Method and apparatus for TRP-related beam failure detection procedures and mobility scenarios

Abstract

To provide a method and an apparatus for beam fault detection procedures related to transmission / reception points (TRPs) and coexistence of Layer 1 / Layer 2 (L1 / L2) and Layer 3 (L3) mobility scenarios under 5G systems of the Third Generation Partnership Project (3GPP).SOLUTION: A method performed by user equipment (UE) includes receiving, from a serving cell, configuration information related to two or more transmission / reception points (TRPs) of the serving cell, detecting beam failures of the TRPs within the two or more TRPs, transmitting a beam failure recovery (BFR) request including information related to the TRPs, detecting further beam failures of further TRPs within the two or more TRPs before receiving a response to the BFR request from the serving cell, and monitoring a physical downlink control channel (PDCCH) within a period of time.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] Embodiments of the present application generally relate to wireless communication technologies, and more particularly to a method and apparatus for beam failure detection procedures related to Transmission Reception Points (TRPs) and coexistence of Layer 1 / Layer 2 (L1 / L2) and Layer 3 (L3) mobility scenarios. [Background technology]

[0002] Currently, the 3rd Generation Partnership Project (3GPP) RAN2 has agreed on both Scenario 1 and Scenario 2 at the RAN2#114 meeting. Scenario 1 refers to a multi-TRP-like model between cells, and Scenario 2 refers to an L1 / L2 mobility model (i.e., with a serving cell change).

[0003] In particular, Scenario 1 refers to a multi-TRP-like model between cells. In Scenario 1, the UE receives from the serving cell the configuration of synchronization signal blocks (SSBs) of TRPs with different physical layer identifiers (PCIDs) for beam measurement and the configuration required to use radio resources for data transmission or reception, including resources for the different PCIDs. The UE performs beam measurement for the TRPs with different PCIDs and reports the measurement results to the serving cell. Based on the above report, the serving cell activates (by L1 / L2 signaling) the transmission configuration indicator (TCI) states associated with the TRPs with different PCIDs. The TCI may be SSBs or Channel State Information Reference Signals (CSI-RS). The UE transmits and receives using UE-dedicated channels on the TRPs with different PCIDs. The UE must always be within the coverage of the serving cell, and even in the case of multi-TRP, the UE must use common channels from the serving cell, such as the Broadcast Control Channel (BCCH) and the Paging Control Channel (PCCH).

[0004] Scenario 2 refers to the L1 / L2 mobility model (i.e., with serving cell change). In scenario 2, the UE receives from the serving cell the configuration of SSBs of a cell with a different PCID for beam measurements or serving cell change. The UE performs beam measurements for the cell with a different PCID and reports the measurement results to the serving cell. The serving cell configuration of the cell with the other PCID is provided to the UE by RRC signaling. Based on the above report, the TCI state of the cell with the different PCID is activated (by L1 / L2 signaling) in conjunction with the serving cell change. The UE changes serving cell and starts receiving or transmitting using the pre-configured UE dedicated channel and TCI state. Summary of the Invention [Problem to be solved by the invention]

[0005] However, some problems related to Scenario 1 and Scenario 2 have not yet been discussed in 3GPP 5G technology, and corresponding solutions have not been specified. The embodiments of the present application aim to provide solutions for both Scenario 1 and Scenario 2, in which a user equipment (UE) is configured with one or more candidate cells, and to solve related problems in these two scenarios. [Means for solving the problem]

[0006] Some embodiments of the present application provide a method performed by a UE, the method including: receiving, from a serving cell, configuration information related to two or more transmission / reception points (TRPs) of the serving cell, detecting beam failures of the TRPs in the two or more TRPs, transmitting a beam failure recovery (BFR) request including information related to the TRPs, detecting further beam failures of further TRPs in the two or more TRPs before receiving a response to the BFR request from the serving cell, and monitoring a physical downlink control channel (PDCCH) within a period of time.

[0007] Some embodiments of the present application also provide a UE, including a processor and a wireless transceiver coupled to the processor, configured to: receive, from a serving cell via the wireless transceiver, configuration information related to two or more TRPs of the serving cell, detect beam failures of TRPs within the two or more TRPs, transmit a BFR request via the wireless transceiver including information related to the TRPs, detect further beam failures of further TRPs within the two or more TRPs before receiving a response to the BFR request from the serving cell, and monitor a PDCCH within a period of time.

[0008] Some embodiments of the present application provide a method performed by a UE, the method including: receiving, from a serving cell, configuration information for a cell switch procedure related to one or more candidate cells, where the cell switch procedure is performed based on a cell switch condition for the cell switch procedure being satisfied or an activation indication for the cell switch procedure being received; and receiving, from the serving cell, one of configuration information for a normal handover command, a Dual Active Protocol Stack (DAPS) handover command, and a Conditional Handover (CHO) procedure.

[0009] Some embodiments of the present application also provide a UE including: a processor; and a wireless transceiver coupled to the processor, wherein the processor is configured to: receive, from a serving cell via the wireless transceiver, configuration information for a cell switch procedure related to one or more candidate cells, where the cell switch procedure is performed based on a cell switch condition for the cell switch procedure being satisfied or an activation indication for the cell switch procedure being received; and receive, from the serving cell via the wireless transceiver, one of a normal handover command, a DAPS handover command, and configuration information related to a CHO procedure.

[0010] Some embodiments of the present application also provide an apparatus for wireless communication, the apparatus including: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit; a transmitting circuit; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit, and the transmitting circuit, the computer-executable instructions causing the processor to perform any of the above-described methods performed by a UE.

[0011] Some embodiments of the present application provide a method performed by a network node (e.g., a base station (BS)), including: transmitting, to a UE, configuration information for a cell switch procedure related to one or more candidate cells, where the cell switch procedure is performed based on a cell switch condition for the cell switch procedure being satisfied or an activation indication for the cell switch procedure being received; and transmitting, to the UE, one of a normal handover command, a DAPS handover command, and configuration information for a CHO procedure.

