Reusing uplink resources without forced reconfiguration upon expiration of time alignment timer, and related devices, methods, and computer programs

Abstract

Apparatuses, methods, and computer programs are disclosed for reusing uplink resources without forced reconfiguration upon expiration of a time alignment timer. At least some example embodiments may allow for the purpose of explicitly signaling a random access procedure to a network node (210) via the use of the disclosed timing advance wireless network temporary identifier.

Description

Technical Field

[0001] This disclosure relates generally to communications, and more specifically, but not exclusively, to the reuse of uplink resources without forced reconfiguration when a time alignment timer expires, and related devices, methods, and computer programs. Background Technology

[0002] When a user equipment loses uplink (UL) synchronization due to the expiration of its time alignment timer, this ultimately leads to a random access (RA) procedure initiated by the Media Access Control (MAC), as follows: - The user equipment releases the physical UL control channel (PUCCH) / semi-persistent scheduling (SRS) resources (including scheduling request indication (SRI)), releases the activity authorization, and refreshes the UL hybrid automatic repeat query (HARQ) buffer; - Notify the user equipment of Radio Resource Control (RRC); and - When SRI is triggered, the RA process initiated by MAC starts.

[0003] However, in at least some cases, it may be necessary to expedite this process and shorten the disruption to UL's operations. Summary of the Invention

[0004] The independent claims define the scope of protection sought by the various exemplary embodiments of the invention. Exemplary embodiments and features (if any) described in this specification that are not within the scope of the independent claims are to be interpreted as examples that aid in understanding the various exemplary embodiments of the invention.

[0005] An example embodiment of a user equipment includes at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment to establish a connection to a source network node, at least via a source cell supported by a source network node of a radio access network. When executed by the at least one processor, the instructions also cause the user equipment to receive timing advance TA parameters from the radio access network, the TA parameters including a TA-Radio Network Temporary Identifier (RNTI) associated with the source cell. When executed by the at least one processor, the instructions also cause the user equipment to use the TA parameters, at least if a relevant TA procedure is triggered.

[0006] In the example embodiments, as an alternative or supplement to the above example embodiments, the user equipment is also configured to receive a Media Access Control (MAC) configuration including the TA-RNTI from the radio access network.

[0007] In the example embodiment, as an alternative or supplement to the above example embodiment, the user equipment is also configured to: monitor the time alignment timer TAT, and trigger the relevant TA process if the TAT expires.

[0008] In the example embodiment, as an alternative or supplement to the above example embodiment, the relevant TA procedure is a random access procedure.

[0009] In the example embodiments, as an alternative or supplement to the above example embodiments, the user equipment is further configured to: send a random access request message to the source cell in the event of a triggered related TA procedure, receive a random access response message from the source cell, and subsequently send a message to the source cell including a TA-RNTI associated with the source cell, wherein sending the random access request message includes using contention-based random access CBRA.

[0010] In the example embodiment, as an alternative or supplement to the above example embodiment, TA-RNTI indicates the reason for the relevant TA process, and the reason indicates at least one of the following: the relevant time alignment timer TAT has expired, asynchrony is detected, the uplink resources allocated for data transmission are currently unused, the uplink resources allocated for data transmission have not been released, data transmission on the allocated uplink resources will continue once the TA is reacquired, and data is waiting to be sent in the buffer.

[0011] In the example embodiments, as an alternative or supplement to the above example embodiments, the user equipment is further configured to: receive configuration from the radio access network indicating at least one candidate cell to which the user equipment can connect; and receive timing advance TA parameters from the radio access network, the TA parameters including a TA-Radio Network Temporary Identifier RNTI associated with the configured candidate cell, and the TA-RNTI associated with the source cell and the TA-RNTI associated with the configured candidate cell may be the same or different.

[0012] In the example embodiments, as an alternative or supplement to the above example embodiments, the source network node supports at least one of the distributed unit (DU) function or the layer 2 protocol of the wireless access network, and / or at least one of the central unit (CU) function or the layer 3 protocol of the wireless access network.

[0013] In the example embodiment, as an alternative or supplement to the above example embodiment, this configuration is related to triggering mobility LTM in layer 1 / layer 2.

[0014] In the example embodiments, as an alternative or supplement to the above example embodiments, the user equipment is further configured to: receive an RRCReconfiguration message from the radio access network, the RRCReconfiguration message including the TA-RNTI associated with the configured candidate cell and / or source cell, and reconfigure the LTM to the user equipment.

[0015] In the example embodiment, as an alternative or supplement to the above example embodiment, the user equipment is also configured to: receive a message including TA acquisition trigger from the source network node to trigger a relevant TA procedure for the source cell having an associated TA-RNTI.

[0016] In the example embodiments, as an alternative or supplement to the above example embodiments, the user equipment is further configured to: send a random access request message to the source cell, receive a random access response message from the source cell, and subsequently send a message to the source cell including a TA-RNTI associated with the source cell.

[0017] In the example embodiment, as an alternative or supplement to the above example embodiment, the user equipment is further configured to: send a random access request message to the triggered candidate cell, receive a random access response message from the candidate cell, and subsequently send a message including the TA-RNTI associated with the triggered cell to the triggered candidate cell.

[0018] In the example embodiment, as an alternative or supplement to the above example embodiment, the user equipment is further configured to: after receiving a random access response message from the triggered candidate cell, subsequently send a message including the TA-RNTI associated with the triggered cell to the source cell.

[0019] In the example embodiments, as an alternative or supplement to the above example embodiments, the user equipment is also configured to: after receiving a random access response message from a triggered candidate cell, subsequently avoid at least one of the following: starting a relevant contention resolution process, starting a relevant contention resolution timer, or treating TA acquisition as invalid when the relevant contention resolution timer expires.

[0020] In the example embodiments, as an alternative or supplement to the above example embodiments, the relevant TA process involves at least one of the following: TA acquisition process, early TA acquisition process, TA acquisition using a random access process, or TA reacquisition process.

[0021] In the example embodiments, as an alternative or supplement to the above example embodiments, the at least one candidate cell to which the user equipment connects includes at least one of the following: a target cell for the user equipment to hand over, or a target cell for the user equipment to add as a second radio link connection.

[0022] In the example embodiments, as an alternative or supplement to the above example embodiments, the TA parameter is a user equipment-specific parameter assigned by the source cell.

[0023] In the example embodiment, as an alternative or supplement to the above example embodiment, an associated timer is assigned together with the TA parameter, the associated timer indicating that the TA parameter will be regarded as a valid time period by the user equipment.

[0024] In the example embodiments, as an alternative or supplement to the above example embodiments, the TA parameters associated with the configured candidate cells are user equipment-specific parameters assigned by the associated configured candidate cells or source cells.

