Beam failure detection and candidate beam detection operations for multi-receiver downlink

Abstract

A user equipment (UE) communicates with a base station having a first transmit and receive point (TRP) and a second TRP. The UE is configured to determine a beam failure of a first beam transmitted by the first TRP, and perform a candidate beam detection (CBD) operation to evaluate candidate beams for communication with the first TRP, where the CBD operation includes determining whether each candidate beam is compatible with an active beam transmitted to the UE by the second TRP.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communications, and more particularly to beam failure detection and candidate beam detection operations for multi-receiver downlinks. Background Art

[0002] Beam failure detection and recovery procedures for user equipment (UE) have been defined for single downlink (DL) reception or single angle of arrival (AoA) reception. However, the UE may be able to receive two DL receptions or two AoA receptions simultaneously. The operations related to beam failure detection (BFD), candidate beam detection (CBD), and beam failure recovery (BFR) in the two DL reception scenario remain undefined. Summary of the Invention

[0003] Some example embodiments relate to a method performed by a user equipment (UE) communicating with a base station having a first transmit and receive point (TRP) and a second TRP. The method includes determining a beam failure of a first beam transmitted by the first TRP, and performing a candidate beam detection (CBD) operation to evaluate candidate beams for communicating with the first TRP, wherein the CBD operation includes determining whether each candidate beam is compatible with an active beam transmitted by the second TRP to the UE.

[0004] Other exemplary embodiments relate to a user equipment (UE) having a transceiver configured to communicate with a base station having a first transmit and receive point (TRP) and a second TRP. The UE further has a processor communicatively coupled to the transceiver and configured to determine a beam failure of a first beam transmitted by the first TRP, and to perform a candidate beam detection (CBD) operation to evaluate candidate beams for communicating with the first TRP, wherein the CBD operation includes determining whether each candidate beam is compatible with an active beam transmitted to the UE by the second TRP.

[0005] Yet another exemplary embodiment relates to a method performed by a base station for communicating with a user equipment (UE) using a first beam from a first transmission and reception point and a second beam from a second transmission point (TRP). The method includes receiving a beam failure detection (BFD) notification from a UE indicating that a first beam of the first TRP has experienced a beam failure, and determining whether the BFD notification includes a new candidate beam for communicating with the UE using the first TRP.

[0006] Additional exemplary embodiments relate to a base station having: a transceiver configured to communicate with a user equipment (UE), and a processor communicatively coupled to the transceiver and configured to: receive a beam failure detection (BFD) notification from the UE indicating that a first beam of a first TRP has experienced a beam failure, and determine whether the BFD notification includes a new candidate beam for communicating with the UE using the first TRP. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Exemplary network arrangements are shown according to various exemplary embodiments.

[0008] Figure 2 An exemplary UE according to various exemplary embodiments is shown.

[0009] Figure 3 An exemplary base station is shown in accordance with various exemplary embodiments.

[0010] Figure 4 An exemplary network arrangement with two transceiver points is shown in accordance with various exemplary embodiments.

[0011] Figure 5 A first flow chart for UE BFR operations according to various exemplary embodiments is shown.

[0012] Figure 6A A second flow chart for UE BFR operations according to various exemplary embodiments is shown.

[0013] Figure 6B A third flow chart for UE BFR operations according to various exemplary embodiments is shown.

[0014] Figure 7A A first flow chart illustrating network behavior for BFD / CBD according to various exemplary embodiments is shown.

[0015] Figure 7B A second flow chart illustrating network behavior for BFD / CBD according to various exemplary embodiments is shown. DETAILED DESCRIPTION

[0016] The exemplary embodiments may be further understood with reference to the following description and associated drawings, wherein like elements are provided with like reference numerals.The exemplary embodiments relate to improvements in UE and network handling of beam failure detection, candidate beam detection, and beam failure recovery.

[0017] The exemplary embodiments are described with reference to a UE. However, reference to a UE is provided for illustrative purposes only. The exemplary embodiments may be utilized with any electronic component that can establish a connection with an accessory device and is configured with hardware, software, and / or firmware for exchanging information and data with the accessory device. Therefore, the term UE as described herein is used to represent any electronic component.

[0018] The exemplary embodiments are also described with reference to fifth generation (5G) New Radio (NR) networks and next generation Node Bs (gNBs). However, reference to 5G NR networks and gNBs is provided for illustrative purposes only. It should be understood that the exemplary embodiments may also be implemented in other types of networks, including but not limited to LTE networks, future evolutions of cellular protocols, or any other type of network.