[0012] Some embodiments of the present application also provide a network node (e.g., a BS), including: a processor; and a wireless transceiver coupled to the processor, wherein the processor is configured to: transmit, via the wireless transceiver, to a UE, configuration information of a cell switch procedure related to one or more candidate cells, where the cell switch procedure is performed based on a cell switch condition of the cell switch procedure being satisfied or an activation indication of the cell switch procedure being received; and transmit, via the wireless transceiver, to the UE, one of a normal handover command, a DAPS handover command, and configuration information related to a CHO procedure.

[0013] Some embodiments of the present application also provide an apparatus for wireless communication, the apparatus including: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit; a transmitting circuit; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit, and the transmitting circuit, the computer-executable instructions causing the processor to perform any of the above-described methods performed by a network node (e.g., a BS).

[0014] The details of one or more examples are set forth in the accompanying drawings and the detailed description below. Other features, objects, and advantages will be apparent from the detailed description and drawings, and from the claims.

[0015] To explain how the advantages and features of the present application can be obtained, the application will be described by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. These drawings depict merely exemplary embodiments of the present application and therefore should not be considered limiting of its scope. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 illustrates a scenario for inter-cell operation, according to some embodiments of the present application. [Figure 2] 1 is an example format diagram of a BFR MAC CE according to 3GPP standard document TS38.321. [Figure 3] 1 is an example format diagram of a BFR MAC CE according to 3GPP standard document TS38.321. [Figure 4] 1 is a flowchart of a method for transmitting a BFR request according to some embodiments of the present application. [Figure 5] 1 is a flowchart of a method for receiving configuration information for a cell switching procedure according to some embodiments of the present application. [Figure 6] 1 is a flowchart of a method for transmitting configuration information for a cell switching procedure according to some embodiments of the present application. [Figure 7] FIG. 1 is an exemplary block diagram of an apparatus according to some embodiments of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0017] The detailed description of the accompanying drawings is intended to illustrate preferred embodiments of the present application and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present application.

[0018] Next, several embodiments of the present application will be described in detail, examples of which are illustrated in the accompanying drawings. For ease of understanding, the embodiments are provided under specific network architectures and new service scenarios, such as 3GPP 5G and 3GPP LTE Release 8. With the development of network architectures and new service scenarios, it is assumed that similar technical problems will apply to all embodiments of the present application. Furthermore, the terms used in the present application may be changed, but this should not affect the principles of the present application.

[0019] FIG. 1 is a diagram illustrating a scenario for inter-cell operation according to some embodiments of the present application.

[0020] In some cases, UE1 may receive from the serving cell the SSB or CSI-RS configuration of a TRP (e.g., TRP#0 and / or TRP#1) with a PCID for beam measurement and the resource configuration for data transmission or data reception associated with the PCID. UE1 performs beam measurement for the TRP with the PCID and reports the measurement results to the serving cell. Based on the report, the TCI state associated with the TRP with the PCID is activated from the serving cell (through L1 signaling or L2 signaling). The TCI may be SSB or CSI-RS. UE1 transmits and receives using a UE-dedicated channel on the TRP with the PCID. UE1 must always be within the coverage of the serving cell. In the case of multiple TRPs, for example, UE1 must use the BCCH, PCCH, etc. from the serving cell. As shown in Figure 1, UE1 is served by TRP#0 and TRP#1. UE1 can receive data from TRP#0 and TRP#1 simultaneously.

[0021] In some embodiments of the present application, UE1 shown in FIG. 1 may include computing devices such as desktop computers, laptop computers, personal digital assistants (PDAs), tablet computers, smart televisions (e.g., Internet-connected televisions), set-top boxes, game consoles, security systems (including security cameras), in-vehicle computers, network nodes (e.g., TRPs, routers, switches, and modems). In some other embodiments of the present application, UE1 may include portable wireless communication devices, smartphones, mobile phones, flip phones, devices with subscriber ID modules, personal computers, selective ringing circuits, or any other devices capable of sending and receiving communication signals over a wireless network. In some other embodiments of the present application, UE1 may include wearable devices such as smart watches, fitness bands, and optical head-mounted displays. Furthermore, UE1 may be referred to as a subscriber unit, mobile, mobile station, user, terminal, mobile terminal, wireless terminal, fixed terminal, subscriber station, user terminal, or device, or may be described using other terms used in the art.

[0022] Currently, further details regarding the UE behavior and the BS behavior in Scenario 1 and Scenario 2 are not very clear, some common problems remain to be solved, and different solutions are needed in different cases. Some embodiments of the present application aim to provide a solution for the case of multiple TRPs in one cell in Scenario 1. Some embodiments of the present application investigate the UE behavior in the case where the UE detects a further beam failure of a further TRP before receiving a response to a Beam Failure Recovery Request (BFRQ) of the TRP from the network node.

[0023] Some embodiments of the present application aim to provide a solution for the case where L1 / L2-centric mobility and L3 mobility coexist in Scenario 2. Some embodiments of the present application aim to solve the problem for the coexistence of L1 / L2-centric mobility and CHO procedure. Some embodiments of the present application aim to solve the problem for the coexistence of L1 / L2-centric mobility and DAPS Handover (HO) procedure. Further details regarding the embodiments of the present application are described in the following text in conjunction with the accompanying drawings.