[0025] In the example embodiment, as an alternative or supplement to the above example embodiment, an associated timer is assigned together with the TA parameter, which indicates the time period during which the TA parameter associated with the configured candidate cell will be considered valid by the user equipment.

[0026] An example embodiment of a source network node includes at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the source network node to establish a connection to a user equipment at least via a source cell of a radio access network supported by the source network node. When executed by the at least one processor, the instructions also cause the source network node to send timing advance TA parameters to the user equipment at least via the radio access network, the TA parameters including a TA-Radio Network Temporary Identifier (RNTI) associated with the source cell.

[0027] In the example embodiment, as an alternative or supplement to the above example embodiment, the source network node is also configured to send a Media Access Control (MAC) configuration, including TA-RNTI, to the user equipment via the radio access network.

[0028] In the example embodiment, as an alternative or supplement to the above example embodiment, the relevant TA procedure is a random access procedure.

[0029] In the example embodiment, as an alternative or supplement to the above example embodiment, the source network node is also configured to: receive a random access request message from the user equipment via the source cell in the event of a triggered related TA procedure, send a random access response message to the user equipment via the source cell, and subsequently receive a message including a TA-RNTI associated with the source cell from the user equipment via the source cell, wherein sending the random access request message includes using contention-based random access CBRA.

[0030] In the example embodiment, as an alternative or supplement to the above example embodiment, TA-RNTI indicates the reason for the relevant TA process, and the reason indicates at least one of the following: the relevant time alignment timer TAT has expired, asynchrony is detected, the uplink resources allocated for data transmission are currently unused, the uplink resources allocated for data transmission have not been released, data transmission on the allocated uplink resources will continue once the TA is reacquired, and data is waiting to be sent in the buffer.

[0031] In the example embodiment, as an alternative or supplement to the above example embodiment, the source network node is further configured to: send a configuration to the user equipment via the radio access network, the configuration indicating at least one candidate cell to which the user equipment can connect; and send a timing advance TA parameter to the user equipment via the radio access network, the TA parameter including a TA-Radio Network Temporary Identifier (RNTI) associated with the configured candidate cell, and the TA-RNTI associated with the source cell and the TA-RNTI associated with the configured candidate cell may be the same or different.

[0032] In the example embodiments, as an alternative or supplement to the above example embodiments, the source network node supports at least one of the distributed unit (DU) function or the layer 2 protocol of the wireless access network, and / or at least one of the central unit (CU) function or the layer 3 protocol of the wireless access network.

[0033] In the example embodiment, as an alternative or supplement to the above example embodiment, this configuration is related to triggering mobility LTM in layer 1 / layer 2.

[0034] In the example embodiments, as an alternative or supplement to the above example embodiments, the source network node is also configured to send an RRCReconfiguration message, including the TA-RNTI associated with the configured candidate cell and / or source cell, to the user equipment via the radio access network.

[0035] In the example embodiment, as an alternative or supplement to the above example embodiment, the source network node is also configured to: send a message including TA acquisition trigger to the user equipment to trigger a relevant TA procedure for the source cell with the associated TA-RNTI.

[0036] In the example embodiments, as an alternative or supplement to the above example embodiments, the source network node is also configured to: receive a random access request message from the user equipment via the source cell, send a random access response message to the user equipment via the source cell, and subsequently receive a message including the TA-RNTI associated with the source cell from the user equipment via the source cell.

[0037] In the example embodiments, as an alternative or supplement to the above example embodiments, the source network node is also configured to: receive a random access request message from the user equipment via the triggered candidate cell, send a random access response message to the user equipment via the candidate cell, and subsequently receive a message including the TA-RNTI associated with the triggered cell from the user equipment via the triggered candidate cell.

[0038] In the example embodiment, as an alternative or supplement to the above example embodiment, the source network node is also configured to: after sending a random access response message to the user equipment via the triggered candidate cell, subsequently receive a message including the TA-RNTI associated with the triggered cell from the user equipment via the source cell.

[0039] In the example embodiments, as an alternative or supplement to the above example embodiments, the relevant TA process involves at least one of the following: TA acquisition process, early TA acquisition process, TA acquisition using a random access process, or TA reacquisition process.

[0040] In the example embodiments, as an alternative or supplement to the above example embodiments, the at least one candidate cell to which the user equipment connects includes at least one of the following: a target cell for the user equipment to hand over, or a target cell for the user equipment to add as a second radio link connection.

[0041] In the example embodiments, as an alternative or supplement to the above example embodiments, the TA parameter is a user equipment-specific parameter assigned by the source cell.

[0042] In the example embodiment, as an alternative or supplement to the above example embodiment, an associated timer is assigned together with the TA parameter, the associated timer indicating that the TA parameter will be regarded as a valid time period by the user equipment.

[0043] In the example embodiments, as an alternative or supplement to the above example embodiments, the TA parameters associated with the configured candidate cells are user equipment-specific parameters assigned by the associated configured candidate cells or source cells.

[0044] In the example embodiment, as an alternative or supplement to the above example embodiment, an associated timer is assigned together with the TA parameter, which indicates the time period during which the TA parameter associated with the configured candidate cell will be considered valid by the user equipment.

[0045] An example embodiment of a method includes: establishing a connection to a source network node via a source cell supported by a source network node of a radio access network. The method further includes: receiving timing advance TA parameters from the radio access network at the user equipment, the TA parameters including a TA-Radio Network Temporary Identifier (RNTI) associated with the source cell. The method further includes: using the TA parameters by the user equipment when a relevant TA procedure is triggered.

[0046] An example embodiment of one method includes: establishing a connection to a user equipment by a source network node via a source cell of a radio access network supported by the source network node. The method further includes: sending a timing advance TA parameter from the source network node to the user equipment via the radio access network, the TA parameter including a TA-Radio Network Temporary Identifier (RNTI) associated with the source cell.

[0047] An example embodiment of an apparatus includes components for performing a method according to any of the above example embodiments.

[0048] An example embodiment of a computer program product includes program code configured to perform any of the methods described in the example embodiments above when the computer program product is executed on a computer. Attached Figure Description

[0049] The accompanying drawings are provided to further illustrate the embodiments and form part of this specification. The drawings depict the embodiments and, together with the specification, help to explain the principles of the embodiments. In the drawings:

[0050] Figure 1 Example embodiments of the subject matter described herein are shown, illustrating example systems in which various embodiments of this disclosure may be implemented;

[0051] Figure 2A Example embodiments of the subject matter described herein are shown, illustrating user equipment;

[0052] Figure 2B An example embodiment of the subject matter described herein is shown, illustrating a source network node;

[0053] Figure 3 An example embodiment of the subject matter described herein is shown, illustrating a method for re-acquiring uplink synchronization with the master time alignment group;

[0054] Figure 4 Example embodiments of the subject matter described herein are shown, illustrating methods for user equipment; and

[0055] Figure 5 An example embodiment of the subject matter described herein is shown, illustrating a method for a source network node.

