Providing multiple prach preambles for early UL synchronization in l1 / l2 triggered mobility

Abstract

Methods are provided to enable a candidate DU to provide additional RACH configurations for UL pre-synch in L1 / L2 Triggered Mobility (LTM) to a source DU A candidate DU is able to provide additional RACH configurations to a source DU for use in early UL synchronization to support LTM cell switch. This allows the candidate DU to reserve and allocate to the source DU more than 64 preambles, and these preambles are specifically for the early UL synchronization procedure. Based on this, methods are described for the UE to select one preamble (if many options exist) and for the network to understand on which preamble(s) the early UL synchronization Msg. 1 could be sent.

Description

[0001] PROVIDING MULTIPLE PRACH PREAMBLES FOR EARLY UL SYNCHRONIZATION IN L1 / L2 TRIGGERED MOBILITY

[0002] RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional patent Application Serial Number 63 / 573238 filed 2 April 2024, the entire contents of which are incorporated herein by reference.

[0004] BACKGROUND

[0005] Wireless communication networks, including network nodes and radio network devices such as cellphones and smartphones, are ubiquitous in many parts of the world. These networks continue to grow in capacity and sophistication. To accommodate both more users and a wider range of types of devices that may benefit from wireless communications, the technical standards governing the operation of wireless communication networks continue to evolve. The fourth generation of network standards (4G, also known as Long Term Evolution, or LTE) has been deployed, the fifth generation (5G, also known as New Radio, or NR) is in development or the early stages of deployment, and the sixth generation (6G) is being planned. Specific technical standards defining new network features and capabilities are promulgated by the Third Generation Partnership Project (3GPP) as a series of numbered Releases, e.g., Rel. 15, Rel. 16, etc.

[0006] Both LTE and NR networks follow a “cellular” architecture, wherein a plurality of generally fixed network nodes, known as base stations (also called eNB in LTE and gNB in NR) provide wireless communication services to both fixed and mobile radio network devices, referred to generally herein as User Equipment (UE), within a coverage area, or “cell.” The term “cell” also refers to a unique logical entity providing wireless communication service; hence one base station may provide a plurality of cells.

[0007] Up through LTE, the base station (eNB) was monolithic entity. NR introduced the concept of splitting the base station (gNB) between a Central Unit (CU) and Distributed Units (DU). FIG. 1 shows this architecture. Access and Mobility Management Function (AMF) and / or User Plane Function (UPF) in the core network connect to base stations (gNB). Each gNB may be divided into a CU and a plurality of DUs. A break between the CU and DU in the network protocol stack is commonly implemented above the Radio Link Control (RLC), with RLC, MAC, and the Physical layer (PHY) implemented in the DU, while RRC, Packet Data Convergence Protocol (PDCP) and higher layer functions are implemented in the CU.

[0008] Mobility is a fundamental aspect of wireless communication networks. As a UE moves throughout a geographic region, it will move from one cell to another. The UE periodically performs measurements of the signal strength and quality of the air interface between it and a current serving cell, as well as neighboring cells. When a neighbor cell provides a consistently higher quality channel, the network performs a “handover” procedure, passing control and servicing of the UE from the current, or “source” cell to the new, or “target” cell. Accordingly, the operation is also referred to as a “cell switch.” Ideally, a handover or cell switch procedure is performed transparently to the user, who experiences no degradation in quality of any ongoing call or data stream as the procedure is executed.

[0009] Handover has conventionally been performed by Radio Resource Control (RRC) signaling, which is a high-level signaling protocol. This involved extensive signaling across the air interface, and extensive processing at the UE, which consumes battery power. Release 18 introduced a cell switch triggered by the Media Access Control (MAC) layer rather than RRC. This procedure operates at lower levels of the protocol stack (e.g., Level 1 or Level 2), and is referred to as L1 / L2 Triggered Mobility (LTM). LTM can achieve faster cell switching, with lower overhead and hence power consumption, than RRC handover.

[0010] Random Access (RA) is a procedure by which a UE initially connects to a cell of a wireless communication network. The Random Access Channel (RACH) is a logical channel dedicated to RA. Upon power-on or arriving in the coverage range of a cell, a UE receives System Information (SI) periodically broadcast by the base station, which includes synchronization signals that allow the UE to roughly synchronize its timing with the cell. The UE then performs RA, which conventionally is a 4-step process. Briefly, the UE transmits one of 64 RACH preambles (e.g., Zadoff-Chu sequences), referred to as Msg. 1 . A base station responds with an RA response, called Msg. 2, which includes a Timing Advance (TA) value allowing the UE to time-align its transmissions, a temporary identifier Random Access Radio Network Temporary Identifier (RA-RNTI), and an uplink grant. The UE uses this grant to transmit Msg. 3, which may include RRC signaling and / or data. Finally, the base station responds with Msg. 4, which is MAC data for Contention Resolution, and assigns a Cell Radio Network Temporary Identifier (C-RNTI) to the UE.

[0011] Release 16 introduced a 2-step RACH procedure. Both messages from the UE to the network (Msg. 1 and Msg. 3) are combined into Msg. A, and both messages from the network to the UE (Msg. 2 and Msg. 4) are combined into Msg. B.

[0012] With the introduction of several features in Release 17 that required an early indication of capabilities already in Msg. 1 , a framework was introduced. The framework creates partitions of preambles that enable the network to configure certain preambles that are allocated to a specific combination of features. The framework is called RACH Partitioning Framework (RPF).

[0013] With the introduction of RPF, it was foreseen that the existing RACH configuration would not be enough if some preambles were dedicated for certain feature combinations. Thus, options to define additional RACH configurations were introduced. These are signaled within RACH-ConfigCommon as AdditionalRACH-ConfigList and contain instances of RACH- ConfigCommon. This list is not configured to more than 32 entries as stated by field description, however the ASN.1 signaling allows for up to 256. In System Information, under BWP-UplinkCommon -> RACHConfigCommon, a list of all the partitions is present, based on the feature combinations that the network supports. Each partition contains one feature combination. The complete structure for AdditionalRACH- ConfigList and FeatureCombinationPreambles is shown in FIG. 2.

[0014] As mentioned above, the Mobility Work Item in Release 18 defined procedures for handover triggered by MAC instead of RRC, known as LTM. This procedure is dependent on the UE performing UL and DL synchronization towards the target cell prior to a handover. For the UL, this is essentially acquiring a correct Timing Advance (TA) value towards the target cell. The TA value is estimated by the DU of the target cell, based on a preamble sent by the UE on the Physical Random Access Channel (PRACH). The receiving (target) DU estimates the TA value and distributes this to the serving DU, which sends the TA value to the UE, together with a cell switch command, as a MAC Control Element (CE). This signaling is shown in FIG. 3.

[0015] There currently exist certain challenge(s).

[0016] Since the UE must synchronize the UL in the target cell, this means that the target DU must understand that a specific random access is not a “normal” random access (also referred to as a contention RA), and instead it should be used for a TA estimation, and the TA value should be forwarded to the Source gNB. 3GPP standardization has not defined any specific preambles for this purpose, so it is up to the network to configure this. This means that the legacy preambles (from 1 to 64) are also used during the early UL synchronization procedure. This also implies that if the network were to associate a given preamble to such procedure, it would need to reserve one of the preamble indexes. Since the early UL synchronization procedure starts with the network sending a Physical Downlink Control Channel (PDCCH) order to the UE with the preamble index, the network must allocate preambles across the DUs for this purpose, and such preambles must be unique for each source DU. This means that each candidate DU must split the available preambles and assign some to each source DU (since one candidate DU may have multiple source DUs), ensuring that a preamble assigned to one source DU (e.g., source DU1) is not also assigned to another source DU (e.g., source DU2). The topology is shown in FIG. 4, where the target DU must forward a TA value to the serving DU.

[0017] Furthermore, the preambles need to be allocated so that they are not used for a contention based random access by any UE in the target cell. Also, a UE might have up to eight LTM candidates, and it might perform early UL synchronization to any one of them. Thus, a large number of preambles need to be allocated across DUs.

[0018] A RACH Configuration has 64 preambles defined, which are shared between all accesses in the cell. Given that LTM will need to reserve preambles for early UL synchronization procedures with many serving cells, a single RACH configuration will not support many LTM candidates, and it would be beneficial to enable additional RACH configurations for LTM candidates. However, the early UL configuration RRC configuration only contains a reference to the generic RACH information, as shown in FIG. 5. Accordingly, it will not be possible for a UE to perform UL synch towards additional RACH configurations.