[0024] 2 and 3 are two example format diagrams of the BFR MAC CE according to the 3GPP standard document TS38.321. In the embodiments of Figures 2 and 3, the fields in the BFR MAC CE are defined as follows: - SP (e.g., "SP" shown in row 1, column 8 of Figure 2 and Figure 3, respectively): This field indicates the beam failure detection for the SpCell of this MAC entity. The SP field is set to 1 to indicate that a beam failure has been detected for the SpCell only if the BFR MAC CE is included in the MAC PDU as part of the Random Access (RA) procedure, and is set to 0 otherwise. - C i (BFR MAC CE) (for example, "C1" to "C7" shown in Figure 2 and "C1" to "C 31 "): This field indicates the presence of an octet containing the BFD and AC field of the SCell with ServCellIndex i as specified in 3GPP standard document TS38.331. i The AC field indicates that a beam failure has been detected and the octet containing the AC field is presented for the SCell with ServCellIndex i. i The field indicates that no beam obstruction is detected and no octets containing AC fields are presented for the SCell with ServCellIndex i. The octets containing AC fields are in ascending order based on ServCellIndex. - AC (e.g., "AC" shown in the first column, second to last row of Figure 2 and "AC" shown in the first column, fifth to last row of Figure 3): This field indicates the presence of a candidate Reference Signal Identifier (RS ID) field in this octet. If at least one SSB in the candidateBeamRSSCellList with an SS-RSRP above rsrp-ThresholdBFR or at least one CSI-RS in the candidateBeamRSSCellList with a CSI-RSRP above rsrp-ThresholdBFR is available, the AC field is set to 1; otherwise, the AC field is set to 0. If the AC field is set to 1, the Candidate RS ID field is present. If the AC field is set to 0, the R bit is present instead. - Candidate RS ID (e.g., "Candidate RS ID" shown in lines 2 to the bottom of Figure 2, and "Candidate RS ID" shown in lines 5 to the bottom of Figure 3): This field is set to the index of the SSB in candidateBeamRSSCellList that has an SS-RSRP above rsrp-ThresholdBFR, or to the index of the CSI-RS in candidateBeamRSSCellList that has a CSI-RSRP above rsrp-ThresholdBFR. The index of the SSB or CSI-RS is the index of the entry in candidateBeamRSSCellList that corresponds to the SSB or CSI-RS. Index 0 corresponds to the first entry in candidateBeamRSSCellList, index 1 corresponds to the second entry in the list, and so on. The length of this field is 6 bits. - R (e.g., "R" shown in the second to last lines of Figure 2 and "R" shown in the fifth to last lines of Figure 3): This field is a reserved bit and is set to 0.

[0025] As agreed in the 3GPP standard document TS38.321, in the BFR procedure for a PSCell, if a beam failure instance indication is received from the physical layer, the UE starts or restarts the beamFailureDetectionTimer and increments the BFI_COUNTER by one. If BFI_COUNTER ≥ beamFailureInstanceMaxCount and the serving cell is a PSCell or PCell, the UE triggers an RA procedure for the SpCell. The UE selects an appropriate beam to perform the BFR procedure (if the BS provides dedicated RA resources for certain beams, the UE will prioritize those beams). Once the RA procedure is completed, the BFR procedure is considered completed.

[0026] Figure 4 is a flowchart of a method for transmitting a BFR request according to some embodiments of the present application. The exemplary method 400 in the embodiment of Figure 4 may be performed by a UE, for example, UE 1 as shown and illustrated in Figure 1. Although described with respect to a UE, it should be understood that other devices may be configured to perform the method as shown and illustrated in Figure 4. Specific examples of the embodiment of Figure 4 are described in Examples 1 and 2 below.

[0027] In the exemplary method 400 shown in FIG. 4, in operation 401, the UE receives, from a serving cell, configuration information related to two or more TRPs of the serving cell. In operation 402, the UE detects a beam failure of a TRP (e.g., TRP#0 as shown in FIG. 1) within the two or more TRPs. In operation 403, the UE transmits a BFR request, which may be referred to as a first BFR request. The first BFR request includes information related to the TRP. In operation 404, before receiving a response to the first BFR request from the serving cell, the UE detects a further beam failure of a further TRP (e.g., TRP#1 as shown in FIG. 1) within the two or more TRPs.

[0028] In operation 405, the UE monitors the PDCCH within a certain period of time. According to some embodiments, the period of time is associated with a time window in the time domain. The time window can start when the first BFR request or the second BFR request is transmitted. The length of the time window can be configured by the serving cell.

[0029] According to some other embodiments, the period is associated with a timer. The period begins when the timer starts. The period ends when the timer expires or is stopped. In one embodiment, the timer starts when: (1) The UE sends a first BFR request and detects further beam obstructions, or (2) Send the first BFR request, or (3) The UE detects further beam obstructions and sends further BFR requests.

[0030] In one embodiment, the UE may stop the timer if it receives a response to the first BFR request from the serving cell. In another embodiment, the UE may stop the timer if it receives a response to a further BFR request, which may be termed a second BFR request, from the serving cell.

[0031] According to some embodiments, the serving cell is a secondary cell (SCell), a primary cell (PCell), or a primary cell (PSCell) of a secondary cell group.

[0032] In some embodiments, if the serving cell is a PCell or PSCell cell and the UE detects a further beam failure of the PCell or PSCell cell, the UE may trigger a further BFR procedure. The further BFR procedure includes transmitting a second BFR request. The UE may transmit the second BFR request. The second BFR request includes information related to a further TRP.

[0033] In one embodiment, the first BFR request or the second BFR request may be a Medium Access Control (MAC) Control Element (CE). The MAC CE includes a field indicating per-TRP information associated with two or more TRPs of the serving cell. In another embodiment, the first BFR request or the second BFR request may be a Scheduling Request (SR).

[0034] In some embodiments, the UE may monitor the PDCCH within the time period in operation 405 if: (1) The first BFR request includes information related to candidate beams of a TRP (e.g., TRP#0 as shown in FIG. 1); or (2) The second BFR request includes information related to candidate beams of a further TRP (e.g., TRP#1 as shown in FIG. 1); or (3) Detect further beam obstructions and send a second BFR request.

[0035] In some embodiments, if the serving cell is an SCell and the UE detects a second beam failure of the SCell, the UE may trigger a further BFR procedure including transmitting a second BFR request, and may transmit the second BFR request including information related to a further TRP (e.g., TRP#1 as shown in FIG. 1). In one embodiment, the first BFR request or the second BFR request may be a MAC CE. The MAC CE includes information related to the SCell, e.g., a legacy cell-level BFR MAC CE as shown in FIGS. 2 and 3 defined in 3GPP standard document TS38.321.

[0036] Some embodiments of the present application employ a new format of BFR MAC CE associated with a TRP, which may also be named "TRP-based BFR MAC CE", "TRP BFR MAC CE", etc.

[0037] Details described in all other embodiments of this application (e.g., details regarding beam failure detection and recovery procedures related to TRP) are also applicable to the embodiment of Figure 4. Furthermore, details described in the embodiment of Figure 4 are applicable to all embodiments of Figures 1-3 and 5-7.