[0056] In the accompanying drawings, the same reference numerals are used to denote the same parts. Detailed Implementation

[0057] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below, in conjunction with the accompanying drawings, is intended as a description of the examples and is not intended to represent the only form in which the examples can be constructed or used. This specification sets forth the functionality of the examples and the sequence of steps for constructing and operating the examples. However, the same or equivalent functionality and sequence can be implemented through different examples.

[0058] Figure 1 Example system 100 in which various embodiments of the present disclosure may be implemented is illustrated. System 100 may include a radio access network 110 of a fifth-generation (5G) new radio (NR) network or a network 110 outside of a 5G wireless network. An example representation of system 100 depicting user equipment 200 and source network node 210 is shown.

[0059] In at least some embodiments, the wireless access network 110 may be included in one or more large-scale machine-to-machine (M2M) networks, large-scale machine-type communication (mMTC) networks, Internet of Things (IoT) networks, Industrial Internet of Things (IIoT) networks, enhanced mobile broadband (eMBB) networks, ultra-reliable low-latency communication (URLLC) networks, etc. In other words, the wireless access network 110 may be configured to serve different service types and / or use cases, and it may logically be considered to include one or more networks.

[0060] User equipment 200 may include, for example, a mobile phone, smartphone, tablet, smartwatch, or any handheld, portable, and / or wearable device. User equipment 200 may also be referred to as user equipment (UE). Source network node 210 may include, for example, a base station. A base station may include, for example, any device adapted to provide an air interface for client equipment to connect to a wireless network via wireless transmission.

[0061] In at least some embodiments, the source network node 210 can be logically divided into nodes referred to as Centralized Units (CUs) and Distributed Units (DUs). For example, a CU may host higher-level protocols such as Radio Resource Control (RRC), Serving Data Adaptation Protocol (SDAP), and / or Packet Data Convergence Protocol (PDCP). A DU may host, for example, Radio Link Control (RLC), Media Access Control (MAC), and / or higher physical (PHY) layers.

[0062] The following description provides further details of examples of network nodes. In a 5G NR network, a gNodeB (also known as a gNB) may include, for example, a node that provides NR user plane and control plane protocol termination toward the UE and is connected to the 5G core (5GC) via an NG interface, as per Section 3.2 of 3GPP TS 38.300 V16.6.0 (2021-06) (which is incorporated herein by reference).

[0063] gNB supports various protocol layers, such as Layer 1 (L1) (i.e., the physical layer), Layer 2 (L2), and Layer 3 (L3).

[0064] NR's Layer 2 (L2) is divided into the following sublayers: Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), among which, for example: The physical layer provides a transmission channel to the MAC sublayer; The MAC sublayer provides logical channels to the RLC sublayer; The RLC sublayer provides RLC channels to the PDCP sublayer; The PDCP sublayer provides radio bearers to the SDAP sublayer; The SDAP sublayer provides Quality of Service (QoS) flows to 5GC; "Comp." refers to header compression, and "Segm." refers to segmentation; The control channels include the Broadcast Control Channel (BCCH) and the Physical Control Channel (PCCH).

[0065] Layer 3 (L3) includes Radio Resource Control (RRC), for example, according to Section 6 of 3GPP TS 38.300 V16.6.0 (2021-06) (which is incorporated herein by reference).

[0066] The gNB Central Unit (gNB-CU) includes, for example, a logical node that hosts, for example, the gNB's Radio Resource Control (RRC), Serving Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols, or the en-gNB's RRC and PDCP protocols. This logical node controls the operation of one or more gNB Distributed Units (gNB-DUs). The gNB-CU terminates the F1 interface connected to the gNB-DU. The gNB-CU may also be referred to herein as a CU, Central Unit, Centralized Unit, or Control Unit.

[0067] A gNB Distributed Unit (gNB-DU) includes, for example, a logical node that hosts the Radio Link Control (RLC), Media Access Control (MAC), and Physical (PHY) layers of, for example, a gNB or en-gNB, and its operation is partially controlled by the gNB-CU. A gNB-DU supports one or more cells. A cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU. The gNB-DU may also be referred to herein as a DU or Distributed Unit.

[0068] The gNB-CU control plane (gNB-CU-CP) includes, for example, a logical node that hosts the control plane portion of the gNB-CU's RRC and PDCP protocols, for example, for en-gNB or gNB. The gNB-CU-CP terminates the E1 interface connected to the gNB-CU user plane (gNB-CU-UP) and the F1-C interface connected to the gNB-DU.

[0069] The gNB-CU user plane (gNB-CU-UP) includes, for example, a logical node that hosts, for example, the user plane portion of the PDCP protocol for the gNB-CU of the en-gNB, and the user plane portions of the PDCP and SDAP protocols for the gNB-CU of the gNB. The gNB-CU-UP terminates the E1 interface connected to the gNB-CU-CP and the F1-U interface connected to the gNB-DU, for example, according to Section 3.1 of 3GPP TS 38.401 V16.6.0 (2021-07) (which is incorporated herein by reference).

[0070] There can be different functional divisions between the central unit and the distributed unit, for example, referred to as options: Option 1 (Class 1A split): The functional breakdown in this option is similar to the 1A architecture in dual connectivity (DC). The RRC resides in the central unit. PDCP, RLC, MAC, physical layer, and RF reside in the distributed units. Option 2 (3C category split): The functional breakdown in this option is similar to the 3C architecture in a DC (Distributed Control) system. RRC and PDCP reside in the central unit. RLC, MAC, physical layer, and RF reside in the distributed units. Option 3 (Split within RLC): Low RLC (part of the RLC functionality), MAC, physical layer, and RF are located in the distributed unit. PDCP and high RLC (another part of the RLC functionality) are located in the central unit. Option 4 (RLC-MAC split): MAC, physical layer, and RF are located in the distributed unit. PDCP and RLC are located in the central unit.

[0071] Otherwise, for example, according to Section 11 of 3GPP TR 38.801 V14.0.0 (2017-03) (incorporated herein by reference).

[0072] As used herein, the term "network node" may refer to any one or any combination thereof, gNB-CU, gNB-DU, gNB-CU-CP, or gNB-CU-UP.

