Beam obstruction recovery in multiple transmission / reception point scenarios

Abstract

The present disclosure relates generally to the field of wireless communications, and in particular to techniques for performing beam failure recovery (BFR) of transmission / reception points (TRPs) in a multi-TRP (mTRP) scenario. More specifically, the present technology includes defining rules by which a UE can determine that TRPs are considered to have failed simultaneously or failed individually in an mTRP scenario. Such rules are defined based on current counter values ​​of beam failure instance (BFI) counters used by the UE for each of the TRPs. In some embodiments, the rules may additionally be defined based on a current timer state of a timer monitoring the BFI counter. Using the rules defined in this way, the UE can clearly determine when it is necessary to use a BFR mechanism for at least one of the TRPs individually or for all TRPs in one or more cells simultaneously.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of wireless communications, and more particularly to techniques that enable a user equipment (UE) to perform beam failure recovery (BFR) individually or simultaneously for multiple transmission / reception points (TRPs) in one or more cells of a wireless communications network. [Background technology]

[0002] In wireless communications, BFR may be initiated by a UE upon detection of one or more beam failure instances (BFIs); for example, a BFI may occur when a serving beam used by the UE to communicate with a TRP is no longer able to provide a desired communication quality (e.g., the quality falls below a threshold determined based on a downlink (DL) reference signal (RS) configured for control and / or data transmission by the TRP). Currently, there are various BFR options being discussed in the 3rd Generation Partnership Project (3GPP).

[0003] More specifically, one issue concerns the BFR mechanism to be used when multiple / all TRPs in a serving cell are in a failure state, i.e., when the corresponding serving beam does not provide the desired communication quality. One aspect that is undefined in this regard is how the UE determines that all TRPs are in a failure state, i.e., when the UE must or is required to trigger the BFR mechanism for the TRPs in the serving cell, individually or simultaneously.

[0004] The simplest way to solve this problem is to determine a simultaneous failure (i.e., when all TRPs are considered to be in a failure state) when the BFI counters used by the TRPs reach a predefined maximum value at the same time. However, this method may not allow the UE to clearly determine the above-mentioned "simultaneous", which may reduce the efficiency of the use of the BFR mechanism (e.g., the UE may erroneously decide to use the BFR mechanism simultaneously for all TRPs in the serving cell, even though it is sufficient to use the BFR mechanism only for one of the TRPs). Summary of the Invention

[0005] This Summary is provided to introduce some concepts in a simplified form that are described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the disclosure, nor is it intended to be used to limit the scope of the disclosure.

[0006] The objective of the present disclosure is to provide a technical solution that enables a UE to clearly determine when it is necessary to initiate a BFR mechanism for multiple TRPs in one or more cells of a wireless communication network, either individually or simultaneously.

[0007] The above object is achieved by the features of the independent claims in the appended claims. Further embodiments and examples are evident from the dependent claims, the detailed description and the accompanying drawings. The embodiments not included in the claims should be construed as examples that help in understanding the disclosure.

[0008] According to a first aspect, a UE for wireless communication is provided. The UE includes a transceiver, a storage, and at least one processor. The storage is configured to store processor-executable instructions. When executed by the at least one processor, the processor-executable instructions cause the at least one processor to operate as follows. First, the at least one processor causes the transceiver to perform wireless communication with a first TRP using at least one first serving beam, and to perform wireless communication with a second TRP using at least one second serving beam. Next, the at least one processor assigns a first counter and a first timer to the first TRP. The first counter has a counter value that is incremented by 1 each time a BFI for the first TRP occurs. The BFI for the first TRP means that the at least one first serving beam cannot provide a predetermined communication quality. The first timer is triggered in response to the BFI for the first TRP, and the first counter is reset when the first timer expires. Next, the at least one processor assigns a second counter and a second timer to the second TRP. Similar to the first counter, the second counter is incremented by one each time a BFI for the second TRP occurs. The BFI for the second TRP means that at least one second serving beam cannot provide a predetermined communication quality. Similar to the first timer, the second timer is triggered in response to a BFI for the second TRP, and the second counter is reset when the second timer expires. Thereafter, the at least one processor determines whether to initiate a BFR mechanism for at least one of the first TRP and the second TRP based on (i) the current counter value of each of the first counter and the second counter, or (ii) the current counter value of at least one of the first counter and the second counter and at least one of the first timer and the second timer. With such a configuration, the UE can clearly determine when it is necessary to use a BFR mechanism for at least one of the TRPs individually or simultaneously for all TRPs in one or more cells.

[0009] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for both the first TRP and the second TRP when (i) a current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a current counter value of the second counter is a predetermined counter value. The predetermined counter value is less than or equal to the maximum counter value of the second counter. In this manner, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in a cell(s).

[0010] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for the first TRP when (i) a current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a current counter value of the second counter is equal to 0. In this manner, the UE can unambiguously determine when it is necessary to use the BFR mechanism for one of the TRPs in the cell(s) individually.

[0011] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for the first TRP when a current counter value of the first counter reaches the maximum counter value of the first counter while a current counter value of the second counter is less than a predefined counter value. The predefined counter value is less than or equal to the maximum counter value of the second counter. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism for one of the TRPs in the cell(s) individually.