[0038] In some embodiments of the present application, in Scenario #1, which refers to multiple TRPs in a cell, specific BFR procedures related to two TRPs can be configured. After a beam failure is detected for one TRP, the UE can send a BFR request, such as a TRP-based BFR MAC CE or a specific SR. Before receiving a response, beam failures may be detected for other TRPs. However, the further question of what the UE's behavior is and whether the UE is able to receive a response to the first TRP BFR MAC CE must be resolved. In Scenario #1, the following two cases are possible: Case A and Case B.

[0039] Case A: This case refers to an SpCell (PCell or PSCell). In Case A, if beam failure is detected in all TRPs of one cell (e.g. PCell or PSCell), the UE performs an RA procedure for BFR purposes. Alternatively, if the new beam of the failed TRP is included in the TRP-based BFR MAC CE, the UE must continue monitoring the PDCCH for a certain period of time. There are three options: (1) Option A-1: ​​When a beam failure of the second TRP among the two TRPs of a cell is detected and a BFR request (e.g., a TRP-based BFR MAC CE) of the first TRP among the two TRPs of the cell is transmitted, the UE continues to monitor the PDCCH within a certain period (e.g., a time window or a timer). When the time window elapses or the timer expires, the UE performs a RACH procedure based on the BFR procedure configuration for the cell. 1) In one embodiment, if the new beam of the failed TRP is included in the TRP-based BFR MAC CE, the UE may continue to monitor the PDCCH within a certain period (e.g., a time window or a timer). Otherwise, the UE may perform a RACH procedure. (2) Option A-2: If the time elapsed since the last transmission of a TRP-based BFR MAC CE is greater than a certain threshold and a beam failure of a second TRP is detected, the UE declares a cell-level beam failure or the UE performs a RACH procedure. (3) Option A-3: The UE transmits a TRP-based BFR MAC CE via the SCell after detecting a beam failure of the second TRP. After the UE transmits the TRP-based BFR MAC CE via the SCell, a timer is started. When the UE receives a response from the BS (e.g., gNB), the UE stops the timer. When the timer expires, the UE performs an RA procedure for BFR.

[0040] Case B: This case refers to an SCell. In Case B, a beam failure of a first TRP in two TRPs is detected on the SCell. After the beam failure of the first TRP on the SCell is detected, the UE transmits a BFR request, such as a TRP-based BFR MAC CE or a specific SR, via the PCell or SCell. Before receiving a response to the BFR request, a beam failure of a second TRP on the SCell is detected. The UE can retransmit a TRP-based BFR MAC CE, such as an additional TRP-based BFR MAC CE. Information about both of the two failed TRPs or only the second failed TRP may be included in the additional TRP-based BFR MAC CE. For example, the additional TRP-based BFR MAC CE may be a legacy BFR MAC CE as shown in Figures 2 and 3, or a new-format TRP-based BFR MAC CE having fields related to TRP information.

[0041] The following text describes specific embodiments 1 and 2 of the method as shown and illustrated in Figure 4. According to embodiments 1 and 2, the UE and the BS may perform the following operations: The UE may be UE1 as shown and illustrated in Figure 1.

[0042] Embodiment 1: This embodiment refers to the solution for Case A, i.e., SpCell (PCell or PSCell). (1) Step 1: A UE accesses a network, for example, a PCell. The serving cell is an SpCell (PCell or PSCell). (2) Step 2: The network, for example, the PCell, sends configuration information to the UE. - Two TRPs for the serving cell, for example TRP#0 and TRP#1, are configured in the UE. - A Beam Failure Detection Reference Signal (BFD-RS) set is configured for each TRP. Each TRP is associated with a BFD-RS set. For example, BFD-RS set #0 is associated with TRP #0, and BFD-RS set #1 is associated with TRP #1. - When a new beam identification RS (NBI-RS) set is configured for each TRP, such as NBI-RS set #0 and NBI-RS set #1, the independent configuration of the NBI-RS set is per TRP. - The combination of MAC layer BFD counter #0 and timer #0 is set for TRP #0, and the combination of MAC layer BFD counter #1 and timer #1 is set for TRP #1. - A TRP can be identified with one CORESET pool in addition to the BFD-RS set, e.g., CORESET pool #0 is TRP #0. (3) Step 3: The UE receives configuration information from the network, for example, the PCell. (4) Step 4: When a beam failure instance indication associated with TRP#0 is received by the UE from the physical layer, the MAC entity of the UE shall start or restart the timer for beam failure detection associated with TRP#0 for each serving cell by incrementing the COUNTER associated with TRP#0 by one. - COUNTER (per TRP) is a counter for beam failure instance indications that is initially set to 0. (5) Step 5: If the COUNTER of a TRP (e.g., TRP#0) is greater than or equal to the maximum count of beam failure instances and the serving cell is an SpCell, the UE triggers the first BFR request for this TRP. This TRP may also be named the first failed TRP. - The UE generates a TRP-based BFR MAC CE triggered by detecting a beam failure of the first failed TRP. (6) Step 6: The UE sends a first BFR request for the first failed TRP. (7) Step 7: The UE may detect a beam failure of a second TRP (e.g., TRP#1) before receiving a response to the transmission of the first BFR request of the failed first TRP. - (Optionally) The UE triggers a BFR procedure for a second TRP. The UE can send a second BFR request, e.g., a TRP-based BFR MAC CE. In one embodiment, the UE can adopt option A-3 above. In one embodiment, if a first BFR request is transmitted without a second BFR request being transmitted, the new beam associated with the failed first TRP may be included in the transmitted first BFR request. In another embodiment, when both a first BFR request and a second BFR request are transmitted, the new beam associated with the first failed TRP may be included in the first BFR request transmitted, and / or the new beam associated with the second failed TRP may be included in the second BFR request transmitted. (8) Step 8: If the transmitted BFR request includes a new beam for the failed TRP, the UE may monitor the PDCCH within a certain period of time. - Adopting Option A-1 above - Adopting Option A-2 above - Adopting option A-3 above (9) Step 9: If a response is received within a certain period, the UE considers the BFR procedure successful. If a response is not received within a certain period, the UE performs an RA to the corresponding PCell or PSCell.