[0073] RAN (Radio Access Network) nodes or network nodes (such as, for example, gNBs, base stations, gNB-CUs or gNB-DUs, or portions thereof) can be implemented using means, for example, having at least one processor and / or at least one memory having processor-readable instructions (“programs”) configured to support and / or provide and / or process CU and / or DU-related functions and / or features, and / or at least one protocol (sub) layer of the RAN (Radio Access Network), such as layer 2 and / or layer 3.

[0074] The gNB CU and gNB DU portions can be, for example, co-located or physically separated. The gNB DU can even be further divided into two parts, for example, one part including processing equipment and the other including antennas. The Central Unit (CU) can also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or a portion thereof. The Distributed Unit (DU) can also be referred to as RRH / RRU / RE / RU, or a portion thereof. In the various exemplary embodiments of this disclosure below, a network node supporting at least one of the Central Unit Control Plane Functions or Layer 3 Protocols of the Radio Access Network can be, for example, a gNB-CU-CP. Similarly, a network node supporting at least one of the Distributed Unit Functions or Layer 2 Protocols of the Radio Access Network can be, for example, a gNB-DU.

[0075] A gNB-CU can support one or more gNB-DUs. A gNB-DU can support one or more cells, and therefore can support the serving cell for a user equipment (UE), or support handover, dual connectivity and / or carrier aggregation and other processes for candidate cells.

[0076] A user equipment (UE) device may be or includes wireless or mobile devices, devices having a radio interface for interacting with a RAN (Radio Access Network), smartphones, in-vehicle devices, IoT devices or M2M devices, and other types of user equipment. Such a UE may include: at least one processor; and at least one memory including program code; wherein the at least one memory and the computer program code are configured, together with the at least one processor, to cause the device to perform at least certain operations, such as, for example, an RRC connection to the RAN. In embodiments, the UE may be configured to generate messages (e.g., including a cell ID) to be transmitted via radio to the RAN (e.g., to reach and communicate with the serving cell). In embodiments, the UE may generate, transmit, and receive RRC messages containing one or more RRC PDUs (Packet Data Units). Those skilled in the art will understand the RRC protocol and other processes that the UE may perform.

[0077] Various example embodiments will be discussed below. At least some of these example embodiments described herein can allow uplink resources to be reused without forced reconfiguration when the time alignment timer expires.

[0078] Furthermore, at least some of the example embodiments described herein may allow the purpose of the random access (RA) procedure to be explicitly indicated to the source network node 210 via the use of the disclosed advance timing radio network temporary identifier (TA-RNTI).

[0079] Furthermore, at least some of the example embodiments described herein can allow for shorter service interruption times because user equipment 200 initiates the RA process immediately after the time alignment timer expires, without waiting for a scheduling request indication (SRI) to be triggered.

[0080] Furthermore, at least some of the example embodiments described herein can allow for minimizing service interruption time and reducing RRC message passing, since it is optional for the source network node 210 to reconfigure UL resources after the RA process is successfully completed, since the user equipment 200 does not release these UL resources in the first place.

[0081] Figure 2A This is a block diagram of user equipment 200 according to an example embodiment.

[0082] User equipment 200 includes one or more processors 202 and one or more memories 204 including computer program code. User equipment 200 may also include other elements, such as a transceiver 206 configured to enable user equipment 200 to send information to and / or receive information from other devices, and... Figure 2AOther elements not shown. In one example, user equipment 200 may use transceiver 206 to send or receive signaling information and data according to at least one cellular communication protocol. Transceiver 206 may be configured to provide at least one wireless radio connection, such as, for example, a 3GPP mobile broadband connection (e.g., 5G or 6G). Transceiver 206 may include or be configured to be coupled to at least one antenna to send and / or receive radio frequency signals.

[0083] Although user equipment 200 is depicted as including only one processor 202, user equipment 200 may include more processors. In one embodiment, memory 204 is capable of storing instructions, such as an operating system and / or various applications. Furthermore, memory 204 may include storage devices, for example, that storage device may be used to store at least some of the information and data used in the disclosed embodiments.

[0084] Furthermore, processor 202 is capable of executing stored instructions. In one embodiment, processor 202 may be embodied as a multi-core processor, a single-core processor, or a combination of one or more multi-core processors and one or more single-core processors. For example, processor 202 may be embodied as one or more of a variety of processing devices, such as a coprocessor, microprocessor, controller, digital signal processor (DSP), processing circuitry system with or without an accompanying DSP, or various other processing devices including integrated circuits, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microcontroller units (MCUs), hardware accelerators, dedicated computer chips, neural network (NN) chips, artificial intelligence (AI) accelerators, tensor processing units (TPUs), neural processing units (NPUs), etc. In one embodiment, processor 202 may be configured to perform hard-coded functions. In one embodiment, processor 202 is embodied as an executor of software instructions, wherein the instructions specifically configure processor 202 to perform the algorithms and / or operations described herein when the instructions are executed.

[0085] Memory 204 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination of one or more volatile memory devices and non-volatile memory devices. For example, memory 204 may be embodied as a semiconductor memory (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

[0086] User equipment 200 may include any of a variety of types of devices that are directly used by end-user entities and are capable of communicating in a wireless network, such as user equipment (UE). Such devices include, but are not limited to, smartphones, tablets, smartwatches, laptops, Internet of Things (IoT) devices, large-scale machine-to-machine (M2M) devices, large machine-type communication (mMTC) devices, industrial Internet of Things (IIoT) devices, enhanced mobile broadband (eMBB) devices, ultra-reliable low-latency communication (URLLC) devices, and / or devices installed in vehicles.

[0087] When executed by at least one processor 202, instructions stored in at least one memory 204 cause the user equipment 200 to establish a connection to the source network node 210 at least via a source cell supported by the source network node 210 of the radio access network 110.

[0088] When executed by at least one processor 202, the instruction also causes user equipment 200 to receive timing advance (TA) parameters from radio access network 110, the TA parameters including a TA-Radio Network Temporary Identifier (RNTI) associated with the source cell. For example, the TA parameters may be user equipment 200-specific parameters assigned by the source cell.

[0089] When executed by at least one processor 202, the instruction also causes the user equipment 200 to use the TA parameters at least when a relevant TA procedure is triggered. For example, the relevant TA procedure may be a random access procedure. In at least some embodiments, the relevant TA procedure may involve at least one of the following: a TA acquisition procedure, an early TA acquisition procedure, a TA acquisition using a random access procedure, or a TA reacquisition procedure.

[0090] In at least some embodiments, the user equipment 200 may also be configured to receive a media access control (MAC) configuration, including the TA-RNTI, from the radio access network 110.

[0091] In at least some embodiments, the user equipment 200 may also be configured to: monitor a time alignment timer (TAT) and trigger a relevant time alignment (TA) process if the TAT expires.