[0019] A gNB may be configured with multiple transmit and receive points (TRPs). Throughout this specification, a TRP generally refers to a group of components configured to transmit and / or receive beams. In some embodiments, multiple TRPs may be deployed locally at the gNB. For example, the gNB may include multiple antenna arrays / panels, each configured to generate a different beam. In other embodiments, multiple TRPs may be deployed at various locations and connected to the gNB via a backhaul connection. For example, multiple small cells may be deployed at different locations and connected to the gNB. However, these examples are provided for illustrative purposes only. Those skilled in the art will understand that TRPs are configured to adapt to a variety of different conditions and deployment scenarios. Therefore, any reference to a TRP as a specific network component or to multiple TRPs deployed in a specific arrangement is for illustrative purposes only. The TRPs described herein may represent any type of network component configured to transmit and / or receive beams.

[0020] In single downlink reception (which may also be referred to as single angle of arrival (AoA) reception), beam fail detection (BFD) and beam recovery operations are well known to those skilled in the art. First, the UE may detect the set At the same time, the UE can measure and evaluate the beam failure of the reference signal (RS) used for the collection The UE may determine that a predefined threshold for beam failure has been met. In this case, the UE has two options. If the serving cell is an SCell, the UE may send a beam failure recovery (BFR) medium access control (MAC) control element (CE) to the serving SCell. Alternatively, if the serving cell is an SpCell, the UE may initiate a random access procedure with the serving SpCell.

[0021] However, these solutions for a single DL reception may not be ideal for two DL receptions. Several areas of UE behavior in multi-receiver chain downlink reception remain undefined. Example embodiments relate to UE and network operations for beam failure detection, candidate beam detection, and beam failure recovery in multi-receiver scenarios.

[0022] Figure 1 An exemplary network arrangement 100 according to various exemplary embodiments is shown. The exemplary network arrangement 100 includes a UE 110. Those skilled in the art will appreciate that the UE 110 can be any type of electronic component configured to communicate via a network, such as a mobile phone, tablet computer, desktop computer, smartphone, phablet, embedded device, wearable device, Internet of Things (IoT) device, etc. It should also be understood that an actual network arrangement can include any number of UEs used by any number of users. Therefore, for illustrative purposes, only an example with one UE 110 is provided.

[0023] UE 110 can be configured to communicate with one or more networks. In the example of network configuration 100, the network with which UE 110 can wirelessly communicate is a 5G NR radio access network (RAN) 120. However, it should be understood that UE 110 can also communicate with other types of networks (e.g., 5G cloud RAN, next generation RAN (NG-RAN), traditional cellular networks, etc.), and UE 110 can also communicate with the network via a wired connection. With respect to the exemplary embodiment, UE 110 can establish a connection with 5G NR RAN 120. Therefore, UE 110 can have a 5G NR chipset to communicate with NR RAN 120.

[0024] The 5G NR RAN 120 may be part of a cellular network that may be deployed by a network operator (e.g., Verizon, AT&T, T-Mobile, etc.). The RAN 120 may include cells or base stations configured to transmit and receive traffic from UEs equipped with appropriate cellular chipsets. In this example, the 5G NR RAN 120 includes a gNB 120A. However, reference to a gNB is provided for illustrative purposes only, and any suitable base station or cell (e.g., a Node B, eNodeB, HeNB, eNB, gNB, gNodeB, macrocell, microcell, small cell, femtocell, etc.) may be deployed.

[0025] Those skilled in the art will appreciate that any relevant procedures may be performed for UE 110 to connect to 5G NR RAN 120. For example, as described above, 5G NR RAN 120 may be associated with a specific network operator, where UE 110 and / or its user has protocol and credential information (e.g., stored on a SIM card). Upon detecting the presence of 5G NR RAN 120, UE 110 may send corresponding credential information to associate with 5G NR RAN 120. More specifically, UE 110 may associate with a specific cell (e.g., gNB 120A).

