate cell for configuration of at least one candidate cell, wherein at least one candidate DU is a candidate to become a target DU; means for receiving configuration information of at least one approved candidate cell from at least one candidate DU, wherein at least one approved candidate cell is a candidate to become a target cell; means for transmitting second configuration information to the serving DU for configuring the UE to switch to at least one approved candidate cell based on communication with at least one candidate DU; and means for transmitting information to at least one candidate DU that identifies each approved candidate cell of at least one approved candidate cell.

[0033] In another embodiment, a distributed unit (DU) for an access network is provided, and the DU includes means for receiving a request for configuration of at least one candidate cell from a central unit (CU) of the access network, where the candidate DU is a candidate to become a target DU, as part of a procedure for pre-configuring user equipment (UE) for switching communication from a serving cell provided via a serving DU of the access network to a target cell of a target DU of the access network; means for transmitting configuration information of at least one approved candidate cell to the CU, where the at least one approved candidate cell is a candidate to become a target cell; and means for receiving information from the CU identifying at least one approved candidate cell provided by at least one further candidate DU.

[0034] Aspects of the present disclosure extend to computer program products such as computer-readable storage media that internally store corresponding systems, devices, and instructions, the instructions being operable to program a programmable processor to perform the methods described above or as stated in the claims, and / or to program a computer appropriately adapted to provide the device stated in any of the claims.

[0035] Each feature disclosed herein (this term includes the claims) and / or shown in the drawings may be incorporated into this disclosure independently of (or in combination with) any other disclosed and / or illustrated features, where it is technically feasible to do so. In particular, but not limited to, any feature of a claim dependent on a particular independent claim may be introduced into that independent claim in any combination or individually, provided that doing so does not result in a technical incompatibility or result in something that does not make technical sense.

[0036] Exemplary embodiments of the present disclosure are described herein by reference to the accompanying drawings. [Brief explanation of the drawing]

[0037] [Figure 1] This is a schematic diagram of a mobile (cellular or wireless) communication system. [Figure 2] This figure shows a typical frame structure that can be used in the communication system shown in Figure 1. [Figure 3] Figure 1 shows an example of an L1 / L2 triggered mobility (LTM) cell switching scenario within a CU that can be used in the communication system shown in Figure 1. [Figure 4] This is a simplified sequence diagram showing an overview of the LTM procedure that can be performed in the communication system shown in Figure 1. [Figure 5] This is a simplified sequence diagram showing in more detail the LTM pre-configuration portion of the LTM procedure in Figure 4. [Figure 6] This is a simplified sequence diagram showing the LTM cell switching section of the LTM procedure in Figure 4 in more detail. [Figure 7] This is a simplified sequence diagram showing another LTM procedure that may be used in the communication system shown in Figure 1. [Figure 8] This is a simplified sequence diagram showing some steps to support Group LTM, which may be used in the communication system shown in Figure 1. [Figure 9] This is a simplified sequence diagram showing another procedure for supporting Group LTM, which may be used in the communication system shown in Figure 1. [Figure 10] This is a simplified sequence diagram showing another procedure for supporting Group LTM, which may be used in the communication system shown in Figure 1. [Figure 11] This is a simplified sequence diagram showing another procedure for supporting Group LTM, which may be used in the communication system shown in Figure 1. [Figure 12] The MAC signals that may be used to support group LTM in the communication system shown in Figure 1 are illustrated. [Figure 13] Figure 1 shows another MAC signal that may be used to support group LTM in the communication system. [Figure 14] Other MAC signals that may be used to support Group LTM in the communication system shown in Figure 1 are also shown. [Figure 15] This is a simplified sequence diagram showing another LTM procedure that may be used in the communication system shown in Figure 1. [Figure 16] This is a simplified sequence diagram showing another LTM procedure that may be used in the communication system shown in Figure 1. [Figure 17] Figure 1 is a schematic block diagram showing the main components of the UE in the communication system. [Figure 18] Figure 1 is a schematic block diagram showing the main components of the access network in the communication system. [Modes for carrying out the invention]

[0038] overview Here, with reference to Figures 1-6, we will describe an exemplary communication system from a general perspective, using it as a simple example.

[0039] Figure 1 is a schematic diagram of a mobile ("cellular" or "wireless") communication system 1 to which exemplary embodiments of the present disclosure can be applied.

[0040] In communication system 1, user equipment (UE) 3-1, 3-2, 3-3 (such as mobile phones and / or other mobile devices) can communicate with each other via (Radio)Access Network ((R)AN) nodes 5 (base stations 5, RAN equipment 5) operating according to one or more compatible radio access technologies (RATs). In the illustrated example, the (R)AN node 5 comprises a distributed NR / 5G base station 5 or "gNB" 5 operating one or more associated cells 9. Communication via the (R)AN node 5 is typically routed via an associated core network 7 (such as a 5G core network or an evolved packet core network (EPC)).

[0041] As those skilled in the art will understand, three UE3s and one (R)AN node 5 are shown in Figure 1 for illustrative purposes, but the system typically includes other (R)AN nodes 5 and UE3s in implementation.

[0042] (R)AN node 5 controls one or more associated cells directly or indirectly through one or more other nodes (e.g., home base stations, relays, remote radio heads, distributed units). It will be understood that (R)AN node 5 may be configured to support both 4G and 5G and / or any other 3GPP or non-3GPP communication protocols.

[0043] In this example, the illustrated (R)AN node 5 comprises a distributed base station 5 having at least one distributed unit (DU) 5b (e.g., gNB-DU) and a central unit (CU) 5c (e.g., gNB-CU). The CU 5c utilizes separate control planes and user planes, and is therefore divided into a control plane function (CU-CP) and a user plane function (CU-UP), which communicate with the DU 5b via the F1-C logical interface and the F1-U logical interface (together forming the F1 interface (or "reference point")), and communicate with each other via the E1 logical interface. In this example, the DU provides the functionality of the lower part of the PHY layer and therefore includes the physical and virtual elements necessary to communicate with the UE 3 via the air interface, but it will be understood that the RAN may alternatively (or additionally) include one or more separate radio units (RUs) (e.g., providing the functionality of the lower part of the PHY layer). Nevertheless, although distributed (R)AN node 5 is shown and described, it will be understood that (R)AN node 5 may also be provided in a non-distributed form, for example, as an integrated gNB or eNB.

[0044] UE3 and their Serving(R)AN Node 5 are connected via appropriate air interfaces (e.g., so-called "Uu" interfaces). Equipment on adjacent(R)AN Node 5 may be connected to each other via appropriate inter-base station interfaces (e.g., so-called "X2" interfaces, "Xn" interfaces, etc.).

[0045] The core network 7 includes several logical nodes (or "functions") to support communication in the communication system 1. In this example, the core network 7 comprises a control plane function (CPF) 10 and one or more user plane functions (UPFs) 11. The CPF 10 includes one or more Access and Mobility Management Functions (AMFs) 10-1, one or more Session Management Functions (SMFs) 10-2, and several other functions 10n (e.g., an Authentication Server Function (AUSF) to facilitate the 5G security process, Unified Data Management (UDM) entities for managing user-specific data (e.g., access permissions, user registration, and data network profiles), a Policy Control Function (PCF), an Application Function (AF), etc.). It will be understood that nodes or functions may have different names in different systems.

[0046] (R)AN node 5 connects to the core network nodes via appropriate interfaces (or "reference points"), such as the N2 reference point between (R)AN node 5's CU5c (CU-CP) and AMF10-1 for control signaling communications, and the N3 reference point between (R)AN node 5's CU5c (CU-UP) and each UPF11 for user data communications. Each UE3 connects to AMF10-1 via a logical non-access stratum (NAS) connection on the N1 reference point (similar to the S1 reference point in LTE). It will be understood that N1 communications are routed transparently through (R)AN node 5.

[0047] One or more UPF11s are connected to an external data network (such as an IP network like the Internet) via a reference point N6 for user data communication.

[0048] The AMF10-1 performs mobility management-related functions, maintains NAS signaling connections with each UE3, and manages UE registration. The AMF10-1 also manages paging.

[0049] SMF10-2 is connected to AMF10-1 via the N11 reference point. SMF10-2 provides session management functionality (which forms part of the MME functionality in LTE) and further combines several control plane functions (provided by the serving gateway and packet data network gateway in LTE). SMF10-2 also assigns IP addresses to each UE3. SMF uses user information provided via AMF to determine which session manager is best assigned to the user. SMF can be effectively considered a gateway from the user plane to the network control plane. SMF10-2 also assigns IP addresses to each UE3.

[0050] (R) AN node 5 is also configured for transmitting control information and user data via several downlink (DL) physical channels, and UE3 is configured for receiving control information and user data via several downlink (DL) physical channels and for transmitting several physical signals. DL physical channels correspond to resource elements (REs) that carry information emitted from higher layers, and DL physical signals correspond to REs used in the physical layer that do not carry information emitted from higher layers.

[0051] Physical channels may include, for example, a physical downlink shared channel (PDSCH), a physical broadcast channel (PBCH), and a physical downlink control channel (PDCCH). The PDSCH carries data that shares its capacity on a time and frequency basis. The PDSCH can carry various data items, including, for example, user data, UE-specific upper-layer control messages mapped down from higher channels, system information blocks (SIBs), and paging. The PDCCH carries downlink control information (DCI) to support several functions, such as scheduling downlink transmissions on the PDSCH and uplink data transmissions on the physical uplink shared channel (PUSCH). The PBCH provides the Master Information Block (MIB) to the UE3. The PBCH also works in conjunction with the PDCCH to support time and frequency synchronization, which assists in cell acquisition, selection, and re-selection.

[0052] DL physical signals may include, for example, a reference signal (RS) and a synchronization signal (SS). The reference signal (sometimes known as a pilot signal) is a signal with a predefined special waveform known to both UE3 and (R)AN node 5. Reference signals may include, for example, a cell-specific reference signal, a UE-specific reference signal (UE-RS), a downlink demodulation signal (DMRS), and a channel state information reference signal (CSI-RS).

[0053] Similarly, UE3 is configured to transmit control information and user data via several uplink (UL) physical channels corresponding to REs that carry information transmitted from higher layers, and via UL physical signals used in the physical layer that correspond to REs that do not carry information transmitted from higher layers, and (R)AN node 5 is configured to receive control information and user data. UL physical channels may include, for example, PUSCH, physical uplink control channel (PUCCH), and / or physical random-access channel (PRACH). UL physical signals may include, for example, demodulation reference signals (DMRS) for UL control / data signals, and / or sounding reference signals (SRS) used for UL channel measurements.

[0054] Frame structure Referring to Figure 2, which shows a typical frame structure that may be used in communication system 1, the (R)AN node 5 and UE3 of communication system 1 communicate with each other in the time domain using resources organized into frames of length 10 ms. Each frame consists of 10 equally sized subframes of length 1 ms. Each subframe is divided into one or more slots containing 14 orthogonal frequency-division multiplexing (OFDM) symbols of equal length.

