Time alignment for inter-cell mobility

Abstract

According to some embodiments, a wireless device performs a method for timing advance (TA) management between the wireless device and at least one target candidate cell for inter-cell mobility of layer 1 (L1) / layer 2 (L2). The wireless device operates in a serving cell different from the target candidate cell. The method comprises: receiving an uplink configuration for a target candidate cell; transmitting an uplink message to the target candidate cell based on the uplink configuration; and receiving a TA value associated with the target candidate cell. The TA value is received in a message from a serving cell.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to wireless communications, and more particularly to time alignment for inter-cell mobility. Background Art

[0002] Fifth Generation (5G) New Radio (NR) is a radio access technology developed by the Third Generation Partnership Project (3GPP) for 5G mobile networks. 5G NR wireless networks use Timing Advance (TA) for uplink synchronization. Different user equipment (UE) in the same cell can typically be located at different locations within the cell and at different distances from the base station (e.g., NR gNodeB). Therefore, transmissions from different UEs experience different delays before reaching the base station. In order to ensure that uplink (UL) transmissions from the UE arrive at the base station within the corresponding receive window of the base station, an uplink timing control procedure is required. This avoids intra-cell interference between UEs assigned to transmit in consecutive subframes and between UEs transmitting on adjacent subcarriers.

[0003] Time alignment of uplink transmissions is achieved by applying a timing advance at the UE transmitter relative to the received downlink timing. Its main effect is to offset different propagation delays between different UEs. Figure 1 An example is shown in .

[0004] Figure 1 is a timing diagram showing time alignment of uplink transmissions. The example shown is for an LTE eNodeB. Case (a) shows uplink transmissions without timing advance, while case (b) shows uplink transmissions with timing advance.

[0005] To achieve time alignment, in order to obtain uplink synchronization, the base station (e.g., gNodeB, eNodeB) derives the timing advance (TA) value that the UE needs for uplink transmission to reach the base station within the receive window, and indicates the TA value to the UE. When the UE first accesses a cell, the UE uses a random access procedure, in which the base station uses the received Msg1 (physical random access channel (PRACH) preamble) to determine the UE's initial TA for uplink transmission in the cell. During the connection, the base station will continuously monitor whether the UE needs to advance / delay uplink transmission to compensate for changes in propagation delay, and indicate to the UE when a change in the timing advance value is required.

[0006] When a UE has connections to several different serving cells, the same TA value may sometimes be used for more than one of these cells, for example if they are located at the same location and therefore always at the same distance from the UE. Such cells may then be configured to belong to the same timing advance group (TAG). The configuration of the TAG is done per cell group, i.e., serving cells may be configured to belong to the same TAG only if they belong to the same cell group (primary cell group (MCG) or secondary cell group (SCG)). Further details are provided below.

[0007] When a UE does not perform uplink transmissions in a serving cell for a period of time, the TA value previously used by the UE may no longer be accurate, for example, because the UE has moved and therefore has different propagation delays. In this case, if the UE uses the latest received TA value to perform uplink transmissions, it may arrive at the base station outside the receiving window and thus cannot be correctly received by the base station. The transmission may then even interfere with other uplink transmissions (from other UEs). Therefore, a timer timeAligmentTimer is configured for each TAG to indicate how long the UE can consider itself to be in uplink time alignment with the serving cell belonging to the associated TAG without receiving any updates to the TA value. Therefore, timeAligmentTimer indicates the duration for which the UE can consider the received TA value to be valid. If the UE does not receive an updated value before the expiration of timeAligmentTimer, the UE is no longer in uplink synchronization with the serving cell belonging to the corresponding TAG.

[0008] In TS 38.300, the summary for NR is as follows: **************************************************************** 9.2.9 Timing Advance In RRC_CONNECTED, the gNB is responsible for maintaining the timing advance to keep L1 synchronization. Serving cells with the same timing advance applied to the UL and using the same timing reference cell are grouped in a TAG. Each TAG contains at least one serving cell with a configured uplink, and the mapping of each serving cell to a TAG is configured by RRC. For the primary TAG, the UE uses the PCell as the timing reference. In a secondary TAG, the UE may use any activated SCell of that TAG as the timing reference cell, but should not change it unless necessary. The timing advance update is signaled by the gNB to the UE via a MAC CE command. Such a command restarts a TAG specific timer which indicates whether L1 can be synchronized: when the timer is running, L1 is considered to be synchronized, otherwise, L1 is considered to be out of synchronization (in this case, uplink transmission can only occur on PRACH). ****************************************************************

[0009] In traditional layer three (L3) mobility, also known as reconfiguration with synchronization to the master cell group (MCG), when the UE changes its PCell, the UE always performs random access with the target PCell. As part of the random access, the UE sends a preamble in the PRACH in the uplink, which enables the target gNodeB to calculate the TA value for the UE, which is provided in the random access response (RAR), so that starting from msg3, the UE can send uplink messages on the physical uplink control channel (PUCCH) and / or the physical uplink shared channel (PUSCH).

[0010] Below is the text from TS 38.321 regarding the initial timing advance configuration during the random access procedure: **************************************************************** 5.1.4 Random Access Response Reception Once the random access preamble is sent, whether or not measurement gaps may occur, the MAC entity shall: […] 1> Otherwise, if a valid (as specified in TS 38.213) downlink allocation has been received on the PDCCH for the RA-RNTI, and the received TB was decoded successfully: […] 2> If the random access response reception is deemed successful: 3> If the Random Access Response includes a MAC subPDU with only RAPID: […] 3> Otherwise: 4> Apply the following actions to the serving cell that sends the random access preamble: 5> Process the received timing advance command (see clause 5.2); […] […] 5.2 Maintaining uplink time alignment RRC configures the following parameters to maintain UL time alignment: - (per TAG) timeAlignmentTimer, which controls the time the MAC entity considers the serving cells belonging to the associated TAG as uplink time aligned. The MAC entity shall: […] 1> When a timing advance command is received in a random access response message of a serving cell belonging to a TAG or in a MSGB for a SpCell: […] 2> Otherwise, if the timeAligmentTimer associated with the TAG is not running: 3> Apply the timing advance command to the TAG; 3>Start the timeAligmentTimer associated with the TAG; […] […] When the timeAligmentTimer associated with the TAG to which the serving cell belongs is not running, the MAC entity shall not perform any uplink transmission on the serving cell except for the random access preamble and MSGA transmission. In addition, when the timeAligmentTimer associated with the PTAG is not running, the MAC entity shall not perform any uplink transmission on any serving cell except for the random access preamble and MSGA transmission on the SpCell. […] 6.2.3 MAC Payload for Random Access Response MAC RAR has the following features: Figure 6 .2.3-1, and consists of the following fields: -R: reserved bit, set to "0"; - Timing Advance Command: The Timing Advance Command field indicates the index value T used to control the timing adjustment amount that the MAC entity must apply in TS 38.213. A The size of the timing advance command field is 12 bits; […] MAC RAR uses octet alignment. < Figure 6 .23-1: MAC RAR is copied as Figure 2 . […] 6.1.3.4 Timing Advance Command MAC CE The Timing Advance Command MAC CE is identified by a MAC subheader with LCID as specified in Table 6.2.1-1. It has a fixed size and consists of a single octet as defined below: Figure 6 .1.3.4-1): -TAG ID: This field indicates the TAG ID of the addressed TAG. The TAG containing the SpCell has a TAG ID of 0. The length of this field is 2 bits; - Timing Advance Command: This field indicates the index value T used to control the timing adjustment amount (as specified in TS 38.213 [6]) that the MAC entity must apply. A (0, 1, 2...63) The length of this field is 6 bits. < Figure 6 .1.3.4-1: Timing Advance Command MAC CE is copied as Figure 3 > [38.213] 4.2 Transmission Timing Adjustment […] Upon receiving the timing advance command for a TAG, the UE sets the timing advance command based on the UE's expectation that all serving cells in the TAG will have the same N TA,offset The uplink timing for PUSCH / SRS / PUCCH transmission on all serving cells in the TAG is adjusted based on the received timing advance command, wherein the uplink timing for PUSCH / SRS / PUCCH transmission is the same for all serving cells in the TAG. ****************************************************************

[0011] After the UE is configured with its serving cell for a given cell group (e.g., primary cell group-MCG and / or secondary cell group-SCG), the UE obtains an initial TA value via a random access response (RAR) and is configured with an association between the serving cell and the TAG identifier, the UE needs to maintain time alignment according to the TA procedure defined in Section 5.2 of TS 38.321. When the UE is connected to the serving cell, the TA is adjusted by an explicit medium access control (MAC) control element (CE) from the network (e.g., if the network detects a possible misalignment) and / or by the UE (e.g., when the time alignment timer timeAligmentTimer for a given TAG expires).

[0012] Upon receiving the timing advance command (which is a MAC CE), the UE applies the command (including the new value(s)) and starts / restarts the TA timer. After the initial TA, further details of the maintenance procedure are as follows: **************************************************************** Timing Advance Group: A group of serving cells configured by RRC and, for cells configured with UL, use the same timing reference cell and the same timing advance value. The timing advance group of the SpCell containing the MAC entity is called the primary timing advance group (PTAG), while the term secondary timing advance group (STAG) refers to other TAGs. […] 5.2 Maintaining uplink time alignment […] The MAC entity shall: 1> When a timing advance command MAC CE is received, and if N is already maintained with the indicated TAG TA (as defined in TS38.211): 2> Apply timing advance command to the indicated TAG; 2> Start or restart the timeAligmentTimer associated with the indicated TAG. […] 1>When timeAligmentTimer expires: 2> If timeAligmentTimer is associated with PTAG: 3> flush all HARQ buffers for all serving cells; 3> Notify RRC to release PUCCH for all serving cells (if configured); 3> Notify RRC to release SRS for all serving cells (if configured); 3> Clear any configured downlink allocations and configured uplink grants; 3> Clear any PUSCH resources used for semi-persistent CSI reporting; 3> Consider all running timeAligmentTimers as expired; 3>Maintain N of all tags TA (Defined in TS 38.211[8]). 2> Otherwise, if timeAligmentTimer is associated with a STAG, then for all serving cells belonging to that TAG: 3>Flush all HARQ buffers; 3>Notify RRC to release PUCCH (if configured); 3>Notify RRC to release SRS (if configured); 3> Clear any configured downlink allocations and configured uplink grants; 3> Clear any PUSCH resources used for semi-persistent CSI reporting; 3> Maintain the N of this TAG TA (Defined in TS 38.211). When the MAC entity stops uplink transmission for the SCell due to exceeding the maximum uplink transmission timing difference between the TAGs of the MAC entity or the maximum uplink transmission timing difference between the TAGs of any MAC entity of the UE, the MAC entity shall consider the timeAligmentTimer associated with the SCell to have expired. When the timeAligmentTimer associated with the TAG to which the serving cell belongs is not running, the MAC entity shall not perform any uplink transmission on the serving cell except for the random access preamble and MSGA transmission. In addition, when the timeAligmentTimer associated with the PTAG is not running, the MAC entity shall not perform any uplink transmission on any serving cell except for the random access preamble and MSGA transmission on the SpCell. ****************************************************************

[0013] 3GPP Release 18 includes work items (WIs) on other NR mobility enhancements, specifically in the technical area titled Layer 1 (L1) / Layer 2 (L2) based inter-cell mobility. The WI description (WID) in RP-213565 includes further details.

[0014] According to the WID, when the UE moves from the coverage area of ​​​​one cell to another cell, a serving cell change needs to be made at some point in time. Currently, the serving cell change is triggered by L3 measurements and is completed through a reconfiguration triggered by RRC signaling, which has synchronization for changes in PCell and PSCell, and the addition of release for SCell when applicable. All cases involve a complete L2 (and L1) reset, resulting in longer latency, greater overhead and longer interruption time than beam switching mobility. The goal of L1 / L2 mobility enhancement is to achieve serving cell changes via L1 / L2 signaling to reduce latency, overhead and interruption time.

[0015] L1-L2 inter-cell mobility should be as similar as possible to inter-cell beam management, i.e., to support L1-L2 inter-cell mobility, the UE should be configured to perform measurements on cells other than the serving cell, as defined in Rel-17.

[0016] In Rel-17, to support inter-PCI mTRP operation, a solution has been standardized where CSI resources can be associated with a PCT that has a different physical cell identifier (PCI) than one of the serving cells. This solution also requires the UE to receive an explicit indication of which beams (SSBs) and PCIs to measure for a given reporting configuration.

[0017] The goal is to specify mechanisms and procedures for L1 / L2-based inter-cell mobility for mobility latency reduction. These include: configuration and maintenance of multiple candidate cells to allow rapid application of configurations for candidate cells; dynamic switching mechanisms between candidate serving cells (including SpCells and SCells) for potential applicable scenarios based on L1 / L2 signaling; L1 enhancements for inter-cell beam management, including L1 measurements and reporting and beam indication; timing advance management; and CU-DU interface signaling for supporting L1 / L2 mobility.

[0018] The L1 / L2-based inter-cell mobility process is applicable to the following scenarios: standalone, CA and NR-DC cases, where the serving cell changes within one CG; intra-DU case and intra-CU inter-DU case (applicable to standalone and CA); both intra-frequency and inter-frequency; both FR1 and FR2; and the source cell and the target cell can be synchronized or asynchronous.

[0019] There are some challenges. For example, one of the issues that need to be solved for L1 / L2 inter-cell mobility is timing advance management. In traditional L3 handover, the timing advance is established between the UE and the target cell through the random access process, where the UE sends a preamble and receives the TA value in the RAR.

[0020] If random access is always performed on the target candidate cell in L1 / L2 inter-cell mobility, the same solution as in conventional L3 handover can be adopted. However, in L1 / L2 inter-cell mobility execution, it is desirable to reduce the interruption time as much as possible, which means that a solution in which the UE does not perform random access with the target cell during L1 / L2 inter-cell mobility execution is likely to be specified. This means that either such a target candidate cell requires uplink synchronization or the existing solution is not applicable.

[0021] One solution is based on the UE performing a random access procedure with the target candidate cell to obtain the TA value for each at least one target candidate cell for L1 / L2 inter-cell mobility, and possibly managing a TA timer to monitor whether the TA value is valid (when the timer runs). One benefit of this solution is that it still relies on a random access procedure with a given cell (the target candidate cell for L1 / L2 inter-cell mobility), which means that the difference mainly lies in the triggering of the procedure, which occurs before the execution, so the UE is ready to perform mobility later without random access because it is uplink synchronized. Figure 4 An example is shown in FIG.

[0022] Figure 4 is a signaling diagram showing an example of performing a random access procedure with a target candidate cell to obtain a TA value for L1 / L2 inter-cell mobility. Despite its benefits, in order to perform random access in the target candidate cell, the UE needs to send a preamble and wait for the RAR, as shown in the figure, and in most scenarios, significantly increases the interruption with the PCell, thereby reducing the data rate with the PCell, in order to prepare one or more cells for L1 / L2 inter-cell mobility. Summary of the invention

[0023] As described above, there are currently certain challenges in time alignment for inter-cell mobility. Certain aspects of the present disclosure and embodiments thereof may provide solutions to these or other challenges. For example, certain embodiments include establishing a timing advance (TA) for a user equipment (UE). The following are some example embodiments.

[0024] Embodiment A1: A method at a UE for TA management between the UE and at least one target candidate cell for layer one (L1) / layer two (L2) inter-cell mobility. The method includes: receiving an uplink configuration for the target candidate cell; sending an uplink message to the target candidate cell based on the uplink configuration; and receiving a TA value associated with the target candidate cell, wherein the TA value is received in a message from a serving cell.

[0025] Embodiment A2. The TA value associated with the target candidate cell received via the serving cell is received in a L1 / L2 inter-cell mobility command indicating that the UE should perform L1 / L2 inter-cell mobility to the target candidate cell.

[0026] Embodiment A3. The TA value associated with the target candidate cell received via the serving cell is received in a radio resource control (RRC) reconfiguration received after the UE has been configured with L1 / L2 inter-cell mobility and after the UE has sent an uplink message to the target candidate cell.

[0027] Embodiment A3b. The TA value associated with the target candidate cell received via the serving cell is received within low layer signaling (eg, medium access control (MAC) control element (CE), downlink control information (DCI)).

[0028] Embodiment A3c. The TA value associated with the target candidate cell received via the serving cell is received within an RRC message (eg, an RRCReconfiguration message).

[0029] Embodiment A4. An uplink configuration for a target candidate cell is received from a first network node, wherein the first network node corresponds to a serving distributed unit (DU).

[0030] Embodiment A5. An uplink configuration for a target candidate cell is generated by a candidate DU associated with the target candidate cell configured for L1 / L2 inter-cell mobility.

[0031] Embodiment A6. A TA value associated with a target candidate cell is received from a first network node, wherein the first network node corresponds to a serving DU.

[0032] Embodiment A7. The uplink configuration for the target candidate cell is a random access channel configuration for the target candidate cell.

[0033] Embodiment A8. The uplink message to the target candidate cell based on the uplink configuration is a random access preamble associated with one or more synchronization signal blocks (SSBs) and / or channel state information reference signal (CSI-RS) resources.

[0034] Embodiment A8a. The uplink message to the target candidate cell based on the uplink configuration is a sounding reference signal (SRS).

[0035] Embodiment A9. (Reestablishment / TA update) The method may further include: receiving an update of the uplink configuration for the target candidate cell, and sending an uplink message to the target candidate cell based on the updated uplink configuration, and receiving a TA value associated with the target candidate cell, wherein the TA value is received in a message from the serving cell.

[0036] Embodiment A10. The uplink configuration includes a triggering condition for sending an uplink message to a target candidate cell.

[0037] Embodiment A11. The trigger condition is a measurement event, such as event A2, A3, A4 or A5.

[0038] Embodiment A12. The triggering condition comprises a timer that is started upon transmission of the uplink message, and wherein expiration of the timer triggers retransmission of the uplink message.

[0039] Some embodiments include establishment of a TA with respect to candidate DUs.

[0040] Embodiment B1. A method for TA management between a UE and at least one target candidate cell for L1 / L2 inter-cell mobility of the candidate DU at a candidate DU. The method comprises: receiving a request for TA establishment for the UE and at least one target candidate cell from a central unit (CU); sending an uplink configuration for the target candidate cell and the UE to the CU; receiving an uplink message from the UE based on the uplink configuration; and calculating a TA value associated with the target candidate cell and sending the TA value to the CU.