[0026] The network arrangement 100 also includes a cellular core network 130, the Internet 140, an IP Multimedia Subsystem (IMS) 150, and a network service backbone 160. The cellular core network 130 manages traffic flowing between the cellular network and the Internet 140. The IMS 150 can generally be described as an architecture for delivering multimedia services to the UE 110 using IP protocols. The IMS 150 can communicate with the cellular core network 130 and the Internet 140 to provide multimedia services to the UE 110. The network service backbone 160 communicates directly or indirectly with the Internet 140 and the cellular core network 130. The network service backbone 160 can generally be described as a collection of components (e.g., servers, network storage arrangements, etc.) that implement a set of services that can be used to extend the functionality of the UE 110 to communicate with various networks.

[0027] Figure 2 An exemplary UE 110 is shown according to various exemplary embodiments. The UE 110 will refer to Figure 1 100. UE 110 may represent any electronic device and may include a processor 205, a memory arrangement 210, a display device 215, an input / output (I / O) device 220, a transceiver 225, and other components 230. Other components 230 may include, for example, an audio input device, an audio output device, a battery providing a limited power source, a data acquisition device, a port for electrically connecting UE 110 to other electronic devices, sensors for detecting conditions of UE 110, and the like.

[0028] Processor 205 may be configured to execute multiple engines of UE 110. For example, these engines may include a multi-beam engine 235 for performing operations such as beam failure detection (BFD), candidate beam detection (CBD), and beam failure recovery (BFR).

[0029] The engines described above as applications (e.g., programs) executed by the processor 205 are merely exemplary. The functionality associated with these engines may also be represented as separate incorporated components of the UE 110, or may be modular components coupled to the UE 110, such as integrated circuits with or without firmware. For example, the integrated circuit may include input circuitry for receiving signals and processing circuitry for processing signals and other information. The engines may also be embodied as one application or multiple separate applications. Furthermore, in some UEs, the functionality described for the processor 205 is split between two or more processors, such as a baseband processor and an application processor. The exemplary embodiments may be implemented in any of these or other configurations of the UE.

[0030] The memory arrangement 210 may be a hardware component configured to store data related to operations performed by the UE 110. The display device 215 may be a hardware component configured to display data to a user, while the I / O device 220 may be a hardware component that enables the user to enter input. The display device 215 and the I / O device 220 may be separate components or may be integrated together (such as a touch screen). The transceiver 225 may be a hardware component configured to establish a connection with the 5G-NR RAN 120. Thus, the transceiver 225 may operate on a variety of different frequencies or channels (e.g., a set of contiguous frequencies).

[0031] Figure 3 An exemplary base station 300 is shown in accordance with various exemplary embodiments. Base station 300 may represent gNB 120A or any other access node that UE 110 may use to establish a connection and manage network operations.

[0032] The base station 300 may include a processor 305, a memory arrangement 310, input / output (I / O) devices 315, a transceiver 320, and other components 325. These other components 325 may include, for example, an audio input device, an audio output device, a battery, a data acquisition device, ports for electrically connecting the base station 300 to other electronic devices and / or a power source, and the like.

[0033] Processor 305 may be configured to execute multiple engines of UE 110. For example, these engines may include a multi-beam engine 330 for performing operations related to beam failure detection (BFD), candidate beam detection (CBD), and beam failure recovery (BFR).

[0034] The memory 310 may be a hardware component configured to store data related to operations performed by the base station 300. The I / O device 315 may be a hardware component or port that enables a user to interact with the base station 300. The transceiver 320 may be a hardware component configured to exchange data with the UE 110 and any other UEs in the network arrangement 100. The transceiver 320 may operate on a variety of different frequencies or channels (e.g., a set of contiguous frequencies). Thus, the transceiver 320 may include one or more components (e.g., radios) to enable data exchange with various networks and UEs.

[0035] In the case of two simultaneous DL receptions (e.g., two AoA receptions), a procedure is required for both the network and the UE to ensure that the UE simultaneously receives both the new beam corresponding to AoA2 and the existing beam corresponding to AoA1. A UE operating in such a scenario may alternatively fall back to a single DL (e.g., using AoA1) reception, or the UE may restore two AoA receptions through the following procedure defined herein.

[0036] Figure 4 An exemplary network arrangement 400 with two TRPs is shown, according to various exemplary embodiments. Network arrangement 400 illustrates the core concept of multiple TRPs, as well as multiple angles of arrival to a UE. UE 110 is depicted as having two antenna panels 404 and 407. Those skilled in the art will recognize that antenna panels can be understood as subcomponents of transceiver 225.