[0055] As shown in Figure 2, communication system 1 supports multiple different numerologies (subcarrier spacing (SCS), slot length, and thus OFDM symbol length). Specifically, each numerology is identified by the parameter μ, where μ=0 represents 15kHz (corresponding to LTE SCS). Currently, SCS for other values ​​of μ can actually be derived from μ=0 by scaling up by a power of 2 (i.e., SCS = 15 × 2). μ (kHz). The relationship between the parameter μ and SCS(Δf) is shown in Table 1. [Table 1]

[0056] CU internal LTM cell switching Referring to Figure 3, an exemplary L1 / L2 triggered mobility (LTM) cell switching scenario within a CU that may occur in communication system 1 is shown. As seen in Figure 3, CU 5c can control multiple DU5b-1, 5b-2, 5b-3, each of which can operate multiple cells 9-1a~9-1c, 9-2a~9-2c, and 9-3a~9-3c (and / or beams), respectively. As UE3 moves through a cell (or beam), as indicated by the dashed arrow A, UE3 passes through several cells (for example, 9-1b==>9-1c==>9-2a==>9-2b==>9-3c==>9-3a, including multiple inter-cell transitions (indicated by "X"). Cell transitions include cell transitions within a DU (e.g., 9-1b==>9-1c, 9-2a=>9-2b, and 9-3c=>9-3a) and cell transitions between DUs (e.g., 9-1c==>9-2a, and 9-2b==>9-3c).

[0057] Beneficially, UE3 and (R)AN node 5 (i.e., CU5c and DU5b-1, 5b-2, 5b-3) are configured together to implement an in-CU LTM procedure that allows UE3 to switch relatively quickly (e.g., without potentially requiring RRC reconfiguration) between pre-configured candidate LTM cells 9-1a~9-1c, 9-2a~9-2c, and 9-3a~9-3c based on the contents of lower-layer (L1 and / or L2) measurement reports. Thus, as UE3 moves around between the pre-configured candidate LTM cells 9-1a~9-1c, 9-2a~9-2c, and 9-3a~9-3c, UE3 can perform fast cell switching potentially without RRC reconfiguration.

[0058] The cell switch in Figure 3 is required when UE3 moves relative to cell 9, but it should be understood that this type of cell switch may be required when one or more cells 9 move relative to UE3 (for example, in a non-terrestrial network (NTN) where each cell is provided via a mobile satellite). Furthermore, this type of cell switch may be required due to a change in cell size resulting from a network energy saving (NES) mode initiated in the RAN by / for one or more DUs. Furthermore, this type of cell switch may be required when cells are turned off (or on) for energy saving (or load management) purposes.

[0059] General LTM procedure Here, with reference to Figures 4-6, the LTM procedure within the exemplary CU is described merely as an example. Possible useful modifications of these procedures will be discussed later.

[0060] Figure 4 is a simplified sequence diagram showing an overview of the LTM procedure that can be implemented in communication system 1.

[0061] Referring to Figure 4, the LTM procedure in this case concerns cell switching within a CU, between DUs, between a cell (e.g., cell 9-1c in the scenario of Figure 3) operating via a source DU5b-1 (e.g., DU5b-1 in the scenario of Figure 3) controlled by a specific CU5c, and another cell (e.g., cell 9-1a in the scenario of Figure 3) operating via a target DU5b-2 (e.g., cell 9-1a in the scenario of Figure 3) controlled by the same CU5c.

[0062] Before the LTM procedure is triggered, (in S402a) UE3 communicates user data via source DU5b-1 and associated CU5c. UE3, source DU5b-1, and associated CU5c perform the L3 measurement control and reporting procedure in S404. This procedure typically involves UE3 sending an L3 measurement report (e.g., an RRC) containing measurement results for one or more cells (e.g., measured values ​​of a reference signal in the serving cell and / or one or more adjacent cells) to source DU5b-1 (e.g., in a "Measurement Report" message). The measurement results may (but do not necessarily) include L3 filtered measurement results for beams and / or cells. Source DU5b-1 can then send an appropriate message (e.g., a UL RRC message forwarding message) to inform CU5c of the received measurement report.

[0063] Next, CU5c can make a decision in S406 to initiate L1 / L2 inter-cell trigger mobility (pre-configuration).

[0064] Next, CU5c, source DU5b-1, target DU5b-2, and UE3 (and optionally one or more other "candidate" DUs) communicate with each other at S410 to perform the LTM preconfiguration procedure (as illustrated, for example, with reference to Figure 5).

[0065] Following the LTM preconfiguration in S410, UE3 and (R)AN node 5 can perform an LTM cell switching procedure, as seen in S450, to switch to the cell of target DU5b-2 (as illustrated, for example, with reference to Figure 6). After UE3 accesses the new cell of target DU5b-2 and target DU5b-2 detects the access, target DU5b-2 can notify CU5c of the successful access in S428. UE3 can then communicate user data via target DU5b-1 and its associated CU5c (as seen in S402b).

[0066] Figure 5 is a simplified sequence diagram showing in more detail the LTM pre-configuration portion of the LTM procedure in Figure 4. In Figure 5, it will be understood that the step shown in S510 roughly corresponds to the procedure in step S410 of Figure 4. Similarly, steps S502a, S504, S506, S550, S528, and S502b roughly correspond to the corresponding steps S402a, S404, S406, S450, S428, and S402b in Figure 4.

[0067] As shown in Figure 5, before the LTM procedure is triggered, UE3 exchanges user data (in S502a) via source DU5b-1 and associated CU5c. UE3, source DU5b-1, and associated CU5c perform the L3 measurement control and reporting procedure in S504. This procedure typically involves UE3 sending an L3 measurement report (e.g., an RRC) containing measurement results for one or more cells (e.g., measured values ​​of a reference signal in the serving cell and / or one or more adjacent cells) to source DU5b-1 (e.g., in a "Measurement Report" message). The measurement results may (but do not necessarily) include L3 filtered measurement results for the beam and / or cells. Source DU5b-1 can then send an appropriate message (e.g., a UL RRC message forwarding message) to inform CU5c of the received measurement report.

[0068] Next, CU5c can make a decision in S1506 to initiate L1 / L2 inter-cell trigger mobility (pre-configuration).

[0069] In S516-1 and S516-2, CU5c sends one or more messages to one or more candidate DUs 5b-3, 5b-2 containing the (candidate) target cell requesting context setup for UE3 (e.g., a UE context setup request as shown in Figure 5). This message is essentially a request for LTM configuration at the receiving DU. If the candidate DU approves the request for LTM configuration for one or more (candidate) target cells, the candidate DU responds to CU5c in S518-1 and S518-2 with an appropriate response message (e.g., a UE context setup response as shown in Figure 5) containing the lower-level configuration generated for one or more approved target candidate cells. Potentially, it will be understood that either a single UE context setup procedure (i.e., one procedure per candidate DU to prepare one or more candidate cells of the DU) or one or more UE context setup procedures (i.e., one procedure per candidate cell) may be used at this stage. In the illustrated procedure, for example, in S518-2, at least target DU5b-2 responds with such a response message that includes a lower-level configuration generated for one or more approved target candidate cells of target DU5b-2.

[0070] At S520, CU5c sends an appropriate message to source DU5b-1, which includes a generated RRC reconfiguration message with an L1 / L2 triggered mobility configuration. This message may be, for example, a UE context change request as shown in Figure 5, or another message such as a DL RRC message forwarding message.

[0071] Source DU5b-1 forwards the received RRC reconfiguration message to UE3 at S522, and UE3 responds at S524 with an RRC reconfiguration complete message (which substantially indicates that the RRC configuration has been successfully applied to the UE).

[0072] In S526, source DU5b-1 forwards an RRC reconfiguration complete message to CU5c (which substantially indicates that the RRC configuration has been successfully applied to the UE) using an appropriate message corresponding to the message sent in S520. This message may be, for example, a UE context change response as shown in Figure 5, or it may be another message, such as a UL RRC message forwarding message.

[0073] Following the LTM pre-configuration procedure (S510), UE3 and (R)AN node 5 may perform the LTM cell switching procedure, as seen in S550, to switch to the cell of target DU5b-2 (as described, for example, with reference to Figure 6). After UE3 accesses the new cell of target DU5b-2 and target DU5b-2 detects the access, target DU5b-2 may notify CU5c of the successful access in S528. UE3 can then communicate user data through target DU5b-2 and the associated CU5c (as seen in S502b).

[0074] Figure 6 is a simplified sequence diagram showing in more detail the LTM cell switching portion of the LTM procedure in Figure 4.

[0075] In Figure 6, it will be understood that the step shown in S650 roughly corresponds to the procedure of step S450 in Figure 4 (and the corresponding part of the procedure in Figure 5). Similarly, steps S602a, S604, S606, S610, S628, and S602b roughly correspond to the corresponding steps S402a, S404, S406, S410, S428, and S402b in Figure 4 (and the corresponding part of the procedure in Figure 5).

[0076] As shown in Figure 6, before the LTM procedure is triggered, UE3 communicates user data via source DU5b-1 and associated CU5c (in S602a). UE3, source DU5b-1, and associated CU5c perform the L3 measurement control and reporting procedure in S604. This procedure typically involves UE3 sending an L3 measurement report (e.g., an RRC) containing measurement results for one or more cells (e.g., measured values ​​of a reference signal in the serving cell and / or one or more adjacent cells) to source DU5b-1 (e.g., in a "Measurement Report" message). The measurement results may (but do not necessarily) include L3 filtered measurement results for the beam and / or cells. Source DU5b-1 can then send an appropriate message (e.g., a UL RRC message forwarding message) to inform CU5c of the received measurement report.

[0077] Next, CU5c can make a decision in S606 to initiate L1 / L2 inter-cell trigger mobility (pre-configuration).

[0078] Next, CU5c, source DU5b-1, target DU5b-2, and UE3 (and optionally one or more "candidate DUs") communicate with each other at S610 to perform the LTM preconfiguration procedure (as illustrated, for example, with reference to Figure 5).

[0079] Following the LTM preconfiguration of S610, UE3 and (R)AN node 5 can perform an LTM cell switching procedure similar to that seen in S650 to switch to the target DU5b-2 cell.

[0080] Specifically, as seen in S652, UE3 can send lower-layer measurement reports (including, for example, one or more L1 / L2 measurement results) to source DU5b-1 (e.g., serving cells and / or one or more target / candidate cells).

[0081] Next, source DU5b-1 decides at S654 to execute LTM and switch to a candidate target cell. It will be understood that source DU5b-1 can also notify other nodes of the LTM cell switching decision. Source DU5b-1 sends the LTM cell switching command to UE3 at S656. It will be understood that any notification of the LTM cell switching decision to other nodes at S658 may occur after source DU5b-1 sends the LTM cell switching command to UE3 at S656 (for example, using a MAC control element (CE)).

[0082] This allows UE3 to detach from the current cell of source DU5b-1 at S660 (and synchronize to the target cell of target DU5b-2 if necessary). Then, at S663, UE3 can perform either a random access channel (RACH) based initial access procedure or a RACH-less initial access procedure with target DU5b-2.

[0083] Furthermore, source DU5b-1 notifies CU5c (via the F1 interface, for example, using the F1 application protocol (F1AP)) at S658 about initiating LTM / sending LTM commands to UE3. In this example, the notification occurs with some delay after the LTM commands are sent at S656, and therefore may be sent in parallel with (or after) UE3 detaching from the current cell of source DU5b-1 / synchronizing to the target cell of target DU5b-2 at S660.

[0084] Target DU5b-2 can detect UE access in S664 and notify CU5c of successful access in S628. UE3 can then communicate user data via Target DU5b-2 and associated CU5c (as seen in S602b).