[0041] Embodiment B2. When requested to provide L1 / L2 inter-cell candidate cell configuration, the candidate DU sends the uplink configuration for the target candidate cell and UE to the CU. Therefore, there is no explicit request for providing TA establishment, but the candidate DU directly sends the request when requested by the CU to set up the candidate cell for L1 / L2 inter-cell mobility.

[0042] Some embodiments include establishment of a TA with respect to a CU.

[0043] Embodiment C1. A method for TA management between a UE and at least one target candidate cell for L1 / L2 inter-cell mobility at a CU. The method comprises: sending a request for TA establishment for the UE and at least one target candidate cell to a candidate DU; receiving an uplink configuration for the target candidate cell and the UE from the candidate DU; sending an uplink message to a serving DU, the uplink message to be sent to the UE, wherein the uplink message includes the uplink configuration; receiving a TA value associated with the target candidate cell from the candidate DU; and sending a TA value (to be provided to the UE) to the serving DU.

[0044] Some embodiments include re-establishment of TA with respect to CU, candidate DUs and serving DU.

[0045] Embodiment D1. A method at a UE for reestablishing / maintaining an existing TA value between the UE and at least one target candidate cell for L1 / L2 inter-cell mobility. The method includes starting a timer when a TA value associated with the target candidate cell is received. After the timer associated with the validity of the TA value expires, the method includes sending an uplink message to a serving DU to request a new TA value associated with the target candidate cell. Alternatively, an uplink message is sent to the target candidate cell based on a previously received uplink configuration. The method also includes: receiving a TA value associated with the target candidate cell, wherein the TA value is received in a message from a serving cell.

[0046] Embodiment D2. The timer started when a TA value is received may be common to all TA values ​​currently being maintained by the UE, or a single timer for each TA value being maintained by the UE. In addition, the timer may be a value for a group of TA values ​​belonging to the same candidate DU, for example.

[0047] Embodiment E1. A method at a serving DU for reestablishing / maintaining an existing TA value between a UE and at least one target candidate cell for L1 / L2 inter-cell mobility. The method includes starting a timer when sending a TA value to a UE associated with a target candidate cell. When a timer associated with the validity of the TA value expires, the method also includes sending a message to the serving DU (via the CU) requesting a new TA value associated with the target candidate cell. Alternatively, sending a message to the CU requesting a new TA value associated with the target candidate cell. The method also includes: receiving a TA value associated with the target candidate cell, wherein the TA value is received in a message from the CU; and sending a new TA value associated with the target candidate cell to the UE.

[0048] Embodiment E2. The timer started when a TA value is received may be common to all TA values ​​currently being maintained by the UE, or a single timer for each TA value being maintained by the UE. In addition, the timer may be a value for a group of TA values ​​belonging to the same candidate DU, for example.

[0049] Embodiment F1. A method at a CU for reestablishing / maintaining an existing TA value between a UE and at least one target candidate cell for L1 / L2 inter-cell mobility. The method includes starting a timer when sending a TA value to be sent to the UE and associated with the target candidate cell to a serving DU. When a timer associated with the validity of the TA value expires, a message is sent to the candidate DU to request a new TA value associated with the target candidate cell. The method also includes: receiving a TA value associated with the target candidate cell, wherein the TA value is received in a message from the candidate DU; and sending a new TA value to be sent to the UE to the serving DU.

[0050] Embodiment F2. The timer started when a TA value is received may be common to all TA values ​​currently being maintained by the UE, or a single timer for each TA value being maintained by the UE. In addition, the timer may be a value for a group of TA values ​​belonging to the same candidate DU, for example.

[0051] Embodiment G1. A method at a candidate DU for reestablishing / maintaining an existing TA value between a UE and at least one target candidate cell for L1 / L2 inter-cell mobility. The method includes starting a timer when sending a TA value to be sent to the UE and associated with the target candidate cell to a CU (or to a serving DU via the CU). Upon expiration of a timer associated with the validity of the TA value, the method also includes sending a message to the CU (or to the serving DU via the CU) including a new TA value associated with the target candidate cell to be sent to the UE.

[0052] Embodiment G2. The timer started when a TA value is received may be common to all TA values ​​currently being maintained by the UE, or a single timer for each TA value being maintained by the UE. In addition, the timer may be a value for a group of TA values ​​belonging to the same candidate DU, for example.

[0053] According to some embodiments, a method is performed by a wireless device for TA management between the wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility. The wireless device operates in a serving cell different from the target candidate cell. The method includes: receiving an uplink configuration for the target candidate cell; sending an uplink message to the target candidate cell based on the uplink configuration; and receiving a TA value associated with the target candidate cell. The TA value is received in a message from the serving cell.

[0054] In a particular embodiment, the TA value associated with the target candidate cell received via the serving cell is received in an L1 / L2 inter-cell mobility command indicating that the wireless device should perform L1 / L2 inter-cell mobility to the target candidate cell, or is received in an RRC reconfiguration received after the wireless device has been configured with L1 / L2 inter-cell mobility and after the UE has sent an uplink message to the target candidate cell.

[0055] In a particular embodiment, the uplink configuration for the target candidate cell is received from a first network node, wherein the first network node corresponds to a serving DU. The uplink configuration for the target candidate cell is generated by a candidate DU associated with the target candidate cell configured for L1 / L2 inter-cell mobility.

[0056] In a particular embodiment, the TA value associated with the target candidate cell is received from a first network node, wherein the first network node corresponds to the serving DU.

[0057] In a particular embodiment, the uplink configuration for the target candidate cell includes a RACH configuration for the target candidate cell.

[0058] In a particular embodiment, the uplink message sent to the target candidate cell based on the uplink configuration includes a random access preamble associated with one or more SSBs and CSI-RS resources.

[0059] In certain embodiments, the uplink message sent to the target candidate cell based on the uplink configuration includes an SRS.

[0060] In a particular embodiment, the uplink configuration includes a trigger condition for sending an uplink message to the target candidate cell.The uplink configuration may be associated with a validity time.

[0061] In a particular embodiment, receiving an uplink configuration for a target candidate cell includes receiving an uplink configuration for the target candidate cell in a first message, and sending an uplink message to the target candidate cell includes sending an uplink message to the target candidate cell in response to receiving a second message. The first message may include an RRC message, and the second message includes a PDCCH command. The second message is received by the wireless device after the wireless device has received the first message.

[0062] In certain embodiments, the method further includes: receiving an update of an uplink configuration for the target candidate cell; sending an uplink message to the target candidate cell based on the updated uplink configuration; and receiving a TA value associated with the target candidate cell. The TA value is received in a message from the serving cell.

[0063] In a particular embodiment, the method further comprises: in response to receiving an uplink configuration for the target candidate cell, starting a timer; in response to expiration of the timer, sending an uplink message to the target candidate cell; and receiving a TA value associated with the target candidate cell. The TA value is received in a message from the serving cell.

[0064] In certain embodiments, sending the uplink message to the target candidate cell is based on the received uplink configuration.

[0065] In a particular embodiment, L1 / L2 inter-cell mobility includes receiving signaling indicating a change of a serving cell via a signaling layer, which is a lower layer than the RRC layer in the protocol stack.

[0066] According to some embodiments, a wireless device comprises a processing circuit operable to perform any of the methods of a wireless device described above.

[0067] Also disclosed is a computer program product comprising a non-transitory computer readable medium storing computer readable program code, which, when executed by a processing circuit, is operable to perform any of the methods performed by the wireless receiver described above.

[0068] According to some embodiments, a method is performed by a network node operating as a candidate DU for TA management between a wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility of the candidate DU. The method includes: receiving a message requesting TA establishment for the wireless device and at least one target candidate cell from a serving CU; sending an uplink configuration for the target candidate cell and the wireless device to the serving CU; receiving an uplink message based on the uplink configuration from the wireless device; and sending a TA value associated with the target candidate cell and calculated based on the received uplink message to the wireless device via the serving CU.

[0069] In certain embodiments, the message requesting TA establishment for the wireless device includes a request to provide L1 / L2 inter-cell candidate cell configuration.

[0070] In certain embodiments, the method further includes: in response to sending the TA value to the wireless device, starting a timer; and in response to expiration of the timer, sending a new TA value associated with the target candidate cell to the wireless device via the serving CU.

[0071] According to some embodiments, a method is performed by a network node operating as a serving CU for TA management between a wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility. The method includes: sending a request to a candidate DU requesting TA establishment for the wireless device and at least one target candidate cell; receiving an uplink configuration for the target candidate cell and the wireless device from the candidate DU; and sending an uplink message to the serving DU to be sent to the wireless device. The uplink message includes the uplink configuration. The method also includes receiving a TA value associated with the target candidate cell from the candidate DU, and sending the TA value to the wireless device via the serving DU.

[0072] In certain embodiments, the message requesting TA establishment for the wireless device includes a request to provide L1 / L2 inter-cell candidate cell configuration.

[0073] In certain embodiments, the method further includes: in response to sending the TA value to the wireless device, starting a timer; and in response to expiration of the timer, sending a request to the candidate DU requesting new TA establishment for the wireless device and the at least one target candidate cell.

[0074] According to some embodiments, a network node comprises processing circuitry operable to perform any of the methods of a network node described above.

[0075] Also disclosed is a computer program product comprising a non-transitory computer readable medium storing computer readable program code, which, when executed by a processing circuit, is operable to perform any of the methods performed by the above network node.

[0076] Certain embodiments may provide one or more of the following technical advantages. For example, in a particular embodiment, the uplink configuration is a random access channel (RACH) configuration, and the UE sends a preamble to a target candidate cell based on the RACH configuration, for example, when the cell is configured as an L1 / L2 inter-cell mobility candidate. However, because the transmission or possible reception in the target candidate may cause the UE's communication with the serving DU to be interrupted, the UE does not expect a random access response from the target candidate cell. Instead, according to the method, the candidate DU that receives the preamble calculates a TA and provides it to the serving DU, which provides the TA to the UE, for example, when L1 / L2 inter-cell mobility is performed.

[0077] In summary, the benefit is that L1 / L2 inter-cell mobility can be performed without performing random access during the execution, which reduces the mobility interruption time. In addition, because the TA value is not received in the RAR and / or MAC CE from the target candidate, but from the serving DU (via the serving cell, for example, in the downlink channel of the serving cell), the interruption of the communication between the UE and the serving DU is minimized to the time of sending the uplink message. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] For a more complete understanding of the disclosed embodiments and their features and advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which: Figure 1 is a timing diagram showing time alignment of uplink transmissions; Figure 2 Shown from TS 38.321 Figure 6 .2.3-1 Duplicate Medium Access Control (MAC) Random Access Response (RAR); Figure 3 Shown from TS 38.321 Figure 6 .1.3.4-1 Copied Timing Advance Command MAC Control Element (CE); Figure 4 is a signaling diagram illustrating an example of performing a random access procedure with a target candidate cell to obtain a timing advance (TA) value for L1 / L2 inter-cell mobility; Figure 5is a block diagram showing the architecture of a Central Unit (CU) and a Distributed Unit (DU) in a Radio Access Network (RAN); Figure 6 An example radio resource control (RRC) configuration for a target candidate configuration is shown; Figure 7 is a signaling diagram illustrating TA establishment for a target candidate cell; Figure 8 is a signaling diagram illustrating an example of TA re-establishment / update with target candidate cell(s); Fig. 9 is a signaling diagram illustrating an example of a candidate DU initiated TA update; Fig.10 is a signaling diagram illustrating an example of a serving DU initiated TA update; Fig.11 An example communication system according to certain embodiments is shown; Fig.12 illustrates an example user equipment (UE) according to certain embodiments; Fig.13 illustrates an example network node according to certain embodiments; Fig.14 shows a block diagram of a host according to some embodiments; Fig.15 illustrates a virtualized environment according to some embodiments, in which functions implemented by some embodiments may be virtualized; Fig.16 A host is shown communicating with a UE via a network node over a partial wireless connection in accordance with certain embodiments; Fig.17 A method performed by a wireless device according to some embodiments is shown; Fig.18 A method performed by a serving network node according to some embodiments is shown; and Fig.19 A method performed by a candidate network node according to certain embodiments is shown. DETAILED DESCRIPTION

[0079] As described above, time alignment for layer 1 (L1) / layer 2 (L2) inter-cell mobility currently presents certain challenges. Certain aspects of the present disclosure and embodiments thereof may provide solutions to these or other challenges. For example, certain embodiments include establishing a timing advance (TA) with respect to a user equipment (UE) and at least one target candidate cell.

[0080] Specific embodiments will be described more fully with reference to the accompanying drawings. However, other embodiments are included within the scope of the subject matter disclosed herein, and the disclosed subject matter should not be interpreted as being limited to the embodiments set forth herein; instead, these embodiments are provided as examples to convey the scope of the subject matter to those skilled in the art.

[0081] Figure 5 is a block diagram illustrating the architecture of a central unit (CU) and a distributed unit (DU) in a radio access network (RAN). The example architecture shows both a next generation RAN (NG-RAN) and a 5G core network (5GC), where the NG-RAN is divided into a CU and a DU connected via an F1 interface. The example shown includes a NG-RAN, which may be referred to as a 5G RAN, however, specific embodiments are applicable to any RAN, such as a 6G RAN architecture.

[0082] The RAN (e.g., NG-RAN) includes a set of RAN nodes (e.g., gNBs) connected to a core network (e.g., 5GC) via a RAN / CN interface (e.g., NG interface). For the NG-RAN, it may include one or more ng-eNBs, where the ng-eNB may include an ng-eNB-CU and one or more ng-eNB-DUs. The gNB may include a gNB-CU and one or more gNB-DUs. The gNB-CU and the gNB-DU are connected via an F1 interface. The gNB-DU may be connected to multiple gNB-CUs in an appropriate implementation manner.

[0083] NG, Xn and F1 are logical interfaces. For NG-RAN, the NG and Xn-C interfaces of the gNB for a gNB consisting of a gNB-CU and a gNB-DU are terminated in the gNB-CU. For EN-DC, the S1-U and X2-C interfaces of the gNB for a gNB consisting of a gNB-CU and a gNB-DU are terminated in the gNB-CU. The gNB-CU and the connected gNB-DU are visible as gNBs only to other gNBs and 5GC.

[0084] The term "L1 / L2-based inter-cell mobility" is used as in the 3GPP work item description, but the terms L1 / L2 mobility, L1 mobility, L1-based mobility, L1 / L2-centric inter-cell mobility or L1 / L2 inter-cell mobility may also be used interchangeably in this document. The basic principle is that the UE receives lower layer signaling from the network, which indicates to the UE a change (or switch or activation) of its serving cell (e.g., a PCell change from a source to a target PCell), where the lower layer signaling is a message / signaling of the lower layer protocol, which may be referred to as an L1 / L2 inter-cell mobility execution command. The change of serving cell (e.g., a change of PCell) may also result in a change of (multiple) Scells of the same cell group, for example, if the command triggers the UE to change to another cell group configuration of the same type (e.g., another master cell group (MCG) configuration).

[0085] A lower layer protocol refers to a protocol at a lower layer in the air interface protocol stack than the radio resource control (RRC) protocol, for example, the medium access control (MAC) is considered a lower layer protocol because it is lower than RRC in the air interface protocol stack, and the lower layer signaling / message may correspond to a MAC control element (CE). Another example of a lower layer protocol is layer 1 (or physical layer L1), and the lower layer signaling / message may correspond to downlink control information (DCI). Signaling information in a protocol layer lower than RRC reduces processing time and therefore reduces interruption time during mobility. In addition, it may also increase mobility robustness because the network may respond more quickly to changes in channel conditions.

[0086] Another relevant aspect in L1 / L2 inter-cell mobility is that in a multi-beam scenario, a cell may be associated with multiple synchronization signal blocks (SSBs), and different SSBs may be transmitted in different spatial directions (i.e., using different beams, across the coverage area of ​​the cell) during a half-frame. Similar reasoning may apply to the channel state information reference signal (CSI-RS) resources, which may also be transmitted in different spatial directions. Thus, in L1 / L2 inter-cell mobility, the receipt of lower layer signaling instructs the UE to change from one beam in the serving cell to another beam in a neighboring cell (which is a configured candidate cell), and thus change serving cell.

[0087] The term "target candidate configuration" refers to the configuration of "L1 / L2 inter-cell mobility candidate cells", which are cells that the UE is configured with when L1 / L2 inter-cell mobility is configured. In other words, the target cell is a cell that the UE can move to in the L1 / L2 inter-cell mobility process when receiving lower layer signaling. These cells may also be referred to as candidate cells, candidates, mobility candidates, non-serving cells, additional cells, target candidate cells, target candidates, etc. This is the cell on which the UE performs measurements (e.g., channel state information (CSI) measurements) so that the UE reports these measurements and the network can make an educated decision on which beam (e.g., transmission configuration indicator (TCI) state) and / or cell to switch to for the UE. The L1 / L2 inter-cell mobility candidate cell may be a candidate for being a target PCell or PSCell or SCell of a cell group (e.g., MCG SCell).

[0088] The content and / or structure of the actual target candidate configuration and its IE and / or embedded message can be referred to as the RRC model of the candidate configuration, or simply the RRC model. The target candidate configuration includes the configuration used by the UE to operate accordingly when the UE receives low-layer signaling indicating L1 / L2-based inter-cell mobility to the target candidate cell (which becomes the target cell and the current (new) PCell or SCell in the serving frequency) to perform (execute) L1 / L2 inter-cell mobility execution on the target candidate cell. The UE can be configured with multiple target candidate cells, so the candidate DU generates and sends multiple configurations to the CU. The target candidate configuration includes at least parameters of a serving cell (or multiple serving cells), which includes one or more parameter groups within the IE SpCellConfig (or IE SCellConfig for a secondary cell).

[0089] Some examples of how signaling may be implemented in RRC for target candidate configurations are described as an RRC model for L1 / L2 based inter-cell mobility:

[0090] a) RRC reconfiguration per candidate cell. In this case, the UE receives (a list of) multiple RRC messages (i.e., RRCReconfiguration messages) within a single RRCReconfiguration message. Each RRCReconfiguration message identifies a target candidate configuration stored by the UE and is applied / used / activated upon receipt of low layer signaling for L1 / L2 inter-cell mobility. As in L3 reconfiguration, this model enables the target node to modify / release / maintain any parameter / field in the RRCReconfiguration message with full flexibility, such as measurement configuration, bearer, etc.