[0037] The network arrangement 400 includes a first TRP 401 and a second TRP 405. TRPs 401 and 405 communicate with UE 110 via transmit beams, where AoA 403 is received by antenna panel 404 of UE 110 and AoA 406 is received by antenna panel 407 of UE 110. Those skilled in the art will appreciate that a UE may have multiple antenna panels. Each antenna panel (e.g., 404 and 407) may communicate with a different TRP. Although Figure 4 Shown as having two antenna panels and two TRPs, this is exemplary only, and other numbers of antenna panels and TRPs for communication with a UE are possible. Figure 4 TRPs 401 and 405 are depicted as distinct entities, but it is also possible that the TRPs occupy the same physical location or device.

[0038] In a first aspect of the exemplary embodiments, UE detection of beam failure and candidate beam detection for multi-receiver chain downlink reception is disclosed herein. When a UE (e.g., UE 110) detects beam failure on an AoA (e.g., AoA 406) and triggers a BFR procedure for AoA 406, there are two variations of the processing scheme. Figure 5It may be understood as applying to the first of the two variants of the first aspect.

[0039] Figure 5 A first flowchart 500 for UE BFR operation according to various exemplary embodiments is shown. Flowchart 500 is applicable to a situation where a UE (e.g., UE 110) has identified BFD, initiated BFR, and must select a new beam (e.g., a candidate beam) via CBD. As will be described in more detail below, the criteria for selecting a new beam is not limited to the beam with the best signal quality, but rather a beam that meets the signal quality requirements and can coexist with the existing beam. In this example, it can be assumed that the beam that has failed is the beam used to receive AoA2, and the new beam to be selected can coexist with the existing beam used to receive AoA1 (e.g., UE 110 can receive both the new beam and the existing beam simultaneously). References to AoA1 and AoA2 can be understood as analogous to Figure 4 AoA 403 and AoA 406 are shown in FIG, although this is exemplary only. Those skilled in the art will recognize that the exemplary embodiments relate to the case where one beam fails; the order in which the beams are defined is not relevant (e.g., any beam can be defined as the first beam).

[0040] The manner in which a candidate beam is determined to be able to coexist with an existing beam may depend on the specific implementation of the UE. In some exemplary embodiments, a general process may be that the UE will estimate the reference signal received power (RSRP) of each beam through layer 1 (L1) measurements. If both beams have satisfactory RSRP, and if the mutual interference between the two beams can be sufficiently resolved to ensure that the Rx signals from the two beams can be correctly decoded in the UE receiver, the UE will determine that the two beams can coexist, for example, be received simultaneously. However, it should be understood that this is an exemplary way to determine whether the beams can coexist. The exemplary embodiments should not be limited to the UE making coexistence determinations in any particular manner.

[0041] In some exemplary embodiments, it may be desirable for UE 110 to quickly report BFD to the network. In the case where UE 110 operates with single downlink control information (sDCI) from a single TRP, there may be a significant (>100 slots) delay from the time BFD is detected at UE 110 to the time CBD completes. Additionally, if UE 110 is unable to correctly receive DCI, the network may not be able to schedule UE 110 for both DL reception or UL transmission despite sufficient link quality for the second connected TRP. Therefore, in some cases, UE 110 may report BFD to the network before selecting a new beam. This is described in more detail below.

[0042] As part of selecting a new beam that can coexist with an existing beam, the CBD can be extended to allow this evaluation. The extended CBD evaluation allows the network to determine whether the existing beam is compatible with the newly selected beam. The timing requirement can be defined as:

[0043] Max(25,Ceil(3x P x N x P CBD )x T SSB +Δ)

[0044] Where Max is the maximum value of the set, 25 refers to 25ms, ceil is the upward rounding function, P is the period, N is the number of candidate beams, P CBD Refers to the period of candidate beam detection, T SSB is the period of SSB in the set, and Δ is the additional time.

[0045] See also Figure 5 In 501, UE 110 may be considered to have detected beam failure. If UE 110 has an sDCI configuration from a single TRP, UE 110 proceeds to 502. In 502, UE 110 immediately reports BFD to the network. Receipt of notification 502 may cause the network to switch sDCI from the failed TRP (e.g., TRP 405) to the working TRP (e.g., TRP 401).

[0046] From 501 or 502, the method proceeds to 503, where the UE 110 selects a new beam. As described above, the criteria for selecting a new beam are beams that meet signal quality requirements and can coexist with existing beams. Candidate beams can be represented by beams whose layer 1 reference signal received power (L1-RSRP) is equal to or greater than a threshold (Q in_LR As described above, the time used to perform CBD can be extended to determine whether the candidate beam can coexist with the existing beam.