[0085] As will be understood by those skilled in the art, in the case of LTM between DUs, any release of resources in the source cell (and any prepared cell) within source DU5b-1 can be achieved (if any) by any suitable means.

[0086] Please understand that the detailed steps of the procedure described with reference to Figures 4-6 are examples and are provided for the purpose of illustrating how the procedure may be implemented. As those skilled in the art will see, there are several variations of the procedure, particularly the LTM pre-configuration and / or LTM cell switching parts of the procedure.

[0087] Further LTM considerations Beneficial in this regard, communication system 1 includes one or more enhancements to a general LTM procedure, as described with reference to Figures 4 to 6 and / or more generally.

[0088] One enhancement, for example, allows communication system 1 to support early notification of LTM to target cells. Specifically, target DU5b-2 can dynamically schedule a first / initial uplink grant for UE3 after it has switched to target cell 9-2 by notifying target DU5b-2 of when UE3 is scheduled to switch to target cell 9-2. This enhancement is particularly beneficial in the context of RACH-less initial access to LTM. Providing target DU5b-2 with early notification of when UE3 is scheduled to switch to target cell 9-2 will also be understood to have potential advantages in the context of configured grant-based initial access, even if dynamic grant procedures are not implemented.

[0089] Another enhancement, for example, would allow communication system 1 to favorably enable LTM to trigger a group of UE3 to switch that group of UE3 to the same target cell (or possibly a different target cell). Such group LTMs are particularly useful in the context of (but not limited to) scenarios involving cell movement within the NTN resulting from satellite movement, and / or scenarios involving cell size changes / cell switching off for NES purposes.

[0090] Another enhancement allows, for example, the current serving (i.e., source) DU5b-1 to be notified of a candidate cell, with the candidate cell pre-configured with an LTM configuration. This is particularly useful for enabling efficient subsequent LTM cell switching after a preceding LTM cell switchover.

[0091] These enhancements will be described in more detail later. From a technical standpoint, it will be understood that the enhancements are not dependent on each other and are not mutually exclusive. Each of them may be implemented in communication system 1 to achieve a corresponding benefit, regardless of whether any of the other enhancements are implemented or not.

[0092] Early notification of LTM to target cells As described above, in one example, communication system 1 supports early notification of LTM to the target cell.

[0093] Here, the procedure for providing such notification will be explained with reference to Figure 7, a simplified sequence diagram showing another LTM procedure that may be used in the communication system of Figure 1, as merely an example.

[0094] As shown in Figure 7, before the LTM procedure is triggered, UE3 communicates user data via source DU5b-1 and associated CU5c (in S702a). UE3, source DU5b-1, and associated CU5c perform the L3 measurement control and reporting procedure in S704. This procedure typically includes, for example, UE3 sending an L3 (e.g., RRC) measurement report (e.g., in a "Measurement Report" message) to source DU5b-1 containing measurement results for one or more cells (e.g., measurement values ​​of reference signals in the serving cell and / or one or more adjacent cells). The measurement results may include, for example, L3 filtered measurement results for beams and / or cells (but not necessarily). Source DU5b-1 can then send an appropriate message (e.g., a UL RRC message forwarding message) to inform CU5c of the received measurement report.

[0095] Next, CU5c, source DU5b-1, target DU5b-2, and UE3 (and optionally one or more other "candidate" DUs) communicate with each other at S710 to perform the LTM preconfiguration procedure (including, for example, the steps described in relation to the LTM preconfiguration procedure S510 with reference to Figure 5).

[0096] Following the LTM preconfiguration on S710, UE3 and (R)AN node 5 can perform an LTM cell switching procedure similar to that seen on S750 to switch to the target DU5b-2 cell.

[0097] Specifically, as seen in S752, UE3 can send lower-layer measurement reports (including, for example, one or more L1 / L2 measurement results) to source DU5b-1 (for example, of the serving cell and / or one or more target / candidate cells).

[0098] Next, source DU5b-1 decides at S754 to execute LTM and switch to a candidate target cell. It will be understood that source DU5b-1 can also notify other nodes of the LTM cell switching decision. Source DU5b-1 sends the LTM cell switching command to UE3 at S756. It will be understood that the decision to switch to a specific candidate target cell at S674 (and any notification of the LTM cell switching decision to other nodes) may occur after source DU5b-1 sends the LTM cell switching command to UE3 at S756 (for example, in MAC CE).

[0099] This allows UE3 to detach from the current cell of source DU5b-1 (and synchronize to the target cell of target DU5b-2 if necessary) on S760.

[0100] Source DU5b-1 also notifies CU5c at 758 to initiate LTM / send LTM commands to UE3 (e.g., via the F1 interface using F1AP). In this example, the notification occurs at the same time as, or if possible, before, the LTM cell switch command is sent at S756 (e.g., at the same time as, or immediately after, the LTM cell switch decision is made at S754).

[0101] In this example, following the receipt of the LTM notification sent in S758, CU5c notifies target DU5b-2 in favor of the LTM cell switchover in S761. It will be understood that the content of the "LTM notification" message sent to target DU5b-2 in S761 does not need to be the same as the "LTM notification" message received by CU5c in S758.

[0102] Therefore, target DU5b-2 is beneficially notified of an upcoming cell switchover. This notification may be advantageously used to facilitate the scheduling of dynamic grants (DGs) for the first / initial resources for UE3 in the target cell (e.g., via DCI provided on the PDCCH as shown in S762). This notification may also be advantageously used in the case of configured grants (CGs), where pre-allocated resources can be periodically allocated to one or more UEs (e.g., during the LTM pre-configuration phase as shown in S710). In this case, each UE with a pre-allocated CG resource can send using the pre-allocated resource without having to make scheduling requests and / or monitor the PDCCH. Specifically, in the case of CGs, if RACH-less initial access (also known as "RACH skip") to the pre-allocated CG resource is pre-configured for the target cell, target DU5b-2 can be beneficially notified in substantially real time when the pre-allocated CG will be used by the UE. If pre-allocated CG is not used by the UE, the resource may be scheduled for another UE or used for another purpose.

[0103] Therefore, UE3 can perform a RACH-less initial access procedure with target DU5b-2 in S763, based on a dynamic grant (if provided in S762).

[0104] Target DU5b-2 can detect UE access in S764 and notify CU5c of successful access in S728. UE3 can then communicate user data via Target DU5b-2 and associated CU5c (as seen in S702b).

[0105] Configured Grant-based RACHless LTM Considering the procedure in Figure 7 in more detail for a configured grant-based RACH-less LTM case (where target DU5b-2 can pre-allocate periodic CG resources for one or more UEs), when the LTM notification message is received by target DU5b-2, target DU5b-2 can assume that UE3 will attempt to access the target cell relatively quickly via the pre-allocated CG resources. Target DU5b-2 can then attempt to receive uplink messages sent from UE3 using the indicated pre-allocated CG resources. Specifically, (R)AN node 5 assumes that uplink transmissions via that CG resource are scrambled by a radio network temporary identifier (RNTI), such as cell-RNTI (C-RNTI), to the incoming UE associated with the LTM notification, and that it attempts to decode the received uplink transmissions using the pre-allocated CG resources based on this C-RNTI. After initial access to the target DU using the pre-allocated CG is confirmed, the pre-allocated CG is released by the UE and target DU5b-2 (e.g., at S728).

[0106] Dynamic Grant-Based RACH-less LTM In the case of a dynamic grant-based RACH-less LTM, examining the procedure in Figure 7 in more detail, if an LTM notification message is received by target DU5b-2 during the cell switching procedure between DUs, target DU5b-2 can assume that UE3 will attempt to access the target cell relatively quickly. This allows target DU5b-2 to directly schedule a PDCCH transmission to the incoming UE3 related to the LTM notification. Specifically, the layer 1 (L1) message may be scrambled by the incoming UE3's C-RNTI. Thus, once UE3 receives the LTM cell switching command and initiates the switch to the target cell, UE3 can monitor the PDCCH and use the C-RNTI for UE3 to descramble and decode the L1 message. This L1 message can carry an uplink grant to the target cell for at least UE3's first uplink transmission. Therefore, in this way, UE3 can obtain a dynamic grant from the target cell without making an uplink scheduling request or RACH signaling (assuming UE3 has already obtained a timing advance (TA)). When target DU5b-2 receives an uplink transmission from UE3, target DU5b-2 can assume that the UE access was successful.

[0107] LTM notification timeline A closer examination of the timing of the extended LTM notification procedure in Figure 7 reveals that there are delays related to backhaul latency between source DU5b-1 and CU5c, and between CU5c and target DU5b-2. Therefore, by ensuring that source DU5b-1 notifies CU5c of UE3's LTM handover (e.g., via the F1 interface using F1AP) substantially simultaneously with, or (if possible) before, source DU5b-1 sends the LTM cell switch command to UE3 (e.g., in MAC CE), target DU5b-2 can be adequately prepared before UE3 attempts to access the target cell. Here, it will be understood that potentially, both the LTM notification by source DU5b-1 to CU5c and the LTM notification by CU5c to target DU5b-2 can be favorably timed to occur as early as possible—potentially before source DU5b-1 sends the LTM cell switch command to UE3.

[0108] Group LTM support As described above, in one example, communication system 1 supports triggering an LTM on a group of UE3s to cause the group of UE3s to switch to the same target cell (or possibly different target cells).

[0109] Some steps to support such group LTMs are described in more detail here, for example, with reference to Figures 8 through 14.

[0110] These procedures instruct a group of UEs (which may be a subset or all of the UEs in a cell) to perform an LTM to switch cells. Such group LTM triggers may be beneficial in several different scenarios where, for example, DU5b wants to move all or a group of UEs away from the current serving cell in a relatively short time window. These scenarios include NES scenarios, such as when a capacity booster cell enters NES mode and some or all of the connected UEs need to move away from that capacity booster cell. These scenarios also include NTN scenarios, such as when some or all of the UEs connected via an NTN cell need to move away from that NTN cell to a replacement (NTN or other) cell (for example, due to an impending service link switchover / satellite switchover). These scenarios also include load balancing scenarios, such as when a cell is congested and some or all of the UEs in the congested cell need to be moved to one or more other cells to alleviate or eliminate that congestion.

[0111] While these procedures are described in the context of group LTM, it should be understood that similar procedures can be applied to support cell switching of UE groups in other mobility / handover scenarios, such as conditional handover (CHO) scenarios.

[0112] Figure 8 is a simplified sequence diagram showing several different procedures for supporting Group LTM that may be used in communication system 1.

[0113] In Figure 8, each procedure represents a different way in which a group LTM can be triggered for any capable UE. These procedures include those for when predefined conditions are met, and / or when a common command is received from a node (e.g., a DU or integrated base station) of (R)AN node 5 (e.g., when an NES is activated, when a cell is turned off, when an NTN satellite switchover occurs or is about to occur, and / or when a common LTM indication is received by one or more UEs). While these procedures make it possible to trigger an LTM for a group of two or more UEs, it will be understood that this does not preclude the triggering of a “group” LTM for a single UE (e.g., when a single UE is servicing a cell, and / or when certain conditions affect only a single UE).