[0043] Embodiment 2: This embodiment refers to the solution for Case B, ie, SCell. (1) Step 1: A UE accesses a network, for example, a PCell. The serving cell is an SCell. (2) Step 2: The network, for example, the PCell, sends configuration information to the UE. - Two TRPs for the serving cell, for example TRP#0 and TRP#1, are configured. - A BFD-RS set is configured for each TRP. Each TRP is associated with a BFD-RS set. For example, BFD-RS Set #0 is associated with TRP #0, and BFD-RS Set #1 is associated with TRP #1. - When a new beam identification RS (NBI-RS) set is configured per TRP, such as NBI-RS set #0 and NBI-RS set #1, the independent configuration of the NBI-RS set is per TRP. - The combination of MAC layer BFD counter #0 and timer #0 is set for TRP #0, and the combination of MAC layer BFD counter #1 and timer #1 is set for TRP #1. - A TRP can be identified with one CORESET pool in addition to the BFD-RS set, e.g., CORESET pool #0 is TRP #0. (3) Step 3: The UE receives configuration information from the network, for example, the PCell. (4) Step 4: When a beam failure instance indication associated with TRP#0 of an SCell is received by the UE from the physical layer, the MAC entity of the UE shall start or restart the timer for beam failure detection associated with TRP#0 for each serving cell by incrementing the COUNTER associated with TRP#0 by 1. - COUNTER (per TRP) is a counter for beam failure instance indications that is initially set to 0. (5) Step 5: If the COUNTER of TRP#0 is greater than or equal to the maximum count of beam failure instances and the serving cell is an SCell, the UE triggers a first BFR request for this TRP, i.e., the first TRP that has failed. - The UE generates a TRP-based BFR MAC CE triggered by detecting a beam failure of the first failed TRP. (6) Step 6: The UE sends a first BFR request for the first failed TRP. (7) Step 7: The UE may detect a beam failure of the second TRP before receiving a response to the transmission of the first BFR request of the failed first TRP. (8) Step 8: The UE triggers a BFR procedure for the second TRP. (9) Step 9: The UE sends a second BFR request for a second TRP. The UE may send this BFR request in a legacy cell-level BFR MAC CE as shown in Figures 2 and 3, or in a new format TRP-based BFR MAC CE with fields related to TRP information.

[0044] Figure 5 is a flowchart of a method for receiving configuration information for a cell switching procedure according to some embodiments of the present application. The exemplary method 500 in the embodiment of Figure 5 may be performed by a UE, for example, UE 1 as shown and illustrated in Figure 1. Although described with respect to a UE, it should be understood that other devices may be configured to perform the method as shown and illustrated in Figure 5. Specific examples of the embodiment of Figure 5 are described in Examples 3 to 5 below.

[0045] 5, in the example method 500, a UE receives configuration information for a cell switch procedure associated with one or more candidate cells from a serving cell in operation 501. The cell switch procedure is performed based on a cell switch condition for the cell switch procedure being met or an activation indication for the cell switch procedure being received.

[0046] In operation 502, the UE receives one of a normal handover command, a DAPS handover command, and configuration information related to a CHO procedure from the serving cell. In some embodiments, the normal handover command, the DAPS handover command, and / or the configuration information related to a CHO procedure is related to a further candidate cell. For example, the further candidate cell may belong to one or more candidate cells in operation 501 or may be a cell different from the one or more candidate cells.

[0047] According to some embodiments, a physical layer or a MAC layer of the UE receives an activation indication of a cell switch procedure from a serving cell. In one embodiment, the activation indication of the cell switch procedure includes a PCID of a candidate cell among one or more candidate cells. In a further embodiment, the activation indication of the cell switch procedure includes an index of the candidate cell, the index being associated with the PCID of the candidate cell or a Cell Global Identifier (CGI) of the candidate cell.

[0048] In some embodiments, if the physical layer or MAC layer of the UE receives an activation indication for the cell switch procedure and the UE receives configuration information for the CHO procedure, the physical layer or MAC layer of the UE may indicate the received activation indication to the RRC layer of the UE.

[0049] In some embodiments, after the RRC layer of the UE receives an activation indication of the cell switch procedure from the physical layer or MAC layer of the UE, the RRC layer of the UE may stop evaluating the conditions for the CHO procedure and may not trigger the CHO procedure. If the conditions for the CHO procedure are met, the UE may preferentially perform the cell switch procedure or may select a candidate cell with the best channel quality from the cell switch procedure and the CHO procedure for cell switching.

[0050] According to some embodiments, a Radio Resource Control (RRC) reconfiguration message is received from a serving cell. The RRC reconfiguration message includes an indication that the RRC reconfiguration message is applicable after the UE's physical layer or MAC layer receives an activation indication from the serving cell. In one embodiment, when the UE receives the RRC reconfiguration message, the UE may check compliance of the received RRC reconfiguration message. For example, if the UE's RRC layer does not comply with the RRC reconfiguration message, the UE may report a compliance failure to the serving cell.

[0051] In some embodiments, if the cell switch condition is met and the UE receives configuration information for the CHO procedure, the physical layer or MAC layer of the UE may send an indication to the RRC layer of the UE indicating that the cell switch condition is met. In one embodiment, after the RRC layer of the UE receives this indication, if the CHO condition of the CHO procedure is not met, the RRC layer of the UE may stop evaluating the CHO condition and not trigger the CHO procedure. Alternatively, if the CHO condition is met, the UE may preferentially perform the cell switch procedure or switch to the candidate cell with the best channel quality through the cell switch procedure and the CHO procedure.

[0052] According to some embodiments, if the UE receives a DAPS handover command, the UE may perform a DAPS handover procedure. The RRC layer of the UE may send an indication to the physical layer or MAC layer of the UE to perform the DAPS handover procedure. In one embodiment, after the physical layer or MAC layer of the UE receives this indication, the physical layer or MAC layer of the UE may stop evaluating the cell switch conditions. In a further embodiment, after the physical layer or MAC layer of the UE receives this indication, the UE may continue evaluating the cell switch conditions and not trigger a cell switch procedure when the cell switch conditions are met.