[0019] Based on this, given the scarcity of available RACH preambles, it may not be feasible for a candidate DU to assign a high number of preambles to a source DU for the sake of performing early UL synchronization procedures in support of LTM cell switches.

[0020] For the candidate DU, striking a balance of how many RACH preambles to allocate to source DUs and how many to keep for the UEs under its own coverage (for which the candidate DU is the source / serving DU) is difficult. If more preambles are reserved for the source DU, then the candidate DU may not have enough preambles to use for legacy operation, and this may cause a degradation of performance in the cell.

[0021] On the other hand, if more preambles are kept for legacy operations, the source DU may not have enough RACH resource to execute the early UL synchronization procedure. In this case, to perform an LTM cell switch procedure, the UE would need to perform the random access procedure, thus increasing the connectivity interruption and the overall handover procedure delay.

[0022] The Background section of this document is provided to place aspects of the present disclosure in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Approaches described in the Background section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.

[0023] SUMMARY

[0024] The following presents a simplified summary of the disclosure in order to provide a basic understanding to those of skill in the art. This summary is not an extensive overview of the disclosure and is not intended to identify key / critical elements of aspects of the disclosure or to delineate the scope of the disclosure. The sole purpose of this summary is to present some concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.

[0025] According to aspects of the present disclosure described and claimed herein, a candidate DU is enabled to provide additional RACH configurations for UL pre-synch in L1 / L2 Triggered Mobility (LTM) to a source DU. This allows the candidate DU to reserve and allocate to the source DU more than 64 preambles, and these preambles are specifically for the early UL synchronization procedure. Based on this, methods are described for the UE to select one preamble (if many options exist) and for the network to understand on which preamble(s) the early UL synchronization Msg. 1 could be sent.

[0026] One aspect relates to a method, performed by a user equipment (UE) operative in a wireless communication network, of acquiring information to perform an early uplink (UL) synchronization procedure to obtain a Timing Advance (TA) value for a L1 / L2 Triggered Mobility (LTM) cell switch procedure. A configuration for performing an early uplink (UL) synchronization procedure for one or more LTM candidate cells is received from a source Distributed Unit (S- DU) of the base station serving the UE. A first trigger to transmit a first Random Access Channel (RACH) preamble for early synchronization to a first configured LTM candidate cell of a first candidate DU (C-DU) is received from the S-DU. The first RACH preamble is transmitted to the first LTM candidate cell of the first C-DU. A TA value is received from the S-DU.

[0027] Another aspect relates to a user equipment (UE) for performing a L1 / L2 Triggered Mobility (LTM) cell switch procedure. The UE includes processing circuitry configured to perform the method described above, and power supply circuitry configured to supply power to the processing circuitry.

[0028] Yet another aspect relates to a method, performed by a network node implementing a source Distributed Unit (S-DU) of a base station serving a first User Equipment (UE), the method being to receive Random Access Channel (RACH) preamble indexes and early uplink (UL) synchronization configurations to send to the first UE, to enable the first UE to initiate an early UL synchronization procedure. A request for one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE is transmitted to a candidate DU (C-DU) or a third network node. One or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE are received from the C-DU or third network node. A RACH preamble index to send to the first UE to trigger an early UL synchronization procedure by the first UE is selected. The selected RACH preamble index is transmitted to the first UE to trigger an early UL synchronization procedure by the first UE.

[0029] Still another aspect relates to a network node for receiving Random Access Channel (RACH) preamble indexes and early uplink (UL) synchronization configurations to send to a first user equipment (UE) to enable the first UE to initiate an early UL synchronization procedure. The network node includes processing circuitry configured to perform the method described above, and power supply circuitry configured to supply power to the processing circuitry.

[0030] Still another aspect relates to a method, performed by a network node implementing a Distributed Unit (DU) of a base station that is a candidate target DU (C-DU) for a L1 / L2 Triggered Mobility (LTM) cell switch procedure by a first User Equipment (UE) served by a source DU (S-DU), the method being to transmit one or more Random Access Channel (RACH) preamble indexes and one or more early uplink (UL) synchronization configurations to the S- DU, to send to the first UE, to enable the first UE to initiate an early UL synchronization procedure. A request from a S-DU or a third network node to provide one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE is received. One or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE are transmitted to the S-DU or third network node.

[0031] Still another aspect relates to a network node for transmitting one or more Random Access Channel (RACH) preamble indexes and one or more early uplink (UL) synchronization configurations to a source Distributed Unit (S-DU), to send to a first UE served by the S-DU, to enable the first UE to initiate an early uplink (UL) synchronization procedure. The network node includes processing circuitry configured to perform the method described above, and power supply circuitry configured to supply power to the processing circuitry.

[0032] Still another aspect relates to a user equipment (UE) for receiving Random Access Channel (RACH) preamble indexes and early uplink (UL) synchronization configurations to send to a first UE to enable the first UE to initiate an early UL synchronization procedure. The UE includes an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry. The processing circuitry is configured to perform the first method described above. The UE further includes an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE.

[0033] BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which aspects of the disclosure are shown. However, this disclosure should not be construed as limited to the aspects set forth herein. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout.

[0035] FIG. 1 is a block diagram of an NG network, showing a division of network layers between a CU and one or more DUs.

[0036] FIG. 2 is a diagram showing the structure of AdditionalRACH-ConfigList with FeatureCombinationPreambles, within the RACH-ConfigCommon structure of defined RACH configurations.

[0037] FIG. 3 is a signaling diagram showing early UL sync and TA value transmission from a candidate DU to source DU to UE in support of LTM.

[0038] FIG. 4 is a block diagram showing serving and target DUs in a gNB.

[0039] FIG. 5 the EarlyUL-SyncConfig IE used to configure random access resources for the early UL synchronization procedure. FIG. 6 is a flow diagram of a method of a UE acquiring information to perform an early UL synchronization procedure to obtain a TA value for an LTM cell switch procedure.

[0040] FIG. 7 is a flow diagram of a method of a source DU of a base station serving a UE receiving RACH preamble indexes and early UL synchronization configurations to send to the UE, to enable the UE to initiate an early UL synchronization procedure.

[0041] FIG. 8 is a flow diagram of a method of a candidate DU for an LTM cell switch procedure by a UE served by a source DU, transmitting one or more RACH preamble indexes and one or more early UL synchronization configurations to the source DU, to send to the UE, to enable the UE to initiate an early UL synchronization procedure.

[0042] FIG. 9 is a block diagram of a communication system.

[0043] FIG. 10 is a block diagram of a UE in the communication system of FIG. 9.

[0044] FIG. 11 is a block diagram of a network node in the communication system of FIG. 9.

[0045] FIG. 12 is a block diagram of a virtualization environment operative with the communication system of FIG. 9.

[0046] DETAILED DESCRIPTION

[0047] For simplicity and illustrative purposes, the present disclosure is described by referring mainly to an exemplary aspect thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be readily apparent to one of ordinary skill in the art that the present disclosure may be practiced without limitation to these specific details. In this description, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure.

[0048] The following disclosure describes methods to enable the candidate DU to provide additional RACH configurations to the source DU for use in early UL synchronization to support LTM cell switch. This allows the candidate DU to reserve and allocate to the source DU a number of preambles which is more than 64, and these preambles are specifically for the early UL synchronization procedure. Based on this, the disclosure then introduces methods for the UE to select one preamble (if many options exist) and for the network to understand on which preamble(s) the early UL synchronization Msg. 1 could be sent.

[0049] The embodiments of this disclosure allow the candidate DU to reserve and allocate to the source DU a number of preambles which is more than 64, and these preambles are specifically for the early UL synchronization procedure. This will allow the source DU to have the necessary random access resource to trigger an early UL synchronization procedure at the UE with consequent benefits in terms of reduced connection interruption, faster LTM cell switch, reduced energy consumption, and reduced latency for executing a handover procedure.