[0047] Once a candidate beam is selected, UE 110 may report the selected beam to the network in 504. The selected beam may be notified, for example, via UCI (uplink control information), MAC CE, or radio resource control (RRC signaling) via MAC CE. In some exemplary embodiments, the existing MAC CE may be modified because BFD transmission before CBD completion exceeds existing standard-based (e.g., 3GPP standard) operations. In the case of carrier aggregation, the report may be based on the BFR MAC CE for the secondary cell (SCell).

[0048] In a second variation of the first aspect, operations are disclosed for the case where the UE cannot find a new beam for AoA2 that is compatible with the ongoing AoA1 via CBD. Figure 6A and Figure 6B UE operation according to this scenario is shown.

[0049] Figure 6A A second flow chart 600 for UE BFR operation according to various exemplary embodiments is shown. In a first alternative of the second variant, in 601, the UE (e.g., UE 110) may fall back to single AoA operation to minimize the duration of the outage by using an ongoing (e.g., real-time or active) beam. In 602, UE 110 may notify the network via UCI, MACCE, RRC, etc. that AoA2 (e.g., AoA 406) has been deactivated (e.g., BFD).

[0050] As mentioned above, it should be understood that reference to AoA2 does not imply an order relationship, ie, either AoA-1 or AoA2 could be defined as "first" without changing the scope of the exemplary embodiments. One skilled in the art will recognize that one of the two beams has failed.

[0051] The second alternative of the second variant is applicable to the case where sDCI is configured and sent from a single TRP. Figure 6B A third flow chart 603 is shown for UE BFR operation according to various exemplary embodiments. At 604, UE 110 determines whether it is operating in an sDCI configuration, where DCI is sent from a single TRP (e.g., TRP 401). If so, UE 110 proceeds to 605, where UE 110 reports BFD to the network via UCI or MAC CE. The network's receipt of report 605 allows for faster handover of sDCI from a failed TRP (e.g., TRP 405).

[0052] Following 605, or directly from 604 (if the answer to 604 is no), UE 110 proceeds to 606. In 606, UE 110 falls back to single AoA operation via an existing (e.g., real-time or active) beam.

[0053] In 607, UE 110 determines whether there are any additional available beam pairs that it can support. Based on previous beam reports to the network (not shown), UE 110 may already know one or more beam pairs that it can use immediately after the beam failure. If there are valid known beam pairs, UE 110 proceeds to 608, where it reports the new beam pair to the network.

[0054] In 608, UE 110 determines whether it is configured with two channel measurement resource (CMR) sets for beam measurement. If the answer to 608 is yes, UE 110 will perform L1-RSRP measurement in 610. If the answer to 607 is no, UE 110 proceeds to 609 and maintains single AoA operation via the existing beam.

[0055] In 611, the UE determines whether it has found a suitable beam pair (e.g., a beam compatible with an existing beam). Unsuitable measurement beams may also be referred to as secondary candidate beams. If not yet complete, the UE 110 returns to 610 to perform further measurements. If the UE 110 has found a suitable beam pair, it proceeds to 612, where the UE 110 reports the new beam pair it can support to the network via a group-based beam reporting mechanism.

[0056] In a third aspect of the exemplary embodiments, UCI-based reporting of new beams or BFD to the network is disclosed. In a first alternative of the third aspect, UCI can be considered as special channel state information (CSI) feedback. The priority of the first alternative UCI can have the same priority as the existing CSI (e.g., L1-RSRP or L1-signal to interference plus noise ratio (SINR)).

[0057] In a second alternative, UCI can be a newly defined UCI that will coexist with existing UCI types such as SR / HARQ-ACK / CSI / CG UCI. The new UCI can be independently encoded using polar codes, or it can be jointly encoded with other types of UCI with polar codes.

[0058] In a fourth aspect of the exemplary embodiments, network behavior of BFD / CBD for multiple RX reception is disclosed herein. Figure 7A A first flow chart 700 illustrates network behavior for BFD / CBD according to various exemplary embodiments. In 701, the network receives a BFD request with a new beam from a UE (e.g., UE 110). Following 701, the network may perform two alternative operations. Operations 702 and 703 should be understood as alternative network behaviors.