[0114] As seen in S812a, in one exemplary procedure, the LTM for groups UE3-1, 3-2, and 3-3 is triggered when a specific time associated with a particular event is reached (or approaching – for example, a time obtained by subtracting a predetermined “delta” time / period from a particular time). The specific time may be the time when the current NTN serving cell will cease to exist (for example, due to satellite switching / service link switching), for example, when the time measured in UE3 is equal to (or approaching) “T service,” this is a parameter (included in system information such as SIB19) that indicates the time information when a cell served via the NTN quasi-earth fixed system is about to cease serving the area it currently covers. The specific time may be the time when the current cell (for example, a capacity-enhanced cell) enters / turns off NES mode.

[0115] In the S812a example, it will be understood that the target cell for LTM switching may be indicated separately by (R)AN node 5 and / or predefined. For example, the target cell may be a cell that replaces the current serving cell in the case of NTN, or a cell that overlaps with the current serving cell in the case of NES.

[0116] As seen in S812b, in another exemplary procedure, when UE3-1, 3-2, and 3-3 are notified that the current serving cell is switching to (or is scheduled to switch to) NES mode, an LTM for the group of UE3-1, 3-2, and 3-3 is triggered (for example, by an indication provided by (R)AN node 5 (for example, by DU5b of (R)AN node 5)).

[0117] As seen in S812c, in another exemplary procedure, when UE3-1, 3-2, and 3-3 receive a paging short message (for example, a message providing paging RNTI via DCI), an LTM is triggered for the group of UE3-1, 3-2, and 3-3, and this paging short message has a dedicated (potentially 1-bit) "LTM" field set to indicate that a group LTM has been triggered (for example, the LTM field is set to "true" or "1").

[0118] As seen in S812d, in another exemplary procedure, when UE3-1, 3-2, and 3-3 receive a generic / common / group LTM command read from system information (or paging information) that includes an LTM command, an LTM is triggered for the group of UE3-1, 3-2, and 3-3.

[0119] As explained above with reference to Figure 8, it will be understood that the target cell may or may not be displayed / defined. If the target cell is not displayed / defined, it is up to UE3 to choose which cell to switch to from among all candidate LTM cells. The selected cell may be, for example, the cell that is ranked best among multiple candidate cells.

[0120] When a group LTM is triggered according to one of the procedures described with reference to Figure 8, the affected UE3-1, 3-2, and 3-3 can perform the LTM procedure to switch to a candidate LTM cell (if the cell is detectable / available), as seen in S870.

[0121] Figure 9 is a simplified sequence diagram showing another procedure for supporting group LTM that may be used in communication system 1.

[0122] In the procedure shown in Figure 9, as seen in S912, the Joint / Group LTM command is transmitted via DCI provided to the PDCCH from a node (e.g., a DU or integrated base station) of (R)AN node 5. In this example, the Joint / Group LTM command includes (or is provided) a UE group identifier so that UE3-1, 3-2, and 3-3 can be recognized as the intended recipients of the Joint / Group LTM command. It will be understood that (R)AN node 5 can configure which UE group each UE3 belongs to by indicating one or more corresponding UE group identifiers for that UE as part of the dedicated configuration of that UE3 (e.g., using dedicated / RRC signaling). It will be understood that a given UE can potentially form part of two or more groups, each group being identified by its respective group identifier configured for that UE.

[0123] When a group LTM is triggered by a joint / group LTM command, the affected UE3-1, 3-2, and 3-3 can perform an LTM procedure to switch to a candidate LTM cell (if the cell is discoverable / available), as seen in S970.

[0124] In the procedure shown in Figure 9, the (R)AN node 5 (e.g., a DU or integrated base station) can also pre-configure / pre-define a shared RNTI for all UEs served in the cell. In this example, when the network sends a joint / group LTM command via the PDCCH (in S912), the joint / group LTM command (indicating which of one or more UE groups should perform the LTM cell switching procedure) can be identified by the shared RNTI (for example, since the DCI has a cyclic redundancy check (CRC) field scrambled using the shared RNTI). Thus, all UE3s in the cell (that have received the shared RNTI) can monitor and receive the PDCCH identified by the configured shared RNTI. However, as seen in S970, only UE3-1, 3-2, and 3-3, whose group identifier matches the group identifier provided in / with the joint / group LTM command, proceed to perform the LTM procedure to switch to the candidate LTM cell.

[0125] Figure 10 is a simplified sequence diagram showing another procedure for supporting group LTM that may be used in communication system 1.

[0126] The procedure in Figure 10 groups the UE3s within a cell by configuring a different shared RNTI for each UE group. Specifically, a node (e.g., a DU or integrated base station) of (R)AN node 5 can (pre-configure) a first shared RNTI ("RNTI A" in the illustrated example) for a first group ("UE Group A" in the illustrated example) of UE3-1A, 3-2A, and 3-3A, and a second shared RNTI ("RNTI B" in the illustrated example) for a second group ("UE Group B" in the illustrated example) of UE3-1B, 3-2B, and 3-3B. It will be understood that a given UE may potentially form part of two or more groups, and each group will be identified by a different shared RNTI (pre-configured) for that UE.

[0127] Subsequently, UE group-specific joint / group LTM commands may be sent via DCI provided by PDCCH, scrambled (i.e., CRC masked) using group-specific RNTIs (e.g., RNTI A or RNTI B).

[0128] Each UE3 in a cell monitors and attempts to decode the DCI sent by the (R)AN node 5 of the PDCCH, which has been scrambled using a group-specific shared RNTI. UE3-1A, 3-2A, and 3-3A, which form part of the first group (UE group A), can decode and therefore receive the joint / group LTM command sent in S1012A using the DCI scrambled using the first RNTI (RNTI A). UE3-1B, 3-2B, and 3-3B, which form part of the second group (UE group B), can decode and therefore receive the joint / group LTM command sent in S1012B using the DCI scrambled using the second RNTI (RNTI B).

[0129] When a group LTM is triggered for the first group (UE group A) by the corresponding joint / group LTM command in S1012A, the affected UE3-1A, 3-2A, and 3-3A can perform the LTM procedure to switch to a candidate LTM cell (if the cell is discoverable / available), as seen in S1070A. When a group LTM is triggered for the second group (UE group B) by the corresponding joint / group LTM command in S1012B, the affected UE3-1B, 3-2B, and 3-3B can perform the LTM procedure to switch to a candidate LTM cell (if the cell is discoverable / available), as seen in S1070B.

[0130] It will be understood that further LTM configuration information may be included in the DCI that provides the joint / group LTM command (in either or both of the steps in Figures 9 and 10). Further LTM configuration information may include, for example, target cell information used when identifying the target cell. For example, this target cell information may enable the identification of the target cell indirectly (for example, by providing a configuration identifier corresponding to the target cell) or it may allow the target cell to be explicitly identified (for example, by physical cell identity (PCI), associated carrier frequency, and / or global cell identity (GCI) / global identifier (CGI)). In this case, the UE3 decodes this group DCI and, having (pre) configured the identified target cell as an LTM candidate target cell, switches to that target cell.

[0131] Further LTM configuration information may include, for example, UE identification information. This may include, for example, a selected list of one or more UE identifiers and / or one or more UE group identifiers. In this case, UE3 can decode this group DCI and verify that its own identification information is present in the list, or that its own UE group identification information is present (which may be (pre)configured in UE3 as described with reference to Figure 9), and trigger LTM to switch away from the current cell.

[0132] Additional information may include, for example, other L2 protocol processing information, such as no MAC reset, partial or complete MAC reset, RLC reset, and / or PDCP data recovery.

[0133] Figure 11 is a simplified sequence diagram showing another procedure for supporting group LTM that may be used in communication system 1. In this example, as seen in S1112, the joint / group LTM command is sent from a node of (R)AN node 5 (e.g., a DU or integrated base station) using MAC CE instead of DCI. When group LTM is triggered by the joint / group LTM command, the affected UEs 3-1, 3-2, and 3-3 can perform the LTM procedure to switch to a candidate LTM cell (if the cell is discoverable / available), as seen in S1170.

[0134] Here, with reference to Figure 12, which shows MAC signals that may be used to support group LTM, we will describe, simply as an example, a group LTM MAC CE that may be used in communication system 1 (for example, in the procedure of Figure 11).

[0135] As shown in Figure 12, the MAC CE has a subheader 1210 and a payload section 1212 that carries joint / group LTM commands and optional additional information 1214.

[0136] The subheader 1210 typically includes a length ("L") field indicating the byte-length of the MAC CE, a format ("F") field indicating the size of the length field, one or more reserved ("R") bits, and a logical channel identification information field for further identifying the MAC CE (e.g., a group LTM MAC CE).

[0137] The additional information may include, for example, target cell information 1214a for identifying the target cell. This target cell information 1214a can enable the identification of the target cell indirectly (for example, by providing a configuration identifier corresponding to the target cell) or explicitly (for example, by physical cell identity (PCI), associated carrier frequency, and / or global cell identity (GCI) / cell global identifier (CGI)). In this case, UE3 decodes this group LTM MAC CE and has an identified target cell that has been (pre)configured as an LTM candidate target cell, and UE3 switches to that target cell.

[0138] The additional information may include, for example, UE identification information S1214b. This may include, for example, a selected list of one or more UE identifiers and / or one or more UE group identifiers. In this case, UE3 can decode this group LTM MAC CE and verify that its own identification information is present in the list, or that its own UE group identification information is present (which may be configured (pre-configured) in UE3 as described with reference to Figure 9), and trigger the LTM to switch away from the current cell.

[0139] Additional information may include, for example, other L2 protocol processing information S1214c, which indicates, for example, no MAC reset, partial or complete MAC reset, RLC reset, and / or PDCP data recovery.

[0140] Nevertheless, it will be understood that the group LTM MAC CE does not need to contain additional information. In this case, UE3, having decoded the received group LTM MAC CE, needs to trigger an LTM and switch from the current serving cell. UE3 can then select which cell to switch to from among all candidate LTM cells. The selected cell may be, for example, the best-ranked cell among several candidate cells.

[0141] It will be understood that a shared RNTI can also be configured within a common search space (CSS) shared by all or a group of connected UEs within a cell. A shared RNTI can be configured and / or used with a group LTM MAC CE in a manner similar to how a shared RNTI was described in relation to Figure 9 (i.e., with respect to all UE3s) or in relation to Figure 10 (i.e., with respect to a particular group of UE3s).

[0142] Figure 13 shows another MAC signal that may be used to support group LTM in the communication system of Figure 1.

[0143] As shown in Figure 13, the MAC CE has a subheader 1310 and a payload section 1312 that carries independent LTM commands 1314a to 1314c for each UE in the UE group.

[0144] The subheader 1310 typically includes a length ("L") field indicating the byte-length of the MAC CE, a format ("F") field indicating the size of the length field, one or more reserved ("R") bits, and a logical channel identification information field for further identifying the MAC CE (e.g., a group LTM MAC CE).

[0145] Figure 14 shows other MAC signals that may be used to correspond to group LTM in communication system 1.

[0146] As shown in Figure 14, in this example, a single transport block (TB) is provided, containing each MAC CE (or MAC SDU) 1412a-1412c that carries the corresponding LTM commands 1414a-1414c for each UE in the UE group.

[0147] Each MAC CE (or MAC SDU) 1412a-1412c has associated subheaders 1410a-1410c that carry LTM commands 1414a-1414c.