[0050] This disclosure refers to the term “L1 / L2 based inter-cell mobility” as used in the Work Item Description in 3GPP, though it interchangeably also uses the terms L1 / L2 mobility, L1- mobility, L1 based mobility, L1 / L2-centric inter-cell mobility, L1 / L2 inter-cell mobility L1 / L2- Triggered Mobility, Lower-layer triggered Mobility or LTM. The basic principle is that the UE normally receives a lower layer signaling from the network indicating to the UE a change (or switch or activation) of its serving cell (e.g., change of PCell, from a source to a target PCell), wherein a lower layer signaling is a message or signaling of a lower layer protocol, which sometimes may be referred as a L1 / L2 inter-cell mobility execution command or LTM cell switch command. The change of serving cell (e.g., change of PCell) may also lead to a change in Scell(s) for the same cell group, e.g., in case the command triggers the UE to change to another cell group configuration of the same type (e.g., another MCG configuration).

[0051] Before the UE receives the LTM cell switch command, the UE is configured by the network with one or more LTM candidate cell configurations (e.g., reception of an RRC Reconfiguration message, with at least one LTM candidate cell configuration). An LTM candidate cell configuration may include parameters in the Information Element (IE) CellGroupConfig for an LTM candidate cell and / or an embedded RRC Reconfiguration for an LTM candidate cell.

[0052] The term LTM cell switch procedure refers to the process of a UE switching (or changing) its cell from a source cell to a target cell (which may be called here an LTM candidate cell or a neighbour cell), using L1 / L2-triggered mobility (LTM). In this context, an LTM cell switch procedure may sometimes also be known as L1 / L2 based inter-cell mobility execution, LTM execution, dynamic switch, LTM switch, (LTM) cell switch, (LTM) serving cell change or (LTM) cell change. In the context of this disclosure, switching to the LTM candidate cell configuration comprises the UE considering that an LTM candidate cell becomes its new special cell (SpCell), e.g., PCell in case of LTM being configured for a Master Cell Group (MCG) and / or PSCell in case of LTM being configured for a Secondary Cell Group (SCG); or, changing its SpCell from the current PCell to an LTM candidate cell.

[0053] Even where the term switch or change of a cell is used, that may comprise a switch or change of a whole cell group configuration, which includes a change in the SpCell (e.g., change of PCell, or change of PSCell) and a change in SCells of the cell group (e.g., addition, modification and / or release of one or more SCells).

[0054] An LTM cell switch procedure may be triggered in the UE by reception of a LTM cell switch command, or alternatively, triggered by some other event, such as a condition, e.g., a triggering condition used for conditional configuration, such as conditional handover, being fulfilled, such as resulting from recovery from radio link failure or handover failure.

[0055] The disclosure refers to an LTM candidate cell, which is a cell with which the UE is configured when configured with L1 / L2-triggered mobility. That is a cell the UE can move to in an LTM cell switch procedure. Such cells may also be called candidate cell(s), candidates, mobility candidates, non-serving cells, additional cells, target candidate cell, target candidate, etc. An LTM candidate cell is a cell on which the UE may perform measurements (e.g., CSI measurements) so that the UE reports these measurements, and the network may take educated decision on which beam (e.g., Transmission Configuration Indicator (TCI) state) and / or cell the UE is to be switched to. An LTM candidate cell may be a candidate to be a target PCell or PSCell, or an SCell of a cell group (e.g., MCG SCell or an SCG SCell).

[0056] The disclosure refers to at least one LTM candidate cell configuration and that the UE has received at least one LTM candidate cell configuration. This is also sometimes referred to as a configuration of an LTM candidate cell, which may be an RRC configuration, such as encapsulated in an RRC Reconfiguration message, that the UE receives when being configured with L1 / L2-Triggered Mobility. A LTM candidate cell configuration comprises the configuration which the UE must start to operate when it performs an LTM cell switch procedure to that LTM candidate cell, e.g., upon reception of the LTM cell switch command directing the UE to perform an LTM cell switch procedure to that LTM candidate cell, which then becomes the target cell and the current (new) SpCell, or an SCell in a serving frequency.

[0057] The LTM candidate cell configuration comprises parameters of a serving cell (or multiple serving cells, such as a cell group), comprising one or more of the groups of parameters, such as an RRCReconfiguration message an IE CellGroupConfig or an IE SpCellConfig (or the IE SCellConfig, in the case of a Secondary Cell). An LTM candidate cell configuration may in one example comprise one or more of: i) the PCell configuration and one or more SCell configuration(s) of a Master Cell Group (MCG); and ii) the PSCell configuration and one or more SCell configuration(s) of a secondary Cell Group (SCG).

[0058] The terms (LTM) candidate configuration, LTM configuration, (LTM) candidate target cell configuration, (LTM) target candidate (cell) configuration may be used interchangeably when referring to LTM candidate cell configuration. An LTM candidate cell configuration is associated with an identifier which is used in the signaling when referring to a certain LTM candidate cell configuration, such as when the UE receives the LTM candidate cell configuration and when the UE receives an LTM cell switch command directing the UE to perform an LTM cell switch procedure to that LTM candidate cell. This identifier is sometimes known as the LTM candidate cell configuration identity or LTM candidate configuration index (or similar).

[0059] The actual LTM candidate cell configuration and its exact contents, and / or the structure of this IE and / or embedded message may be called an RRC model for the candidate configuration, or simply RRC model. An LTM candidate cell configuration comprises the configuration in which the UE needs to operate when it performs (executes) L1 / L2 based intercell mobility execution to an LTM candidate cell, upon reception of the lower layer signaling (MAC CE) indicating a L1 / L2 based inter-cell mobility to a LTM candidate cell (which becomes the target cell and the current (new) PCell, or an SCell in a serving frequency), or upon reception of the lower layer signaling (MAC CE) indicating a L1 / L2 based inter-cell mobility to an LTM candidate cell configuration indicated with a candidate configuration index (sometimes also denoted candidate configuration ID). The UE may be configured with multiple LTM candidate cell configurations, so a Candidate DU (C-DU) generates and sends to the CU multiple configuration(s).

[0060] The actual LTM candidate cell configuration the UE receives during the LTM configuration may be a delta signaling to be applied on top of a reference configuration, so that the actual configuration the UE is to use in the candidate cell upon an LTM cell switch is the combination of the LTM candidate cell configuration and the reference configuration, e.g., separately signaled by the network.

[0061] In this disclosure, the term “early TA acquisition procedure” is used to describe the procedure which is executed by the UE and the network to calculate a TA value before triggering an actual LTM cell switch procedure by the UE. Nevertheless, the terms “TA acquisition”, “early UL sync”, “early sync”, “early UL synchronization”, and “early synchronization”, can also be used to describe the same procedure.

[0062] Methods and Options

[0063] A1 . Methods at a User Equipment (UE) to acquire a TA value to be used when executing an LTM cell switch procedure, comprising:

[0064] Receiving a configuration for performing an early synchronization procedure for one or more LTM candidate cell which comprise one or more of the following: o A list of random access resources (spaced in time and frequency) which can be used for one or more random access preamble. o A mapping between one or more random access preamble index and one or more random access resources which provide on which time and special domain such random access preambles can be sent.

[0065] Receiving from the S-DU a first trigger (e.g. first PDCCH order) to transmit a first preamble for Early Uplink (UL) sync to a first configured LTM candidate cell of a first Candidate DU (C-DU) which comprise one or more of the following: o An LTM candidate cell identifier o A random access configuration identifier of a random access configuration which provide one or more random access resource in the time and frequency domain that can be used to send the random access preamble to the indicated LTM candidate cell o A random access preamble identifier o A time resource domain on which to send the random access preamble o A frequency resource domain on which to send the random access preamble

[0066] If no timer and frequency random access resource are indicated by the S-DU, determining a set of time and frequency random access resource on which to transmit the random access preamble to the indicated LTM candidate cell. Transmitting the first preamble to the first LTM candidate cell of the first C-DU on the indicated or determined time and frequency domain resources;

[0067] Receiving a TA value from the S-DU;

[0068] Applying the received TA value during the execution of an LTM cell switch procedure;

[0069] A2. A method according to A1 , wherein the configuration for the early UL synchronization received by the S-DU may include one or more or the following:

[0070] • An LTM candidate cell identifier

[0071] • A list of time resources which should be used to send a preamble

[0072] • A list of frequency resources which should be used to send a preamble

[0073] • A mapping for each time and frequency resource

[0074] • An indication about which preamble index(es) can be sent with this configuration

[0075] • An indication about for what feature such configuration can be used (e.g., only for the early UL synchronization, both early UL synchronization and LTM cell switch procedure).