[0053] Details described in all other embodiments of this application (e.g., details regarding beam failure detection and recovery procedures related to TRP) are also applicable to the embodiment of Figure 5. Furthermore, details described in the embodiment of Figure 5 are applicable to all embodiments of Figures 1-4, 6, and 7.

[0054] 6 is a flowchart of a method for transmitting configuration information for a cell switching procedure according to some embodiments of the present application. The exemplary method 600 in the embodiment of FIG. 6 may be performed by a network node, for example, a BS. Although described with respect to a network node, it should be understood that other devices may be configured to perform the method as shown and illustrated in FIG. 6. Specific examples of the embodiment of FIG. 6 are described in the following embodiments 3 to 5.

[0055] In the example method 600 as shown in Figure 6, a network node (e.g., a BS) transmits configuration information for a cell switch procedure associated with one or more candidate cells to a UE (e.g., UE1 as shown and illustrated in Figure 1) in operation 601. The cell switch procedure is performed based on a cell switch condition for the cell switch procedure being met or an activation indication for the cell switch procedure being received.

[0056] In operation 602, the network node sends to the UE a normal handover command or a DAPS handover command or configuration information related to the CHO procedure. According to some embodiments, the normal handover command, the DAPS handover command and / or the configuration information related to the CHO procedure relates to a further candidate cell. For example, the further candidate cell may belong to one or more candidate cells in operation 601 or may be a different cell from the one or more candidate cells.

[0057] In some embodiments, the physical layer or MAC layer of the network node may send an activation indication to the UE for a candidate cell within the one or more candidate cells, where the activation indication may include (1) a physical layer identifier (PCID) of the candidate cell within the one or more candidate cells, or (2) an index of the candidate cell that is associated with the PCID of the candidate cell or the CGI of the candidate cell.

[0058] In some embodiments, the network node transmits an RRC reconfiguration message to the UE. The RRC reconfiguration message may include an indication that the RRC reconfiguration message is applicable after a physical layer or a MAC layer of the UE receives an activation indication from the network node. In one embodiment, the network node may receive from the UE a compliance failure between the RRC layer of the UE and the RRC reconfiguration message.

[0059] According to some embodiments, when the RRC layer of the network node sends the DAPS handover command, the RRC layer of the network node may further send an indication to a physical layer or a MAC layer of the network node to send the DAPS handover command. In some embodiments, when the physical layer or MAC layer of the network node receives this indication, the physical layer or MAC layer of the network node may not send an activation indication of the cell switch procedure to the UE.

[0060] Details described in all other embodiments of this application (e.g., details regarding beam failure detection and recovery procedures related to TRP) are also applicable to the embodiment of Figure 6. Furthermore, details described in the embodiment of Figure 6 are applicable to all embodiments of Figures 1-5 and 7.

[0061] The following text describes specific embodiments 3 to 5 of the method shown and illustrated in Figures 5 and 6. Embodiments 3 to 5 refer to a coexistence scenario of L1 / L2-centric mobility and L3 mobility. According to embodiments 3 to 5, the UE and the BS may perform the following operations: The UE may be UE1 as shown and illustrated in Figure 1.

[0062] Embodiment 3 (1) Step 1: The UE accesses the network, e.g., a PCell. (2) Step 2: The network, for example, the PCell, sends configuration information to the UE. - The parameters for beam obstruction recovery per TRP can be configured in the UE. - The RRC configuration message for the candidate cell is associated with the cell change procedure based on activation signaling. The UE is configured to support "physical layer signaling-based activation for cell change" or "MAC layer signaling-based activation for cell change" or "condition-based activation for cell change". - If L1 / L2-centric mobility is also included in the RRC reconfiguration message with the reconfigurationWithSync IE, one indication may be added to indicate that this mobility information is applicable after receiving an L1 / L2-related activation indication. This behavior allows to distinguish between L1 / L2-centric and L3 mobility handover commands. - A CHO configuration of a candidate cell can be configured in the UE. The candidate cell associated with the CHO configuration may be the same as (or different from) the candidate cell associated with the RRC configuration message. (3) Step 3: The UE receives configuration information from the network, for example, the PCell. - When the UE receives an RRC reconfiguration message at its RRC layer, the UE checks compliance when it receives an RRC reconfiguration message related to a cell change procedure based on activation signaling. If the UE cannot comply with any part of the configuration included in the RRC reconfiguration message, the UE can report a compliance check failure to the network. This behavior defines when to check compliance of received RRC reconfiguration messages related to activation-based mobility. (4) Step 4: The UE reports the measurement results, including the physical layer and RRC layer of the UE, to the network. (5) Step 5: The network, for example, a PCell or a PSCell, sends an activation indication related to one candidate cell via the physical layer or MAC layer. The content of the L1 / L2 signaling is as follows: - Option 1: PCID of one candidate cell. - Option 2: One candidate cell index among all configured candidate cells. When a source BS (e.g., gNB) sends the configuration of one candidate cell, the candidate cell index is added among all configured cells. (6) Step 6: The UE receives, via the physical layer or the MAC layer, an activation indication associated with one candidate cell. - If an L1 / L2 activation indication is received, the UE checks compliance upon receiving an RRC reconfiguration message related to a cell change procedure based on the activation signaling. If the UE is unable to comply with any part of the configuration contained in the RRC reconfiguration message, the UE reports a compliance check failure to the network. This behavior defines when to check compliance of received RRC reconfiguration messages related to activation-based mobility. - If CHO configuration is also configured, the UE's lower layers must instruct the UE's RRC layer upon receiving an L1 / L2 activation indication. After that, the UE's RRC layer must stop evaluating the CHO conditions after receiving the UE's lower layer indication and does not need to trigger the CHO procedure. This behavior defines the content of the L1 / L2 signaling, when the UE receives L1 / L2 signaling for switching, and whether to instruct the UE's RRC layer. - If both L1 / L2 centric mobility and CHO procedures are configured, when the UE receives an activation indication via L1 / L2 and at the same time the CHO conditions are met, it may use one of the following criteria for options 1 and 2: Option 1: L1 / L2 centric mobility configuration should be implemented as a priority. · Option 2: The UE selects the candidate cell with the best channel quality for handover. (7) Step 7: The UE performs a cell change procedure.