[0092] In at least some embodiments, the user equipment 200 may also be configured to: send a random access request message to the source cell, receive a random access response message from the source cell, and subsequently send a message to the source cell including a TA-RNTI associated with the source cell, wherein sending the random access request message includes using contention-based random access (CBRA).

[0093] In at least some embodiments, TA-RNTI can indicate the cause of the relevant TA process, indicating the cause including indicating at least one of the following: the relevant time alignment timer TAT has expired, asynchrony has been detected, the uplink resources allocated for data transmission are currently unused, the uplink resources allocated for data transmission have not been released, data transmission on the allocated uplink resources will continue once the TA is reacquired, or data is waiting to be sent in the buffer.

[0094] In at least some embodiments, the user equipment 200 may also be configured to: receive configuration from the radio access network 110 indicating at least one candidate cell to which the user equipment 200 may connect; and receive timing advance (TA) parameters from the radio access network 110, the TA parameters including a TA-Radio Network Temporary Identifier (RNTI) associated with the configured candidate cell, and the TA-RNTI associated with the source cell and the TA-RNTI associated with the configured candidate cell may be the same or different. For example, the configuration may be associated with Layer 1 / Layer 2 Triggered Mobility (LTM).

[0095] In at least some embodiments, user equipment 200 may also be configured to: receive an RRCReconfiguration message from radio access network 110 including TA-RNTI associated with a configured candidate cell and / or source cell, and reconfigure LTM to user equipment 200.

[0096] In at least some embodiments, the user equipment 200 may also be configured to: receive a message from the source network node 210 including a TA acquisition trigger to trigger a relevant TA procedure for a source cell with an associated TA-RNTI.

[0097] In at least some embodiments, the user equipment 200 may also be configured to: send a random access request message to the source cell, receive a random access response message from the source cell, and subsequently send a message to the source cell including a TA-RNTI associated with the source cell.

[0098] In at least some embodiments, the user equipment 200 may also be configured to: send a random access request message to the triggered candidate cell, receive a random access response message from the candidate cell, and subsequently send a message to the triggered candidate cell including a TA-RNTI associated with the triggered cell.

[0099] In at least some embodiments, the user equipment 200 may also be configured to: after receiving a random access response message from the triggered candidate cell, subsequently send a message to the source cell including the TA-RNTI associated with the triggered cell.

[0100] In at least some embodiments, the user equipment 200 may also be configured to: after receiving a random access response message from a triggered candidate cell, subsequently avoid at least one of the following: initiating a relevant contention resolution process, starting a relevant contention resolution timer, or treating the acquisition of TA as invalid when the relevant contention resolution timer expires.

[0101] In at least some embodiments, the candidate cell to which the user equipment 200 connects may include at least one of the following: a target cell for which the user equipment 200 switches, or a target cell for which the user equipment 200 adds as a second radio link connection.

[0102] In at least some embodiments, an associated timer may be assigned together with the TA parameter, the associated timer indicating that the TA parameter will be considered a valid time period by the user equipment 200.

[0103] In at least some embodiments, the TA parameter associated with the configured candidate cell can be a user equipment-specific parameter assigned by the associated configured candidate cell or source cell.

[0104] In at least some embodiments, an associated timer may be assigned together with the TA parameter, which indicates the time period during which the TA parameter associated with the configured candidate cell will be considered valid by the user equipment 200.

[0105] When executed by at least one processor 202, instructions stored in at least one memory 204 may also cause user equipment 200 to at least perform the following: in response to the expiration of the TA timer, suspend the use of the uplink (UL) resource set without releasing the UL resource set. For example, the TA timer may expire for a Master Time Alignment Group (PTAG), for example, when user equipment 200 has not received a timing advance command (TAC) for a period longer than defined by the TA timer.

[0106] In at least some embodiments, the UL resource set may include resources associated with the Physical UL Control Channel (PUCCH), the Sound Reference Signal (SRS), the Semi-Persistent Scheduling (SPS), and / or the Physical UL Shared Channel (PUSCH).

[0107] When executed by at least one processor 202, the instruction may also cause the user equipment 200 to perform at least the following: send an instruction to the source network node 210 to initiate a random access (RA) procedure.

[0108] In at least some embodiments, sending an instruction to the source network node 210 to initiate the RA procedure can be performed without waiting for a scheduling request indication (SRI) to be triggered.

[0109] In at least some embodiments, when executed by at least one processor 202, the instruction may also cause the user equipment 200 to: receive a Random Access Response (RAR) UL authorization from the source network node 210 in response to an instruction to initiate an RA procedure.

[0110] When executed by at least one processor 202, this instruction may also cause user equipment 200 to at least perform the following: send a TA-Radio Network Temporary Identifier (TA-RNTI) Media Access Control (MCE) element to source network node 210. The TA-RNTI MCE includes the TA-RNTI previously assigned to user equipment 200 by source network node 210.

[0111] For example, TA-RNTI can be allocated from a common pool of RNTIs. At least in some embodiments, TA-RNTI may not be used for any transmission in any direction (e.g., not used as a scrambling sequence by any physical channel).

[0112] In at least some embodiments, the TA-RNTI MCE can be sent in a transmission scheduled by the received RAR UL license.

[0113] For example, a TA-RNTI MCE may include a fixed-size UL MCE with a dedicated logical channel identifier (LCID) or a dedicated enhanced LCID (eLCID). In at least some embodiments, a TA-RNTI MCE may be used as Msg3 of a CBRA to carry the TA-RNTI (e.g., using RAR licensing and scrambling with Temp C-RNTI).

[0114] In at least some embodiments, the standard MAC subheader (R / R / LCID / (eLCID)) for fixed-size Media Access Control (MAC) Packet Data Units (PDUs) can be used. For example, when it is decided to use the LCID for the TA-RNTI MCE, two reserved bits and a 6-bit LCID can be used. Alternatively, when it is decided to use an octet of eLCID for the TA-RNTI MCE, two reserved bits and a 6-bit LCID (set to 34) can be used in the first octet, and an 8-bit eLCID can be used in the second octet.

[0115] In at least some embodiments, the allocation of TA-RNTI from the service source network node 210 to the user equipment 200 can be performed as part of the Media Access Control (MAC) configuration, and the initiated RA procedure can include a MAC-initiated RA procedure.

[0116] When executed by at least one processor 202, the instruction may also cause the user equipment 200 to at least perform the following: restart the use of the UL resource set in response to the successful completion of the initiated RA procedure.

[0117] Figure 2B This is a block diagram of source network node 210 according to an example embodiment. In at least some embodiments, source network node 210 may be associated with a serving cell for user equipment 200. In at least some embodiments, source network node 210 may support at least one of distributed unit (DU) functions or layer 2 protocols of radio access network 110, and / or central unit (CU) functions or layer 3 protocols of radio access network 110.