[0059] In a first alternative (shown by 702), the network may configure an active transmission configuration indicator (TCI) state based on the new beam received in 701. After 702, the UE may now receive with two downlinks (via two beams) again.

[0060] In a second alternative (shown by 703), the network configures the UE to provide channel state feedback (CSF) to the network. The channel state feedback can be a channel quality indicator, a rank indicator, and / or a precoding matrix indicator. The network can configure the UE by configuring a CSI processing unit (CPU) for the UE to report the CSF.

[0061] Figure 7B A second flow chart 704 illustrates network behavior for BFD / CBD according to various exemplary embodiments. In 705, the network receives BFD without a new beam from the UE (e.g., the BFD notification does not include a new beam). Operations 706, 708, and 709 can be understood as three different alternatives to the scenario of 705.

[0062] In a first alternative shown in 706, the network deconfigures the TCI state corresponding to the disabled beam. In 707, the network sends a request to the UE 110 requesting the UE to fall back to one AoA reception (ie, a single beam).

[0063] In a second alternative shown in 708, the network may initiate a TCI state switch. If the UE 110 reports a new beam pair during group-based beam reporting (e.g., Figure 6B 607 and 608 in ), enabling TCI state switching allows UE110 to determine the new beam pair.

[0064] In a third alternative shown in 709, if group-based beam reporting has stopped, the network may reconfigure group-based beam reporting to UE 110. This may allow UE 110 to continue measuring the appropriate beam pairs.

[0065] For operations 706, 708, and 709 (three alternatives), the network may be configured The CBD resources in The CBD RS resources in the UEFI are configured for each TRP that can be linked to two sets of channel measurement resources (CMRs). The CBD resources for each TRP can be included in the CMR set for each TRP. In this scenario, the likelihood that a new beam selected from the CBD RS is compatible with an existing beam used for another AoA is increased.

[0066] Example

[0067] In a first embodiment, a method is performed by a base station that communicates with a user equipment (UE) using a first beam from a first transmit and receive point (TRP) and a second beam from a second TRP, the method comprising: receiving a beam failure detection (BFD) notification from the UE indicating that the first beam of the first TRP has experienced a beam failure, and determining whether the BFD notification includes a new candidate beam for communicating with the UE using the first TRP.

[0068] In a second embodiment, according to the method described in the first embodiment, the method further includes: generating a channel measurement resource (CMR) set for each TRP, the two CMR sets further including one or more configured candidate beam detection (CBD) reference signal (RS) resources for the first TRP and the second TRP, respectively; and sending an indication of the CMR set to the UE.

[0069] In a third embodiment, the method according to the first embodiment, wherein the BFD notification is received via a medium access control (MAC) control element (CE), uplink control information (UCI), or radio resource signaling (RRC).

[0070] In a fourth embodiment, the method according to the third embodiment, wherein the BFD notification is received as channel state information (CSI) feedback via UCI.

[0071] In a fifth embodiment, the method according to the third embodiment is received via UCI independently encoded using a polar code or UCI jointly encoded using a polar code and other types of UCI.

[0072] Those skilled in the art will appreciate that the exemplary embodiments described above can be implemented with any suitable software configuration or hardware configuration or combination thereof. Exemplary hardware platforms for implementing the exemplary embodiments may include, for example, Intel x86-based platforms with compatible operating systems, Windows OS, Mac platforms and MAC OS, mobile devices with operating systems such as iOS, Android, etc. The exemplary embodiments of the above-described methods may be embodied as a program comprising lines of code stored on a non-transitory computer-readable storage medium, which, when compiled, can be executed on a processor or microprocessor.

[0073] Although this application describes various embodiments, each having different features in various combinations, those skilled in the art will understand that any feature of one embodiment may be combined with features of other embodiments in any manner that is not expressly disavowed or that is not functionally or logically inconsistent with the operation of the device or the stated function of the disclosed embodiment.

[0074] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of authorized use should be clearly stated to users.

[0075] It will be apparent to those skilled in the art that various modifications may be made to the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, it is intended that the present disclosure covers modifications and variations of the present disclosure as long as they come within the scope of the appended claims and their equivalents.

Claims

1. A method performed by a user equipment (UE) communicating with a base station including a first transmit and receive point (TRP) and a second TRP, the method comprising: determining a beam failure of a first beam transmitted by the first TRP; as well as A candidate beam detection (CBD) operation is performed to evaluate candidate beams for communicating with the first TRP, wherein the CBD operation includes determining whether each candidate beam is compatible with an active beam sent by the second TRP to the UE.