[0076] A3. A method according to A1 and A2, wherein the frequency resources to be used to send the preamble are described by one or more of the following information:

[0077] • A frequency range

[0078] • A starting point on the frequency domain

[0079] • Number of PRACH transmission occasions over the frequency domain in one time instance.

[0080] A4. A method according to A1 and A2, wherein the time resources to be used to send the preamble is one or more PRACH configuration indexes.

[0081] A5. A method according to A1 and A2, wherein the list of time and frequency resources have a direct relationship. In this case, the UE receives a mapping which indicate a particular time domain resource to be used with a particular frequency domain resource, and vice versa.

[0082] • In one option, the relation or mapping of time and frequency resources is a specific point in the time and frequency domain, e.g., 2ndslot I frequency 2.5 GHz.

[0083] • In one option, the relation or mapping of time and frequency resources is a range in the time and frequency domain, e.g., 2nd-7thslots I frequency 2.5-3 GHz.

[0084] • In one option, the relation or mapping of time and frequency resources is a combination of a specific point in time and a range in frequency, or vice versa, a rang in time and a specific frequency, e.g. 2ndslot I frequency 2.5-3 GHz or 2nd- 7thslots / frequency 2.5 GHz. A6. A method according to A1 , wherein the UE, upon receiving a list of preambles to be used with a certain early UL sync configuration, receives a PDCCH order indicating a RACH preamble index. According to this the UE may perform one or more of the following actions:

[0085] • The UE checks in which configuration the preamble can be used according to the received RACH preamble index

[0086] • The UE associates to a particular RACH preamble index, time and frequency resources according to the allowed RACH preamble indexes that can be used with a certain early UL synchronization configuration. o In an alternative option, if no allowed RACH preamble indexes are received within a certain early UL synchronization configuration, the UE selects:

[0087] • In one option, randomly a time and frequency resource over which to send the RACH preamble, among the ones present in the receives early UL synchronization configuration.

[0088] • In one option, based on the order in which the random access resources are received. For instance, UE1 the first resources in the list, UE2 the second resources in the list, UE3 the third resources in the list and so on.

[0089] • The UE sends the preamble over the associated time and frequency resources

[0090] A7. A method according to A1 and A7, wherein the indication received by the source DU to initiate an early UL synchronization procedure may include one or more of the following information:

[0091] • A RACH preamble index

[0092] • An early UL synchronization procedure index

[0093] • An SSB index on which to send the RACH preamble

[0094] • An LTM candidate cell index.

[0095] B1 . Methods at a source network node, such as a source gNB or a source DU (S-DU), to receives from a candidate DU or a third network node (e.g., CU) one or more preamble indexes and one or more early UL synchronization configurations to be send to the UE in order to initiate an early UL synchronization procedure, comprising:

[0096] • Transmitting a request to a candidate DU or a third network node (e.g., a CU) to receive one or more preamble indexes to be used to trigger an early UL synchronization procedure at the UE.

[0097] • Receiving a response from a candidate DU or a CU, which include one or more preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure at the UE.

[0098] • Selecting a preamble index to send to the UE to trigger an early UL synchronization procedure at the UE. • Transmitting the selected preamble index to the UE to trigger an early UL synchronization procedure at the UE.

[0099] B2. A method according to B1 , wherein the request to the candidate DU may include one or more of the following:

[0100] • A 1 -bit indication to indicate the need for one or more RACH preamble indexes to be used for the early UL synchronization procedure.

[0101] • A request of a number “X” of RACH preambles to be used for the early UL synchronization procedure

[0102] • A 1 -bit indication to indicate the need for one or more early UL synchronization configurations

[0103] • A request of a number “Y” of early UL synchronization configurations

[0104] B3. A method according to B1 , wherein the source DU receives from the candidate DU one or more RACH preambles and one or more early UL synchronization configurations.

[0105] • In one option, the one or more random access preambles to be used for an early UL synchronization procedure does not have any relationship with the one or more early UL synchronization configurations. This means that each RACH preamble can be used with every one or more received early UL synchronization configurations. In such a case the Source DU needs simply to signal a RACH preamble index to the UE and then is the UE who figures out the association of a certain RACH preamble index with a certain early UL synchronization procedure.

[0106] • In one option, the one or more random access preambles to be used for an early UL synchronization procedure are mapped to a certain one or more early UL synchronization configurations. This means that one RACH preamble can only be used or one or more specific early UL synchronization configurations.

[0107] B4. A method according to B1 and B3, wherein the source DU select a RACH preamble to be send to the UE in order to initiate an early UL synchronization procedure according to the information received by the candidate DU.

[0108] • In one option, the source DU transmits a RACH preamble index to the UE and then is the UE who figures out the association of a certain RACH preamble index with a certain early UL synchronization procedure.

[0109] • In one option, the source DU select a RACH preamble index to transmit to the UE according to the mapping between preamble indexes and early UL synchronization configuration provided by the candidate DU.

[0110] B5. The method according to B1 , wherein the signalling between the source DU and a candidate DU is via a direct interface among DUs.

[0111] B6. The method according to B1 , wherein the signalling between the source DU and a candidate DU or a CU is via a F1AP interface. B7. The method according to B1 , wherein the source DU sends to a candidate DU one or more early UL synchronization configurations and one or more RACH preamble indexes via the CU.

[0112] C1 . Methods at a target network node, such as a target gNB or a candidate DU (C-DU), to transmit to a source DU (S-DU) one or more preamble indexes and one or more early UL synchronization configurations to be send to the UE in order to initiate an early UL synchronization procedure, comprising:

[0113] • Receiving a request from a source DU or a third network node (e.g., a CU) to provide one or more preamble indexes to be used to trigger an early UL synchronization procedure at the UE.

[0114] • Transmitting a response to a source DU or a CU, which includes one or more preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure at the UE.

[0115] C2. The method according to C1 , wherein the candidate DU receives from the source DU a request which may include one or more of the following:

[0116] • A 1 -bit indication to indicate the need for one or more RACH preamble indexes to be used for the early UL synchronization procedure.

[0117] • A request of a number “X” of RACH preambles to be used for the early UL synchronization procedure

[0118] • A 1 -bit indication to indicate the need for one or more early UL synchronization configurations

[0119] • A request of a number “Y” of early UL synchronization configurations

[0120] C3. The method according to C1 , wherein the candidate DU provides to the source DU one or more preamble indexes and one or more early UL synchronization configurations to be send to the UE according to the following:

[0121] • In one option, the candidate DU reserve one or more RACH preamble indexes in the time and frequency domain specifically for the source DU. This means that the preamble indexes reserved are unique for the source DU and cannot be reserved for any other DUs (in case the candidate DU has multiple source DUs). In this case, the number of preamble depends on the time and frequency resources reserved and, in principle, the number can be higher than 64, even if the RACH preamble indexes are still from 1 to 64. This means that for a given RACH preamble index, multiple time and frequency resources can be allocated, as far as those time and frequency resources are not allocated to any other RACH preamble index. For example, we can have the following allocation: o RACH index 1 a [time = 2ndslot, frequency 2.51 GHz] o RACH index 2 a [time = 3rd- 5thslots, frequency = 2.58 GHz] o RACH index 3 a [time = 6th- 8thslots, frequency = 2.6-2.7 GHz] o RACH index 1 a [time = 10th- 11thslots, frequency = 2.75-2.8 GHz] o RACH index 2 a [time = 1stslot, frequency = 2.2 GHz]

[0122] • In one option, the candidate DU reserve one or more RACH preamble indexes in the time and frequency domain specifically for the source DU and maps the reserved RACH preamble indexes to a certain early UL synchronization configuration. In such a case, this means that a certain preamble can only be used in a certain time and frequency domain which is part of a certain early UL synchronization procedure. For example, we can have the following: o RACH index 1 a [time = 2ndslot, frequency 2.51 GHz, Config ID = 1] o RACH index 2 a [time = 3rd- 5thslots, frequency = 2.58 GHz, Config ID

[0123] = 2] o RACH index 3 a [time = 6th- 8thslots, frequency = 2.6-2.7 GHz, Config ID = 3] o RACH index 1 a [time = 10th- 11thslots, frequency = 2.75-2.8 GHz, Config ID = 2] o RACH index 2 a [time = 1stslot, frequency = 2.2 GHz, Config ID = 1]