[0091] b) CellGroupConfig for each candidate cell. With this model, the UE receives a list of CellGroupConfig IEs within the RRCReconfiguration, and each of them identifies the target candidate configuration. Each CellGroupConfig IE is stored at the UE and is applied / used / activated when low-layer signaling for L1 / L2 inter-cell mobility is received. This model enables the target node to modify / release / maintain any parameters / fields that are part of the CellGroupConfig IE, while the rest of the RRCReconfiguration message (i.e., where the UE receives the CellGroupConfig IE) remains unchanged. This means that, for example, measurement configuration, bearer and security remain the same and are not changed by the target node.

[0092] c), d) and e) either "K"SpCellConfig or "K"ServingCellConfigCommon per cell or both. With this model, the UE receives "K"SpCellConfig per cell (option c), "K"ServingCellConfigCommon per cell (option e) or "K"SpCellConfig and "K"ServingCellConfigCommon per cell (option d) as target candidate configurations. This solution provides only minimal flexibility for the target node, as only cell-specific parameters (e.g., bandwidth fractions, downlink and uplink configurations) can be modified / released / kept.

[0093] f) "K" PCIs in the same PCell. With this model, multiple physical cell identifiers (PCIs) are configured for the same TCI state configuration, where each PCI identifies a target candidate configuration. This approach does not provide flexibility because all parameters / fields used to configure the target candidate configuration are fixed, and only changes in the PCI, scrambling identifier, and cell radio network temporary identifier (C-RNTI) are possible for the target node.

[0094] Figure 6 Example RRC configurations for target candidate configurations are shown. The examples shown include the examples af above.

[0095] The L1 / L2 inter-cell mobility configuration may correspond to fields and / or information elements defined in an RRC protocol (e.g., ASN.1 format) that includes one or more target candidate cell configurations. When the UE is configured with multiple target candidate cells for L1 / L2 inter-cell mobility, the L1 / L2 inter-cell mobility configuration may include multiple target candidate cell configurations. The L1 / L2 inter-cell mobility configuration may be included in an RRCReconfiguration message (as defined in 3GPP TS38.331) or an RRC recovery message received by the UE, for example, during a state transition to RRC_CONNECTED.

[0096] The L1 / L2 inter-cell mobility configuration may be generated by a central unit (CU) (e.g., a gNB-CU) and include information generated and sent from a candidate distributed unit (DU), such as a target candidate cell configuration and / or a measurement configuration instructing the UE to perform measurements on reference signals (e.g., SSB and / or CSI-RS resources) of the target candidate cell for reporting to the network to assist in making L1 / L2 inter-cell mobility decisions.

[0097] The target candidate cell configuration includes the configuration based on which the UE operates in the target candidate cell if the cell is indicated as the target cell in the L1 / L2 inter-cell mobility execution command.

[0098] Some embodiments include TA establishment of target candidate cells for L1 / L2 inter-cell mobility.In the following, a possible signaling flow is used to illustrate the general idea of ​​the method and a set of various embodiments showing different alternatives for actions in UE, serving DU, candidate DU and CU.

[0099] Figure 7 is a signaling diagram showing TA establishment of a target candidate cell. Typically, in the example shown, when a UE is configured with an L1 / L2 mobility candidate, the UE sends an uplink signal to the candidate DU, and the candidate DU calculates a TA value based on the uplink signal. The candidate DU then provides the TA value to the serving DU for L1 / L3 mobility execution.

[0100] In one set of embodiments, the UE transmits an RRC measurement report message (e.g., Figure 7Step 1), the RRC measurement report message includes measurements of one or more neighboring cells in frequency (e.g., based on the cell's reference signal received power (RSRP), reference signal received quality (RSRQ) and / or signal to interference and noise ratio (SINR)), where the neighboring cells may include beam measurement information (later used to configure the TA establishment process). Sending a report in response to network configuration: The UE is configured by the network (e.g., by the CU) to send an RRC measurement report including neighbor cells and serving cells (e.g., based on satisfying conditions associated with A3 and / or A5 measurement events, as defined in TS 38.331).

[0101] Depending on the reporting configuration, the UE includes beam measurement information of one or more neighboring cells in the RRC measurement report (based on the measurement configuration), such as RSRP and / or RSRQ and / or SINR of one or more beams (e.g., of one or more SSBs and / or CSI-RS resources) of the neighboring cell, with an associated beam identifier (e.g., SSB index and / or CSI-RS resource identifier) ​​or only the beam identifier.

[0102] The network (e.g., CU, CU-gNB) determines to configure the UE with L1 / L2 inter-cell mobility. It may determine to request to configure one or more neighboring cells included in the RRC measurement report as target candidate cells for L1 / L2 inter-cell mobility.

[0103] In one set of embodiments, a CU (e.g., CU-gNB, gNB) transmits a request message to a candidate DU (e.g., candidate gNB-DU, via the CU) to configure L1 / L2 inter-cell mobility for at least one target candidate cell. In one option, the same request is for multiple target candidate cells of the same candidate DU; in one option, there is a request per target candidate cell, even if the request is for cells of the same candidate DU; in one option, the CU sends requests for multiple candidate DUs, one per target candidate cell and / or one for multiple target candidate cells in the same candidate DU. The requested target candidate cell may be one of the neighboring cells included in the RRC measurement report that the CU may have received.

[0104] In one set of embodiments, the CU also requests the candidate DU to provide a link between the UE and at least one of its target candidate cells (e.g., Figure 72a), for example, by including an indication of the TA in the above request message. When the CU determines to configure L1 / L2 inter-cell mobility for at least one target candidate cell in the candidate DU, the CU determines that the UE is not synchronized with at least one target candidate cell in the uplink (UL), and decides to request TA establishment from the candidate DU (responsible for the target candidate cell). This can be referred to as CU-initiated TA establishment for L1 / L2 inter-cell mobility.

[0105] In one embodiment, the CU includes a TA establishment request for each target candidate cell with which it wishes to establish a TA, for example, if they are in different candidate DUs, or in the same candidate DU but in different transmit / receive points (TRPs).

[0106] In one embodiment, the CU sends a request for establishing a TA to multiple candidate DUs, one request for each target candidate cell. In one embodiment, the CU sends a request for establishing a TA for a group of target candidate cells in the same candidate DU.

[0107] In one embodiment, the CU also includes beam measurement information associated with the requested target candidate cell in the request for the candidate DU (e.g., beam measurement of one or more SSBs of the requested target candidate cell of the candidate DU). This enables the candidate DU to generate an uplink configuration based on the beam measurement information, for example, a PRACH preamble mapped to one or more SSBs reported as sufficiently good / suitable in terms of RSRP and / or RSRQ and / or SINR.

[0108] In one embodiment, the request message from the CU to the candidate DU may correspond to a UE context establishment request (F1AP message).

[0109] In one embodiment, the request to establish a TA between the UE and at least one of its target candidate cells is an indication (encoded as an Information Element (IE)) in a UE Context Setup Request (F1AP message).

[0110] In one embodiment, for example, when the candidate DU is the same as the serving DU, the request message from the CU to the candidate DU may correspond to a UE context modification request (F1AP message).

[0111] In one embodiment, the request to establish a TA between the UE and at least one of its target candidate cells is an indication (encoded as IE) in a UE context modification request (F1AP message), for example, when the candidate DU is the same as the serving DU.

[0112] In one set of embodiments, when the CU determines to configure L1 / L2 inter-cell mobility for at least one target candidate cell in the candidate DU, this indicates an implicit request by the candidate DU for TA establishment. The candidate DU then determines by itself whether to provide one TA valid for all L1 / L2 inter-cell mobility target candidate cells being configured or to provide one TA for each of the L1 / L2 inter-cell mobility target candidate cells.

[0113] In one set of embodiments, the candidate DU accepts a request to configure L1 / L2 inter-cell mobility (for at least one target candidate cell) and accepts a request to establish a TA for at least one target candidate cell (or multiple target candidate cells). In this case, the candidate DU responds to the request from the CU with a response message that includes the target candidate configuration (e.g., for target candidate cell X) and includes an uplink configuration for establishing a TA between the UE and the target candidate cell (e.g., target candidate cell X). The UE later receives the uplink configuration.

[0114] In one embodiment, in addition to the uplink configuration, the response message also includes an indication that the TA establishment has been accepted by the candidate DU, for example, as an indication of an IE of the F1AP message. This can be used so that the serving DU does not have to parse the RRC fields in the response message to find the uplink configuration and determine the acceptance of the TA establishment. The serving DU can use this when the triggering of the TA establishment later results in a message with a TA value from the candidate DU to the serving DU (via the CU).

[0115] In one embodiment, the response from the candidate DU may correspond to a UE Context Setup Response (F1AP message).

[0116] In one embodiment, a response from a candidate DU (e.g., Figure 7 Step 2b) may correspond to a UE context modification response (F1AP message), for example, when the candidate DU is a serving DU, which may be the case when the requested target candidate cell is in the serving DU.

[0117] When the UE receives the uplink configuration, further details about the uplink configuration for establishing a TA between the UE and the target candidate cell are provided in a later step.

[0118] In one set of embodiments, the candidate DU accepts a request to configure L1 / L2 inter-cell mobility (for at least one target candidate cell), but rejects a request to establish a TA for at least one target candidate cell (or multiple target candidate cells). In this case, the candidate DU responds to the request from the CU with a response message including the target candidate configuration (e.g., for target candidate cell X). This may include an indication of rejection of TA establishment, which may include or exclude parameters or configurations in the response message (e.g., the absence or presence of F1AP IE). In this scenario, the serving DU knows that if L1 / L2 inter-cell mobility is to be performed for the target candidate cell, random access may be required with the target candidate during execution to establish TA / UL synchronization.

[0119] In one set of embodiments, the candidate DU rejects the request to configure L1 / L2 inter-cell mobility and sends a message to the CU indicating the rejection, which may optionally include a cause value, such as overload.

[0120] In one set of embodiments, the candidate DU requests to establish a TA for the UE with a target candidate cell (for at least one target candidate cell) for L1 / L2 inter-cell mobility. In this case, the candidate DU responds to the request for L1 / L2 inter-cell mobility from the CU with a response message, which includes a target candidate configuration (e.g., for target candidate cell X) and includes an uplink configuration for establishing a TA between the UE and the target candidate cell (e.g., target candidate cell X), which can be used as an indication that the candidate DU is requesting TA establishment between the UE and one or more of its target candidate cells. The UE then receives the uplink configuration.

[0121] The following steps may be used to include reconfiguration by the serving DU in the serving cell before the UE is configured with L1 / L2 inter-cell mobility, e.g., to reconfigure CSI measurements. In this case, the CU generates an RRC reconfiguration (e.g., RRCReconfiguration) message (e.g., Figure 7 The CU also includes an L1 / L2 inter-cell mobility configuration having one or more target candidate cell configurations and necessary configurations for the UE to establish a TA with one or more target candidate cells for L1 / L2 inter-cell mobility.

[0122] In a set of embodiments, a UE (e.g., from a CU via a serving DU) receives an RRCReconfiguration message that configures L1 / L2 inter-cell mobility. The message includes an L1 / L2 inter-cell mobility configuration that configures one or more target candidate cells for L1 / L2 inter-cell mobility, i.e., the L1 / L2 inter-cell mobility configuration includes one or more target candidate cell configurations, and an uplink configuration for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X), as described above.

[0123] In one embodiment, a user equipment receives an uplink configuration for establishing a TA for a target candidate cell.

[0124] In one embodiment, the UE receives multiple UL configurations for establishing TAs for multiple target candidate cells, one UL configuration for each target candidate cell.

[0125] In one embodiment, the UE receives an indication associated with a target candidate cell indicating that this is the cell for which the UE will establish a TA, e.g., by sending an uplink signal. The UE may have received at least one uplink configuration for each target candidate cell for which it should establish a TA, and the UE sends a message to the target candidate cell based on the at least one uplink configuration.

[0126] In one embodiment, the target candidate cells configured for the UE (for which the UE has established a TA) include a subset of the target candidate cells for L1 / L2 inter-cell mobility. In other words, the UE may be configured with "N" L1 / L2 inter-cell mobility candidates and be configured to establish a TA with "N1" (N1 < N) candidate cells. The reason may be that some target candidate cells may not require the establishment of a TA, e.g., if they are in the same serving DU and / or are synchronized with one or more serving cells, and / or some of these candidate cells are co-located with one or more serving cells in other serving cells, such that the same TA value can be assumed (i.e., it can be assumed that some target candidate cells are in UL synchronization with the UE).

[0127] In one embodiment, the UE receives an indication of target candidate cells for which the UE does not need to establish a TA, and in addition, the UE receives an indication that for candidate cells, the UE can assume the same TA value for a given serving cell. For example, the UE receives a target cell configuration associated with the serving cell index of one of its configured serving cells. Then, when the UE receives an L1 / L2 inter-cell mobility execution command (e.g., an MAC CE indicating a target candidate cell), the UE determines that this is the cell for which the TA value to be considered is the same as the TA value of the indicated serving cell, and the UE applies the TA value accordingly when accessing the target candidate cell.

[0128] In one embodiment, the UE receives an indication of a target candidate cell for which the UE does not need to establish a TA, and in addition, the UE receives a TA value for the candidate cell. For example, the UE receives a target cell configuration associated with a serving cell index of one of its configured serving cells. Then, when the UE receives an L1 / L2 inter-cell mobility execution command (e.g., a MACCE indicating the target candidate cell), the UE applies the TA value provided in the L1 / L2 inter-cell mobility execution command.

[0129] In a related embodiment, the UE receives an indication of a target candidate cell for which the UE does not need to establish a TA, and in addition, the UE receives a TA value of 0 for the candidate cell. For example, the UE receives a target cell configuration associated with a serving cell index of one of its configured serving cells. Then, when the UE receives an L1 / L2 inter-cell mobility execution command (e.g., a MACCE indicating the target candidate cell), the UE applies the TA value 0 provided in the L1 / L2 inter-cell mobility execution command.

[0130] In one embodiment, the UE receives an indication of a target candidate cell for which the UE does not need to establish a TA (e.g., there is no uplink configuration or explicit indication for TA establishment in the target candidate cell configuration), and in addition, the UE receives an indication that the UE may need to perform random access with the target candidate cell when an L1 / L2 inter-cell mobility execution command (e.g., a MAC CE indicating the target candidate cell) is received.

[0131] In one embodiment, the UE receives an uplink configuration for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X), which uplink configuration may include an indication (e.g., an uplink configuration for the target candidate cell), and the UE sends an uplink signal or message to the target candidate cell (e.g., a PRACH preamble code) based on the indication, so that the candidate DU can establish a TA and indicate the TA value to the CU and the serving DU.

[0132] In one embodiment, the UE receives an uplink configuration (e.g., as a field, parameter, set of parameters and / or fields, IE, etc.) for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X) within a target candidate configuration (e.g., for target candidate cell X, in an RRCReconfiguration container and / or IE CellGroupConfig and / or SpCell configuration). This can be, for example, one or more parameters in a random access configuration of a SpCell configuration in the target candidate configuration.

[0133] In one embodiment, the UE receives an uplink configuration for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X), which uplink configuration is configured as an IE and / or a field and / or a set of IEs and fields in an L1 / L2 inter-cell mobility configuration, which may correspond to an IE for configuring one or more target candidate cells for L1 / L2 inter-cell mobility.

[0134] In one option, the uplink configuration is set for the target candidate cell, for example, the target candidate cell has its uplink configuration for TA establishment. In one option, the uplink configuration is set for a set of target candidate cells. The uplink configuration can still be used for a given target candidate cell because the parameters are defined for a given uplink channel of a given cell, but when the UE establishes a TA for that single cell, it is valid for the set of cells, which is applicable if multiple cells have the same candidate DU and / or the same TRP and / or have some common transceiver properties and / or are uplink synchronized.

[0135] In one embodiment, the UE receives an uplink configuration for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X), the uplink configuration being configured as IEs and / or fields and / or sets of IEs and fields in an RRC reconfiguration message in which the UE receives L1 / L2 inter-cell mobility configuration.

[0136] In one embodiment, the UE receives an uplink configuration for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X), the uplink configuration including configuration of uplink signals / messages and / or configuration of channels for the UE to send uplink signals / messages (to be received at the candidate DU).

[0137] The uplink signal / message may correspond to a random access preamble (or an equivalent sequence defined in the physical layer) indicated by a random access preamble index in the uplink configuration (eg, ra-PreambleIndex of IEINTEGER(0··63)).

[0138] The uplink configuration may also include at least one beam identifier / index associated with the uplink signal, such as an SSB index and / or a CSI-RS resource identifier.

[0139] For example, when the uplink signal corresponds to a preamble, the uplink configuration may include at least one TA establishment resource as a pair (ssb of IE SSB-Index, ra-PreambleIndex or IE INTEGER (0··63)). The uplink configuration may include multiple of these pairs because the candidate DU does not know which SSB and / or CSI-RS resource the UE will select to establish the TA. The configured beam (e.g., SSB) may be referred to as a candidate beam for TA establishment.

[0140] In the following example, a UE is provided to build a list of resources for a target candidate cell's TA(s), where each resource has a preamble index and an associated SSB index:

[0141] In another example, the UE is provided with a list of (multiple) TA establishment resources for the target candidate cell, where each resource has a preamble index and an associated CSI-RS resource. In addition to the pair, there is also a list of random access opportunities for each resource. These are the RA opportunities that the UE should use when performing TA establishment with the target candidate cell when selecting the candidate beam identified by the corresponding CSI-RS.

[0142] The candidate DU determines which beam identifiers / indexes to configure for TA establishment based on the beam measurement information obtained from the CU in / with the L1 / L2 inter-cell mobility request (e.g., measurement information about the SSB and / or CSI-RS of the candidate cell). The network (e.g., CU) may have configured the UE to report beam measurement information because it intends to trigger the UE to establish a TA with the target candidate when it configures the UE with L1 / L2 inter-cell mobility. For example, for the neighbor cells included in the measurement report, the UE may have reported SSB index X and SSB index Y and their corresponding RSRP values ​​(e.g., above a threshold in the reporting configuration), indicating that these are suitable beams in the neighbor cells.