[0118] The source network node 210 includes one or more processors 212 and one or more memories 214 including computer program code. The source network node 210 may also include other elements, such as a transceiver 216 configured to enable the source network node 210 to send information to and / or receive information from other devices, and... Figure 2B Other elements not shown. In one example, source network node 210 may use transceiver 216 to send or receive signaling information and data according to at least one cellular communication protocol. Transceiver 216 may be configured to provide at least one wireless radio connection, such as, for example, a 3GPP mobile broadband connection (e.g., 5G or 6G). Transceiver 216 may include or be configured to be coupled to at least one antenna to send and / or receive radio frequency signals.

[0119] Although source network node 210 is depicted as including only one processor 212, source network node 210 may include more processors. In one embodiment, memory 214 is capable of storing instructions, such as an operating system and / or various applications. Furthermore, memory 214 may include storage devices, for example, that storage device may be used to store at least some of the information and data used in the disclosed embodiments.

[0120] Furthermore, processor 212 is capable of executing stored instructions. In one embodiment, processor 212 may be embodied as a multi-core processor, a single-core processor, or a combination of one or more multi-core processors and one or more single-core processors. For example, processor 212 may be embodied as one or more of a variety of processing devices, such as a coprocessor, microprocessor, controller, digital signal processor (DSP), processing circuitry system with or without an accompanying DSP, or various other processing devices including integrated circuits, such as, for example, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microcontroller units (MCUs), hardware accelerators, dedicated computer chips, neural network (NN) chips, artificial intelligence (AI) accelerators, tensor processing units (TPUs), neural processing units (NPUs), etc. In one embodiment, processor 212 may be configured to perform hard-coded functions. In one embodiment, processor 212 is embodied as an executor of software instructions, wherein the instructions specifically configure processor 212 to perform the algorithms and / or operations described herein when the instructions are executed.

[0121] Memory 214 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination of one or more volatile memory devices and non-volatile memory devices. For example, memory 214 may be embodied as a semiconductor memory (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.).

[0122] Source network node 210 may include a base station. The base station may include, for example, a 5G or 6G base station (gNB) or any such device that provides an air interface for user equipment to connect to a wireless network via wireless transmission. In at least some embodiments, source network node 210 may be logically split into a centralized unit (CU) and a distributed unit (DU).

[0123] When executed by at least one processor 212, instructions stored in at least one memory 214 cause the source network node 210 to establish a connection with the user equipment 200 at least via a source cell of the radio access network 110 supported by the source network node 210.

[0124] When executed by at least one processor 212, the instruction also causes the source network node 210 to at least: send TA parameters, including the TA-RNTI associated with the source cell, to the user equipment 200 via the radio access network 110.

[0125] In at least some embodiments, the source network node 210 may also be configured to send a MAC configuration, including the TA-RNTI, to the user equipment 200 via the radio access network 110.

[0126] In at least some embodiments, the source network node 210 may also be configured to: receive a random access request message from the user equipment 200 via the source cell in the event of a triggered associated TA procedure, the random access request message including sending a random access response message to the user equipment 200 via the source cell using CBRA, and subsequently receive a message from the user equipment 200 via the source cell including a TA-RNTI associated with the source cell.

[0127] In at least some embodiments, the source network node 210 may also be configured to: send a configuration to the user equipment 200 via the radio access network 110, the configuration indicating at least one candidate cell to which the user equipment 200 may connect; and send TA parameters to the user equipment 200 via the radio access network 110, the TA parameters including a TA-RNTI associated with the configured candidate cell, and the TA-RNTI associated with the source cell and the TA-RNTI associated with the configured candidate cell may be the same or different.

[0128] In at least some embodiments, the source network node 210 may also be configured to send an RRCReconfiguration message, including a TA-RNTI associated with the configured candidate cell and / or source cell, to the user equipment 200 via the radio access network 110.

[0129] In at least some embodiments, the source network node 210 may also be configured to send a message to the user equipment 200 including a TA acquisition trigger to trigger a relevant TA procedure for the source cell with an associated TA-RNTI.

[0130] In at least some embodiments, the source network node 210 may also be configured to: receive a random access request message from the user equipment 200 via the source cell, send a random access response message to the user equipment 200 via the source cell, and subsequently receive a message including a TA-RNTI associated with the source cell from the user equipment 200 via the source cell.

[0131] In at least some embodiments, the source network node 210 may also be configured to: receive a random access request message from the user equipment 200 via the triggered candidate cell, send a random access response message to the user equipment 200 via the candidate cell, and subsequently receive a message from the user equipment 200 via the triggered candidate cell including a TA-RNTI associated with the triggered cell.

[0132] In at least some embodiments, the source network node 210 may also be configured to: after sending a random access response message to the user equipment 200 via the triggered candidate cell, subsequently receive a message from the user equipment 200 via the source cell including a TA-RNTI associated with the triggered cell.

[0133] When executed by at least one processor 212, instructions stored in at least one memory 214 may also cause the source network node 210 to at least perform: receiving an instruction from user equipment 200 to initiate an RA procedure.

[0134] In at least some embodiments, when executed by at least one processor 202, the instruction may also cause the source network node 210 to send a RAR UL authorization to the user equipment 200 in response to receiving an instruction to initiate an RA procedure.

[0135] When executed by at least one processor 212, this instruction may also cause the source network node 210 to at least perform the following: receive a TA-RNTI MCE from the user equipment 200. As discussed in more detail above, the TA-RNTI MCE includes the TA-RNTI previously assigned to the user equipment 200 by the source network node 210.

[0136] In at least some embodiments, the TA-RNTI MCE can be received in a transmission scheduled by the transmitted RAR UL license.

[0137] In at least some embodiments, the allocation of TA-RNTI from the service source network node 210 to the user equipment 200 can be performed as part of the MAC configuration, and the initiated RA procedure can include the MAC-initiated RA procedure.

[0138] When executed by at least one processor 212, the instruction may also cause the source network node 210 to at least perform the following: identify the purpose of the initiated RA process based on the received TA-RNTI MCE.

[0139] When executed by at least one processor 212, the instruction may also cause the source network node 210 to at least perform the following: in response to the TA timer expiring being the identified purpose of the initiated RA procedure, determine that reconfiguring UL resources for user equipment 200 is optional after the successful completion of the initiated RA procedure.

[0140] Other characteristics of the source network node 210 are derived directly from the functions and parameters of the user equipment 200, and therefore will not be repeated here.

[0141] Figure 3An example signaling diagram 300 is illustrated in an example embodiment of the method of using the disclosed TA-RNTIMCE in a contention-based RA (CBRA) to reacquire uplink synchronization with the Master Time Alignment Group (PTAG).