[0124] C4. A method according to C1 and C3, wherein the candidate DU maintains a mapping between a certain RACH preamble index (which time and frequency reserved) and a certain source DU for which one or more RACH preamble indexes were reserved. This means that one or more RACH preamble indexes (in time and frequency) are assigned in a unique way only to one source DU. This is necessary because when the candidate DU calculate the TA value, according to the RACH preamble received (in time and frequency), it will send the TA value to the right source DU according to the mapping RACH preamble index / source DU. This means that is not only the RACH preamble index that helps the candidate DU to identify the source DU, but is also the time and frequency in which has been received that map to a certain source DU. For example, we can have the following situation: o RACH index 1 (time, frequency) -> Source ID = 1 o RACH index 2 (time, frequency) -> Source ID = 1 o RACH index 3 (time, frequency) -> Source ID = 2 o RACH index 4 (time, frequency) -> Source ID = 3 o RACH index 5 (time, frequency) -> Source ID = 3 o RACH index 1 (timel , frequencyl) -> Source ID = 1 o RACH index 3 (timel , frequencyl) -> Source ID = 3 o RACH index 1 (time2, frequency2) -> Source ID = 2 3GPP Standards Implementation

[0125] The following provides one representative, non-limiting implementation of the methods in 3GPP Technical Standards (TS) 38.331 v18.0.0 and TS 38.473 v18.0.0: - TS 38 331 -

[0126] - EarlyUL-SyncConfig

[0127] The IE Early UL-SyncConfig is used to configure random access resources for the early UL synchronization procedure.

[0128] EarlyUL-SyncConfig information element

[0129] - AS N1 START

[0130] - TAG-EARLYUL-SYNCCONFIG-START

[0131] EarlyUL-SyncConfig-r18 ::= SEQUENCE { frequencylnfoUL-r18 FrequencylnfoUL, rach-ConfigGeneric-r18 RACH-ConfigGeneric, bwp-GenericParameters-r18 BWP, ssb-PerRACH-Occasion-r18 ENUMERATED {oneEighth, oneFourth, oneHalf, one, two, four, eight, sixteen} OPTIONAL, - Need M prach-RootSequencelndex-r18 CHOICE {

[0132] I839 INTEGER (0..837),

[0133] 1139 INTEGER (0..137)

[0134] }, ltm-prach-SubcarrierSpacing-r18 SubcarrierSpacing, n-TimingAdvanceOffset-r18 ENUMERATED { nO, n25600, n39936 } OPTIONAL, -

[0135] - Need R additionalRACH-Configl_ist-r18 SetupRelease { AdditionalRACH-ConfigList-r17 } OPTIONAL, - Need R

[0136] - TAG-EARLYUL-SYNCCONFIG-STOP

[0137] - ASN1STOP

[0138] The IE FeatureCombination indicates a feature or a combination of features to be associated with a set of Random Access resources (i.e. an instance of FeatureCombinationPreambles).

[0139] Featurecombination information element

[0140] - AS N1 START

[0141] - TAG-FEATURECOMBINATION-START

[0142] FeatureCombination-r17 ::= SEQUENCE { redCap-r17 ENUMERATED {true} OPTIONAL, - Need R smallData-r17 ENUMERATED {true} OPTIONAL, - Need R nsag-r17 NSAG-List-r17 OPTIONAL, - Need R msg3-Repetitions-r17 ENUMERATED {true} OPTIONAL, - Need R msg1-Repetitions-r18 ENUMERATED {true} OPTIONAL, - Need R eRedCap-r18 ENUMERATED {true} OPTIONAL, - Need R Itm ENUMERATED {true} OPTIONAL, - Need R sparel ENUMERATED {true} OPTIONAL - Need R

[0143] }

[0144] NSAG-List-r17 ::= SEQUENCE (SIZE (1.. maxSlicelnfo-r17)) OF NSAG-ID-r17

[0145] - TAG-FEATURECOMBINATION-STOP

[0146] - ASN1STOP

[0147] - TS 38 331 -

[0148] 9.2.2.1 UE Context Management messages

[0149] UE CONTEXT SETUP REQUEST

[0150] This message is sent by the gNB-CU to request the setup of a UE context.

[0151] Direction: gNB-CU gNB-DU.

[0152] 9.2.2.2 UE CONTEXT SETUP RESPONSE

[0153] This message is sent by the gNB-DU to confirm the setup of a UE context. Direction: gNB-DU gNB-CU.

[0154] 9.2.2.7 UE CONTEXT MODIFICATION REQUEST

[0155] This message is sent by the gNB-CU to provide UE Context information changes to the gNB- DU.

[0156] Direction: gNB-CU^ gNB-DU

[0157] 9.2.2.8 UE CONTEXT MODIFICATION RESPONSE

[0158] This message is sent by the gNB-DU to confirm the modification of a UE context. Direction: gNB-DU gNB-CU.

[0159] Methods

[0160] FIG. 6 depicts steps in a method 100, performed by a UE operative in a wireless communication network, of acquiring information to perform an early UL synchronization procedure to obtain a TA value for a LTM cell switch procedure. A configuration for performing an early UL synchronization procedure for one or more LTM candidate cells is received from a source DU (S-DU) of the base station serving the UE (block 102). A first trigger to transmit a first RACH preamble for early synchronization to a first configured LTM candidate cell of a first candidate DU (C-DU) is received from the S-DU (block 104). The first RACH preamble is transmitted to the first LTM candidate cell of the first C-DU (block 106). A TA value is received from the S-DU (block 108). FIG. 7 depicts steps in a method 200, performed by a network node implementing an S- DU of a base station serving a first UE, the method being to receive RACH preamble indexes and early UL synchronization configurations to send to the first UE, to enable the first UE to initiate an early UL synchronization procedure. A request for one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE is transmitted to a C-DU or a third network node (block 202). One or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE is received from the C-DU or third network node (block 204). A RACH preamble index to send to the first UE to trigger an early UL synchronization procedure by the first UE is selected (block 206). The selected RACH preamble index is transmitted to the first UE to trigger an early UL synchronization procedure by the first UE (block 208). The third network node may be a CU.

[0161] FIG. 8 depicts steps in a method 300, performed by a network node implementing a DU of a base station that is a C-DU for an LTM cell switch procedure by a first UE served by an S- DU, the method being to transmit one or more RACH preamble indexes and one or more early UL synchronization configurations to the S-DU, to send to the first UE, to enable the first UE to initiate an early UL synchronization procedure. A request is received from a S-DU or a third network node to provide one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE (block 302). One or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE are transmitted to the S-DU or third network node (block 304). The third network node may be a CU.

[0162] Network Architecture and Hardware

[0163] FIG. 9 shows an example of a communication system QQ100 in accordance with some embodiments.

[0164] In the example, the communication system QQ100 includes a telecommunication network QQ102 that includes an access network QQ104, such as a radio access network (RAN), and a core network QQ106, which includes one or more core network nodes QQ108. The access network QQ104 includes one or more access network nodes, such as network nodes QQ110a and QQ110b (one or more of which may be generally referred to as network nodes QQ110), or any other similar 3rd Generation Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network QQ102 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network QQ102 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network QQ102, including one or more network nodes QQ110 and / or core network nodes QQ108.

[0165] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1 , F1 , W1 , E1 , E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes QQ110 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs QQ112a, QQ112b, QQ112c, and QQ112d (one or more of which may be generally referred to as UEs QQ112) to the core network QQ106 over one or more wireless connections.

[0166] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system QQ100 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system QQ100 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0167] The UEs QQ112 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes QQ110 and other communication devices. Similarly, the network nodes QQ110 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs QQ112 and / or with other network nodes or equipment in the telecommunication network QQ102 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network QQ102. In the depicted example, the core network QQ106 connects the network nodes QQ110 to one or more host computing systems, such as host QQ116. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network QQ106 includes one more core network nodes (e.g., core network node QQ108) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node QQ108. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0168] The host QQ116 may be under the ownership or control of a service provider other than an operator or provider of the access network QQ104 and / or the telecommunication network QQ102. The host QQ116 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0169] As a whole, the communication system QQ100 of FIG. 9 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low- power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0170] In some examples, the telecommunication network QQ102 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network QQ102 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network QQ102. For example, the telecommunications network QQ102 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC)ZMassive loT services to yet further UEs.