[0143] The uplink configuration may also include one or more of the following parameters: Root Sequence Index: PRACH root sequence index used for TA establishment in L1 / L2 inter-cell mobility, which may be defined in TS38.211. This may be a field such as rootSequenceIndex of IE INTEGER (0...137). RSRP threshold for SSB: L1-RSRP threshold used to determine whether the UE can use the candidate beam to attempt contention-free random access to establish a TA with the target candidate cell. This can be the field rsrp-ThresholdSSB. SSBs per RACH occasion: The number of SSBs per RACH occasion used for establishing a contention-free TA with the target candidate cell. This can be the field ssb-perRACH-Occasion {oneEth, onefourth, oneHalf, one, two, four, eight, sixteen} of the IE ENUMERATED. RA SSB occasion mask index: The explicit signaling PRACH mask index used for RA resource selection, valid for one or more SSB resources. This can be the field ra-ssb-OccamsionMaskIndex. Subcarrier spacing for MSG1: The subcarrier spacing for establishing a contention-free TA with the target candidate cell, for example, values ​​15kHz or 30kHz (FR1), and 60kHz or 120kHz (FR2). This can be the parameter msg1-SubcarrierSpacing of the IE SubcarrierSpacing. A trigger condition in the form of measurement events A2, A3, A4 or A5 to be met before triggering TA establishment with the target candidate cell.

[0144] The uplink configuration may correspond to contention-free resources and / or dedicated resources such that when a candidate DU receives a preamble in an uplink timeslot in a frequency resource, the candidate DU is able to determine which UE the UE has been configured for and / or which serving DU / CU is serving the UE.

[0145] The uplink configuration may also include one or more parameters of the random access configuration, such as RACH parameters, such as preambles, time and frequency resources for PRACH, and / or one or more parameters, fields and / or IEs within IEs RACH-Config, RACH-ConfigCommon, RACH-ConfigDedicated, RACH-ConfigGeneric as defined in TS38.331. This may be a special RACH configuration containing only transmission parameters (i.e., no random access response parameters) because the UE is not expected to receive a response from the target candidate in response to the preamble transmission.

[0146] In one embodiment, the UE receives an uplink configuration for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X), the uplink configuration included in one or more parameters in a beam failure recovery (BFR) configuration of the target candidate cell (e.g., IE BeamFailureRecoveryConfig) associated with an uplink bandwidth part (BWP), which target candidate cell can be assumed to be active when L1 / L2 inter-cell mobility is performed. Using this, the candidate DU can distinguish the preamble and RACH messages used for TA establishment from other preamble and RACH attempts. BFR is any method that is not used for the UE before accessing the target candidate during L1 / L2 inter-cell mobility, which facilitates this without the need for further detailed configuration.

[0147] In one embodiment, the UE obtains the uplink configuration at least in part from the random access configuration of the target candidate configuration (e.g., the RACH configuration of the SpCell configuration of the target candidate configuration). The UE may receive a time / frequency resource partition for PRACH and / or a preamble partition indicating a subset of RACH resources for that purpose, so that the candidate DU knows that it should not respond to the sent preamble in the RAR, but should calculate the TA and provide it to the serving DU. In this sense, the candidate DU may provide the UE with different PRACH resource partitions in different serving DUs for multiple requests.

[0148] In one set of embodiments, the UE (e.g., from the CU via the serving DU) receives an RRCReconfiguration message including an uplink configuration for establishing a TA between the UE and a target candidate cell (e.g., target candidate cell X) only after the UE has received an L1 / L2 inter-cell mobility configuration of one or more target candidate cells configured for L1 / L2 inter-cell mobility (i.e., an L1 / L2 inter-cell mobility configuration including one or more target candidate cell configurations). This means that the CU or serving DU can request the establishment of a TA from the candidate DU only after they decide that L1 / L2 inter-cell mobility should be performed to the candidate DU. This also means that the serving DU receives the uplink configuration before sending a lower layer handover command to the UE for performing L1 / L2 inter-cell mobility.

[0149] In one set of embodiments, the UE sends a signal based on the uplink configuration (e.g., Figure 7 Step 5) in step 11) sends an uplink signal (eg, a PRACH preamble) to the target candidate cell with which the TA should be established.

[0150] In one set of embodiments, the UE sends an uplink signal in response to receiving an RRCReconfiguration configuring L1 / L2 inter-cell mobility, the RRCReconfiguration including an indication of TA establishment for the target candidate cell.

[0151] In one set of embodiments, what triggers the UE to send an uplink signal to a target candidate cell is a subsequent message (e.g., MAC CE, PDCCH command, DCI, RRC message) received by the UE after RRCReconfiguration for configuring L1 / L2 inter-cell mobility, which RRCReconfiguration includes an indication of TA establishment for the target candidate cell. This may be useful in scenarios where the candidate DU accepts TA establishment from the CU, but the serving DU has some freedom to trigger TA establishment to the UE when the interruption time is not so critical, because in order to send an uplink signal to the target candidate, the UE may need to stop listening to (multiple) serving cells / serving DUs. Upon receiving the subsequent message, the UE sends the uplink signal / message based on the previously received uplink configuration for TA establishment in L1 / L2 inter-cell mobility preparation. This scheme can also be used for the TA update / maintenance mechanism described in the following sections.

[0152] In one embodiment, the uplink configuration is associated with a validity time so that the serving DU and / or CU has a limited time to trigger subsequent messages. This can be used to limit the uplink resources reserved for the TA, for example, if they are UE-specific / contention-free resources.

[0153] In one embodiment, when triggering TA establishment with a target candidate, the process initiated by the UE includes one or more of the following steps: · Perform one or more measurements on the SSB and / or CSI-RS resources of the target candidate cells for which the UE should establish a TA; · Perform uplink channel resource selection, such as RACH resource selection, associated with the SSB and / or CSI-RS resources of the target candidate cell for which the UE should establish a TA. For example, the UE selects an SSB or CSI-RS resource with a measurement above a threshold (which may be configured in the uplink configuration), such as SSB RSRP>rsrp-ThresholdSSB; and the UE selects uplink channel resources (e.g., time / frequency resources and preamble) for TA establishment associated with the selected SSB, where the association is also part of the uplink configuration. • Sending an uplink signal / message (eg, preamble) in the selected resources.

[0154] In one set of embodiments, the candidate DU receives at least one uplink signal (e.g., a PRACH preamble) in an uplink channel (PRACH time / frequency resource slot) allocated for TA establishment for L1 / L2 inter-cell mobility, calculates a TA value valid for the UE and at least one target candidate cell. The candidate DU sends a message (e.g., Figure 7 6A in step 6).

[0155] In one embodiment, the candidate DU sends a message to the CU including the TA value and one or more associated target candidate cells that the TA value applies to. Using this information, the CU (and possibly the serving DU, which also receives this information) will know that a given TA value applies to one or more target candidate cells that the UE is configured with, which may be required during L1 / L2 inter-cell mobility execution for one of these candidate cells.

[0156] In one embodiment, the candidate DU sends a message to the CU using the UE signaling connection so that the CU knows that the TA value associated with the target candidate cell corresponds to the UE used for the UE signaling connection.

[0157] In one embodiment, when the candidate DU sends a message to the CU, the candidate DU starts a timer (which may be referred to as a TA timer), and while the timer is running, the candidate DU considers the TA value it has provided to the CU as "valid", which means that while the timer is running, the candidate DU can receive incoming UEs with L1 / L2 inter-cell mobility without random access because the TA is valid, assuming that the TA value is provided to the UE via the CU and / or the serving DU. When the timer expires, the candidate DU considers the TA value as "invalid", and when the TA value is invalid, the candidate DU may trigger a TA update procedure.

[0158] In one embodiment, the CU receives a message including a TA value configured for L1 / L2 inter-cell mobility associated with a target candidate cell and a UE, and the CU starts a timer. When the timer is running, the CU regards the TA value as "valid"; when the timer expires, the CU regards the TA value as "invalid". When the TA value is invalid, the CU can trigger a TA update procedure.

[0159] In one option, the candidate DU also includes a timer value (e.g., a TA timer) associated with the TA value (applicable to at least one target candidate cell) in the message to the CU, where the TA value is considered "valid" while the timer is running and is considered invalid when the timer expires. In this case, the candidate DU can also start a timer with the same or similar value so that it can also know when the TA value is invalid for the UE and the target candidate cell.

[0160] In one embodiment, the uplink signals and / or resources may have been configured for a specific UE (e.g., per-UE resources for TA establishment, contention-free preambles, and / or PRACH resources) such that upon reception, the candidate DU knows which UE, and therefore which CU, this is associated with because there is a UE signaling connection for that UE (because this is the UE for which the candidate DU has accepted a request to configure L1 / L2 inter-cell mobility).

[0161] The candidate DU calculates the TA value of the UE and the target candidate cell based on the received signal and sends the value to the serving DU (via the CU) for use by the UE in performing L1 / L2 inter-cell mobility (at a later time) (e.g. Figure 7 Step 6b).

[0162] In one set of embodiments, the CU sends a message including at least one TA value to the serving DU to which the UE is connected. The candidate DU receives at least one uplink signal (e.g., a PRACH preamble) in an uplink channel (PRACH time / frequency resource slot) allocated for TA establishment for L1 / L2 inter-cell mobility, calculates a TA value valid for the UE and at least one target candidate cell, and the candidate DU sends a message including at least one TA value to the CU, causing the CU to send to the serving DU.

[0163] As an embodiment, the serving DU receives the message from the CU including the TA value and one or more associated target candidate cells to which the TA value applies. The serving DU knows that a given TA value applies to one or more target candidate cells with which the UE is configured, which may be required during L1 / L2 inter-cell mobility execution for one of these candidate cells.

[0164] In one embodiment, the serving DU receives a message from the CU in a UE signaling connection so that the serving DU knows that the TA value associated with the target candidate cell corresponds to the UE for the UE signaling connection.

[0165] In one embodiment, the serving DU receives a message including a TA value associated with a target candidate cell and a UE configured for L1 / L2 inter-cell mobility, and the serving DU starts a timer (which may be referred to as a TA timer). When the timer is running, the serving DU considers the TA value to be "valid"; when the timer expires, the serving DU considers the TA value to be "invalid". When the TA value is invalid, the serving DU may trigger a TA update procedure.

[0166] In one option, the serving DU receives a timer value (e.g., a TA timer) associated with a TA value (applicable to at least one target candidate cell) in a message from the CU, wherein the TA value is considered "valid" while the timer is running and is not valid when the timer expires. In this case, the candidate DU and / or the CU may also start a timer with the same or similar value so that it may also know when the TA value is invalid for the UE and the target candidate cell.

[0167] In one set of embodiments, the UE may transmit measurements to assist the serving DU and / or candidate DU and / or CU in triggering L1 / L2 inter-cell mobility execution, for example, including CSI measurements of target candidate cells for L1 / L2 inter-cell mobility for which the UE has triggered TA establishment (e.g., Figure 7 Step 7).

[0168] In response to the reported measurements (L1 RSRP) for a given target candidate cell, the network (e.g., serving DU) may determine to trigger L1 / L2 inter-cell mobility execution of the UE to the target candidate cell for which the UE has triggered TA establishment (e.g., Figure 7 Step 8).

[0169] As an embodiment, the serving DU performs one or more of the following actions: If the serving DU determines that the target candidate cell (e.g., cell X) that triggers the L1 / L2 inter-cell mobility execution is a cell for which the serving DU has a valid TA value for the UE and the target candidate cell (e.g., a TA timer is running), the serving DU sends to the UE a lower layer signaling (e.g., MAC CE) indicating the target candidate cell for L1 / L2 inter-cell mobility and including a TA value to be applied by the UE to communicate with the target candidate cell. If the serving DU determines that the target candidate cell (e.g., cell X) that triggers the L1 / L2 inter-cell mobility execution is a cell for which the serving DU has an invalid TA value for the UE (e.g., a TA timer has expired) and the target candidate cell, the serving DU sends to the UE a lower layer signaling (e.g., MAC CE) indicating that the target candidate cell for L1 / L2 inter-cell mobility does not include a TA value.

[0170] In one embodiment, the serving DU performs one or more of the following actions. If the TA timer is running, the network (e.g., serving DU) sends lower layer signaling (e.g., MAC CE) to the UE indicating the target candidate cell for L1 / L2 inter-cell mobility and including the TA value. If the TA timer has expired or stopped, the network (e.g., serving DU) sends lower layer signaling (e.g., MAC CE) to the UE indicating the target candidate cell for L1 / L2 inter-cell mobility without including the TA value.

[0171] In one embodiment, the serving DU performs one or more of the following actions. If the serving DU determines that the target candidate cell (e.g., cell X) that triggers the L1 / L2 inter-cell mobility execution is a cell for which the serving DU has a valid TA value for the UE (e.g., the TA timer is running) and the target candidate cell is the same cell as the TA value for the serving cell with which the UE is configured, the serving DU sends a lower layer signaling (e.g., MAC CE) to the UE, which indicates the target candidate cell for L1 / L2 inter-cell mobility and includes the TA value of the serving cell with which the UE is configured and to be applied by the UE to communicate with the target candidate cell.

[0172] Another alternative is that instead of providing the TA value, the serving DU provides a serving cell index, indicating to the UE that the UE should use the TA value between the UE and the serving cell, the index of which has been indicated as the TA value for the UE and the target candidate cell, also indicated in the lower layer signaling.

[0173] The UE receives lower layer signaling (e.g., MACCE) indicating a target candidate cell for L1 / L2 inter-cell mobility, and if the signaling includes a TA value, the UE applies the TA value to the target candidate cell (for UL transmission). If the signaling does not include a TA value or the indicated target candidate cell is a cell with the same TA as the serving cell (and the UE knows the TA based on the target candidate configuration), the UE applies the TA value of the associated serving cell to the target candidate cell (for uplink transmission). If the signaling does not include a TA value or the indicated target candidate cell is a cell for which a TA has not yet been established, the UE performs random access to the indicated target candidate cell.

[0174] If the signaling includes a serving cell index, the UE uses the TA value between the UE and the target candidate cell, the index of which has been indicated as the TA value between the UE and the target candidate cell, also indicated in the lower layer signaling.

[0175] After applying the indicated TA value to the target candidate cell according to the method, the UE sends an uplink message (e.g., Figure 7 9 in the previous step).

[0176] Some embodiments include TA maintenance / update of target candidate cells for L1 / L2 inter-cell mobility.Some embodiments include CU initiated TA update.

[0177] Figure 8is a signaling diagram illustrating an example of TA re-establishment / update with a target candidate cell. In one set of embodiments, the TA value for the target candidate cell is managed by the CU. When the CU receives a TA value for the UE and at least one target candidate cell configured for L1 / L2 inter-cell mobility, the CU starts an associated timer (referred to as the TA timer), whose value may have been received from the candidate DU.

[0178] In one set of embodiments, when the CU determines that the TA value for the UE and the target candidate cell configured for L1 / L2 inter-cell mobility is invalid (eg, by expiration of a TA timer), the CU performs one or more of the following actions.

[0179] In one embodiment, the CU sends a message (e.g., Figure 8 In one option, the message is sent on a UE signaling connection to indicate that this is for a given UE and may include one or more target candidate cells associated with the received candidate DU. In one option, the message is a UE context modification request including an indication that the previously provided TA value is invalid.

[0180] In one option, the TA re-establishment request is similar to the TA establishment request, for example the same IE as the request to the UE to establish a new uplink configuration and / or uplink resources for the TA as described above. One difference may be that the initial TA establishment is indicated in the UE context establishment request, which also includes a request for configuring a target candidate cell for L1 / L2 inter-cell mobility, and now this cell has been configured, so that the request is included in the UE context modification request message.

[0181] In one option, TA re-establishment uses the same procedure used to modify the L1 / L2 inter-cell mobility configuration of the target candidate cell associated with the candidate DU.

[0182] In one option, the TA re-establishment includes an indication of a target candidate cell (and / or a target candidate cell configuration, eg, configuration ID) associated with the previously configured TA value.

[0183] In one embodiment, the message includes beam measurement information that the candidate DU can use to configure a UE-specific uplink configuration (e.g., contention-free RACH resources) for transmission of uplink signals for TA establishment between the UE and the target candidate cell. The beam measurement information can be equivalent to the beam measurement information disclosed above, such as measurement information obtained based on RRC measurement reports and / or from CSI reports to the serving DU, making it available to the CU.

[0184] In one embodiment, the candidate DU accepts the request for TA re-establishment and sends a response message (similar to that disclosed above) including an uplink configuration to be used by the UE to re-establish the TA (e.g., Figure 8 Step 2 in the above example.

[0185] In one embodiment, the candidate DU accepts the TA re-establishment request and sends a response message including an authorization for the UE to use the previously provided uplink configuration for the UE to use to re-establish the TA. In other words, in this case, no new uplink configuration needs to be provided, but the response is a confirmation that the previously provided uplink configuration can be used.

[0186] In one set of embodiments, the candidate DU accepts a request for TA update / re-establishment for at least one target candidate cell (or multiple target candidate cells).The candidate DU responds to the request from the CU with a response message, which may be referred to as an acknowledgement (ACK).

[0187] In one embodiment, the response from the candidate DU to the CU includes an uplink configuration for reestablishing / updating the TA between the UE and the target candidate cell (eg, target candidate cell X). The UE may receive the uplink configuration later.

[0188] In one embodiment, the response from the candidate DU to the CU does not include an uplink configuration for reestablishing / updating the TA between the UE and the target candidate cell (e.g., target candidate cell X), but it includes an indication that the TA between the UE and the target candidate cell can be reestablished / updated based on the previously configured uplink configuration.

[0189] In one embodiment, in addition to the uplink configuration, the response message also includes an indication that the TA establishment has been accepted by the candidate DU, for example as an indication of an IE of the F1AP message. This can be used so that the serving DU does not need to parse the RRC fields in the response message to find the uplink configuration and determine the acceptance of the TA establishment. The serving DU can use when the triggering of the TA re-establishment / update later results in a message with the TA value from the candidate DU to the serving DU (via the CU).

[0190] In one embodiment, the response from the candidate DU may correspond to a UE Context Modification Response (F1AP message).The candidate DU may correspond to a neighbor DU or a serving DU, which may be the case when the requested target candidate cell is in the serving DU.

[0191] In one set of embodiments, the details of the uplink configuration for re-establishing a TA between the UE and the target candidate cell are similar to the uplink configuration for establishing a TA between the UE and the target candidate cell, except that the values ​​set to the fields and / or IEs and / or parameters may be different.

[0192] In one set of embodiments, the candidate DU responds with a pointer to the previously configured uplink configuration provided to the UE during TA establishment.

[0193] In one set of embodiments, the candidate DU rejects a request to reestablish / update a TA for at least one target candidate cell (or multiple target candidate cells). In this case, the candidate DU responds to the request from the CU with a response message that includes an indication of the rejection of TA reestablishment / update, where the indication may include or not include a parameter or configuration in the response message (e.g., the absence or presence of a F1AP IE). In this scenario, the serving DU knows that if L1 / L2 inter-cell mobility is to be performed for the target candidate cell, random access may be required with the target candidate during the execution to establish TA / UL synchronization.