2. The method according to claim 1, further comprising: selecting one of the candidate beams to communicate with the first TRP; as well as Information identifying the one of the candidate beams is sent to the base station.

3. The method of claim 1 , wherein the information identifying the one of the candidate beams sent to the network is sent via a medium access control (MAC) control element (CE), uplink control information (UCI), or radio resource signaling (RRC).

4. The method of claim 3, wherein the information is sent as channel state information (CSI) feedback via UCI, wherein the CSI feedback has a priority equal to L1-reference signal received power (RSRP) CSI feedback. The method of claim 3 , wherein the information is transmitted via UCI independently encoded using a polar code or UCI jointly encoded using a polar code and other types of UCI. The method of claim 1 , wherein evaluating the candidate beams comprises determining whether each candidate beam satisfies a beam quality threshold.

7. The method according to claim 1, further comprising: When the UE is configured with a single downlink control information (sDCI) configuration sent from one of the first TRP or the second TRP, a beam failure detection (BFD) notification is sent to the base station before completing the CBD operation, wherein the BFD notification indicates the beam failure.

8. The method of claim 7, wherein the BFD notification is sent via uplink control information (UCI) or a medium access control (MAC) control element (CE).

9. The method of claim 8, wherein the BFD notification is sent via UCI as channel state information (CSI) feedback, wherein the CSI feedback has a priority equal to L1-reference signal received power (RSRP) CSI feedback. 10 . The method of claim 8 , wherein the BFD notification is sent via UCI independently encoded using a polar code or UCI jointly encoded using a polar code with other types of UCI.

11. The method according to claim 1, wherein When the UE cannot identify a candidate beam among the candidate beams that is compatible with the active beam, the method further includes: Perform a rollback operation.

12. The method according to claim 11, wherein the rollback operation comprises: Switch to single beam operation mode using the active beam communicating with the second TRP.

13. The method according to claim 12, further comprising: A beam failure detection (BFD) notification indicating the beam failure of the first beam is sent to the network via a MAC CE.

14. The method according to claim 11, wherein the rollback operation comprises: When the UE is configured with a single downlink control information configuration (sDCI) sent from one of the first TRP or the second TRP, a beam failure detection (BFD) notification is sent to the network before completing the CBD operation.

15. The method according to claim 14, wherein the rollback operation comprises: Reporting to the base station candidate beam pairs supported by the UE, wherein the candidate beam pairs do not include the active beam currently sent by the second TRP, and wherein the reporting is performed using group-based beam reporting.

16. The method according to claim 15, wherein the rollback operation further comprises: When the UE is configured with two channel measurement resource (CMR) sets, L1-reference signal received power (RSRP) measurement is performed on one or more candidate beam pairs, wherein the candidate beam pairs are selected from the candidate beam pairs.

17. A method performed by a base station, the base station communicating with a user equipment using a first beam from a first transmission and reception point and a second beam from a second transmission point (TRP), the method comprising: receiving a beam fail detection (BFD) notification from the UE indicating that the first beam of the first TRP has experienced a beam fail; as well as Determine whether the BFD notification includes a new candidate beam for communicating with the UE using the first TRP.

18. The method according to claim 17, wherein When the BFD notification includes the new candidate beam, the method further includes: A configuration including an active transmission configuration indicator (TCI) state for the new candidate beam is sent to the UE.

19. The method according to claim 17, wherein When the BFD notification includes the new candidate beam, the method further includes: A configuration is sent to the UE, the configuration indicating that the UE is to use the new candidate beam to perform measurements to provide channel state feedback to the base station.

20. The method according to claim 17, wherein When the BFD notification does not include the new candidate beam, the method further includes: deconfiguring a transmission configuration indicator (TCI) state corresponding to the first beam; and The UE is configured to fall back to single beam reception using the second beam from the second TRP.

21. The method according to claim 17, wherein When the BFD notification does not include the new candidate beam, the method further includes: receiving an indication of candidate beam pairs supported by the UE; A transmission configuration indicator (TCI) state switch associated with the candidate beam pair is sent to the UE.

22. The method according to claim 17, wherein When the BFD notification does not include the new candidate beam, the method further includes: The UE is reconfigured with group-based beam reporting.

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