[0142] At operation 301, user equipment 200 may be configured with TA-RNTI by the serving cell. It can be configured as part of the basic MAC configuration (e.g., similar to TPC-x-RNTI).

[0143] The source network node 210 can use the TA-RNTI MCE to identify the purpose of the RA from the context. If the source network node 210 is associated with the serving cell for user equipment 200, it indicates that the source network node 210 is handling the resynchronization with the PTAG.

[0144] At operation 302, the timer used for PTAG time alignment expires.

[0145] At operation 303, user equipment 200 stopped using UL resources (PUCCH, SRS, SPS, PUSCH), but they were not released.

[0146] At operation 304, the RRC of user equipment 200 is notified of operation 303 (UL resources are suspended but not released).

[0147] At operation 305, user equipment 200 immediately initiates a MAC-initiated RA procedure by sending Msg1 (Physical RA Channel (PRACH) transmission). It should be noted that the disclosed CBRA variant can also be followed if the source network node 210 initiates the procedure itself.

[0148] At operation 306, the serving cell sends a RAR to user equipment 200, and user equipment 200 applies a TAC.

[0149] At operation 307, user equipment 200 transmits Msg3 using RAR grant and scrambles it using Temporary Cell RNTI (TempC-RNTI). TA-RNTI MCE is then transmitted.

[0150] At operation 308, when the serving cell decodes the TA-RNTI MCE, it can identify the purpose of user equipment 200 and the RA procedure. Therefore, the source network node 210 knows that the RA procedure is being performed because the time alignment timer has expired, and that user equipment 200 has not yet released UL resources.

[0151] At operations 309 and 310, source network node 210 and user equipment 200 continue to perform CBRA completion (e.g., contention resolution can be performed in the same manner as conventional CBRA).

[0152] At operation 311, once the RA process is successfully completed, user equipment 200 can restart and use all UL resources. There is no need to reconfigure them.

[0153] At operations 312-313, the source network node 210 can still decide, for example, to reconfigure the user equipment 200 in a suitable conventional manner. However, such reconfiguration is optional.

[0154] The following describes an exemplary implementation of TA-RNTI:

[0155] Regarding TA-RNTI configuration: TA-RNTI (and its associated TA-RNTI values) can be configured using a Radio Resource Control Information Element (RRC IE). CellGroupConfig and / or MAC-CellGroupConfig, similar to those in the RRC IE, can be used to set the TA-RNTI value via the masterCellGroup in RRCSetup / RRCResume / RRCReconfiguration. This can be achieved by appropriately modifying future versions of 3GPP TS38.331 v17.6.0 (2023-09), particularly Section 6.3.2, or several other specifications.

[0156] Regarding the modified RA procedure using TA-RNTI (e.g., sending a TA-RNTI MACCE after receiving a RAR), appropriate modifications can be added to future versions of, for example, 3GPP TS38.321 v17.6.0 (2023-09), particularly sections 5.1.1 and / or 5.1.1a, or (multiple) other specifications. Similarly, at least one of the following sections of TS38.321 can be modified to cover the corresponding TA-RNTI procedure modification, such as 5.1.4 (new options for sending TA-RNTI MAC CE), 5.1.5 (new options for covering TA-RNTI MAC CE), 5.2 (adding new options to suspend UL resources instead of releasing them in the case of PTAG time alignment timers expiring), 6.1.3 (including new MAC CE definitions for new TA-RNTI), 6.2.1 (new LCID / eLCID for new UL MAC CE: TA-RNTI MCE), and 7.1 (new RNTI values ​​for new TA-RNTI).

[0157] Figure 4An example flowchart of a method 400 of a user equipment 200 according to an example embodiment is shown.

[0158] At operation 401, user equipment 200 establishes a connection to source network node 210 via a source cell supported by source network node 210 of radio access network 110.

[0159] At operation 402, user equipment 200 receives TA parameters from radio access network 110, including TA-RNTI associated with the source cell.

[0160] At operation 403, when the relevant TA procedure is triggered, user equipment 200 uses TA parameters.

[0161] about Figure 4 The embodiments and examples can be provided by Figure 2A The user equipment 200 performs the operation. For example, operations 401 to 403 can be performed by at least one processor 202 and at least one memory 204. Other features of method 400 that arise directly from the functions and parameters of user equipment 200 will not be repeated here. Method 400 can be performed by a computer program or a portion thereof.

[0162] Suitable for performing about Figure 4 Another example of the apparatus of the embodiments and examples includes components for the following:

[0163] At operation 401, a connection to source network node 210 is established via a source cell supported by source network node 210 of radio access network 110.

[0164] At operation 402, TA parameters, including the TA-RNTI associated with the source cell, are received from the radio access network 110; and

[0165] At operation 403, the TA parameter is used when the relevant TA procedure is triggered.

[0166] Figure 5 An example flowchart of a method 500 for a source network node 210 according to an example embodiment is shown.

[0167] At operation 501, source network node 210 establishes a connection to user equipment 200 via a source cell of radio access network 110 supported by source network node 210.

[0168] At operation 502, the source network node 210 sends TA parameters, including the TA-RNTI associated with the source cell, to the user equipment 200 via the radio access network 110.

[0169] about Figure 5 The embodiments and examples can be provided by Figure 2BThe source network node 210 executes the method. For example, operations 501 to 502 can be executed by at least one processor 212 and at least one memory 214. Other features of method 500 that are directly generated by the functions and parameters of the source network node 210 will not be repeated here. Method 500 can be executed by a computer program or a part thereof.

[0170] Applicable to the execution of about Figure 5 Another example of the apparatus of the embodiments and examples includes components for the following:

[0171] At operation 501, a connection to user equipment 200 is established via the source cell of radio access network 110 supported by source network node 210; and

[0172] At operation 502, TA parameters including the TA-RNTI associated with the source cell are sent to user equipment 200 via radio access network 110.

[0173] User equipment 200 may include components for performing at least one method described herein. In one example, the components may include at least one processor 202 and at least one memory 204 storing instructions that, when executed by at least one processor 202, cause user equipment 200 to perform the method.

[0174] The source network node 210 may include components for performing at least one method described herein. In one example, the components may include at least one processor 212 and at least one memory 214 storing instructions that, when executed by the at least one processor 212, cause the source network node 210 to perform the method.

[0175] The functions described herein may be performed at least in part by one or more computer program product components, such as software components. According to one embodiment, user equipment 200 and / or source network node 210 may include a processor or processor circuitry, such as, for example, a microcontroller, configured by program code that, when executed, performs embodiments of the described operations and functions. Alternatively or additionally, the functions described herein may be performed at least in part by one or more hardware logic components. Exemplary types of hardware logic components that may be used, such as but not limited to, include field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), tensor processing units (TPUs), and graphics processing units (GPUs).