[0194] In one set of embodiments, the CU sends to the serving DU information received from the candidate DU in a previous step regarding TA re-establishment / update between the UE and a target candidate cell configured for L1 / L2 inter-cell mobility. This information is provided so that the serving DU can trigger the UE to initiate TA re-establishment / update with the target candidate cell, potentially using a previously stored uplink configuration. The serving DU may provide a message (e.g., MAC CE, PDCCH command, TA re-establishment command, etc.) to the UE, the message including an indication that enables the UE to determine the uplink configuration and the target candidate cell to re-establish the TA, and the UE sends an uplink signal to the indicated target candidate cell based on the indication. This may correspond to a subsequent message from the serving DU to the UE that triggers TA re-establishment to the target candidate cell.

[0195] In one set of embodiments, the CU generates an RRC reconfiguration message to be provided to the UE via the serving DU, the message including an indication to the UE to reestablish / update the TA with the target candidate configuration, e.g., by including an indication associated with the target candidate cell (e.g., Figure 8 Step 3 in the above example).

[0196] In one embodiment, the RRC reconfiguration message is provided to the serving DU in a F1AP message in an RRC container and also includes an indication that the TA reestablishment has been accepted by the candidate DU, for example as an indication of an IE of the F1AP message. This can be used so that the serving DU does not have to parse the RRC fields in the response message to find the uplink configuration and determine the acceptance of the TA establishment. The serving DU can use when the triggering of the TA reestablishment / update later results in a message with a TA value from the candidate DU to the serving DU (via the CU).

[0197] In one set of embodiments, the UE receives a message from a serving DU (possibly originating from a CU) based on which the UE re-establishes a TA with a target candidate cell (e.g., Figure 8 4 in the previous step).

[0198] In one embodiment, the UE receives a message from the serving DU that may correspond to a MAC CE, a PDCCH command, a TA re-establishment command, wherein the message includes an indication enabling the UE to determine the uplink configuration and a target candidate cell for re-establishing the TA, and the UE sends an uplink signal to the indicated target candidate cell based on the indication. This may correspond to a subsequent message from the serving DU to the UE that triggers TA re-establishment to the target candidate cell.

[0199] In one embodiment, the UE receives a message from the CU via the serving DU that may correspond to an RRC reconfiguration message. In response to the message, the UE initiates TA reestablishment / update by sending an uplink signal based on the uplink configuration to the indicated target candidate cell.

[0200] In one embodiment, the RRC reconfiguration includes an uplink configuration to the user equipment regarding a target candidate cell for which the user equipment should re-establish a TA, before the UE has received an uplink configuration for that cell, for previously establishing a TA with the same target candidate cell, but this configuration may have been a one-time configuration, so that the UE will use the new configuration to transmit uplink messages.

[0201] In one embodiment, the RRC reconfiguration does not include an uplink configuration to the UE for a target candidate cell for which the UE is to re-establish a TA, but its absence may indicate that the UE is to use a previously received uplink configuration for that cell for a previous establishment of a TA with the same target candidate cell.

[0202] In one set of embodiments, the UE sends a signal based on the uplink configuration (e.g., Figure 8 Step 5) transmits an uplink signal (eg, a PRACH preamble) to a target candidate cell for which the TA should be reestablished.

[0203] In one set of embodiments, the content that triggers the UE to send an uplink signal to the target candidate cell is a message as described above, such as a MAC CE, a PDCCH command, a DCI, an RRC message, including an indication of TA re-establishment for the target candidate cell, and may at least include the target candidate cell for which the UE needs to re-establish the TA (i.e., for which the UE sends an uplink signal). Upon receiving the message, the UE sends an uplink signal / message based on the previously received uplink configuration for TA establishment in L1 / L2 inter-cell mobility preparation.

[0204] In one embodiment, the previously received uplink configuration is associated with a validity time, so that after the serving DU and / or CU has received confirmation that the candidate DU has accepted the re-establishment / update of the TA, the serving DU and / or CU has a limited time to send a message to the UE. This can be used to limit the uplink resources reserved for TA establishment, for example, if these are UE-dedicated / contention-free resources.

[0205] In one set of embodiments, the UE sends an uplink signal in response to receiving an RRCReconfiguration configuring L1 / L2 inter-cell mobility, the RRCReconfiguration including an indication of TA establishment for the target candidate cell and / or an updated uplink configuration.

[0206] In one embodiment, when triggering TA re-establishment / update with a target candidate cell, the UE initiates a process including one or more of the following steps: Perform one or more measurements on the SSB and / or CSI-RS resources of the target candidate cell for which the UE should establish a TA; · Perform uplink channel resource selection, such as RACH resource selection, associated with the SSB and / or CSI-RS resources of the target candidate cell for which the UE should establish a TA. For example, the UE selects an SSB or CSI-RS resource with a measurement above a threshold (which may be configured in the uplink configuration), such as SSB RSRP>rsrp-ThresholdSSB; and the UE selects uplink channel resources (e.g., time / frequency resources and preamble) for TA establishment associated with the selected SSB, where this association is also part of the uplink configuration. • Sending an uplink signal / message (eg, preamble) in the selected resources.

[0207] In one set of embodiments, the candidate DU receives at least one uplink signal (e.g., a PRACH preamble) in an uplink channel (PRACH time / frequency resource slot) allocated for the purpose of TA establishment for L1 / L2 inter-cell mobility, calculates a TA value valid for the UE and at least one target candidate cell. The candidate DU sends a message (e.g., Figure 8 6 in the previous step).

[0208] From this point on, the steps may be similar to the initial TA setup.

[0209] Some embodiments include candidate DU initiated TA updates.

[0210] Fig. 9 is a signaling diagram illustrating an example of a candidate DU initiated TA update. In one set of embodiments, the TA value for a target candidate cell is managed by the candidate DU that has configured the target candidate cell. When the candidate DU sends (e.g., provided to the serving DU) a TA value for the UE and at least one target candidate cell configured for L1 / L2 inter-cell mobility to the CU, the candidate DU starts an associated timer (referred to as a TA timer).

[0211] In one set of embodiments, when the candidate DU determines that the TA value between the UE and the target candidate cell configured for L1 / L2 inter-cell mobility is invalid (e.g., by expiration of a TA timer), the candidate DU performs one or more of the following actions. In one embodiment, the candidate DU sends a message with a TA re-establishment request (or TA update) to the CU, where the request is associated with the target candidate cell for which the TA timer has expired (e.g., Fig. 9 Step 1) in the above code.

[0212] In one option, the message is sent on the UE signaling connection to indicate to the CU that this is for a given UE and may include one or more target candidate cells associated with sending the candidate DU.

[0213] In one option, the message is a UE Context Modification Request including an indication that the previously provided TA value is invalid.

[0214] In one option, TA re-establishment uses the same procedure used to modify the L1 / L2 inter-cell mobility configuration of the target candidate cell associated with the candidate DU, where the modification is triggered by the candidate DU.

[0215] In one option, the TA re-establishment includes an indication of a target candidate cell (and / or a target candidate cell configuration, eg, a configuration ID) associated with the previously configured TA value.

[0216] In one embodiment, the candidate DU includes in the request for TA re-establishment an uplink configuration (similar to those disclosed above) to be used by the UE to re-establish the TA.

[0217] In one embodiment, the candidate DU includes in the TA re-establishment request an authorization for the UE to re-establish the TA using the previously provided uplink configuration. In other words, in this case, no new uplink configuration needs to be provided, but the response is a confirmation that the previously provided uplink configuration can be used.

[0218] In one set of embodiments, the candidate DU includes one or more of the following in the TA re-establishment request: an uplink configuration for re-establishing / updating the TA between the UE and the target candidate cell (e.g., target candidate cell X). The UE may subsequently receive the uplink configuration. The request may not include an uplink configuration for re-establishing / updating the TA between the UE and the target candidate cell (e.g., target candidate cell X), but it includes an indication that the TA between the UE and the target candidate cell may be re-established / updated based on the previously configured uplink configuration.

[0219] In addition to the UL configuration, the request may also include an indication that TA re-establishment is allowed, for example, as an indication of an IE of the F1AP message. This can be used so that the serving DU does not have to parse the RRC fields in the response message to find the uplink configuration and determine the acceptance for TA establishment. The serving DU can use this indication when the triggering of TA re-establishment / update later results in a message with a TA value from the candidate DU to the serving DU (via the CU).

[0220] In one embodiment, the request from the candidate DU may correspond to a UE context modification request (F1AP message). The candidate DU may correspond to a neighbor DU or a serving DU, which may be the case when the requested target candidate cell is in the serving DU.

[0221] In one set of embodiments, the details of the uplink configuration for re-establishing a TA between the UE and the target candidate cell are similar to the uplink configuration for establishing a TA between the UE and the target candidate cell, except that the values ​​set to the fields and / or IEs and / or parameters may be different.

[0222] In one set of embodiments, the candidate DU includes in the request a pointer to a previously configured uplink configuration provided to the UE during TA establishment.

[0223] In one set of embodiments, the CU sends to the serving DU the information it received from the candidate DU in the previous step regarding the TA re-establishment / update between the UE and the target candidate cell configured for L1 / L2 inter-cell mobility. (e.g., Fig. 9At this time, the actions of the CU and the serving DU may be similar to the actions for the CU-initiated TA update described above.

[0224] Some embodiments include serving DU initiated TA update.

[0225] Fig.10 is a signaling diagram illustrating an example of a TA update initiated by a serving DU. In one set of embodiments, the TA value for a target candidate cell is managed by the serving DU. When the serving DU receives a TA value for a UE and at least one target candidate cell configured for L1 / L2 inter-cell mobility, the serving DU starts an associated timer (referred to as a TA timer), whose value may have been received from the candidate DU.

[0226] In one set of embodiments, when the serving DU determines that the TA value for the UE and the target candidate cell configured for L1 / L2 inter-cell mobility is invalid (eg, by expiration of a TA timer), the serving DU performs one or more of the following actions.

[0227] In one embodiment, the serving DU sends a message (to be provided to the candidate DU) with a TA re-establishment request (or TA update) to the CU associated with the target candidate cell whose TA timer has expired (e.g., Fig.10 Step 1) in the above code.

[0228] In one option, the message is sent on the UE signaling connection to indicate that this is for a given UE, and may include one or more target candidate cells to indicate to the CU the associated candidate DUs to contact for re-establishing the TA.

[0229] In one option, the message is a UE Context Modification Required including an indication that the previously provided TA value is invalid.

[0230] In one option, the TA re-establishment request is similar to the TA establishment request, e.g., the same IE, as a request to establish a new uplink configuration and / or uplink resources for the TA with the UE, as described above, in this case if this is a TA establishment request initiated by the serving DU. The initial TA establishment triggered by the serving DU may be triggered after the serving DU knows that the UE is configured with L1 / L2 inter-cell mobility of one or more target candidate cells (e.g., cells associated with the candidate DU) that are not synchronized with the serving DU.

[0231] In one option, TA re-establishment uses the same procedure used to modify the L1 / L2 inter-cell mobility configuration of the target candidate cell associated with the candidate DU, where the modification is triggered by the serving DU.

[0232] In one option, the TA re-establishment includes an indication of a target candidate cell (and / or a target candidate cell configuration, eg, a configuration ID) associated with the previously configured TA value.

[0233] In one embodiment, the message includes beam measurement information, which can be used by the CU and / or candidate DU to configure a UE-specific uplink configuration (e.g., contention-free RACH resources) for transmission of uplink signals between the UE and the target candidate cell for TA establishment. The beam measurement information can be obtained from the CSI report to the serving DU, which can be available to the CU in the request to be provided to the candidate DU.

[0234] When the CU receives a request from the serving DU, the process is similar to the steps described for CU-initiated TA update, e.g., the CU sends a request for TA update to the candidate DU (which may accept or reject), as in the steps for CU-initiated TA update.

[0235] Some embodiments include UE-based TA management. In one set of embodiments, the TA value for the target candidate cell is managed by the UE. In one set of embodiments, the UE receives an RRC reconfiguration message from the CU (e.g., via a serving DU) that includes at least one TA value for the UE and at least one target candidate cell. This may be received after the UE has received an RRC reconfiguration including L1 / L2 inter-cell mobility and after the UE has sent an uplink signal to the target candidate cell according to the received uplink configuration.

[0236] The candidate DU receives at least one uplink signal (e.g., PRACH preamble) in an uplink channel (PRACH time / frequency resource slot) allocated for the purpose of TA establishment for L1 / L2 inter-cell mobility, calculates a TA value valid for the UE and at least one target candidate cell, and the candidate DU sends a message including the at least one TA value to the CU, so that the CU includes it in the RRC reconfiguration, sends it to the serving DU, and the serving DU provides it to the UE. After reception, the UE starts the TA timer.

[0237] At the UE, when the TA timer expires for a given TA value (i.e., for a target candidate cell configured for L1 / L2 inter-cell mobility), the UE considers the TA value invalid, so that if the UE receives an L1 / L2 inter-cell mobility command for the target candidate cell, and the TA value for the target candidate cell is invalid, the UE triggers random access during L1 / L2 inter-cell mobility execution.

[0238] In one embodiment, a TA timer value associated with the TA value is included in an RRC reconfiguration that includes the TA value.

[0239] Fig.11 An example of a communication system 100 according to some embodiments is shown. In this example, the communication system 100 includes a telecommunications network 102 and a core network 106, the telecommunications network 102 including: an access network 104 such as a radio access network (RAN); the core network 106 includes one or more core network nodes 108. The access network 104 includes one or more access network nodes, such as network nodes 110a and 110b (one or more of which may be generally referred to as network nodes 110), or any other similar third generation partnership project (3GPP) access nodes or non-3GPP access points. The network node 110 facilitates direct or indirect connection of user equipment (UE), such as connecting UE 112a, UE 112b, UE 112c, and UE 112d (one or more of which may be generally referred to as UE 112) to the core network 106 through one or more wireless connections.

[0240] Example wireless communications over wireless connections include sending 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. In addition, in different embodiments, the communication system 100 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 via a wired or wireless connection. The communication system 100 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar types of systems.

[0241] UE 112 may be any of a variety of communication devices, including wireless devices that are arranged, configured and / or operable to wirelessly communicate with network node 110 and other communication devices. Similarly, network node 110 is arranged, capable, configured and / or operable to communicate directly or indirectly with UE 112 and / or with other network nodes or devices in telecommunication network 102 to enable and / or provide network access, such as wireless network access, and / or perform other functions, such as management in telecommunication network 102.

[0242] In the depicted example, the core network 106 connects the network node 110 to one or more hosts, such as the host 116. These connections may be direct or indirect via one or more intermediate networks or devices. In other examples, the network node may be directly coupled to the host. The core network 106 includes one or more core network nodes (e.g., core network node 108) constructed with hardware components and software components. The features of these components may be substantially similar to those described with respect to the UE, network nodes, and / or hosts, so that their descriptions are generally applicable to the corresponding components of the core network node 108. The example core network node includes the functions of one or more of a mobile switching center (MSC), a mobility management entity (MME), a home subscriber server (HSS), an access and mobility management function (AMF), a session management function (SMF), an authentication server function (AUSF), a subscription identifier de-contention function (SIDF), a unified data management (UDM), a security edge protection proxy (SEPP), a network open function (NEF), and / or a user plane function (UPF).

[0243] The host 116 may be under the ownership or control of a service provider other than the operator or provider of the access network 104 and / or the telecommunications network 102, and may be operated by or on behalf of the service provider. The host 116 may host various applications to provide one or more services. Examples of such applications include live and pre-recorded audio / video content, data collection services (such as retrieving and compiling data about various environmental conditions detected by multiple UEs), analysis functions, social media, functions for controlling or otherwise interacting with remote devices, functions for alarm and monitoring centers, or any other such functions performed by a server.

[0244] As a whole, Fig.11 The communication system 100 enables connections between UEs, network nodes, and hosts. In this sense, the communication system can be configured to operate according to predefined rules or procedures (such as specific standards), including but 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 next-generation standards (e.g., 6G); Wireless Local Area Network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard (WiFi); and / or any other suitable wireless communication standards, such as 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.

[0245] In some examples, the telecommunication network 102 is a cellular network implementing 3GPP standardized features. Therefore, the telecommunication network 102 can support network slicing to provide different logical networks to different devices connected to the telecommunication network 102. For example, the telecommunication network 102 can provide ultra-reliable low-latency communication (URLLC) services to some UEs, while providing enhanced mobile broadband (eMBB) services to other UEs, and / or providing massive machine type communication (mMTC) / massive IoT services to other UEs.

[0246] In some examples, UE 112 is configured to send and / or receive information without direct human interaction. For example, the UE may be designed to transmit information to access network 104 on a predetermined schedule when triggered by an internal or external event or in response to a request from access network 104. In addition, the UE may be configured to operate in a single RAT or multi-RAT or multi-standard mode. For example, the UE may operate with any one or a combination of Wi-Fi, NR (New Radio), and LTE, i.e., be configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved UMTS Terrestrial Radio Access Network) New Radio-Dual Connectivity (EN-DC).

[0247] In this example, the hub 114 communicates with the access network 104 to facilitate indirect communication between one or more UEs (e.g., UE 112c and / or UE 112d) and a network node (e.g., network node 110b). In some examples, the hub 114 can be a controller, a router, a content source and analysis, or any other communication device described herein with respect to the UE. For example, the hub 114 can be a broadband router that allows the UE to access the core network 106. As another example, the hub 114 can be a controller that sends commands or instructions to one or more actuators in the UE. Commands or instructions can be received from the UE, the network node 110, or through executable code, scripts, processes, or other instructions in the hub 114. As another example, the hub 114 can be a data collector that acts as a temporary storage of UE data, and in some embodiments, analysis or other processing of the data can be performed. As another example, the hub 114 can be a content source. For example, for a UE that is a VR headset, display, speaker, or other media delivery device, the hub 114 can retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, and then the hub 114 directly provides the VR assets, video, audio, or other media or data to the UE after performing local processing and / or after adding additional local content. In another example, the hub 114 acts as a proxy server or coordinator for the UE, especially when one or more UEs are low-energy IoT devices.