[0171] In some examples, the UEs QQ112 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network QQ104 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network QQ104. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0172] In the example, the hub QQ114 communicates with the access network QQ104 to facilitate indirect communication between one or more UEs (e.g., UE QQ112c and / or QQ112d) and network nodes (e.g., network node QQ110b). In some examples, the hub QQ114 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub QQ114 may be a broadband router enabling access to the core network QQ106 for the UEs. As another example, the hub QQ114 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes QQ110, or by executable code, script, process, or other instructions in the hub QQ114. As another example, the hub QQ114 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub QQ114 may be a content source. For example, for a UE that is a VR device, display, loudspeaker, or other media delivery device, the hub QQ114 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub QQ114 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub QQ114 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0173] The hub QQ114 may have a constant / persistent or intermittent connection to the network node QQ110b. The hub QQ114 may also allow for a different communication scheme and / or schedule between the hub QQ114 and UEs (e.g., UE QQ112c and / or QQ112d), and between the hub QQ114 and the core network QQ106. In other examples, the hub QQ114 is connected to the core network QQ106 and / or one or more UEs via a wired connection. Moreover, the hub QQ114 may be configured to connect to an M2M service provider over the access network QQ104 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes QQ110 while still connected via the hub QQ114 via a wired or wireless connection. In some embodiments, the hub QQ114 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node QQ110b. In other embodiments, the hub QQ114 may be a non- dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node QQ110b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0174] FIG. 10 shows a UE QQ200 in accordance with some embodiments. The UE QQ200 presents additional details of some embodiments of the UE QQ112 of FIG. 1. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage / playback device, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), an Augmented Reality (AR) or Virtual Reality (VR) device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-loT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0175] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0176] The UE QQ200 includes processing circuitry QQ202 that is operatively coupled via a bus QQ204 to an input / output interface QQ206, a power source QQ208, a memory QQ210, a communication interface QQ212, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in FIG. 10. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0177] The processing circuitry QQ202 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory QQ210. The processing circuitry QQ202 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry QQ202 may include multiple central processing units (CPUs).

[0178] In the example, the input / output interface QQ206 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE QQ200. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0179] In some embodiments, the power source QQ208 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source QQ208 may further include power circuitry for delivering power from the power source QQ208 itself, and / or an external power source, to the various parts of the UE QQ200 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source QQ208. Power circuitry may perform any formatting, converting, or other modification to the power from the power source QQ208 to make the power suitable for the respective components of the UE QQ200 to which power is supplied.

[0180] The memory QQ210 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable readonly memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory QQ210 includes one or more application programs QQ214, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data QQ216. The memory QQ210 may store, for use by the UE QQ200, any of a variety of various operating systems or combinations of operating systems.

[0181] The memory QQ210 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUlCC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory QQ210 may allow the UE QQ200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory QQ210, which may be or comprise a device-readable storage medium.

[0182] The processing circuitry QQ202 may be configured to communicate with an access network or other network using the communication interface QQ212. The communication interface QQ212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna QQ222. The communication interface QQ212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter QQ218 and / or a receiver QQ220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter QQ218 and receiver QQ220 may be coupled to one or more antennas (e.g., antenna QQ222) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0183] In the illustrated embodiment, communication functions of the communication interface QQ212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11 , Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0184] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface QQ212, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0185] As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0186] A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE QQ200 shown in FIG. 10.

[0187] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-loT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0188] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0189] FIG. 11 shows a network node QQ300 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

[0190] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0191] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0192] The network node QQ300 includes a processing circuitry QQ302, a memory QQ304, a communication interface QQ306, and a power source QQ308. The network node QQ300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node QQ300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node QQ300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory QQ304 for different RATs) and some components may be reused (e.g., a same antenna QQ310 may be shared by different RATs). The network node QQ300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node QQ300, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node QQ300.

[0193] The processing circuitry QQ302 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node QQ300 components, such as the memory QQ304, to provide network node QQ300 functionality.

[0194] In some embodiments, the processing circuitry QQ302 includes a system on a chip (SOC). In some embodiments, the processing circuitry QQ302 includes one or more of radio frequency (RF) transceiver circuitry QQ312 and baseband processing circuitry QQ314. In some embodiments, the radio frequency (RF) transceiver circuitry QQ312 and the baseband processing circuitry QQ314 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry QQ312 and baseband processing circuitry QQ314 may be on the same chip or set of chips, boards, or units.

[0195] The memory QQ304 may comprise any form of volatile or non-volatile computer- readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry QQ302. The memory QQ304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry QQ302 and utilized by the network node QQ300. The memory QQ304 may be used to store any calculations made by the processing circuitry QQ302 and / or any data received via the communication interface QQ306. In some embodiments, the processing circuitry QQ302 and memory QQ304 is integrated.

[0196] The communication interface QQ306 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface QQ306 comprises port(s) / terminal(s) QQ316 to send and receive data, for example to and from a network over a wired connection. The communication interface QQ306 also includes radio front-end circuitry QQ318 that may be coupled to, or in certain embodiments a part of, the antenna QQ310. Radio front-end circuitry QQ318 comprises filters QQ320 and amplifiers QQ322. The radio front-end circuitry QQ318 may be connected to an antenna QQ310 and processing circuitry QQ302. The radio front-end circuitry may be configured to condition signals communicated between antenna QQ310 and processing circuitry QQ302. The radio front-end circuitry QQ318 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry QQ318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters QQ320 and / or amplifiers QQ322. The radio signal may then be transmitted via the antenna QQ310. Similarly, when receiving data, the antenna QQ310 may collect radio signals which are then converted into digital data by the radio frontend circuitry QQ318. The digital data may be passed to the processing circuitry QQ302. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0197] In certain alternative embodiments, the network node QQ300 does not include separate radio front-end circuitry QQ318, instead, the processing circuitry QQ302 includes radio frontend circuitry and is connected to the antenna QQ310. Similarly, in some embodiments, all or some of the RF transceiver circuitry QQ312 is part of the communication interface QQ306. In still other embodiments, the communication interface QQ306 includes one or more ports or terminals QQ316, the radio front-end circuitry QQ318, and the RF transceiver circuitry QQ312, as part of a radio unit (not shown), and the communication interface QQ306 communicates with the baseband processing circuitry QQ314, which is part of a digital unit (not shown).

[0198] The antenna QQ310 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna QQ310 may be coupled to the radio frontend circuitry QQ318 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna QQ310 is separate from the network node QQ300 and connectable to the network node QQ300 through an interface or port.

[0199] The antenna QQ310, communication interface QQ306, and / or the processing circuitry QQ302 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna QQ310, the communication interface QQ306, and / or the processing circuitry QQ302 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment. The power source QQ308 provides power to the various components of network node QQ300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source QQ308 may further comprise, or be coupled to, power management circuitry to supply the components of the network node QQ300 with power for performing the functionality described herein. For example, the network node QQ300 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source QQ308. As a further example, the power source QQ308 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0200] Embodiments of the network node QQ300 may include additional components beyond those shown in FIG. 11 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node QQ300 may include user interface equipment to allow input of information into the network node QQ300 and to allow output of information from the network node QQ300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node QQ300. In some embodiments providing a core network node, such as core network node 108 of FIG. QQ1 , some components, such as the radio front-end circuitry QQ318 and the RF transceiver circuitry QQ312 may be omitted.

[0201] FIG. 12 is a block diagram illustrating a virtualization environment QQ400 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments QQ400 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment QQ400 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface. Virtualization may facilitate distributed implementations of a network node, UE, core network node, or host. Applications QQ402 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0202] Hardware QQ404 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers QQ406 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs QQ408a and QQ408b (one or more of which may be generally referred to as VMs QQ408), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer QQ406 may present a virtual operating platform that appears like networking hardware to the VMs QQ408.

[0203] The VMs QQ408 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer QQ406. Different embodiments of the instance of a virtual appliance QQ402 may be implemented on one or more of VMs QQ408, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0204] In the context of NFV, a VM QQ408 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs QQ408, and that part of hardware QQ404 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs QQ408 on top of the hardware QQ404 and corresponds to the application QQ402.