[0063] Embodiment 4 (1) Step 1: The UE accesses the network, e.g., a PCell. (2) Step 2: The network, e.g., PCell, sends the configuration to the UE. - Beam failure recovery parameters per TRP can be configured. - The RRC configuration message for the candidate cell is associated with the cell change procedure based on activation signaling. The UE is configured to support "physical layer signaling-based activation for cell change" or "MAC layer signaling-based activation for cell change" or "condition-based activation for cell change". - If L1 / L2-centric mobility is also included in the RRC reconfiguration message with the reconfigurationWithSync IE, one indication may be added to indicate that this mobility information is applicable after receiving an L1 / L2-related activation indication. This behavior allows to distinguish between L1 / L2-centric and L3 mobility handover commands. - The CHO configuration of a candidate cell can be configured in the UE, which may be the same as (or different from) the candidate cell associated with the RRC configuration message. (3) Step 3: The UE receives the configuration from the network, for example, the PCell. - When the RRC layer of the UE receives an RRC reconfiguration message, the UE checks compliance upon reception of an RRC reconfiguration message related to a cell change procedure based on activation signaling. If the UE is unable to comply with any part of the configuration included in the RRC reconfiguration message, the UE may report a compliance check failure to the network. This behavior defines when to check compliance of received RRC reconfiguration messages related to activation-based mobility. (4) Step 4: The UE reports the measurement results, including the physical layer and RRC layer of the UE, to the network. (5) Step 5: For candidate cells related to the cell change procedure based on the activation signaling, the UE evaluates the conditions. If the conditions related to one candidate cell are met, the UE performs the cell change procedure based on the lower layer conditions. - If the CHO setting is also configured, the lower layers of the UE must indicate to the RRC layer of the UE that the lower layer conditions for the cell change procedure are met. After that, the RRC layer of the UE must stop evaluating the CHO conditions after receiving the indication from the lower layers and does not need to trigger the CHO procedure. - If both L1 / L2 condition-based mobility configuration and CHO are configured, if the L1 / L2 conditions for cell change are met and the CHO conditions are met at the same time, one of the following criteria can be used: Option 1: L1 / L2 centric mobility configuration should be implemented as a priority. · Option 2: The UE selects the candidate cell with the best channel quality for handover. (6) Step 6: The UE performs a cell change procedure.

[0064] Embodiment 5 (1) Step 1: The UE accesses the network, e.g., a PCell. (2) Step 2: The network, e.g., PCell, sends the configuration to the UE. - The parameters for beam obstruction recovery per TRP can be configured in the UE. - The RRC configuration message for the candidate cell is associated with the cell change procedure based on activation signaling. The UE is configured to support "physical layer signaling-based activation for cell change" or "MAC layer signaling-based activation for cell change" or "condition-based activation for cell change". - If L1 / L2 centric mobility is also included in the RRC reconfiguration message with the reconfigurationWithSync IE, one indication may be added to indicate that this mobility information is applicable after receiving the L1 / L2 activation indication. (3) Step 3: The UE receives the configuration from the network, for example, the PCell. - When the RRC layer of the UE receives an RRC reconfiguration message, the UE checks compliance upon reception of the RRC reconfiguration message related to the cell change procedure based on activation signaling. If the UE cannot comply with any part of the configuration included in the RRC reconfiguration, the UE reports a compliance check failure to the network. (4) Step 4: The UE reports the measurement results, including the physical layer and the RRC layer, to the network. (5) Step 5: The network, for example, PCell, sends a DAPS handover command to the UE. The RRC layer of the network, e.g., the PCell, notifies the physical layer or MAC layer of the network that a DAPS handover command has been sent, after which the physical layer or MAC layer of the network does not send an activation indication of the cell switching procedure to the UE. (6) Step 6: The UE receives the DAPS handover command and performs the DAPS handover procedure. - The UE's RRC layer must notify the UE's lower layers, which then stop evaluating the condition. Optionally, the UE can continue evaluating the condition, but the UE will not trigger a condition-based switching procedure even if the condition is met. This behavior defines when the UE should perform a DAPS handover procedure and whether the UE's RRC layer should instruct the UE's MAC or physical layer.

[0065] 7 is an exemplary block diagram of an apparatus according to some embodiments of the present application. As shown in FIG. 7, the apparatus 700 may include at least one processor 704 and at least one transceiver 702 coupled to the processor 704. The apparatus 700 may be a UE or a network node (e.g., a BS).

[0066] In this figure, elements such as at least one transceiver 702 and processor 704 are described in the singular, but the plural is assumed unless limitation to the singular is explicitly stated. In some embodiments of the present application, the transceiver 702 may be divided into two devices, such as a receive circuit and a transmit circuit. In some embodiments of the present application, the apparatus 700 may further include an input device, a memory, and / or other components.

[0067] In some embodiments of the present application, the apparatus 700 may be a UE. The transceiver 702 in the UE may be configured to receive, from a serving cell, configuration information related to two or more TRPs of the serving cell. The processor 704 may be configured to detect beam failures of TRPs within the two or more TRPs. The transceiver 702 in the UE may be further configured to transmit a BFR request including information related to the TRPs. The processor 704 may be further configured to detect further beam failures of further TRPs within the two or more TRPs and monitor a PDCCH within a period of time before receiving a response to the BFR request from the serving cell.

[0068] In some embodiments of the present application, the apparatus 700 may be a UE. A transceiver 702 in the UE may be configured to: receive, from a serving cell, configuration information for a cell switch procedure related to one or more candidate cells, where the cell switch procedure is performed based on a cell switch condition for the cell switch procedure being satisfied or an activation indication for the cell switch procedure being received; and receive, from the serving cell via the wireless transceiver, one of a normal handover command, a DAPS handover command, and configuration information for a CHO procedure.

[0069] In some embodiments of the present application, the apparatus 700 may be a network node (e.g., a BS). A transceiver 702 in the network node may be configured to: transmit, to the UE, configuration information for a cell switch procedure related to one or more candidate cells, where the cell switch procedure is to be performed based on a cell switch condition for the cell switch procedure being met or an activation indication for the cell switch procedure being received; and transmit, via the wireless transceiver, to the UE, one of a normal handover command, a DAPS handover command, and configuration information for a CHO procedure.