[0248] The hub 114 may have a constant / persistent or intermittent connection to the network node 110b. The hub 114 may also allow different communication schemes and / or scheduling between the hub 114 and the UE (e.g., UE 112c and / or UE 112d) and between the hub 114 and the core network 106. In other examples, the hub 114 is connected to the core network 106 and / or one or more UEs via a wired connection. In addition, the hub 114 may be configured to be connected to an M2M service provider and / or to another UE via a direct connection through the access network 104. In some scenarios, the UE may establish a wireless connection with the network node 110 while still being connected via the hub 114 via a wired connection or a wireless connection. In some embodiments, the hub 114 may be a dedicated hub, i.e., its main function is to route communications to / from the UE from / to the network node 110b. In other embodiments, the hub 114 may be a non-dedicated hub, ie, a device operable to route communications between UEs and the network node 110b, but which is also operable as a communications origin and / or destination for certain data channels.

[0249] Fig.12 UE 200 according to some embodiments is shown. As used herein, UE refers to a device capable of, configured, arranged and / or operable to wirelessly communicate with a network node and / or other UEs. Examples of UEs include, but are not limited to, smart phones, mobile phones, cellular phones, voice over IP (VoIP) phones, wireless local loop phones, desktop computers, personal digital assistants (PDAs), wireless cameras, game consoles or devices, music storage devices, rechargeable devices, wearable terminal devices, wireless endpoints, mobile stations, tablet computers, laptop computers, laptop embedded devices (LEEs), laptop mounted devices (LMEs), smart devices, wireless customer terminal equipment (CPEs), vehicle-mounted or vehicle embedded / integrated wireless devices, etc. Other examples include any UE identified by the Third Generation Partnership Project (3GPP), including narrowband Internet of Things (NB-IoT) UEs, machine type communications (MTC) UEs, and / or enhanced MTC (eMTC) UEs.

[0250] The UE may support device-to-device (D2D) communications, such as by implementing 3GPP standards for sidelink communications, dedicated short-range communications (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 associated device. Instead, a UE may represent a device that is intended to be sold to or operated by a human user but may not be associated with a specific human user (e.g., a smart sprinkler controller) or may not initially be associated with a specific human user. Alternatively, a UE may represent a device that is not intended to be sold to or operated by an end user but may be associated with or operated for the benefit of a user (e.g., a smart meter).

[0251] UE 200 includes processing circuitry 202, which is operatively coupled to input / output interface 206, power supply 208, memory 210, communication interface 212, and / or any other components or any combination thereof via bus 204. Some UEs may utilize Fig.12 All or a subset of the components shown in . The level of integration between components may vary from one UE to another UE. In addition, some UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0252] The processing circuit 202 is configured to process instructions and data, and may be configured to implement any sequential state machine operable to execute instructions stored in the memory 210 as a machine-readable computer program. The processing circuit 202 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 microprocessors or digital signal processors (DSPs)) together with appropriate software; or any combination of the above. For example, the processing circuit 202 may include multiple central processing units (CPUs).

[0253] In this example, the input / output interface 206 can be configured to provide one or more interfaces to an input device, an output device, or one or more input and / or output devices. Examples of output devices include speakers, sound cards, video cards, displays, monitors, printers, actuators, transmitters, smart cards, another output device, or any combination thereof. An input device can allow a user to capture information into the UE 200. Examples of input devices include touch-sensitive or presence-sensitive displays, cameras (e.g., digital cameras, digital video cameras, web cameras, etc.), microphones, sensors, mice, trackballs, direction pads, trackpads, rollers, smart cards, etc. The presence-sensitive display can include a capacitive or resistive touch sensor to sense input from a user. The sensor can be, for example, 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 can use an interface port of the same type as an input device. For example, a universal serial bus (USB) port can be used to provide input devices and output devices.

[0254] In some embodiments, the power supply 208 is configured as a battery or a battery pack. Other types of power supplies may be used, such as an external power supply (e.g., a power socket), a photovoltaic device, or a battery. The power supply 208 may also include a power circuit for delivering power from the power supply 208 itself and / or an external power supply to various parts of the UE 200 via an input circuit or an interface such as a power cable. The delivered power may be, for example, for charging the power supply 208. The power circuit may perform any formatting, conversion, or other modification on the power from the power supply 208 so that the power is suitable for the corresponding components of the UE 200 to which the power is supplied.

[0255] The memory 210 may be or be configured to include a memory such as a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic disk, an optical disk, a hard disk, a removable cartridge, a flash drive, etc. In one example, the memory 210 includes one or more application programs 214 (such as an operating system, a web browser application, a gadget, a gadget engine, or other application) and corresponding data 216. The memory 210 may store any of a variety of operating systems or a combination of operating systems used by the UE 200.

[0256] The memory 210 may be configured to include a plurality of physical drive units, such as a redundant array of independent disks (RAID), a flash memory, a USB flash drive, an external hard drive, a thumb drive, a pen drive, a key drive, a high-density digital versatile disk (HD-DVD) optical drive, an internal hard drive, a Blu-ray optical drive, a holographic digital data storage (HDDS) optical drive, an external micro dual in-line memory module (DIMM), a synchronous dynamic random access memory (SDRAM), an external micro DIMM SDRAM, a smart card memory (such as a tamper-proof module in the form of a universal integrated circuit card (UICC), including one or more subscriber identity modules (SIMs), such as USIM and / or ISIM), other memories, or any combination thereof. The UICC may be, for example, an embedded UICC (eUICC), an integrated UICC (iUICC), or a removable UICC commonly referred to as a “SIM card”. The memory 210 may allow the UE 200 to access instructions, applications, etc. stored on a transient memory medium or a non-transitory memory medium to offload data or upload data. An article of manufacture such as utilizing a communication system may be tangibly embodied as or in memory 210 , which may be or include a device-readable storage medium.

[0257] The processing circuit 202 may be configured to communicate with an access network or other network using a communication interface 212. The communication interface 212 may include one or more communication subsystems and may include or be communicatively coupled to an antenna 222. The communication interface 212 may include one or more transceivers for communication, 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 218 and / or a receiver 220 suitable for providing network communications (e.g., optical, electrical, frequency allocation, etc.). In addition, the transmitter 218 and the receiver 220 may be coupled to one or more antennas (e.g., antenna 222) and may share circuit components, software, or firmware, or alternatively be implemented separately.

[0258] In the illustrated embodiment, the communication functionality of the communication interface 212 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communication such as Bluetooth, near field communication, location-based communication such as using a global positioning system (GPS) to determine location, another similar communication functionality, or any combination thereof. Communication may be implemented according to one or more communication protocols and / or standards, such as IEEE 802.11, code division multiple 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), etc.

[0259] Regardless of the type of sensor, the UE may provide an output of the data captured by its sensor via a wireless connection to a network node through its communication interface 212. The data captured by the UE's sensor may be communicated to the network node via another UE via a wireless connection. The output may be periodic (e.g., once every 15 minutes if it reports a sensed temperature), random (e.g., to even out the load from reports from several sensors), in response to a trigger event (e.g., sending an alarm when moisture is detected), in response to a request (e.g., a user-initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0260] As another example, the UE includes an actuator, motor, or switch associated with a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input, the state of the actuator, motor, or switch can change. For example, the UE can include a motor that adjusts a control surface or rotor of a drone in flight based on the received input, or adjusts a robotic arm performing a medical procedure based on the received input.

[0261] When in the form of an Internet of Things (IoT) device, a UE may be a device for use in one or more application domains including, but not limited to, urban wearable technology, extended industrial applications, and healthcare. Non-limiting examples of such IoT devices are the following devices or devices embedded in the following: a connected refrigerator or freezer, a TV, connected lighting devices, an electric meter, a robotic 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 (such as 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 head-mounted display for augmented reality (AR) or virtual reality (VR), a wearable device for tactile enhancement or sensory enhancement, a sprinkler, an animal or item tracking device, a sensor for monitoring plants or animals, an industrial robot, an unmanned aerial vehicle (UAV), and any kind of medical device (such as a heart rate monitor or a remotely controlled surgical robot). In addition to the description of Fig.12 In addition to the other components depicted in the illustrated UE 200 , a UE in the form of an IoT device may include circuitry and / or software depending on the intended application of the IoT device.

[0262] As another specific example, in an IoT scenario, a UE may represent a machine or other device that performs monitoring and / or measurement and transmits the results of such monitoring and / or measurement to another UE and / or a network node. In this case, the UE may be an M2M device, which may be referred to as an MTC device in the 3GPP context. As a specific example, a UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, bus, truck, ship, and airplane, or other equipment capable of monitoring and / or reporting its operating status or other functions associated with its operation.

[0263] In fact, any number of UEs may be used together with respect to a single use case. For example, a first UE may be a drone or integrated in a drone and provide speed information of the drone (obtained by a speed sensor) to a second UE that is a remote controller operating the drone. When a user makes a change 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 speed of the drone. The first UE and / or the second UE may also include more than one of the above functions. For example, a UE may include a sensor and an actuator and handle data communications for both the speed sensor and the actuator.

[0264] Fig.13A network node 300 according to some embodiments is shown. As used herein, a network node refers to a device capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or other network nodes or devices in a telecommunications 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 Node Bs (gNBs)).

[0265] Base stations may be classified based on the amount of coverage they provide (or in other words, their transmission power level), and therefore depending on the amount of coverage provided, a base station may be referred to as a femto base station, a pico base station, a micro base station, or a macro base station. A base station may be a relay node or a relay donor node that controls a relay. A network node may also include one or more (or all) parts of a distributed radio base station, such as a centralized digital unit and / or a remote radio unit (RRU), sometimes referred to as a remote radio head (RRH). Such a remote radio unit may or may not be integrated with an antenna as an antenna-integrated radio. Portions of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0266] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as an MSR BS, a network controller such as a radio network controller (RNC) or a base station controller (BSC), a base transceiver station (BTS), a transmission point, a transmission node, a multi-cell / multicast coordination entity (MCE), an operation and maintenance (O&M) node, an operation support system (OSS) node, a self-organizing network (SON) node, a positioning node (e.g., an evolved serving mobile location center (E-SMLC)), and / or minimization of drive tests (MDT).

[0267] The network node 300 includes a processing circuit 302, a memory 304, a communication interface 306, and a power supply 308. The network node 300 may be composed of multiple physically separated components (e.g., a node B component and an RNC component, or a BTS component and a BSC component, etc.), each of which may have its own components. In certain scenarios where the network node 300 includes multiple separated components (e.g., a BTS component and a BSC component), one or more separated components may be shared between several network nodes. For example, a single RNC may control multiple node Bs. In such scenarios, each unique node B and RNC pair may be considered to be a single separated network node in some instances. In some embodiments, the network node 300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memories 304 for different RATs), and some components may be reused (e.g., the same antenna 310 may be shared by different RATs). The network node 300 may also include multiple sets of the various illustrated components for different wireless technologies (e.g., GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, radio frequency identification (RFID), or Bluetooth wireless technologies) integrated into the network node 300. These wireless technologies may be integrated into the same or different chips or chipsets and other components within the network node 300.

[0268] The processing circuit 302 may include a microprocessor, a controller, a microcontroller, a central processing unit, a digital signal processor, an application specific integrated circuit, a field programmable gate array, or any other suitable computing device, a combination of one or more of resources, or a combination of hardware, software and / or encoded logic that is operable to provide network node 300 functionality alone or in conjunction with other network node 300 components (such as memory 304).

[0269] In some embodiments, processing circuitry 302 includes a system on a chip (SOC). In some embodiments, processing circuitry 302 includes one or more of radio frequency (RF) transceiver circuitry 312 and baseband processing circuitry 314. In some embodiments, radio frequency (RF) transceiver circuitry 312 and baseband processing circuitry 314 may be on separate chips (or chipsets), boards, or units (such as a radio unit and a digital unit). In alternative embodiments, part or all of RF transceiver circuitry 312 and baseband processing circuitry 314 may be on the same chip or chipset, board, or unit.

[0270] Memory 304 may include any form of volatile or non-volatile computer-readable memory, including, but not limited to, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (e.g., hard disk), removable storage media (e.g., flash drive, compact disk (CD) or digital video disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory device that stores information, data and / or instructions that can be used by processing circuit 302. Memory 304 may store any suitable instructions, data or information, including computer programs, software, applications including one or more of logic, rules, codes, tables, and / or other instructions that can be executed by processing circuit 302 and utilized by network node 300. Memory 304 may be used to store any calculations performed by processing circuit 302 and / or any data received via communication interface 306. In some embodiments, processing circuit 302 and memory 304 are integrated.

[0271] The communication interface 306 is used for wired or wireless communication of signaling and / or data between network nodes, access networks and / or UEs. As shown in the figure, the communication interface 306 includes a port / terminal 316 for sending data to the network and receiving data from the network, for example, via a wired connection. The communication interface 306 also includes a radio front-end circuit 318, which can be coupled to the antenna 310 or to a part of the antenna 310 in some embodiments. The radio front-end circuit 318 includes a filter 320 and an amplifier 322. The radio front-end circuit 318 can be connected to the antenna 310 and the processing circuit 302. The radio front-end circuit can be configured to adjust the signal communicated between the antenna 310 and the processing circuit 302. The radio front-end circuit 318 can receive digital data to be sent to other network nodes or UEs via a wireless connection. The radio front-end circuit 318 can use a combination of a filter 320 and / or an amplifier 322 to convert the digital data into a radio signal with appropriate channel and bandwidth parameters. The radio signal can then be sent via the antenna 310. Similarly, when receiving data, antenna 310 may collect radio signals, which are then converted into digital data by radio front end circuitry 318. The digital data may be passed to processing circuitry 302. In other embodiments, the communication interface may include different components and / or different combinations of components.

[0272] In certain alternative embodiments, the network node 300 does not include a separate radio front end circuit 318, but rather the processing circuit 302 includes the radio front end circuit and is connected to the antenna 310. Similarly, in some embodiments, all or some of the RF transceiver circuit 312 is part of the communication interface 306. In other embodiments, the communication interface 306 includes one or more ports or terminals 316, the radio front end circuit 318, and the RF transceiver circuit 312 as part of a radio unit (not shown), and the communication interface 306 communicates with the baseband processing circuit 314 as part of a digital unit (not shown).

[0273] Antenna 310 may include one or more antennas or antenna arrays configured to send and / or receive wireless signals. Antenna 310 may be coupled to radio front end circuit 318 and may be any type of antenna capable of wirelessly transmitting and receiving data and / or signals. In a particular embodiment, antenna 310 is separate from network node 300 and may be connected to network node 300 via an interface or port.

[0274] Antenna 310, communication interface 306 and / or processing circuit 302 may be configured to perform any receiving operation and / or specific acquisition operation described herein as being performed by a network node. Any information, data and / or signal may be received from a UE, another network node and / or any other network device. Similarly, antenna 310, communication interface 306 and / or processing circuit 302 may be configured to perform any transmission operation described herein as being performed by a network node. Any information, data and / or signal may be sent to a UE, another network node and / or any other network device.

[0275] The power supply 308 provides power to the various components of the network node 300 in a form suitable for the respective components (e.g., at the voltage and current levels required by each respective component). The power supply 308 may also include or be coupled to a power management circuit to provide power to the components of the network node 300 to perform the functions described herein. For example, the network node 300 may be connected to an external power source (e.g., an electrical grid, an electrical outlet) via an input circuit or an interface such as a cable, whereby the external power source provides power to the power circuit of the power supply 308. As another example, the power supply 308 may include a power source in the form of a battery or battery pack that is connected to or integrated in the power circuit. If the external power source fails, the battery may provide backup power.

[0276] Embodiments of the network node 300 may include, in addition to Fig.13Additional components beyond those shown are used to provide functionality for specific aspects of the network node, including any functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 300 may include a user interface device to allow information to be input into the network node 300 and to allow information to be output from the network node 300. This may allow a user to perform diagnostics, maintenance, repair, and other management functions of the network node 300.

[0277] Fig.14 is a block diagram of a host 400 according to various aspects described herein, and the host 400 may be Fig.11 1. The host 400 may be or include various combinations of hardware and / or software, including processing resources in a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, a container, or a server cluster. The host 400 may provide one or more services to one or more UEs.

[0278] Host 400 includes processing circuitry 402, which is operably coupled to input / output interface 406, network interface 408, power supply 410, and memory 412 via bus 404. Other components may be included in other embodiments. The features of these components may be substantially similar to those described with respect to previous figures (such as Figure 3 and Figure 4 ) so that its description is generally applicable to corresponding components of host 400.

[0279] The memory 412 may include one or more computer programs, including one or more host applications 414 and data 416, which may include user data, such as data generated by the UE for the host 400 or data generated by the host 400 for the UE. An embodiment of the host 400 may utilize only a subset or all of the components shown. The host application 414 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Codec (VVC), High Efficiency Video Codec (HEVC), Advanced Video Codec (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, Advanced Audio Codec (AAC), MPEG, G.711), including transcoding for multiple different categories, types, or implementations of UEs (e.g., mobile phones, desktop computers, wearable display systems, head-up display systems). The host application 414 may also provide user authentication and permission checks, and may periodically report health, routing, and content availability to a central node (such as a device in or on the edge of a core network). Thus, the host 400 may select and / or indicate different hosts for over-the-top services for the UE. The main application 414 can support various protocols, such as HTTP Live Streaming (HLS) protocol, Real Time Messaging Protocol (RTMP), Real Time Streaming Protocol (RTSP), HTTP Dynamic Adaptive Streaming (MPEG-DASH), etc.

[0280] Fig.15 5 is a block diagram showing a virtualized environment 500 in which the functions implemented by some embodiments can be virtualized. In this context, virtualization means creating a virtual version of a device or equipment, which may include a virtualized hardware platform, storage device, and network resources. As used herein, virtualization can be applied to any device or component thereof described herein, and relates to an implementation in which at least a portion of a function is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components performed by one or more virtual machines (VMs), which are implemented in one or more virtual environments 500 hosted by one or more hardware nodes, such as hardware computing devices operating as network nodes, UEs, core network nodes, or hosts. In addition, in embodiments where a virtual node does not require a radio connection (e.g., a core network node or host), the node may be fully virtualized.

[0281] Application 502 (which may alternatively be referred to as a software instance, a virtual device, a network function, a virtual node, a virtual network function, etc.) runs in a virtualized environment Q400 to implement some features, functions and / or benefits of some embodiments disclosed herein.

[0282] Hardware 504 includes processing circuitry, memory storing software and / or instructions executable by the hardware processing circuitry, and / or other hardware devices as described herein, such as network interfaces, input / output interfaces, etc. The software may be executed by the processing circuitry to instantiate one or more virtualization layers 506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 508a and VMs 508b (one or more of which may be generally referred to as VMs 508), and / or perform any of the functions, features, and / or benefits described with respect to some embodiments described herein. Virtualization layer 506 may present a virtual operating platform that looks like networked hardware to VMs 508.