[0205] Hardware QQ404 may be implemented in a standalone network node with generic or specific components. Hardware QQ404 may implement some functions via virtualization. Alternatively, hardware QQ404 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration QQ410, which, among others, oversees lifecycle management of applications QQ402. In some embodiments, hardware QQ404 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system QQ412 which may alternatively be used for communication between hardware nodes and radio units.

[0206] Although the computing devices described herein (e.g., UEs, network nodes) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0207] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer- readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer- readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0208] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc., are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the aspects disclosed herein may be applied to any other aspect, wherever appropriate. Likewise, any advantage of any of the aspects may apply to any other aspects, and vice versa. Other objectives, features and advantages of the enclosed aspects will be apparent from the description.

[0209] The term “unit” may have conventional meaning in the field of electronics, electrical devices and / or electronic devices and may include, for example, electrical and / or electronic circuitry, devices, modules, processors, memories, logic solid state and / or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and / or displaying functions, and so on, as such as those that are described herein.

[0210] As used herein, the term “configured to” means set up, organized, adapted, or arranged to operate in a particular way; the term is synonymous with “designed to,” or with respect to processing circuitry, “programmed to.”

[0211] Some of the aspects contemplated herein are described more fully with reference to the accompanying drawings. Other aspects, however, are contained within the scope of the subject matter disclosed herein. The disclosed subject matter should not be construed as limited to only the aspects set forth herein; rather, these aspects are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0212] The present disclosure may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the disclosure. The present aspects are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended aspects are intended to be embraced therein.

Claims

CLAIMSWhat is claimed is:

1. A method (100), performed by a user equipment, UE (QQ200), operative in a wireless communication network (QQ102), of acquiring information to perform an early uplink, UL, synchronization procedure to obtain a Timing Advance, TA, value for a L1 / L2 Triggered Mobility, LTM, cell switch procedure, the method comprising: receiving (102), from a source Distributed Unit, S-DU, of the base station serving the UE (QQ200), a configuration for performing an early UL synchronization procedure for one or more LTM candidate cells; receiving (104), from the S-DU, a first trigger to transmit a first Random Access Channel, RACH, preamble for early synchronization to a first configured LTM candidate cell of a first candidate DU, C-DU; transmitting (106) the first RACH preamble to the first LTM candidate cell of the first C- DU; and receiving (107), from the S-DU, a TA value.

2. The method (100) of claim 1 , further comprising applying the received TA value during execution of an LTM cell switch procedure.

3. The method (100) of claim 1 , wherein time and frequency domain resources for transmitting the first RACH preamble are included in the early UL synchronization configuration or first trigger, and wherein transmitting (106) the first RACH preamble to the first LTM candidate cell comprises transmitting the first RACH preamble on the time and frequency domain resources included in the early UL synchronization configuration or first trigger.

4. The method (100) of claim 3 wherein the early UL synchronization configuration comprises a mapping between one or more RACH preamble indexes and one or more random access resources on which random access preambles can be transmitted.

5. The method (100) of claim 1 , wherein no time and frequency domain resources for transmitting (106) the first RACH preamble are included in the early UL synchronization configuration or first trigger, and further comprising: determining a set of time and frequency random access resources on which to transmit the first RACH preamble to the first candidate DU; wherein transmitting the first RACH preamble to the first LTM candidate cell comprises transmitting the first RACH preamble on the determined time and frequency domain resources.

6. The method (100) of claim 1 wherein the early UL synchronization configuration comprises an LTM candidate cell identifier.

7. The method (100) of claim 1 wherein the early UL synchronization configuration comprises a list of time resources which should be used to send a RACH preamble.

8. The method (100) of claim 1 wherein the early UL synchronization configuration comprises a list of frequency resources which should be used to send a RACH preamble.

9. The method (100) of claim 1 wherein the early UL synchronization configuration comprises a mapping for each time and frequency resource.

10. The method (100) of claim 1 wherein the early UL synchronization configuration comprises an indication about which RACH preamble index(es) can be sent with this configuration.

11. The method (100) of claim 1 wherein the early UL synchronization configuration comprises an indication whether the configuration can be used only for the early UL synchronization or for both the early UL synchronization and an LTM cell switch procedure.

12. The method (100) of claim 1 wherein the first trigger is a Physical Downlink Control Channel (PDCCH) order.

13. The method (100) of claim 1 wherein the first trigger comprises an LTM candidate cell identifier.

14. The method (100) of claim 1 wherein the first trigger comprises a random access configuration identifier of a random access configuration which identifies one or more random access resources in the time and frequency domain that can be used to send the RACH preamble to the indicated LTM candidate cell.

15. The method (100) of claim 1 wherein the first trigger comprises a RACH preamble identifier.

16. The method (100) of claim 1 wherein the first trigger comprises a time domain resource on which to send the RACH preamble.

17. The method (100) of claim 1 wherein the first trigger comprises a frequency domainresource on which to send the RACH preamble.

18. The method (100) of any preceding claim wherein the frequency domain resources to be used to send the RACH preamble are described by a frequency range.

19. The method (100) of any of claims 1-16 wherein the frequency domain resources to be used to send the preamble are described by a starting point on the frequency domain.

20. The method (100) of any of claims 1-18 wherein the frequency domain resources to be used to send the RACH preamble are described by a number of Physical Random Access Channel (PRACH) transmission occasions over the frequency domain in one time instance.

21. The method (100) of any preceding claim wherein the time domain resources to be used to send the RACH preamble comprise one or more Physical Random Access Channel, PRACH, configuration indexes.

22. The method (100) of any preceding claim wherein the indicated of time and frequency domain resources have a direct relationship, and further comprising: receiving, from the network, a mapping indicating a particular time domain resource to be used with a particular frequency domain resource, or vice versa.

23. The method (100) of claim 22 wherein the relation or mapping of time and frequency resources relates to specific points in the time and frequency domains.

24. The method (100) of claim 22 wherein the relation or mapping of time and frequency resources relates to a range in both the time and frequency domains.

25. The method (100) of claim 22 wherein the relation or mapping of time and frequency resources relates to a specific point in one of the time and frequency domains and a range in the other.

26. The method (100) of any preceding claim, further comprising: receiving, from the network, a list of RACH preambles to be used with a certain early UL synchronization configuration; and receiving, from the network, a Physical Downlink Control Channel, PDCCH, order indicating a RACH preamble index.

27. The method (100) of claim 26, further comprising ascertaining in which configuration theRACH preamble can be used according to the received RACH preamble index.

28. The method (100) of claim 26, further comprising associating to a particular RACH preamble index, time and frequency domain resources according to the allowed RACH preamble indexes that can be used with a certain early UL synchronization configuration.

29. The method (100) of any of claims 1-25, further comprising: receiving, from the network, a list of RACH preambles to be used with a certain early UL synchronization configuration but with no indication of allowed RACH preambles; and randomly selecting time and frequency domain resources from among those received in the first early UL synchronization configuration.

30. The method (100) of any of claims 1-25, further comprising: receiving, from the network, a list of RACH preambles to be used with a certain early UL synchronization configuration but with no indication of allowed preambles; and selecting time and frequency domain resources from among those received in the first early UL synchronization configuration in order of the UE.

31. A method (200), performed by a network node (QQ110A, QQ300) implementing a source Distributed Unit, S-DU, of a base station serving a first User Equipment, UE (QQ200), the method (200) being to receive Random Access Channel, RACH, preamble indexes and early uplink, UL, synchronization configurations to send to the first UE (QQ200), to enable the first UE (QQ200) to initiate an early UL synchronization procedure, the method (200) comprising: transmitting (202), to a candidate DU, C-DU or a third network node (QQ110B, QQ300), a request for one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE (QQ200); receiving (204), from the C-DU or third network node (QQ110B, QQ300), one or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE (QQ200); selecting (206) a RACH preamble index to send to the first UE (QQ200) to trigger an early UL synchronization procedure by the first UE (QQ200); and transmitting (208) the selected RACH preamble index to the first UE (QQ200) to trigger an early UL synchronization procedure by the first UE (QQ200).

32. The method (200) of claim 31 , wherein the request to the C-DU or third network node (QQ110B, QQ300) includes a flag indicating the need for one or more RACH preamble indexes to be used for the early UL synchronization procedure.

33. The method (200) of claim 31 , wherein the request to the C-DU or third network node (QQ110B, QQ300) includes a request of a number “X” of RACH preambles to be used for the early UL synchronization procedure.