[0148] Each subheader 1410a-14c typically includes a length ("L") field indicating the byte-length of the MAC CE (or MAC SDU), a format ("F") field indicating the size of the length field, one or more reserved ("R") bits, and a logical channel identification information field for further identifying the MAC CE (MAC SDU) (e.g., a group LTM MAC CE or MAC SDU).

[0149] With respect to MAC signaling as described with reference to Figure 13 or Figure 14, it will be understood that shared RNTIs can also be configured within a common search space (CSS) common to all or groups of connected UEs within a cell. Shared RNTIs can be configured and / or used with the “group” LTM command in a similar manner to how shared RNTIs were described in relation to Figure 9 (i.e., with respect to all UE3s) or in relation to Figure 10 (i.e., with respect to a particular group of UE3s).

[0150] Support for subsequent LTM procedures As described above, in one example, communication system 1 provides support to enable efficient subsequent LTM cell switching after preceding LTM cell switching.

[0151] More specifically, it is beneficial for not only the first serving DU5b-1 but also any subsequent servings DU5b-2, 5b-3 to recognize all candidate target cells in order to facilitate the continuation of subsequent cell switching management (for example, to track which cells the UE can move to).

[0152] Here, with reference to Figure 15, a simplified sequence diagram showing another LTM procedure that may be used in communication system 1, we will describe, simply as an example, one procedure that provides support for enabling efficient subsequent LTM cell switching.

[0153] In summary, the procedure in Figure 15 involves CU5c sending a list of candidate cells to the new serving DU5b-2 following an LTM cell switch (for example, after receiving "Access Success"). This procedure may be used for each cell switch, and therefore each new serving DU may be notified of candidate LTM cells after each LTM cell switch.

[0154] In Figure 15, it will be understood that the step shown in S1510 generally corresponds to the procedure in step S410 in Figure 4 (and the corresponding step in the other similar procedures described above), although there are some differences as described below. Similarly, steps S1502a, S1504, S1506, S1550, and S1528 generally correspond to the corresponding steps S1402a, S1404, S1406, S1450, and S1428 in Figure 4 (and the corresponding step in the other similar procedures described above).

[0155] As shown in Figure 15, before the LTM procedure is triggered, UE3 communicates user data via source DU5b-1 and associated CU5c (in S1502a). UE3, source DU5b-1, and associated CU5c perform the L3 measurement control and reporting procedure in S1504. This procedure typically involves UE3 sending an L3 measurement report (e.g., an RRC) containing measurement results for one or more cells (e.g., measured values ​​of a reference signal in the serving cell and / or one or more adjacent cells) to source DU5b-1 (e.g., in a "Measurement Report" message). The measurement results may (but do not necessarily) include, for example, L3 filtered measurement results for the beam and / or cells. Source DU5b-1 can then send an appropriate message (e.g., a UL RRC message forwarding message) to inform CU5c of the received measurement report.

[0156] Next, CU5c can make a decision in S1506 to initiate L1 / L2 inter-cell trigger mobility (pre-configuration).

[0157] In S1516-1 and S1516-2, CU5c sends one or more messages to one or more candidate DUs 5b-3, 5b-2 containing the (candidate) target cell requesting the setup of a context for UE3 (e.g., a UE context setup request as shown in Figure 15). This message is essentially a request for LTM configuration at the receiving DU. If the candidate DU approves the request for LTM configuration at one or more (candidate) target cells, the candidate DU responds to CU5c in S1518-1 and S1518-2 with an appropriate response message (e.g., a UE context setup response as shown in Figure 15) containing the lower-layer configuration generated for one or more approved target candidate cells. Potentially, it will be understood that either a single UE context setup procedure (i.e., one procedure per candidate DU to prepare one or more candidate cells of the DU) or one or more UE context setup procedures (i.e., one procedure per candidate cell) may be used at this stage. In the illustrated procedure, for example, in S1518-2, at least target DU5b-2 responds with such a response message that includes a lower-level configuration generated for one or more approved target candidate cells of target DU5b-2.

[0158] In S1520, CU5c sends an appropriate message to source DU5b-1, which includes a generated RRC reconfiguration message with an L1 / L2 triggered mobility configuration. This message may be, for example, a UE context change request as shown in Figure 15, or another message such as a DL RRC message forwarding message. In this example, the message sent in S1520 also includes a list of LTM candidate cells, thereby advantageously allowing source (i.e., the current serving) DU5b-1 to recognize the LTM candidate cells.

[0159] Source DU5b-1 forwards the received RRC reconfiguration message to UE3 in S1522, and UE3 responds in S1524 with an RRC reconfiguration complete message (which substantially indicates that the RRC configuration has been successfully applied to the UE).

[0160] In S1526, source DU5b-1 forwards an RRC reconfiguration complete message to CU5c (which substantially indicates that the RRC configuration has been successfully applied to the UE) using an appropriate message corresponding to the message sent in S1520. This message may be, for example, a UE context change response as shown in Figure 15, or it may be another message such as a UL RRC message forwarding message.

[0161] Following the LTM pre-configuration procedure (S1510), UE3 and (R)AN node 5 may perform the LTM cell switching procedure, as seen in S1550, to switch to the cell of target DU5b-2 (as described, for example, with reference to Figure 6). After UE3 accesses the new cell of target DU5b-2 and target DU5b-2 detects the access, target DU5b-2 can notify CU5c of the successful access in S1528. UE3 can then communicate user data via target DU5b-2 and the associated CU5c, as previously described.

[0162] Following the receipt of the access success notification in S1528, CU5c in S1530 sends an appropriate message containing a list of LTM candidate cells to the previous target (i.e., the new serving) DU5b-2, thereby advantageously making the previous target (i.e., the new serving) DU5b-2 aware of the LTM candidate cells. This message could be, for example, a UE context change request as shown in Figure 15, or another appropriate message. The previous target (i.e., the new serving) DU5b-2 responds in S1532 with an appropriate message corresponding to the message sent in S1530. This message could be, for example, a UE context change response as shown in Figure 15, or another appropriate message.

[0163] Here, with reference to Figure 16, a simplified sequence diagram showing another LTM procedure that may be used in communication system 1, we will describe, simply as an example, another procedure that provides support for enabling efficient subsequent LTM cell switching.

[0164] In summary, in the procedure shown in Figure 16, CU5c sends a list of candidate cells to the new serving DU5b-2 before the LTM cell is switched over.

[0165] In Figure 16, it will be understood that the step shown in S1610 largely corresponds to the procedure in step S410 in Figure 4 (and the corresponding step in the other similar procedures described above), although there are some differences as described below. Similarly, steps S1602a, S1604, S1606, and S1650 largely correspond to the corresponding steps S1402a, S1404, S1406, and S1450 in Figure 4 (and the corresponding step in the other similar procedures described above).

[0166] As shown in Figure 16, before the LTM procedure is triggered, UE3 communicates user data via source DU5b-1 and associated CU5c (in S1602a). UE3, source DU5b-1, and associated CU5c perform the L3 measurement control and reporting procedure in S1604. This procedure typically involves UE3 sending an L3 measurement report (e.g., an RRC) containing measurement results for one or more cells (e.g., measured values ​​of a reference signal in the serving cell and / or one or more adjacent cells) to source DU5b-1 (e.g., in a "Measurement Report" message). The measurement results may (but do not necessarily) include, for example, L3 filtered measurement results for the beam and / or cells. Source DU5b-1 can then send an appropriate message (e.g., a UL RRC message forwarding message) to inform CU5c of the received measurement report.

[0167] User equipment Figure 17 is a simplified block diagram showing the main components of UE3 for implementation in the system shown in Figure 1.

[0168] Signals from (R)AN node 5 via air interface 33 and one or more antennas.

[0169] UE3 has a controller 37 that controls the operation of UE3. The controller 37 is associated with memory 39 and coupled to transceiver circuit 31. Although not necessarily required for its operation, UE3 can, of course, have all the usual features of a conventional UE3 (such as a user interface 35, like a touchscreen / keypad / microphone / speaker, to enable direct control and interaction with the user), which can be provided, as appropriate, by hardware, software, and firmware, one or any combination thereof.

[0170] In this example, the controller 37 is configured to control the overall operation of the UE3 by program instructions or software instructions stored in memory 39. The software may be pre-installed in memory 39 and / or downloaded, for example, via a communication system or from a removable data storage device (RMD). As shown in the figure, these software instructions include, among other things, an operating system 41 and a communication control module 43.

[0171] The communication control module 43 is operable to control communication between the UE3 and one or more of its Serving(R)AN nodes 5 (and other communication devices connected to the (R)AN node 5, such as further UEs and / or core network nodes). The communication control module 43 is configured to handle uplink communication in general via associated uplink channels (e.g., via a physical uplink control channel (PUCCH), a random access channel (RACH), and / or a physical uplink shared channel (PUSCH)), including both dynamic and quasi-static signaling (e.g., such as SRS). The communication control module 43 is also configured to handle the reception of downlink communications in general via associated downlink channels (e.g., via physical downlink control channels (PDCCH) and / or physical downlink shared channels (PDSCH)), including both dynamic and quasi-static signaling (e.g., CSI-RS, SSBs, etc.).

[0172] It will be recognized that the communication control module 43 may include several submodules (or "layers") that support specific functions. For example, the communication control module 63 may include a PHY submodule, a MAC submodule, an RLC submodule, a PDCP submodule, an SDAP submodule, an IP submodule, an RRC submodule, and so on.

[0173] RAN (distributed) Figure 18 is a simplified block diagram showing the main components of a distributed (R)AN node 5, including a distributed base station, for implementation in the system shown in Figure 1.

[0174] As shown in the figure, the (R)AN node 5 includes a central unit 5c and a distributed unit 5b (however, it may also include other DUs as described above). Each unit 5c, 5b includes its respective transceiver circuits 51c, 51b.

[0175] The distributed unit 5b transceiver circuit 51b is operable to transmit signals to UE3 via the air interface 53b and one or more antennas and to receive signals from UE3, and is also operable to transmit signals to central unit 5c via the distributed unit side of an interface, for example, the F1 interface (which may be provided via a satellite radio interface) and to receive signals from central unit 5c.

[0176] The central unit 5c transceiver circuit 51c is operable to transmit signals to and receive signals from the functions of the core network 7 and / or other (R)AN nodes 5 via the network interface 55c. The network interface typically includes N1, N2 and / or N3 interfaces for communicating with the core network and base station-to-base station interfaces (e.g., Xn) for communicating with other (R)AN nodes 5. The central unit 5c transceiver circuit 51c is also operable to transmit signals to and receive signals from one or more distributed units 5b, such as the central unit side of the provided F1 interface.

[0177] Each unit 5c, 5b includes its respective controller 57c, 57b, which controls the operation of the corresponding transceiver circuits 51c, 51b according to the software stored in the respective memories 59c, 59b of the distributed unit 5b and the central unit 5c. The software for each unit may be pre-installed in the memories 59c, 59b and / or downloaded, for example, via the communication system 1 or from a removable data storage device (RMD). The software for each unit includes, among other things, its respective operating systems 61c, 61b and its respective communication control modules 63c, 63b.