[0283] The VM 508 includes virtual processing, virtual memory, virtual networking or interfaces, and virtual storage, and may be run by a corresponding virtualization layer 506. Different embodiments of instances of virtual devices 502 may be implemented on one or more VMs 508, and may be implemented in different ways. Virtualization of hardware is referred to in some contexts as network function virtualization (NFV). NFV may be used to consolidate many network device types onto industry standard high-capacity server hardware, physical switches, and physical storage that may be located in data centers and customer premises equipment.

[0284] In the context of NFV, VMs 508 can be software implementations of physical machines that run programs as if they were executed on physical non-virtualized machines. Each of the VMs 508 and the portion of the hardware 504 on which the VM is executed (which is hardware dedicated to the VM and / or hardware shared by the VM with other VMs in the VM) form a separate virtual network element. Still in the context of NFV, a virtual network function is responsible for handling a specific network function running in one or more VMs 508 on top of the hardware 504 and corresponding to an application 502.

[0285] Hardware 504 may be implemented in a standalone network node with general or specific components. Hardware 504 may implement some functions via virtualization. Alternatively, hardware 504 may be part of a larger hardware cluster (e.g., such as in a data center or CPE), where many hardware nodes work together and are managed via management and orchestration 510, which in particular oversees the lifecycle management of application 502. In some embodiments, hardware 504 is coupled to one or more radio units, each of which includes one or more transmitters and one or more receivers that may be coupled to one or more antennas. The radio unit may communicate directly with other hardware nodes via one or more appropriate network interfaces, and may be used in combination with virtual components to provide a virtual node with radio capabilities, such as a radio access node or base station. In some embodiments, a control system 512 may be used to provide some signaling, which may alternatively be used for communication between hardware nodes and radio units.

[0286] Fig.16 A communication diagram of a host 602 communicating with a UE 606 via a network node 604 over a partially wireless connection according to some embodiments. Figure 6 Describe the UE discussed in the previous paragraph (such as Fig.11 UE 112a and / or Fig.12 UE 200), network nodes (such as Fig.11 The network node 110a and / or Fig.13 network nodes 300) and hosts (such as Fig.11 Host 116 and / or Fig.14 An example implementation of host 400).

[0287] Similar to the host 400, an embodiment of the host 602 includes hardware, such as a communication interface, a processing circuit, and a memory. The host 602 also includes software stored in or accessible by the host 602 and executable by the processing circuit. The software includes a host application operable to provide services to a remote user, such as a UE 606 connected via an over-the-top (OTT) connection 650 extending between the UE 606 and the host 602. When providing services to the remote user, the host application can provide user data transmitted using the OTT connection 650.

[0288] The network node 604 includes hardware that enables it to communicate with the host 602 and the UE 606. The connection 660 can be direct or through a core network (such as Fig.11 The core network 106 of the present invention) and / or one or more other intermediate networks, such as one or more public networks, private networks or managed networks. For example, the intermediate network can be a backbone network or the Internet.

[0289] UE 606 includes hardware and software, which is stored in UE 606 or accessible by UE 606 and can be executed by UE processing circuitry. The software includes a client application, such as a web browser or an operator-specific "app", which is operable to provide services to human or non-human users via UE 606 with the support of host 602. In host 602, the execution host application can communicate with the execution client application via an OTT connection 650 terminated at UE 606 and host 602. When providing services to the user, the client application of the UE can receive request data from the host application of the host and provide user data in response to the request data. The OTT connection 650 can transmit both request data and user data. The client application of the UE can interact with the user to generate user data that it provides to the host application via the OTT connection 650.

[0290] The OTT connection 650 may extend via a connection 660 between the host 602 and the network node 604 and via a wireless connection 670 between the network node 604 and the UE 606 to provide a connection between the host 602 and the UE 606. The connection 660 and the wireless connection 670 over which the OTT connection 650 may be provided have been drawn abstractly to illustrate communications between the host 602 and the UE 606 via the network node 604 without explicit reference to any intermediate devices and the precise routing of messages via those devices.

[0291] As an example of transmitting data via OTT connection 650, in step 608, host 602 provides user data, which can be performed by executing a host application. In some embodiments, the user data is associated with a specific human user interacting with UE 606. In other embodiments, the user data is associated with UE 606, and UE 606 shares data with host 602 without explicit human interaction. In step 610, host 602 initiates a transmission carrying user data to UE 606. Host 602 can initiate the transmission in response to a request transmitted by UE 606. The request can be caused by human interaction with UE 606 or by the operation of a client application executed on UE 606. According to the teachings of the embodiments described throughout the present disclosure, the transmission can be transmitted via network node 604. Therefore, according to the teachings of the embodiments described throughout the present disclosure, in step 612, network node 604 transmits the user data carried in the transmission initiated by host 602 to UE 606. In step 614 , the UE 606 receives the user data carried in the transmission, which may be performed by a client application executing on the UE 606 that is associated with a host application executed by the host 602 .

[0292] In some examples, UE 606 executes a client application that provides user data to host 602. The user data may be provided as a reaction or response to data received from host 602. Therefore, in step 616, UE 606 may provide the user data, which may be performed by executing the client application. In providing the user data, the client application may also take into account user input received from the user via the input / output interface of UE 606. Regardless of the specific manner in which the user data is provided, UE 606 initiates transmission of the user data to host 602 via network node 604 in step 618. In step 620, in accordance with the teachings of the embodiments described throughout the present disclosure, network node 604 receives user data from UE 606 and initiates transmission of the received user data to host 602. In step 622, host 602 receives the user data carried in the transmission initiated by UE 606.

[0293] One or more of the various embodiments improve the performance of OTT services provided to UE 606 using OTT connection 650, where wireless connection 670 forms the last leg. More specifically, the teachings of these embodiments can improve the latency of directly activating SCells through RRC and the power consumption of user equipment, thereby providing benefits such as reduced user waiting time and extended battery life.

[0294] In an example scenario, plant status information may be collected and analyzed by the host 602. As another example, the host 602 may process audio and video data that may have been retrieved from the UE for use in creating a map. As another example, the host 602 may collect and analyze real-time data to help control vehicle congestion (e.g., control traffic lights). As another example, the host 602 may store surveillance videos uploaded by the UE. As another example, the host 602 may store or control access to media content (such as video, audio, VR, or AR that may be broadcast, multicast, or unicast to the UE). As other examples, the host 602 may be used for energy pricing, remote control of non-time-critical electrical loads to balance power generation demand, location services, presentation services (such as compiling maps of data collected from remote devices, etc.), or any other function that collects, retrieves, stores, analyzes, and / or transmits data.

[0295] In some examples, a measurement process may be provided for the purpose of monitoring data rates, delays, and other factors improved by one or more embodiments. In response to changes in the measurement results, there may also be an optional network function for reconfiguring the OTT connection 650 between the host 602 and the UE 606. The measurement process and / or network function for reconfiguring the OTT connection may be implemented in software and hardware of the host 602 and / or the UE 606. In some embodiments, sensors (not shown) may be deployed in or associated with other devices through which the OTT connection 650 passes; the sensors may participate in the measurement process by providing the values ​​of the monitored quantities exemplified above, or by providing the values ​​of other physical quantities from which the software can calculate or estimate the monitored quantities. The reconfiguration of the OTT connection 650 may include message formats, retransmission settings, preferred routes, etc.; the reconfiguration does not require direct changes to the operation of the network node 604. Such processes and functions may be known and practiced in the art. In a particular embodiment, the measurement may involve proprietary UE signaling that facilitates the host 602 to measure throughput, propagation time, etc., etc. Measurements can be made because the software enables the transmission of messages, particularly empty or "dummy" messages, using the OTT connection 650 while monitoring propagation times, errors, etc.

[0296] Fig.17 is a flow chart illustrating an example method in a wireless device according to certain embodiments. In certain embodiments, Fig.17 One or more steps may be performed by Fig.12 The described UE 200 performs. The wireless device is capable of performing TA management between the wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility. The wireless device operates in a serving cell different from the target candidate cell.

[0297] The method begins at step 1712, where a wireless device (e.g., UE 200) receives an uplink configuration for a target candidate cell. In a specific embodiment, the uplink configuration for the target candidate cell is received from a first network node, where the first network node corresponds to a serving DU. The uplink configuration for the target candidate cell is generated by a candidate DU associated with the target candidate cell configured for L1 / L2 inter-cell mobility.

[0298] In a particular embodiment, the uplink configuration for the target candidate cell includes a RACH configuration for the target candidate cell.

[0299] In a particular embodiment, the uplink configuration includes a trigger condition for sending an uplink message to the target candidate cell.The uplink configuration may be associated with a validity time.

[0300] In a particular embodiment, a wireless device may receive an uplink configuration according to any of the embodiments and examples described herein.

[0301] The wireless device may start a timer at step 1714. In some embodiments, the wireless device may use a timer to determine when to refresh the TA value.

[0302] At step 1716, the wireless device sends an uplink message to the target candidate cell based on the uplink configuration. In a particular embodiment, the uplink message sent to the target candidate cell based on the uplink configuration includes a random access preamble associated with one or more SSBs and CSI-RS resources.

[0303] In certain embodiments, the uplink message sent to the target candidate cell based on the uplink configuration includes an SRS.

[0304] In certain embodiments, the wireless device may send an uplink message according to any of the embodiments and examples described herein.

[0305] The wireless device receives a TA value associated with the target candidate cell at step 1718. The TA value is received in a message from the serving cell.

[0306] In a particular embodiment, the TA value associated with the target candidate cell received via the serving cell is received in an L1 / L2 inter-cell mobility command indicating that the wireless device should perform L1 / L2 inter-cell mobility to the target candidate cell, or is received in an RRC reconfiguration received after the wireless device has been configured with L1 / L2 inter-cell mobility and after the UE has sent an uplink message to the target candidate cell.

[0307] In a particular embodiment, the TA value associated with the target candidate cell is received from a first network node, wherein the first network node corresponds to the serving DU.

[0308] In a particular embodiment, receiving an uplink configuration for a target candidate cell includes receiving an uplink configuration for the target candidate cell in a first message, and sending an uplink message to the target candidate cell includes sending an uplink message to the target candidate cell in response to receiving a second message. The first message may include an RRC message, and the second message includes a PDCCH command. The second message is received by the wireless device after the wireless device has received the first message.

[0309] In some embodiments, the wireless device may need to refresh the TA value. For example, the wireless device may have moved to a new location with a larger or smaller TA value. The wireless device may autonomously perform the refresh based on a timer started at step 1714 or based on other events or conditions. For example, to refresh in some embodiments, the method may return to step 1712, where the wireless device receives an update to the uplink configuration for the target candidate cell; step 1716, where the wireless device sends an uplink message to the target candidate cell based on the updated uplink configuration; and step 1718, where the wireless device receives the TA value associated with the target candidate cell. The TA value is received in a message from the serving cell.

[0310] In a particular embodiment, L1 / L2 inter-cell mobility includes receiving signaling indicating a change of a serving cell via a signaling layer, which is a lower layer than the RRC layer in the protocol stack.

[0311] Can Fig.17 Method 1700 may be modified, added, or omitted. In addition, Fig.17 One or more steps in the method may be performed in parallel or in any suitable order.

[0312] Fig.18 is a flow chart illustrating an example method in a serving network node according to certain embodiments. In certain embodiments, Fig.18 One or more steps may be performed by Fig.13 The described network node 300 performs. The network node is operable as a candidate DU for TA management between a wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility of the candidate DU.

[0313] The method starts at step 1812, where a network node (e.g., network node 300) receives a message from a serving CU requesting TA establishment for a wireless device (e.g., UE 200) and at least one target candidate cell. The message requesting TA establishment may include any message described with respect to the embodiments and examples described herein.

[0314] At step 1814, the network node sends the uplink configuration for the target candidate cell and the wireless device to the serving CU. Fig.17 And the above-mentioned embodiments and examples describe the uplink configuration in more detail.

[0315] At step 1816, the network node receives an uplink message from the wireless device based on the uplink configuration.The uplink configuration is described in more detail with respect to the above embodiments and examples.

[0316] At step 1818, the network node sends the TA value associated with the target candidate cell and calculated based on the received uplink message to the wireless device via the serving CU.

[0317] In certain embodiments, the method may also continue to step 1820, where the wireless device starts a timer in response to sending the TA value to the wireless device. In response to the timer expiring, the method may return to step 1818, where the network node sends a new TA value associated with the target candidate cell to the wireless device via the serving CU.

[0318] In certain embodiments, the message requesting TA establishment for the wireless device includes a request to provide L1 / L2 inter-cell candidate cell configuration.

[0319] Can Fig.18 Method 1800 may be modified, added, or omitted. In addition, Fig.18 One or more steps in the method may be performed in parallel or in any suitable order.

[0320] Fig.19 is a flow chart illustrating an example method in a candidate network node according to certain embodiments. In certain embodiments, Fig.19 One or more steps may be performed by Fig.13 The described network node 300 performs. The network node is operable as a serving CU for TA management between a wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility.

[0321] The method starts at step 1912, where a network node (eg, network node 300) sends a request to a candidate DU requesting TA establishment for a wireless device (eg, UE 200) and at least one target candidate cell.

[0322] In certain embodiments, the message requesting TA establishment for the wireless device includes a request to provide L1 / L2 inter-cell candidate cell configuration.

[0323] At step 1914, the network node receives an uplink configuration for the target candidate cell and the wireless device from the candidate DU. The uplink configuration is described in more detail with respect to the above embodiments and examples.

[0324] At step 1916, the network node sends an uplink message to the serving DU, the uplink message to be sent to the wireless device. The uplink message includes an uplink configuration.

[0325] At step 1918, the network node receives a TA value associated with the target candidate cell from the candidate DU.

[0326] At step 1920, the network node sends the TA value to the wireless device via the serving DU.

[0327] In certain embodiments, the method may continue to step 1922, where the network node starts a timer in response to sending the TA value to the wireless device. In response to the timer expiring, the wireless device may return to step 1912, where the network node sends a request to the candidate DU requesting a new TA establishment for the wireless device and at least one target candidate cell.

[0328] Can Fig.19 Method 1900 is modified, added or omitted. In addition, Fig.19 One or more steps in the method may be performed in parallel or in any suitable order.

[0329] Without departing from the scope of the present invention, the methods disclosed herein may be modified, added or omitted. These methods may include more, less or other steps. In addition, the steps may be performed in any suitable order.

[0330] The foregoing description sets forth many specific details. However, it should be appreciated that the embodiments may be practiced without these specific details. In other cases, well-known circuits, structures, and techniques are not shown in detail to avoid obscuring the understanding of this specification. With the included description, one of ordinary skill in the art will be able to implement appropriate functionality without undue experimentation.

[0331] References in the specification to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0332] Although the present disclosure has been described in terms of specific embodiments, changes and substitutions of the embodiments will be apparent to those skilled in the art. Therefore, the above description of the embodiments does not limit the present disclosure. Other changes, substitutions and variations are possible without departing from the scope of the present disclosure as defined by the following claims.