34. The method (200) of claim 31 , wherein the request to the C-DU or third network node (QQ110B, QQ300) includes a flag indicating the need for one or more early UL synchronization configurations.

35. The method (200) of claim 31 , wherein the request to the C-DU or third network node (QQ110B, QQ300) includes a request of a number “Y” of early UL synchronization configurations.

36. The method (200) of claim 31 , wherein the received one or more RACH preamble indexes and one or more early UL synchronization configurations are independent, wherein the UE (QQ200) determines an association of the transmitted RACH preamble index to an early UL synchronization procedure.

37. The method (200) of claim 31 , wherein the received one or more RACH preamble indexes are mapped to the received one or more early UL synchronization configurations, whereby one RACH preamble can only be used with one or more particular early UL synchronization configurations, and wherein selecting (206) a RACH preamble index to send to the first UE (QQ200) comprises selecting the RACH preamble index according to the mapping between RACH preamble indexes and early UL synchronization configurations provided by the C-DU or third network node (QQ110B, QQ300).

38. The method (200) of claim 31 wherein signaling between the S-DU and the C-DU is via a direct interface among DUs.

39. The method (200) of claim 31 wherein signaling between the S-DU and the C-DU or third network node (QQ110B, QQ300) is via a F1AP interface.

40. The method (200) of any of claims 31-39 wherein the third network node (QQ110B, QQ300) is a Central Unit, CU, of the base station.

41. The method (200) of claim 40, further comprising: transmitting, to a C-DU, one or more early UL synchronization configurations and one or more RACH preamble indexes via the CU.

42. A method (300), performed by a network node (QQ110B, QQ300) implementing a Distributed Unit, DU, of a base station that is a candidate target DU, C-DU, for a L1 / L2 Triggered Mobility, LTM, cell switch procedure by a first User Equipment, UE (QQ300), served by a source DU, S-DU, the method (300) being to transmit one or more Random Access Channel (RACH) preamble indexes and one or more early uplink, UL, synchronization configurations to the S-DU, to send to the first UE (QQ300), to enable the first UE (QQ300) to initiate an early UL synchronization procedure, the method (300) comprising: receiving (302) a request from a S-DU or a third network node (QQ110A, QQ300) to provide one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE (QQ300); and transmitting (302), to the S-DU or third network node (QQ110A, QQ300), one or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE (QQ300).

43. The method (300) of claim 42, wherein the request from the S-DU or third network node (QQ110A, QQ300) includes a flag indicating the need for one or more RACH preamble indexes to be used for the early UL synchronization procedure.

44. The method (300) of claim 42, wherein the request from S-DU or third network node (QQ110A, QQ300) includes a request of a number “X” of RACH preambles to be used for the early UL synchronization procedure.

45. The method (300) of claim 42, wherein the request from S-DU or third network node (QQ110A, QQ300) includes a flag indicating the need for one or more early UL synchronization configurations.

46. The method (300) of claim 42, wherein the request from S-DU or third network node (QQ110A, QQ300) includes a request of a number “Y” of early UL synchronization configurations.

47. The method (300) of claim 42, further comprising: reserving one or more RACH indexes in the time and frequency domains specifically for the requesting S-DU; and not sending the reserved RACH indexes to any other S-DU.

48. The method (300) of claim 47, wherein two or more time and frequency domain resourcesare allocated to a RACH preamble index, and those time and frequency domain resources are not allocated to any other RACH preamble index.

49. The method (300) of claim 48, wherein the number of PRACH preambles reserved by the C-DU exceeds 64.

50. The method (300) of claim 47, further comprising: mapping each reserved RACH index to one or more specific early UL synchronization configurations; whereby a certain RACH preamble can only be used in a time and frequency domain that is part of the associated early UL synchronization configuration(s).

51. The method (300) of any of claims 42-50 wherein the third network node (QQ110A, QQ300) is a Central Unit (CU) of the base station.

52. A user equipment (QQ200) for performing a L1 / L2 Triggered Mobility (LTM) cell switch procedure, comprising: processing (QQ2020 circuitry configured to receive (102), from a source Distributed Unit, S-DU, of the base station serving the UE (QQ200), a configuration for performing an early UL synchronization procedure for one or more LTM candidate cells; receive (104), from the S-DU, a first trigger to transmit a first Random Access Channel, RACH, preamble for early synchronization to a first configured LTM candidate cell of a first candidate DU, C-DU; transmit (106) the first RACH preamble to the first LTM candidate cell of the first C- DU; and receive (107), from the S-DU, a TA value; and power supply circuitry (QQ208) configured to supply power to the processing circuitry (QQ202).

53. The user equipment (QQ200) of claim 52, wherein the processing circuitry (QQ202) is further configured to perform any of the steps of any of claims 2-30.

54. A network node (QQ110A, QQ300) for receiving Random Access Channel, RACH, preamble indexes and early uplink, UL, synchronization configurations to send to a first UE (QQ200) to enable the first UE (QQ200) to initiate an early UL synchronization procedure, the network node (QQ110A, QQ300) comprising: processing circuitry (QQ302) configured totransmit (202), to a candidate DU, C-DU or a third network node (QQ110B, QQ300), a request for one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE (QQ200); receive (204), from the C-DU or third network node (QQ110B, QQ300), one or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE (QQ200); select (206) a RACH preamble index to send to the first UE (QQ200) to trigger an early UL synchronization procedure by the first UE (QQ200); and transmit (208) the selected RACH preamble index to the first UE (QQ200) to trigger an early UL synchronization procedure by the first UE (QQ200) and power supply circuitry (QQ308) configured to supply power to the processing circuitry (QQ302).

55. The network node (QQ110A, QQ300) of claim 54, wherein the processing circuitry (QQ302) is further configured to perform any of the steps of any of claims 32-41 .

56. A network node (QQ110B, QQ300) for transmitting one or more Random Access Channel, RACH, preamble indexes and one or more early uplink, UL, synchronization configurations to a source Distributed Unit, S-DU, to send to a first UE (QQ200) served by the S-DU, to enable the first UE (QQ200) to initiate an early UL synchronization procedure, the network node (QQ300) comprising: processing circuitry (QQ302) configured to receive (302) a request from a S-DU or a third network node (QQ110A, QQ300) to provide one or more RACH preamble indexes to be used to trigger an early UL synchronization procedure by the first UE (QQ300); and transmit (302), to the S-DU or third network node (QQ110A, QQ300), one or more RACH preamble indexes and one or more early UL synchronization configurations to be used to trigger an early UL synchronization procedure by the first UE (QQ300); and power supply circuitry (QQ308) configured to supply power to the processing circuitry (QQ302).

57. The network node (QQ110B, QQ300) of claim 56, wherein the processing circuitry (QQ302) is further configured to perform any of the steps of any of claims 43-51 .

58. A user equipment, UE (QQ200), for receiving Random Access Channel, RACH, preamble indexes and early uplink, UL, synchronization configurations to send to a first UE (QQ200) toenable the first UE (QQ200) to initiate an early UL synchronization procedure, the UE (QQ200) comprising: an antenna (QQ222) configured to send and receive wireless signals; radio front-end circuitry (QQ212) connected to the antenna and to processing circuitry (QQ202), and configured to condition signals communicated between the antenna (QQ222) and the processing circuitry (QQ202); the processing circuitry (QQ202) being configured to receive (102), from a source Distributed Unit, S-DU, of the base station serving the UE (QQ200), a configuration for performing an early UL synchronization procedure for one or more LTM candidate cells; receive (104), from the S-DU, a first trigger to transmit a first Random Access Channel, RACH, preamble for early synchronization to a first configured LTM candidate cell of a first candidate DU, C-DU; transmit (106) the first RACH preamble to the first LTM candidate cell of the first C- DU; and receive (107), from the S-DU, a TA value; an input interface (QQ206) connected to the processing circuitry (QQ202) and configured to allow input of information into the UE (QQ200) to be processed by the processing circuitry (QQ202); an output interface (QQ206) connected to the processing circuitry (QQ202) and configured to output information from the UE (QQ200) that has been processed by the processing circuitry (QQ202); and a battery (QQ208) connected to the processing circuitry (QQ202) and configured to supply power to the UE (QQ200).

59. The UE (QQ200) of claim 58 wherein the processing circuitry (QQ202) is further configured to perform any of the steps of any of claims 2-30.

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