[0176] Any ranges or device values ​​given herein can be extended or modified without losing the desired effect. Furthermore, unless expressly prohibited, any embodiment can be combined with another embodiment.

[0177] Although the subject matter has been described in language specific to structural features and / or actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as examples of implementing the claims, and other equivalent features and actions are intended to fall within the scope of the claims.

[0178] It should be understood that the above benefits and advantages may relate to one embodiment or several embodiments. The embodiments are not limited to embodiments that solve any or all of the described problems, nor are they limited to embodiments that have any or all of the described benefits and advantages. Further understanding is that references to the 'an' item may refer to one or more of these items.

[0179] The steps of the methods described herein can be performed in any suitable order, or simultaneously where appropriate. Furthermore, individual blocks can be removed from any method without departing from the spirit and scope of the subject matter described herein. Aspects of any of the above embodiments can be combined with aspects of any other described embodiments to form further embodiments without losing the desired effects.

[0180] The term “comprising” is used herein to mean including the identified method, block or element, but not including the exclusion list, and the method or apparatus may include additional blocks or elements.

[0181] It should be understood that the above description is given by way of example only, and various modifications can be made by those skilled in the art. The foregoing specification, examples, and data provide a complete description of the structure and use of the exemplary embodiments. Although various embodiments have been described above in a certain degree of detail or by reference to one or more individual entities, those skilled in the art can make many modifications to the disclosed embodiments without departing from the spirit or scope of this specification.

Claims

1. A user equipment (200), comprising: At least one processor (202); as well as At least one memory (204) stores instructions that, when executed by the at least one processor (202), cause the user equipment (200) to at least: A connection to the source network node (210) is established via a source cell supported by the source network node (210) of the wireless access network (110); Receive timing advance TA parameters from the radio access network (110), the TA parameters including a TA-radio network temporary identifier RNTI associated with the source cell; as well as The TA parameters are used when the relevant TA process is triggered.

2. The user equipment (200) according to claim 1, wherein the user equipment (200) is further configured to: receive a media access control (MAC) configuration including the TA-RNTI from the radio access network (110).

3. The user equipment (200) according to claim 1, wherein the user equipment (200) is further configured to: monitor the time alignment timer TAT, and trigger the relevant TA process if the TAT expires.

4. The user equipment (200) according to claim 1, wherein the related TA process is a random access process.

5. The user equipment (200) according to claim 4, wherein the user equipment (200) is further configured to: in the event of a triggered associated TA procedure, send a random access request message to the source cell, receive a random access response message from the source cell, and subsequently send a message to the source cell including the TA-RNTI associated with the source cell, wherein sending the random access request message includes using contention-based random access CBRA.

6. The user equipment (200) of claim 1, wherein the TA-RNTI indicates the cause of the related TA process, and the indication of the cause includes indicating at least one of the following: the related time alignment timer (TAT) expires, asynchrony is detected, the uplink resources allocated for data transmission are currently unused, the uplink resources allocated for data transmission have not been released, data transmission on the allocated uplink resources will continue once the TA is reacquired, and data is waiting to be sent in the buffer.

7. The user equipment (200) according to claim 1, wherein the user equipment (200) is further configured to: Receive configuration from the radio access network (110), the configuration indicating at least one candidate cell to which the user equipment (200) can connect; and Receive timing advance TA parameters from the radio access network (110), the TA parameters including TA-Radio Network Temporary Identifier RNTI associated with a configured candidate cell, and the TA-RNTI associated with the source cell and the TA-RNTI associated with the configured candidate cell may be the same or different.

8. The user equipment (200) according to claim 1, wherein the source network node (210) supports at least one of the distributed unit (DU) function or the layer 2 protocol of the radio access network (110), and / or the central unit (CU) function or the layer 3 protocol of the radio access network (110).

9. The user equipment (200) of claim 7, wherein the configuration is associated with triggering mobility LTM in layer 1 / layer 2.

10. The user equipment (200) of claim 9, wherein the user equipment (200) is further configured to: receive an RRCReconfiguration message from the radio access network (110), the RRCReconfiguration message including the TA-RNTI associated with the configured candidate cell and / or the source cell, and reconfigure the LTM to the user equipment (200).

11. The user equipment (200) according to claim 1, wherein the user equipment (200) is further configured to: receive from the source network node (210) a message including a TA acquisition trigger to trigger the associated TA process for the source cell having an associated TA-RNTI.

12. The user equipment (200) of claim 1, wherein the user equipment (200) is further configured to: send a random access request message to the source cell, receive a random access response message from the source cell, and subsequently send a message to the source cell including the TA-RNTI associated with the source cell.

13. The user equipment (200) of claim 7, wherein the user equipment (200) is further configured to: send a random access request message to the triggered candidate cell, receive a random access response message from the candidate cell, and subsequently send a message to the triggered candidate cell including the TA-RNTI associated with the triggered cell.

14. The user equipment (200) of claim 13, wherein the user equipment (200) is further configured to: after receiving the random access response message from the triggered candidate cell, subsequently send a message to the source cell including the TA-RNTI associated with the triggered cell.

15. The user equipment (200) of claim 13, wherein the user equipment (200) is further configured to: after receiving the random access response message from the triggered candidate cell, subsequently avoid at least one of the following: initiating a related contention resolution process, starting a related contention resolution timer, or treating the TA acquisition as invalid when the related contention resolution timer expires.

16. The user equipment (200) according to claim 1, wherein the related TA process involves at least one of the following: TA acquisition process, early TA acquisition process, TA acquisition using a random access process, or TA reacquisition process.

17. The user equipment (200) of claim 7, wherein the at least one candidate cell to which the user equipment (200) connects includes at least one of the following: a target cell for which the user equipment (200) switches, or a target cell for which the user equipment (200) adds as a second radio link connection.

18. The user equipment (200) according to claim 1, wherein the TA parameter is a user equipment (200) specific parameter assigned by the source cell.

19. The user equipment (200) of claim 18, wherein an associated timer is assigned together with the TA parameter, the associated timer indicating a time period during which the TA parameter will be considered valid by the user equipment (200).

20. The user equipment (200) of claim 7, wherein the TA parameter associated with the configured candidate cell is a user equipment (200) specific parameter assigned by the associated configured candidate cell or the source cell.

21. The user equipment (200) of claim 20, wherein an associated timer is allocated together with the TA parameter, the associated timer indicating that the TA parameter associated with the configured candidate cell will be considered a valid time period by the user equipment (200).

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