[0333] Some example embodiments are described below. Group A Embodiment 1. A method for timing advance (TA) management between a wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility, performed by a wireless device, the method comprising: - receiving an uplink configuration for a target candidate cell; -sending an uplink message to the target candidate cell based on the uplink configuration; and - Receiving a TA value associated with a target candidate cell, wherein the TA value is received in a message from a serving cell. 2. A method according to embodiment 1, wherein the TA value associated with the target candidate cell received via the serving cell is received in an L1 / L2 inter-cell mobility command, and the L1 / L2 inter-cell mobility command indicates that the wireless device should perform L1 / L2 inter-cell mobility on the target candidate cell. 3. A method according to embodiment 1, wherein the TA value associated with the target candidate cell received via the serving cell is received in an RRC reconfiguration received after the wireless device has been configured with L1 / L2 inter-cell mobility and after the UE has sent an uplink message to the target candidate cell. 4. The method of embodiment 1, wherein the uplink configuration for the target candidate cell is received from a first network node, and the first network node corresponds to a serving DU. 5. The method of embodiment 1, wherein the uplink configuration for the target candidate cell is generated by a candidate DU associated with the target candidate cell configured for L1 / L2 inter-cell mobility. 6. The method of embodiment 1, wherein the uplink configuration for the target candidate cell is received from a first network node, wherein the first network node corresponds to the serving DU. 7. According to the method of embodiment 1, the uplink configuration for the target candidate cell is a random access channel configuration for the target candidate cell. 8. A method according to embodiment 1, wherein the uplink message to the target candidate cell based on the UL configuration is a random access preamble associated with one or more SSB and / or CSI-RS resources. 9. The method according to embodiment 1, wherein the uplink message to the target candidate cell based on the UL configuration is a sounding reference signal (SRS). 10. The method according to embodiment 1 further includes: receiving an update of an uplink configuration for a target candidate cell, and sending an uplink message to the target candidate cell based on the updated uplink configuration, and receiving a TA value associated with the target candidate cell, wherein the TA value is received in a message from a serving cell. 11. The method according to embodiment 1, wherein the uplink configuration includes a trigger condition for sending an uplink message to the target candidate cell. 12. A method performed by a wireless device for reestablishing / maintaining an existing timing advance (TA) value between a UE and at least one target candidate cell for L1 / L2 inter-cell mobility, the method comprising: - When a TA value associated with a target candidate cell is received, a timer is started; - upon expiration of a timer associated with the validity of the TA value: sending a UL message to the serving DU requesting a new TA value associated with the target candidate cell, or sending a UL message to the target candidate cell based on a previously received UL configuration; and - Receiving a TA value associated with a target candidate cell, wherein the TA value is received in a message from a serving cell. 13. A method performed by a wireless device, the method comprising: -Any of the above-mentioned wireless device steps, features or functions may exist alone or in combination with the above-mentioned other steps, features or functions. 14. The method according to the preceding embodiment further comprises one or more of the above-mentioned additional wireless device steps, features or functions. 15. The method according to any of the preceding embodiments, further comprising: - provide user data; and - Forwarding user data to a host computer via transmission to a base station. Group B Example 16. A method performed by a base station operating as a candidate distributed unit (candidate DU) for timing advance (TA) management between a wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility of the candidate DU, the method comprising: - receiving a request from the CU for TA establishment for the wireless device and at least one target candidate cell; - Sending uplink (UL) configuration for target candidate cells and wireless devices to the CU; - receiving a UL message from the wireless device based on the UL configuration; and - Calculate the TA value associated with the target candidate cell and send the TA value to the CU. 17. A method performed by a base station operating as a central unit (CU) for timing advance (TA) management between a wireless device and at least one target candidate cell for L1 / L2 inter-cell mobility of a candidate DU, the method comprising: - Sending a request to the candidate DU requesting TA establishment for the wireless device and at least one target candidate cell; - receiving a UL configuration for a target candidate cell and wireless device from a candidate DU; - Sending a UL message to the serving DU, the UL message to be sent to the wireless device, wherein the UL message includes a UL configuration; - receiving a TA value associated with a target candidate cell from the candidate DU; and -Send TA value to serving DU. 18. A method performed by a base station, the method comprising: - Any of the steps, features or functions described above with respect to the base station may exist alone or in combination with the other steps, features or functions described above. 19. The method according to the aforementioned embodiment further includes one or more of the above-mentioned additional base station steps, features or functions. 20. The method according to any of the preceding embodiments, further comprising: - Access user data; and -Forward user data to a host computer or wireless device. Group C Example 21. A mobile terminal, comprising: - a processing circuit configured to perform any of the steps of any of the embodiments of Group A; and - A power circuit configured to provide power to the wireless device. 22. A base station, comprising: - a processing circuit configured to perform any of the steps of any of the embodiments of Group B; - A power circuit configured to provide power to the wireless device. 23. A user equipment (UE), comprising: - an antenna configured to send and receive wireless signals; - a radio front end circuit connected to the antenna and the processing circuit and configured to condition signals transmitted between the antenna and the processing circuit; - a processing circuit configured to perform any of the steps of any of the embodiments of group A; - an input interface connected to the processing circuitry and configured to allow information to be input to the UE for processing by the processing circuitry; - an output interface connected to the processing circuit and configured to output information that has been processed by the processing circuit from the UE; - A battery connected to the processing circuit and configured to supply power to the UE. 24. A communication system including a host computer, comprising: - processing circuitry configured to provide user data; and - a communication interface configured to forward user data to a cellular network for transmission to a user equipment (UE), The cellular network comprises a base station having a radio interface and a processing circuit, the processing circuit of the base station being configured to perform any of the steps of any one of the embodiments of Group B. 25. The communication system according to the aforementioned embodiment further includes a base station. 26. The communication system according to the two aforementioned embodiments further includes a UE, wherein the UE is configured to communicate with the base station. 27. The communication system according to any one of the preceding three embodiments, wherein: - the processing circuitry of the host computer is configured to execute a host application to provide user data; and - The UE comprises a processing circuit configured to execute a client application associated with a host application. 28. A method implemented in a communication system, the communication system comprising a host computer, a base station and a user equipment (UE), the method comprising: - at the host computer, providing user data; and - At a host computer, initiating transmission of bearer user data to the UE via a cellular network including a base station, wherein the base station performs any of the steps of any of the Group B embodiments. 29. The method according to the aforementioned embodiment further includes sending user data at the base station. 30. The method according to the preceding two embodiments, wherein the user data is provided by executing a host application at a host computer, the method further comprising executing a client application associated with the host application at a UE. 31. A user equipment (UE) configured to communicate with a base station, the UE comprising a radio interface and a processing circuit, the processing circuit being configured to perform any one of the above three embodiments. 32. A communication system including a host computer, comprising: - processing circuitry configured to provide user data; and - a communication interface configured to forward user data to a cellular network for transmission to a user equipment (UE), - wherein the UE comprises a radio interface and a processing circuit, the components of the UE being configured to perform any of the steps of any of the Group A embodiments. 33. The communication system according to the preceding embodiment, wherein the cellular network further comprises a base station configured to communicate with the UE. 34. The communication system according to the above two embodiments, wherein: - the processing circuitry of the host computer is configured to execute a host application to provide user data; and - The processing circuitry of the UE is configured to execute a client application associated with the host application. 35. A method implemented in a communication system, the communication system comprising a host computer, a base station and a user equipment (UE), the method comprising: - at the host computer, providing user data; and - At a host computer, initiating transmission of bearer user data to a UE via a cellular network including a base station, wherein the UE performs any of the steps of any one of the embodiments of Group A. 36. The method according to the aforementioned embodiment further includes, at the UE, receiving user data from the base station. 37. A communication system including a host computer, comprising: - a communication interface configured to receive user data originating from a transmission from a user equipment (UE) to a base station, - wherein the UE comprises a radio interface and a processing circuit, the processing circuit of the UE being configured to perform any of the steps of any one of the Group A embodiments. 38. The communication system according to the aforementioned embodiment further includes a UE. 39. The communication system according to the aforementioned two embodiments further includes a base station, wherein the base station includes a radio interface and a communication interface, the radio interface is configured to communicate with the UE, and the communication interface is configured to forward user data carried by the transmission from the UE to the base station to the host computer. 40. The communication system according to any one of the preceding three embodiments, wherein: - the processing circuitry of the host computer is configured to execute a host application; and - The processing circuitry of the UE is configured to execute a client application associated with the host application, thereby providing user data. 41. The communication system according to any one of the preceding four embodiments, wherein: - the processing circuitry of the host computer is configured to execute the host application to provide the requested data; and - The processing circuitry of the UE is configured to execute a client application associated with the host application to provide user data in response to the request data. 42. A method implemented in a communication system, the communication system comprising a host computer, a base station and a user equipment (UE), the method comprising: - At a host computer, receiving user data sent from a UE to a base station, wherein the UE performs any one of the steps of any one of the embodiments of Group A. 43. The method according to the aforementioned embodiment further includes, at the UE, providing user data to the base station. 44. The method according to the above two embodiments further includes: - at the UE, executing a client application, thereby providing user data to be sent; and - At the host computer, executing a host application associated with the client application. 45. The method according to any of the above three embodiments further comprises: - At the UE, executing a client application; and - receiving, at the UE, input data to the client application, the input data being provided at the host computer by executing a host application associated with the client application, - wherein user data to be transmitted is provided by the client application in response to input data. 46. ​​A communication system comprising a host computer, the host computer comprising a communication interface, the communication interface being configured to receive user data originating from a transmission from a user equipment (UE) to a base station, wherein the base station comprises a radio interface and a processing circuit, the processing circuit of the base station being configured to perform any of the steps of any one of the embodiments of Group B. 47. According to the communication system of the foregoing embodiment, it also includes a base station. 48. The communication system according to the aforementioned two embodiments further includes a UE, wherein the UE is configured to communicate with the base station. 49. The communication system according to any one of the preceding three embodiments, wherein: - the processing circuitry of the host computer is configured to execute a host application; - The UE is configured to execute a client application associated with a host application, thereby providing user data to be received by the host computer. 50. A method implemented in a communication system, the communication system comprising a host computer, a base station and a user equipment (UE), the method comprising: - receiving, at a host computer, from a base station user data originating from a transmission that the base station has received from a UE, wherein the UE performs any of the steps of any of the Group A embodiments. 51. The method according to the aforementioned embodiment further includes receiving user data from the UE at the base station. 52. The method according to the above two embodiments further comprises initiating, at the base station, transmission of the received user data to a host computer.

Claims

1. A method for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1) / layer two (L2) inter-cell mobility, performed by a wireless device, wherein the wireless device operates in a serving cell different from the target candidate cell, the method comprising: receiving (1712) an uplink configuration for a target candidate cell; sending (1716) an uplink message to the target candidate cell based on the uplink configuration; as well as A TA value associated with the target candidate cell is received (1718), wherein the TA value is received in a message from the serving cell.

2. The method of claim 1 , wherein the TA value associated with the target candidate cell received via the serving cell is received in an L1 / L2 inter-cell mobility command, the L1 / L2 inter-cell mobility command indicating that the wireless device should perform L1 / L2 inter-cell mobility on the target candidate cell.

3. The method of claim 1 , wherein the TA value associated with the target candidate cell received via the serving cell is received in a radio resource control (RRC) reconfiguration received after the wireless device has been configured with L1 / L2 inter-cell mobility and after the UE has sent the uplink message to the target candidate cell.

4. The method according to any one of claims 1 to 3, wherein the uplink configuration for the target candidate cell is received from a first network node, wherein the first network node corresponds to a serving distributed unit (DU).

5. The method according to any one of claims 1 to 4, wherein the uplink configuration for a target candidate cell is generated by a candidate distributed unit (DU) associated with the target candidate cell configured for L1 / L2 inter-cell mobility.

6. The method according to any one of claims 1 to 5, wherein the TA value associated with the target candidate cell is received from a first network node, wherein the first network node corresponds to a serving distributed unit (DU).

7. The method according to any one of claims 1 to 6, wherein the uplink configuration for the target candidate cell comprises a random access channel (RACH) configuration for the target candidate cell.

8. A method according to any one of claims 1 to 7, wherein the uplink message sent to the target candidate cell based on the uplink configuration includes a random access preamble code associated with one or more synchronization signal blocks (SSBs) and channel state information reference signal (CSI-RS) resources.

9. The method according to any one of claims 1 to 7, wherein the uplink message sent to the target candidate cell based on the uplink configuration includes a sounding reference signal (SRS).

10. The method according to any one of claims 1 to 9, wherein the uplink configuration comprises a trigger condition for sending the uplink message to the target candidate cell.

11. The method according to any one of claims 1 to 10, wherein the uplink configuration is associated with a validity time.

12. The method according to any one of claims 1 to 11, wherein: Receiving the uplink configuration for the target candidate cell includes: receiving the uplink configuration for the target candidate cell in a first message; and Sending the uplink message to the target candidate cell includes: sending the uplink message to the target candidate cell in response to receiving a second message.

13. The method of claim 12, wherein the first message comprises a radio resource control (RRC) message and the second message comprises a physical downlink control channel (PDCCH) command, and wherein the second message is received by the wireless device after the wireless device has received the first message.

14. The method according to any one of claims 1 to 13, further comprising: receiving (1712) an update of the uplink configuration for the target candidate cell; sending (1716) an uplink message to the target candidate cell based on the updated uplink configuration; as well as A TA value associated with the target candidate cell is received (1718), wherein the TA value is received in a message from the serving cell.

15. The method according to any one of claims 1 to 13, further comprising: in response to receiving the uplink configuration for the target candidate cell, starting (1714) a timer; In response to expiration of the timer, sending (1716) an uplink message to the target candidate cell; as well as A TA value associated with the target candidate cell is received (1718), wherein the TA value is received in a message from the serving cell.

16. The method of claim 15, wherein sending the uplink message to the target candidate cell is based on the received uplink configuration.

17. The method according to any one of claims 1 to 16, wherein L1 / L2 inter-cell mobility comprises: Signaling indicating the change of the serving cell is received via a signaling layer, which is a lower layer than a radio resource control (RRC) layer in a protocol stack.

18. A wireless device (200) operable to perform timing advance (TA) management between the wireless device and at least one target candidate cell for layer one (L1) / layer two (L2) inter-cell mobility when the wireless device is operating in a serving cell different from the target candidate cell, the wireless receiver comprising a processing circuit (202) operable to: receiving an uplink configuration for a target candidate cell; Based on the uplink configuration, sending an uplink message to the target candidate cell; as well as A TA value associated with the target candidate cell is received, wherein the TA value is received in a message from the serving cell.

19. The wireless device of claim 18, wherein the TA value associated with the target candidate cell received via the serving cell is received in an L1 / L2 inter-cell mobility command, the L1 / L2 inter-cell mobility command indicating that the wireless device should perform L1 / L2 inter-cell mobility on the target candidate cell.

20. The wireless device of claim 18, wherein the TA value associated with the target candidate cell received via the serving cell is received in a radio resource control (RRC) reconfiguration received after the wireless device has been configured with L1 / L2 inter-cell mobility and after the UE has sent the uplink message to the target candidate cell.

21. The wireless device of any one of claims 18 to 20, wherein the uplink configuration for the target candidate cell is received from a first network node, wherein the first network node corresponds to a serving distributed unit (DU).

22. The wireless device of any one of claims 18 to 21, wherein the uplink configuration for a target candidate cell is generated by a candidate distributed unit (DU) associated with the target candidate cell configured for L1 / L2 inter-cell mobility.

23. The wireless device of any one of claims 18 to 22, wherein the TA value associated with the target candidate cell is received from a first network node, wherein the first network node corresponds to a serving distributed unit (DU).

24. The wireless device of any one of claims 18 to 23, wherein the uplink configuration for the target candidate cell comprises a random access channel (RACH) configuration for the target candidate cell.

25. A wireless device according to any one of claims 18 to 24, wherein the uplink message sent to the target candidate cell based on the uplink configuration includes a random access preamble code associated with one or more synchronization signal blocks (SSBs) and channel state information reference signal (CSI-RS) resources.

26. The wireless device of any one of claims 18-25, wherein the uplink message sent to the target candidate cell based on the uplink configuration comprises a sounding reference signal (SRS).

27. The wireless device according to any one of claims 18 to 26, wherein the uplink configuration comprises a trigger condition for sending the uplink message to the target candidate cell.

28. The wireless device of any one of claims 18 to 27, wherein the uplink configuration is associated with a validity time.

29. A wireless device according to any one of claims 18 to 28, wherein: The processing circuit is operable to receive the uplink configuration for the target candidate cell by receiving the uplink configuration for the target candidate cell in a first message; as well as The processing circuit is operable to send the uplink message to the target candidate cell by sending the uplink message to the target candidate cell in response to receiving a second message.

30. The wireless device of claim 29, wherein the first message comprises a radio resource control (RRC) message and the second message comprises a physical downlink control channel (PDCCH) command, and wherein the second message is received by the wireless device after the wireless device has received the first message.

31. The wireless device of any one of claims 18 to 30, the processing circuit further operable to: receiving an update of the uplink configuration for the target candidate cell; sending an uplink message to a target candidate cell based on the updated uplink configuration; A TA value associated with the target candidate cell is received, wherein the TA value is received in a message from the serving cell.

32. The wireless device of any one of claims 18 to 31, the processing circuit further operable to: In response to receiving the uplink configuration for the target candidate cell, starting a timer; In response to expiration of the timer, sending an uplink message to the target candidate cell; as well as A TA value associated with the target candidate cell is received, wherein the TA value is received in a message from the serving cell.

33. The wireless device of claim 32, wherein the processing circuit is operable to send the uplink message to the target candidate cell based on the received uplink configuration.

34. The wireless device of any one of claims 18 to 33, wherein L1 / L2 inter-cell mobility comprises: Signaling indicating the change of the serving cell is received via a signaling layer, which is a layer lower than a radio resource control (RRC) layer in a protocol stack.

35. A method performed by a network node operating as a candidate distributed unit (DU), the method being used by the network node for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1) / layer two (L2) inter-cell mobility of the candidate DU, the method comprising: receiving (1812) a message from a serving central unit (CU) requesting TA establishment for the wireless device and at least one target candidate cell; sending (1814) to the serving CU an uplink configuration for a target candidate cell and the wireless device; receiving (1816) an uplink message from the wireless device based on the uplink configuration; as well as A TA value associated with the target candidate cell and calculated based on the received uplink message is sent (1818) to the wireless device via the serving CU.

36. The method of claim 35, wherein the message requesting TA establishment for the wireless device comprises a request to provide L1 / L2 inter-cell candidate cell configuration.

37. The method according to any one of claims 35 to 36, further comprising: In response to sending the TA value to the wireless device, starting (1820) a timer; as well as In response to expiration of the timer, a new TA value associated with the target candidate cell is sent (1818) to the wireless device via the serving CU.

38. A network node (300) operable as a candidate distributed unit (DU) for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1) / layer two (L2) inter-cell mobility of the candidate DU, the network node comprising a processing circuit (302) operable to: receiving a message from a serving central unit (CU) requesting TA establishment for the wireless device and at least one target candidate cell; Sending an uplink configuration for a target candidate cell and the wireless device to the serving CU; receiving an uplink message from the wireless device based on the uplink configuration; as well as A TA value associated with the target candidate cell and calculated based on the received uplink message is sent to the wireless device via the serving CU.

39. The network node of claim 38, wherein the message requesting TA establishment for the wireless device comprises a request to provide L1 / L2 inter-cell candidate cell configuration.

40. The network node according to any one of claims 38 to 39, the processing circuit is further operable to: In response to sending the TA value to the wireless device, starting a timer; and In response to expiration of the timer, a new TA value associated with the target candidate cell is sent to the wireless device via the serving CU.

41. A method performed by a network node, the network node operating as a serving central unit (CU) for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1) / layer two (L2) inter-cell mobility, the method comprising: sending (1912) a request to a candidate distributed unit (DU) requesting TA establishment for the wireless device and at least one target candidate cell; receiving (1914) an uplink configuration for a target candidate cell and the wireless device from the candidate DU; sending (1916) an uplink message to a serving DU, the uplink message to be sent to the wireless device, wherein the uplink message includes the uplink configuration; receiving (1918) from the candidate DU a TA value associated with the target candidate cell; as well as The TA value is sent (1920) to the wireless device via the serving DU.

42. The method of claim 41, wherein the message requesting TA establishment for the wireless device comprises a request to provide L1 / L2 inter-cell candidate cell configuration.

43. The method according to any one of claims 41 to 42, further comprising: In response to sending the TA value to the wireless device, starting (1922) a timer; as well as In response to expiration of the timer, a request is sent (1912) to the candidate DU requesting a new TA establishment for the wireless device and at least one target candidate cell.

44. A network node (300) operable as a service central unit (CU) for timing advance (TA) management between a wireless device and at least one target candidate cell for layer one (L1) / layer two (L2) inter-cell mobility, the network node comprising a processing circuit (302) operable to: sending a request to a candidate distributed unit (DU) requesting TA establishment for the wireless device and at least one target candidate cell; receiving, from the candidate DU, an uplink configuration for a target candidate cell and the wireless device; sending an uplink message to a serving DU, the uplink message to be sent to the wireless device, wherein the uplink message includes the uplink configuration; receiving, from the candidate DU, a TA value associated with the target candidate cell; as well as The TA value is sent to the wireless device via the serving DU.

45. The network node of claim 44, wherein the message requesting TA establishment for the wireless device comprises a request to provide L1 / L2 inter-cell candidate cell configuration.

46. ​​The network node according to any one of claims 44 to 45, the processing circuit is further operable to: In response to sending the TA value to the wireless device, starting a timer; and In response to expiration of the timer, a request is sent to the candidate DU requesting a new TA establishment for the wireless device and at least one target candidate cell.

Images