[0070] In some embodiments of the present application, the apparatus 700 may further include at least one non-transitory computer-readable medium. In some embodiments of the present disclosure, the non-transitory computer-readable medium may store computer-executable instructions for causing a processor to perform the method with respect to a UE or a network node (e.g., a BS), as described above. For example, the computer-executable instructions, when executed, cause the processor 704 to interact with the transceiver 702 to perform the operations of the method described, for example, with respect to any of FIGS. 4-6.

[0071] While the present disclosure has been described using specific embodiments thereof, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments can be exchanged, added, or substituted in other embodiments. Also, not all elements in the figures are necessary for the operation of the disclosed embodiments. For example, one skilled in the art would be able to make and use the teachings of the present disclosure by simply employing the elements of the independent claims. Accordingly, the embodiments of the present disclosure described herein are intended to be illustrative, not limiting. Various changes can be made without departing from the spirit and scope of the present disclosure.

[0072] As used in this document, the terms "include," "including," or any other variation thereof, are intended to cover a non-exclusive inclusion, whereby a process, method, article, or apparatus that includes a list of elements not only includes those elements, but may also include other elements not expressly listed or that are inherent to such process, method, article, or apparatus. The use of an element preceded by "a," "an," etc., without further constraints, does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element. Also, the term "another" is defined as at least a second, or more. As used herein, the terms "having," etc. are defined as "including." [Explanation of symbols]

[0073] 700 equipment 702 Transceiver 704 processor

Claims

1. 1. A method performed by a user equipment (UE), comprising: receiving, from a serving cell, configuration information relating to two or more transmission / reception points (TRPs) of the serving cell; Detecting a first beam failure of a first TRP in the two or more TRPs; transmitting a first beam failure recovery (BFR) request including information related to the first TRP; detecting a second beam failure of a second TRP in the two or more TRPs before receiving a response to the first BFR request from the serving cell; monitoring a physical downlink control channel (PDCCH) within a period of time; A method comprising:

2. performing a random access channel (RACH) procedure in response to the period expiring.

10. The method of claim 1, further comprising:

3. The method of claim 2 , wherein the RACH procedure is based on configuration information related to a BFR procedure of the serving cell.

4. the period is associated with a time window in the time domain, the time window starting when the first BFR request or the second BFR request is transmitted, and the length of the time window is configured by the serving cell; or the period is associated with a timer, the period starting in response to the timer starting, and the period ending in response to the timer expiring or the timer being stopped; The method of claim 1.

5. transmitting the first BFR request and detecting the second beam failure; or transmitting said first BFR request; or Detecting the second beam failure and transmitting the second BFR request. The method of claim 4 , wherein the timer is started in response to

6. receiving the response to the first BFR request from the serving cell; or receiving a response to the second BFR request from the serving cell; 5. The method of claim 4, further comprising stopping the timer in response to:

7. 1. A method performed by a user equipment (UE), comprising: receiving, from a serving cell, configuration information of a cell switch procedure related to one or more candidate cells, the cell switch procedure being performed based on a cell switch condition of the cell switch procedure being met or an activation indication of the cell switch procedure being received; From the serving cell, Normal handover command, Dual Active Protocol Stack (DAPS) handover command, and Configuration information for conditional handover (CHO) procedures receiving one of A method comprising:

8. receiving, by a physical layer or a medium access control (MAC) layer of the UE, the activation indication from the serving cell, wherein the activation indication comprises: a physical layer identifier (PCID) of a candidate cell within said one or more candidate cells; or an index of the candidate cell, the index being associated with the PCID of the candidate cell or a cell global identifier (CGI) of the candidate cell; a receiving step including:

8. The method of claim 7, further comprising:

9. In response to the activation indication being received by the physical layer or the MAC layer of the UE and in response to receiving the configuration information related to the CHO procedure, indicating the activation indication to an RRC layer of the UE by the physical layer or the MAC layer of the UE.

9. The method of claim 8, further comprising:

10. In response to receiving the activation indication by the RRC layer of the UE from the physical layer or the MAC layer of the UE, stopping, by the RRC layer of the UE, evaluation of the conditions for the CHO procedure and not triggering the CHO procedure; or In response to satisfying said conditions of said CHO procedure, performing said cell switching procedure preferentially; or selecting a candidate cell with the best channel quality from the cell switching procedure and the CHO procedure for cell switching; 10. The method of claim 9, further comprising:

11. receiving a radio resource control (RRC) reconfiguration message from the serving cell, the RRC reconfiguration message including an indication that the RRC reconfiguration message is applicable after a physical layer or a MAC layer of the UE receives the activation indication from the serving cell; 8. The method of claim 7, further comprising:

12. In response to receiving the RRC reconfiguration message, checking compliance of the received RRC reconfiguration message.

12. The method of claim 11, further comprising:

13. reporting a compliance failure to the serving cell in response to the RRC layer of the UE not complying with the RRC reconfiguration message.

13. The method of claim 12, further comprising:

14. a processor; a wireless transceiver coupled to the processor; 1. A user equipment (UE) comprising: receiving, from a serving cell via the wireless transceiver, configuration information associated with two or more transmission / reception points (TRPs) of the serving cell; Detecting a first beam failure of a first TRP in the two or more TRPs; transmitting, via the wireless transceiver, a first beam failure recovery (BFR) request including information related to the first TRP; detecting a second beam failure of a second TRP in the two or more TRPs before receiving a response to the first BFR request from the serving cell; monitoring a physical downlink control channel (PDCCH) within a period of time; A user equipment (UE) configured to perform the following:

15. a processor; a wireless transceiver coupled to the processor; 1. A user equipment (UE) comprising: receiving, from a serving cell via the wireless transceiver, configuration information of a cell switch procedure related to one or more candidate cells, the cell switch procedure being performed based on a cell switch condition of the cell switch procedure being satisfied or an activation indication of the cell switch procedure being received; from the serving cell via the wireless transceiver; Normal handover command, Dual Active Protocol Stack (DAPS) handover command, and Configuration information for conditional handover (CHO) procedures receiving one of A user equipment (UE) configured to perform the following:

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