[0178] Each communication control module 63c, 63b is operable to control the communication of the corresponding units 5c, 5b, including communication from one unit to the other. The communication control module 63b of the distributed unit 5b controls the communication between the distributed unit 5b and the UE3, and the communication control module 63c of the central unit 5c controls the communication between the central unit 5c and other network entities connected to the distributed (R)AN node 5.

[0179] Communication control modules 63c and 63b also control the portions of the uplink and downlink user traffic flow that are handled by the distributed unit 5b and the central unit 5c, respectively, and control the data transmitted to communication devices served by the (R)AN node 5, including, for example, data for managing the operation of UE3. Each communication control module 63c and 63b plays a role in controlling the portions of the uplink communication reception and decoding that are handled by the distributed unit 5b and the central unit 5c, respectively, via the relevant uplink channels (e.g., via the physical uplink control channel (PUCCH), the random-access channel (RACH), and / or the physical uplink shared channel (PUSCH)), including both dynamic and quasi-static signaling (e.g., SRS). Each communication control module 63c, 63b plays a role in controlling the portion of downlink communication transmission that is handled by the distributed unit 5b and the central unit 5c, respectively, via the associated downlink channel, which includes both dynamic and quasi-static signaling (e.g., CSI-RS, SSB, etc.) (e.g., via the physical downlink control channel (PDCCH) and / or the physical downlink shared channel (PDSCH)).

[0180] It will be understood that the communication control modules 63c, 63b may also include several submodules (or "layers") to support specific functions of the corresponding units 5c, 5b. The included modules depend on how the corresponding units 5c, 5b are configured (e.g., the exact CU-DU partitioning). For example, the communication control module 63c of the distributed unit 5b may include a PHY submodule, a MAC submodule, and an RLC submodule, while the communication control module 63c of the central unit 5c may include a PDCP submodule, an SDAP submodule, an IP submodule, an RRC submodule, and so on.

[0181] Variations and alternative examples Detailed embodiments have been described above. As those skilled in the art will understand, several modifications and substitutions can be made to the exemplary embodiments described above, while still benefiting from the disclosure embodied therein.

[0182] For example, while terminology specific to cellular communication generations (such as 2G, 3G, 4G, 5G, and 6G) ​​may be used to refer to specific communication entities for clarity, it should be understood that the technical features described for a given entity are not limited to devices of that particular communication generation. Technical features can be implemented in any functionally equivalent communication entity, regardless of the differences in terminology used to refer to them.

[0183] In the above description, the UE and base station are described as having several separate functional components or modules for the sake of ease of understanding. These modules may thus be provided in certain applications, for example, where an existing system is modified to implement the present disclosure, but in other applications, for example, systems designed from the outset with the features of the present invention in mind, these modules may be incorporated into the overall operating system or code, and therefore these modules may not be identified as separate entities.

[0184] In the exemplary embodiments described above, several software modules have been explained. As those skilled in the art will understand, software modules may be provided in compiled or uncompiled form and supplied to a base station or UE as a signal over a computer network or on a recording medium. Furthermore, some or all of the functions performed by this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred because it facilitates updating the base station or UE to update its functions.

[0185] Each controller may include, but is not limited to, one or more hardware-implemented computer processors, microprocessors, central processing units (CPUs), arithmetic logic units (ALUs), input / output (IO) circuits, internal memory / cache (programs and / or data), processing registers, communication buses (such as control buses, data buses, and / or address buses), direct memory access (DMA) functions, hardware or software-implemented counters, pointers, and / or timers, and any other suitable form of processing circuitry. Various other modifications will be obvious to those skilled in the art and will not be described in further detail here.

[0186] A base station may comprise a “distributed” base station having a central unit (CU) and one or more individual distributed units (DU).

[0187] In this disclosure, user equipment (or "UE," "mobile station," "mobile device," or "wireless device") is an entity connected to a network via a wireless interface.

[0188] Please note that this disclosure is not limited to dedicated communication devices, but can be applied to any device having communication functions as described in the following paragraphs.

[0189] The terms “User Equipment” or “UE” (as used by 3GPP), “Mobile Station,” “Mobile Device,” and “Radio Device” are generally intended to be synonymous with each other and include standalone mobile stations such as terminals, cell phones, smartphones, tablets, cellular IoT devices, IoT devices, and machines. The terms “Mobile Station” and “Mobile Device” will be understood to also include devices that remain stationary for extended periods.

[0190] UE may be items of equipment for production or manufacturing and / or items of energy-related machinery, such as equipment or machinery (for example, boilers, engines, turbines, solar panels, wind turbines, hydroelectric generators, thermal generators, nuclear generators, batteries, nuclear systems and / or related equipment, heavy electrical machinery, pumps including vacuum pumps, compressors, fans, blowers, hydraulic equipment, pneumatic equipment, metalworking machinery, manipulators, robots and / or their application systems, tools, molds or dies, rolls, conveying equipment, elevators, material handling equipment, textile machinery, sewing machinery, printing and / or related machinery, paper conversion machinery, chemical machinery, mining machinery and / or construction machinery and / or related equipment, machinery and / or equipment for agriculture, forestry and / or fisheries, safety and / or environmental protection equipment, tractors, precision bearings, chains, gears, power transmission equipment, lubrication equipment, valves, pipe fittings and / or application systems for any of the aforementioned equipment or machinery, etc.).

[0191] For example, UE may be an item of transport equipment (such as transport equipment such as railway cars, automobiles, motorcycles, bicycles, trains, buses, carts, rickshaws, ships and other vessels, aircraft, rockets, satellites, drones, balloons, etc.).

[0192] UE may be, for example, an item of information and communication equipment (such as electronic computers and related equipment, communication and related equipment, electronic components, etc.).

[0193] UE may include, for example, refrigerators, refrigerator applications, trading and / or service industry equipment items, vending machines, automated service machines, office machines or equipment, and household appliances and electronic devices (such as audio equipment, video equipment, loudspeakers, radios, televisions, microwave ovens, rice cookers, coffee machines, dishwashers, washing machines, dryers, electronic fans or related equipment, vacuum cleaners, etc.).

[0194] The UE may be an electrical application system or device, for example, such as an X-ray system, particle accelerator, radioisotope equipment, sound wave equipment, electromagnetic application equipment, power application equipment, etc.

[0195] UE may include, for example, electronic lamps, lighting fixtures, measuring instruments, analyzers, testers, or measuring or detection equipment (such as smoke detectors, motion sensors, wireless tags, etc.), watches or clocks, laboratory equipment, optical devices, medical equipment and / or systems, weapons, bladed weapons, hand tools, etc.

[0196] The UE may be, for example, a wireless-equipped personal digital assistant or related device (such as a wireless card or module designed to be attached to or inserted into another electronic device, such as a personal computer or electrical measuring instrument).

[0197] The UE may be part of a device or system that uses various wired and / or wireless communication technologies to provide the applications, services, and solutions described below with respect to the Internet of Things (IoT).

[0198] Internet of Things (IoT) devices (or "Things") may be equipped with appropriate electronics, software, sensors, network connectivity, etc., that enable them to collect and exchange data with each other and with other communication devices. IoT devices may include automated devices that follow software instructions stored in internal memory. IoT devices may operate without requiring human supervision or interaction. IoT devices may also remain stationary and / or inactive for extended periods. IoT devices may be implemented as part of (generally) stationary equipment. IoT devices may also be incorporated into non-stationary equipment (such as a vehicle) or attached to animals or people being monitored / tracked.

[0199] It will be understood that IoT technology can be implemented on any communication device that can connect to a communication network to send / receive data, regardless of whether such communication device is controlled by human input or by software instructions stored in memory.

[0200] It will be understood that IoT devices are sometimes called Machine-Type Communication (MTC) devices or Machine-to-Machine (M2M) communication devices. It will be understood that a UE may support one or more IoT or MTC applications. Some examples of MTC applications are listed in the table below. This list is not exhaustive and is intended to show some examples of machine-type communication applications. [Table 2]

[0201] Applications, services, and solutions may include MVNO (Mobile Virtual Network Operator) services, emergency radio communication systems, PBX (Private Branch eXchange) systems, PHS / digital cordless telecommunications systems, POS (Point of Sale) systems, incoming advertising systems, MBMS (Multimedia Broadcast and Multicast Service), V2X (Vehicle to Everything) systems, train radio systems, location-related services, disaster / emergency radio communication services, community services, video streaming services, femtocell application services, VoLTE (Voice over LTE) services, billing services, wireless on-demand services, roaming services, activity monitoring services, telecommunications carrier / communication network selection services, function restriction services, PoC (Proof of Concept) services, personal information management services, ad hoc network / DTN (Delay Tolerant Networking) services, and others.

[0202] Furthermore, the aforementioned UE categories are merely examples of applications of the technical concepts and exemplary embodiments described in this document. Needless to say, these technical concepts and exemplary embodiments are not limited to the UEs described above and are subject to various modifications.

[0203] Various other examples of modifications will be obvious to those skilled in the art and will not be described in further detail here.

[0204] For example, all or part of the exemplary embodiments disclosed above may be described, but are not limited to, as follows: (Note 1) A method performed by a first unit of an access network, This includes transmitting capability information indicating the capabilities of the first unit to a second unit of the access network, Information demonstrating capabilities is, The ability of a first unit to communicate with user equipment (UE) using a communication scheme in which at least one time resource is configured for uplink communication, at least one time resource is configured for downlink communication, and at least one time resource is configured for both downlink and uplink communication, or The ability of a first unit to isolate downlink communications from uplink communications in at least one time resource configured for both downlink communications and uplink communications, A method that demonstrates at least one of the following. (Note 2) The capability information is the method described in Appendix 1, which includes information indicating the separation capability for each of several different separation methods. (Note 3) The capability information is the method described in Appendix 1, which includes information indicating the combined separation capability for multiple different separation schemes. (Note 4) The method described in Appendix 3, wherein capability information includes information identifying the configuration of different separation schemes used to determine the combined separation capability. (Note 5) The method described in Appendix 3 or 4, wherein capability information includes information indicating the combined separation capability for each of several different configurations of different separation schemes. (Note 6) The method according to any one of Annexes 2 to 5, wherein the different separation scheme includes at least one of the following: a first separation scheme in which at least one guard band is used to separate downlink communications from uplink communications; a second separation scheme in which different beams are used to separate downlink communications from uplink communications; a third separation scheme in which different antenna configurations are used to separate downlink communications from uplink communications; or a fourth separation scheme in which at least one cancellation mechanism is used to separate downlink communications from uplink communications. (Note 7) The method described in any one of the appendices 1 to 6, further comprising receiving a request from a second unit, wherein capability information is provided in response to the request. (Note 8) A method performed by a second unit of the access network, The ability of a first unit to communicate with user equipment (UE) using a communication scheme in which at least one time resource is configured for uplink communication, at least one time resource is configured for downlink communication, and at least one time resource is configured for both downlink and uplink communication, or The ability of a first unit to separate downlink communications from uplink communications in at least one time resource configured for both downlink communications and uplink communications, A method for receiving capability information indicating at least one of the following from a first unit of an access network. (Note 9) A method performed by a second unit of the access network, A method comprising transmitting configuration information for a communication scheme to a first unit of an access network, wherein at least one of a plurality of time resources is configured as a first type for uplink communication, at least one of the plurality of time resources is configured as a second type for downlink communication, and at least one of the plurality of time resources is configured as a third type for both downlink and uplink communication. (Note 10) 10. The method according to Appendix 9, wherein the configuration information is for configuring the first unit to communicate with at least one user equipment (UE) using multiple time resources according to a communication scheme. (Note 11) The method according to Appendix 9 or 10, wherein the configuration information includes information indicating whether, for each time resource of multiple time resources, that time resource is of type 1, type 2, or type 3. (Note 12) The method according to Appendix 9 or 10, wherein the first unit has an existing configuration of multiple time resources, in which at least one time resource is configured as a first type and at least one time resource is configured as a second type, and the configuration information includes information indicating which of the multiple time resources in the existing configuration should be changed from the first type or from the second type to the third type. (Note 13) 13. Configuration information is: First information for configuring each of multiple time resources to either a first type for uplink communication or a second type for downlink communication in a first frequency domain, The method according to Appendix 9 or 10, further comprising: second information for configuring each of a plurality of time resources to a first type for uplink communication or a second type for downlink communication in a second frequency domain. (Note 14) Further information is transmitted to the first unit, and the information is, At least one time resource of the first type, and / or at least one time resource of the second type, and / or which should be dynamically modified to become a third type of time resource. The method described in any one of the appendices 9 to 13, which indicates at least one time resource of a third type that should be dynamically modified to become a time resource of a first type or a time resource of a second type. (Note 15) The method according to Appendix 14, wherein the transmission of further information is timed to be received by the first unit at the minimum time before the first unit receives control information relating to the transmission of data for at least one UE by the second unit. (Note 16) Further information is transmitted along with control information relating to data transmission for at least one UE by the second unit, as described in Appendix 14. (Note 17) The method according to any one of the Supplements 9 to 16, further comprising transmitting an indication of at least one frequency domain of an uplink subband, a downlink subband, and / or a guard band to a first unit. (Note 18) The method described in any one of the appendices 9 to 16, further comprising sending to the first unit an indication of the filters applied to the time resources configured as a third type. (Note 19) The method according to Appendix 9, wherein the configuration information includes at least one of the following: information indicating the configuration of a communication scheme to be implemented in a first unit; information indicating the intended configuration for a communication scheme in a second unit; and / or information indicating the configuration of a communication scheme for an adjacent unit of an access network or another access network. (Note 20) The method according to Appendix 9 or 19, wherein the configuration information includes information for configuring at least one time resource as a third type, which includes at least one of the following: a display of frequency resources for at least one uplink subband, a display of frequency resources for at least one downlink subband, a display of frequency resources for at least one guard band, a display of the time position of at least one uplink subband or downlink subband, and / or the time position of at least one time resource of a third type. (Note 21) The method according to Appendix 9, 19, or 20, wherein the configuration information is transmitted on the condition that the first unit supports receiving configuration information containing information for configuring at least one time resource as a third type, or that at least one time resource supports operation according to a communication scheme configured as a third type. (Note 22) The method according to Appendix 9, 19, or 20, wherein the configuration information includes information for configuring at least one time resource as a third type, provided that the first unit supports receiving configuration information including information for configuring at least one time resource as a third type, or that at least one time resource supports operation according to a communication scheme configured as a third type. (Note 23) The method according to Appendix 9, wherein the configuration information is second configuration information, and transmission includes transmitting first configuration information for configuring at least one time resource as a first type and at least one time resource as a second type, without configuring the time resource as a third type. (Note 24) The method according to Appendix 9, wherein the configuration information includes first configuration information for configuring at least one time resource as a first type and at least one time resource as a second type, and second configuration information for configuring at least one time resource configured as a first or second type by the first configuration information as a third type. (Note 25) A method performed by a first unit of an access network, A method comprising receiving configuration information for a communication scheme from a second unit of an access network, wherein at least one of a plurality of time resources is configured as a first type for uplink communication, at least one of the plurality of time resources is configured as a second type for downlink communication, and at least one of the plurality of time resources is configured as a third type for both downlink and uplink communication. (Note 26) The configuration information is for configuring the first unit to communicate with at least one user equipment (UE) using multiple time resources according to a communication scheme, as described in Appendix 25. (Note 27) The method according to Appendix 25 or 26, further comprising determining a filter to be applied between the uplink subband and the downlink subband based on a guard band composed of a second unit. (Note 28) Configuration information is second configuration information, and receiving includes receiving first configuration information for configuring at least one time resource as a first type and at least one time resource as a second type, without configuring the time resource as a third type. The method is, If the first unit does not support receiving configuration information containing information for configuring at least one time resource as a third type, or does not support operation according to a communication method in which at least one time resource is configured as a third type, the second configuration information is ignored and the first configuration information is used. The method according to Appendix 25, further comprising using second configuration information if the first unit supports receiving configuration information that includes information for configuring at least one time resource as a third type, or if it supports operating in accordance with a communication scheme in which at least one time resource is configured as a third type. (Note 29) The configuration information includes first configuration information for configuring at least one time resource as a first type and at least one time resource as a second type, The system includes, a second configuration information for configuring at least one time resource configured as a first or second type by first configuration information as a third type, The method is, If the first unit does not support receiving configuration information containing information for configuring at least one time resource as a third type, or does not support operation according to a communication method in which at least one time resource is configured as a third type, the second configuration information is ignored and the first configuration information is used. The method according to Appendix 25, further comprising using the first and second configuration information if the first unit supports receiving configuration information that includes information for configuring at least one time resource as a third type, or if it supports operating in accordance with a communication scheme in which at least one time resource is configured as a third type. (Note 30) The method according to Appendix 28 or 29, further comprising using a configuration of time resources based on whether or not a first configuration information and / or a second configuration is used, and transmitting to a second unit an indication that the configuration of time resources used in a first unit is a configuration that includes at least one time resource configured as a third type, or an indication that the configuration of time resources used in a first unit is a configuration that does not include at least one time resource configured as a third type. (Note 31) The method according to any one of the appendices 25 to 30, further comprising providing the second unit with an indication of whether the first unit supports receiving configuration information including information for configuring at least one time resource as a third type, or an indication of whether the first unit supports operation according to a communication scheme in which at least one time resource is configured as a third type. (Note 32) The method according to any one of the appendices 25 to 30, further comprising sending an error message to the second unit in response to the reception of configuration information if the first unit does not support receiving configuration information containing information for configuring at least one time resource as a third type, or does not support operating in accordance with a communication scheme in which at least one time resource is configured as a third type. (Note 33) A method performed by a first unit of an access network, First information relating to at least one first beam configuration for at least one time resource configured for both downlink and uplink communication, and at least one second beam configuration for at least one time resource configured exclusively for downlink communication or exclusively for uplink communication. Second information indicating at least one first beam pattern for at least one time resource configured for both downlink and uplink communication, and at least one second beam pattern for at least one time resource configured exclusively for downlink communication or exclusively for uplink communication. A third piece of information indicating at least one first set of antenna components that can or cannot be used for uplink communication in at least one time resource configured for both downlink and uplink communication, and / or, A fourth piece of information showing at least one first configuration for an antenna for uplink communication in at least one time resource, configured for both downlink and uplink communication, and at least one second configuration for an antenna for downlink communication in at least one time resource, configured for both downlink and uplink communication. A method comprising transmitting beam or antenna-related information, including at least one of the following, to a second unit of an access network. (Note 34) A method performed by a second unit of the access network, First information indicating at least one first beam configuration of at least one time resource configured for both downlink and uplink communications, and at least one second beam configuration of at least one time resource configured for either downlink communications only or uplink communications only. Second information showing at least one first beam pattern of at least one time resource configured for both downlink and uplink communications, and at least one second beam pattern of at least one time resource specifically configured for either downlink or uplink communications. Third information indicating at least one first set of antenna components that can or cannot be used for uplink communication in at least one time resource configured for both downlink and uplink communication, and / or Fourth information relating to at least one first configuration of an antenna for uplink communication in at least one time resource configured for both downlink and uplink communication, and at least one second configuration of an antenna for downlink communication in at least one time resource configured for both downlink and uplink communication, A method comprising receiving beam or antenna-related information from a first unit of an access network, including at least one of the following. (Note 35) The method according to Appendix 34, further comprising using beam or antenna-related information when identifying a beam used for at least one time resource configured for both downlink and uplink communications. (Note 36) The method according to Appendix 34 or 35, further comprising using beam or antenna-related information when identifying at least one weight to be applied to beamforming of at least one time resource configured for both downlink and uplink communications. (Note 37) A first unit for an access network, The access network includes a second unit with means for transmitting capability information indicating the capabilities of the first unit, Information demonstrating capabilities is, The ability of a first unit to communicate with user equipment (UE) using a communication scheme in which at least one time resource is configured for uplink communication, at least one time resource is configured for downlink communication, and at least one time resource is configured for both downlink and uplink communication, or The ability of a first unit to isolate downlink communications from uplink communications in at least one time resource configured for both downlink communications and uplink communications, A first unit that shows at least one of the following. (Note 38) A second unit for an access network, comprising means for receiving capability information from a first unit of the access network, Ability information is, The ability of a first unit to communicate with user equipment (UE) using a communication scheme in which at least one time resource is configured for uplink communication, at least one time resource is configured for downlink communication, and at least one time resource is configured for both downlink and uplink communication, or The ability of a first unit to separate downlink communications from uplink communications in at least one time resource configured for both downlink communications and uplink communications, A second unit that shows at least one of the following. (Note 39) A second unit for the access network, A second unit comprising means for transmitting configuration information for a communication scheme to a first unit of an access network, wherein at least one of a plurality of time resources is configured as a first type for uplink communication, at least one of the plurality of time resources is configured as a second type for downlink communication, and at least one of the plurality of time resources is configured as a third type for both downlink and uplink communication. (Note 40) A first unit for an access network, A first unit comprising means for receiving configuration information for a communication scheme from a second unit of an access network, wherein at least one of a plurality of time resources is configured as a first type for uplink communication, at least one of the plurality of time resources is configured as a second type for downlink communication, and at least one of the plurality of time resources is configured as a third type for both downlink and uplink communication. (Note 41) A first unit for an access network, First information indicating at least one first beam configuration for at least one time resource configured for both downlink and uplink communications, and at least one second beam configuration for at least one time resource configured for either downlink communications only or uplink communications only. Second information indicating at least one first beam pattern for at least one time resource configured for both downlink and uplink communication, and at least one second beam pattern for at least one time resource configured exclusively for downlink communication or exclusively for uplink communication. In at least one time resource configured for both downlink and uplink communication, a first set of at least one antenna components that can or cannot be used for uplink communication, and third information indicating a second set of at least one antenna components that can or cannot be used for downlink communication in at least one time resource configured for both downlink and uplink communication, and / or Fourth information relating to at least one first configuration of an antenna for uplink communication in at least one time resource configured for both downlink and uplink communication, and at least one second configuration of an antenna for downlink communication in at least one time resource configured for both downlink and uplink communication, A first unit comprising means for transmitting beam or antenna-related information, including at least one of the following, to a second unit of an access network. (Note 42) A second unit for the access network, First information indicating at least one first beam configuration for at least one time resource configured for both downlink and uplink communications, and at least one second beam configuration for at least one time resource configured for either downlink communications only or uplink communications only. Second information indicating at least one first beam pattern for at least one time resource configured for both downlink and uplink communication, and at least one second beam pattern for at least one time resource configured exclusively for downlink communication or exclusively for uplink communication. In at least one time resource configured for both downlink and uplink communication, a first set of at least one antenna components that can or cannot be used for uplink communication, and third information indicating a second set of at least one antenna components that can or cannot be used for downlink communication in at least one time resource configured for both downlink and uplink communication, and / or Fourth information relating to at least one first configuration of an antenna for uplink communication in at least one time resource configured for both downlink and uplink communication, and at least one second configuration of an antenna for downlink communication in at least one time resource configured for both downlink and uplink communication, A second unit comprising means for receiving beam or antenna-related information, including at least one of the following, from a first unit of an access network.

[0205] This application claims priority based on UK Patent Application No. 2305108.9, filed on April 5, 2023, the disclosure thereof, which is incorporated herein by reference in its entirety. [Explanation of Symbols]

[0206] 1. Communication System 3. User equipment 5 base station 5b Distributed Unit (DU) 5c Central Unit (CU) 7 Core Network 9 cells 10 Control Plane Functions 11. User Plane Functions 20 External data network 31 Transceiver Circuit 33 Antennas 35 User Interface 37 Controllers 39 memory 41 Operating Systems 43 Communication control module 51b Transceiver Circuit (DU) 51c Transceiver Circuit (CU) 53b Air Interface 55c Network Interface 57b DU Controller 57c CU Controller 59b DU memory 59c CU memory 61b DU Operating System 61c CU Operating System 63b DU Communication Control Module 63c CU Communication Control Module F1 Interface

Claims

1. A method performed by the central unit (CU) of an access network, Receiving a first notification from the first DU of the access network indicating that a layer 1 / layer 2 triggered mobility (LTM) procedure for user equipment (UE) has been initiated or will be initiated from a first cell operated by a first distributed unit (DU) to a second cell operated by a second DU of the access network, A method comprising sending a second notification to the second DU indicating that the LTM procedure for the UE has been initiated or will be initiated.

2. The second notification is sent before the first notification is received and before a message to initiate the LTM procedure for the UE is sent from the first DU to the UE. The method according to claim 1.

3. The aforementioned LTM procedure is performed without using a random access channel (RACH). The method according to claim 1 or 2.

4. The first and second notices indicate when the resources of the second DU will be used for communication with the UE. The method according to any one of claims 1 to 3.

5. The first notice includes first information, and the second notice includes second information that is different from the first information. The method according to any one of claims 1 to 4.

6. A method performed by a second distributed unit (DU) of the access network, Receiving a notification from the central unit (CU) of the access network indicating that a layer 1 / layer 2 triggered mobility (LTM) procedure for user equipment (UE) has been initiated or will be initiated from a first cell operated by the first DU of the access network to a second cell operated by the second DU, A method comprising receiving uplink data from the UE based on the aforementioned notification.

7. Receiving the aforementioned means, based on the aforementioned notice, Dynamically scheduling resources for the uplink data based on the aforementioned notification, Receiving the uplink data using the aforementioned resources, Executed by The method according to claim 6.

8. This further includes pre-configuring the resources for the uplink data before receiving the aforementioned notification, The aforementioned receiving is performed by decoding the uplink data using the resources based on the notification. The method according to claim 6.

9. A method performed by a first distributed unit (DU) of an access network, Sending a first notification to the central unit (CU) of the access network indicating that a layer 1 / layer 2 triggered mobility (LTM) procedure for user equipment (UE) from a first cell operated by the first DU to a second cell operated by the second DU of the access network has been initiated or will be initiated, This includes sending a message to the UE to initiate the LTM procedure for the UE, A method in which, when the first notification is sent, a second notification is sent from the CU to the second DU indicating that the LTM procedure for the UE has been started or will be started.

10. The first and second notifications are sent before the message is sent. The method according to claim 9.

11. A method performed by an access network node, A method comprising transmitting to each of the multiple user equipment (UEs) in a group information regarding a trigger for a group procedure to switch from a first cell to a second cell operated by the access network node, respectively.

12. The aforementioned information is transmitted in a common message for each of the plurality of UEs in the group to receive. The method according to claim 11.

13. The aforementioned information is, The first cell is switched to network energy saving mode. The first cell is turned off, or In the first cell, a non-terrestrial network (NTN) satellite / service link switchover is performed. Showing at least one of the following: The method according to claim 11 or 12.

14. The aforementioned information is sent via paging short message. The method according to any one of claims 11 to 13.

15. The paging short message includes a field for triggering the group procedure, The method according to claim 14.

16. The aforementioned information is transmitted in system information or paging information, including a command to trigger the group procedure. The method according to any one of claims 11 to 13.

17. The aforementioned information is transmitted as downlink control information (DCI) to trigger the group procedure. The method according to any one of claims 11 to 13.

18. The aforementioned information is transmitted via media access control (MAC) signaling to trigger the group procedure. The method according to claim 11 or 12.

19. The MAC signaling includes a MAC control element (MAC CE) or a MAC service data unit (MAC SDU), The method according to claim 18.

20. The information is transmitted in a transport block (TB) that carries the MAC signaling for each of the UEs in the group in order to trigger one of the UEs in the group to switch from the first cell to the second cell. The method according to claim 18 or 19.

21. The method according to claim 18 or 19, wherein the MAC signaling includes, for each of the plurality of UEs in the group, a command for triggering each of the plurality of UEs in the group to switch from the first cell to the second cell.

22. The aforementioned information includes the group identification information, The method according to any one of claims 17 to 20.

23. The information that identifies the group is, At least one UE group identifier, or A Radio Network Temporary Identifier (RNTI) shared with each of the plurality of UEs in the group, Including at least one of the following: The method according to claim 22.

24. The information includes a list containing the respective identifiers for each of the multiple UEs for which the group procedure is triggered, The method according to any one of claims 17 to 23.

25. The aforementioned information is configured to be received using a shared wireless network temporary identifier. The method according to any one of claims 17 to 24.

26. The information is configured to be received by both any UE in the first cell that is a member of the group and any UE in the first cell that is not a member of the group, using the shared wireless network temporary identifier. The method according to claim 25.

27. The information is configured to be received by any UE in the first cell that is a member of the group, using the shared wireless network temporary identifier, but not by any UE in the first cell that is not a member of the group. The method according to claim 25.

28. The aforementioned information includes Layer 2 (L2) protocol processing information. The method according to any one of claims 17 to 27.

29. The information includes information for identifying at least one target cell for the group procedure. The method according to any one of claims 11 to 28.

30. The aforementioned group procedure is part of the Layer 1 / Layer 2 Triggered Mobility (LTM) procedure. The method according to any one of claims 11 to 29.

31. The aforementioned group procedure is part of a conditional handover procedure. The method according to any one of claims 11 to 29.

32. A method performed by user equipment (UE), In each of the multiple UEs in the group including the aforementioned UE, information regarding the group's trigger is received from the access network node, and the system switches from the first cell to the second cell operated by the access network node, respectively. A method comprising: initiating a procedure to switch from the first cell to the second cell based on the aforementioned information.

33. A method performed by the central unit (CU) of an access network, The user equipment (UE) transmits information indicating at least one candidate target cell for executing a Layer 1 / Layer 2 triggered mobility (LTM) procedure to the distributed unit (DU) of the access network, A method comprising transmitting the information indicating the at least one candidate target cell for the UE to perform a subsequent LTM procedure to at least one further DU of the access network.

34. The first cell further includes receiving information from the other DU of the at least one further DU to a second cell operated by another DU indicating that the LTM procedure was successful, The UE transmitting the information indicating the at least one candidate target cell for executing a subsequent LTM procedure to the at least one further DU is performed by the UE transmitting the information indicating the at least one candidate target cell for executing a subsequent LTM procedure to the other DU when it receives the information indicating that the LTM procedure was successful. The method according to claim 33.

35. The UE transmitting the information indicating the at least one candidate target cell for executing the LTM procedure to the DU means causing the DU to configure the UE using the information indicating the at least one candidate target cell for executing the LTM procedure. The aforementioned method, The process includes receiving a response message from the DU indicating that the UE has configured at least one candidate target cell for the UE to perform the LTM procedure, The UE sending the information indicating the at least one candidate target cell for executing a subsequent LTM procedure to the at least one further DU is performed upon receiving the response message. The method according to claim 33.

36. A method performed by a candidate distributed unit (DU) for an access network, A method comprising, as part of a procedure for pre-configuring user equipment (UE) for a layer 1 / layer 2 triggered mobility (LTM) procedure from a serving cell operated by a serving DU to a target cell of a target DU of the access network, the serving DU of the access network receives information from a central unit (CU) of the access network indicating at least one candidate target cell, wherein the candidate DU is a candidate to become the target DU.

37. A central unit (CU) for an access network, Means for receiving a first notification from the first DU of the access network indicating that a layer 1 / layer 2 triggered mobility (LTM) procedure for user equipment (UE) has been initiated or will be initiated from a first cell operated by a first distributed unit (DU) to a second cell operated by a second DU of the access network, A central unit comprising means for sending a second notification to the second DU indicating that the LTM procedure for the UE has been initiated or will be initiated.

38. A second distributed unit (DU) for the access network, Means for receiving a notification from the central unit (CU) of the access network indicating that a layer 1 / layer 2 triggered mobility (LTM) procedure for user equipment (UE) from a first cell operated by the first DU of the access network to a second cell operated by the second DU has been initiated or will be initiated, A second distributed unit comprising means for receiving uplink data from the UE based on the aforementioned notification.

39. A first distributed unit (DU) for an access network, Means for transmitting a first notification to the central unit (CU) of the access network indicating that a layer 1 / layer 2 triggered mobility (LTM) procedure for user equipment (UE) from a first cell operated by the first DU to a second cell operated by the second DU of the access network has been initiated or will be initiated, The process includes sending a message to the UE to initiate the LTM procedure for the UE, A first distributed unit, which, when sending the first notification, sends a second notification from the CU to the second DU indicating that the LTM procedure for the UE has been started or will be started.

40. Access network node, An access network node comprising means for transmitting information regarding triggers for a group procedure to each of the multiple user equipment (UEs) in the group, in order to switch from a first cell to a second cell operated by the access network node, in each of the multiple user equipment (UEs) in the group.

41. User equipment (UE), In each of the multiple UEs in the group including the aforementioned UE, there is a means for receiving information regarding the trigger of a group procedure from the access network node in order to switch from a first cell to a second cell operated by the access network node, A user device comprising means for initiating a procedure to switch from the first cell to the second cell based on the aforementioned information.

42. A central unit (CU) for an access network, Means for transmitting information to a distributed unit (DU) of the access network indicating at least one candidate target cell for user equipment (UE) to perform a layer 1 / layer 2 triggered mobility (LTM) procedure, A central unit comprising means for transmitting the information indicating the at least one candidate target cell for the UE to perform a subsequent LTM procedure to at least one further DU of the access network.

43. A candidate distributed unit (DU) for an access network, A distributed unit comprising means for receiving information from a central unit (CU) of the access network indicating at least one candidate target cell, as part of a procedure for pre-configuring user equipment (UE) by the serving DU of the access network for a layer 1 / layer 2 triggered mobility (LTM) procedure from a serving cell operated by a serving DU to a target cell of a target DU of the access network, wherein the candidate DU is a candidate to become the target DU.

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