[0012] In an exemplary embodiment of the first aspect, each of the first and second counters has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate the BFR mechanism for both the first and second TRPs when the sum of the current counter values ​​of the first and second counters is equal to (i) the minimum or maximum of the maximum counter values ​​of the first and second counters, or (ii) the sum of the maximum counter values ​​of the first and second counters, or (iii) a predefined threshold. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0013] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate the BFR mechanism for both the first TRP and the second TRP if (i) a current counter value of the first counter reaches the maximum counter value of the first counter at a time point, and (ii) a current counter value of the second counter reaches the maximum counter value of the second counter within a predetermined period from the time point. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell(s).

[0014] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for both the first TRP and the second TRP if (i) a current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a new BFI for the second TRP occurs before the second timer expires, causing the current counter value of the second counter to be equal to the maximum counter value of the second counter. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0015] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for both the first TRP and the second TRP if (i) a current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a new BFI for the second TRP occurs before the second timer expires, and the new BFI causes the current counter value of the second counter to be equal to a predetermined counter value. The predetermined counter value is less than or equal to the maximum counter value of the second counter. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0016] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for both the first TRP and the second TRP if (i) a current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a new BFI for the second TRP occurs before the second timer expires. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0017] In an exemplary embodiment of the first aspect, each of the first and second counters has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for both the first and second TRPs when (i) the current counter values ​​of the first and second counters are equal to the maximum counter values ​​of the first and second counters, respectively, and (ii) a new BFI for the first TRP occurs before the second timer expires. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0018] In an exemplary embodiment of the first aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the at least one processor is configured to initiate a BFR mechanism for the first TRP when (i) a current counter value of the first counter is equal to the maximum counter value of the first counter and (ii) the second timer expires. In this manner, the UE can clearly determine when it is necessary to use the BFR mechanism for one of the TRPs in the cell(s) individually.

[0019] In one exemplary embodiment of the first aspect, the first TRP and the second TRP are located in a single cell or in two different cells, which allows the UE according to the first aspect to be used more flexibly since it can operate in both intra-cell and inter-cell scenarios.

[0020] According to a second aspect, a wireless communication method is provided. The method starts with a step of having a UE communicate with a first TRP by using at least one first serving beam and communicate with a second TRP by using at least one second serving beam. The method then proceeds to a step of assigning a first counter and a first timer to the first TRP. The first counter has a counter value that is incremented by one each time a new BFI for the first TRP occurs. The BFI for the first TRP means that the at least one first serving beam will not be able to provide a predetermined communication quality. The first timer is triggered in response to the BFI for the first TRP, and the first counter is reset when the first timer expires. The method then proceeds to a step of assigning a second counter and a second timer to the second TRP. Similar to the first counter, the second counter has a counter value that is incremented by one each time a new BFI for the second TRP occurs. The BFI for the second TRP means that the at least one second serving beam will not be able to provide a predetermined communication quality. Similar to the first timer, the second timer is triggered in response to a BFI for the second TRP, and the second counter is reset when the second timer expires. The method then proceeds to determine whether to initiate a BFR mechanism for at least one of the first and second TRPs based on (i) the current counter values ​​of the first and second counters, respectively, or (ii) the current counter values ​​of at least one of the first and second counters and at least one of the first and second timers. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism for at least one TRP individually or for all TRPs simultaneously in one or more cells.

[0021] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for both the first TRP and the second TRP when (i) the current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) the current counter value of the second counter is equal to a predefined counter value. The predefined counter value is less than or equal to the maximum counter value of the second counter. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell(s).

[0022] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for the first TRP when (i) the current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) the current counter value of the second counter is equal to 0. By doing so, the UE can clearly determine when it is necessary to use the BFR mechanism for one of the TRPs in the cell(s) individually.

[0023] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for the first TRP when the current counter value of the first counter reaches the maximum counter value of the first counter while the current counter value of the second counter is less than the maximum counter value of the second counter. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism for one of the TRPs in the cell individually.

[0024] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for both the first TRP and the second TRP when the sum of the current counter values ​​of the first counter and the second counter is equal to (i) the minimum or maximum of the maximum counter values ​​of the first counter and the second counter, or (ii) the sum of the maximum counter values ​​of the first counter and the second counter, or (iii) a predefined threshold. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0025] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, if (i) the current counter value of the first counter reaches the maximum counter value of the first counter at a certain time point, and (ii) the current counter value of the second counter reaches the maximum counter value of the second counter within a predetermined period from the time point, the BFR mechanism is initiated for both the first TRP and the second TRP. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell(s).

[0026] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for both the first TRP and the second TRP if (i) the current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a new BFI for the second TRP occurs before the second timer expires, causing the current counter value of the second counter to be equal to the maximum counter value of the second counter. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0027] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for both the first TRP and the second TRP if (i) the current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a new BFI for the second TRP occurs before the second timer expires, which BFI makes the current counter value of the second counter equal to a predefined counter value. The predefined counter value is less than or equal to the maximum counter value of the second counter. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0028] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for both the first TRP and the second TRP if (i) the current counter value of the first counter is equal to the maximum counter value of the first counter, and (ii) a new BFI for the second TRP occurs before the second timer expires. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0029] In an exemplary embodiment of the second aspect, each of the first and second counters has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for both the first and second TRPs if (i) the current counter values ​​of the first and second counters are equal to the maximum counter values ​​of the first and second counters, respectively, and (ii) a new BFI for the first TRP occurs before the second timer expires. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism simultaneously for all TRPs in the cell.

[0030] In an exemplary embodiment of the second aspect, each of the first counter and the second counter has a maximum counter value. In this exemplary embodiment, the BFR mechanism is initiated for the first TRP when (i) the current counter value of the first counter is equal to the maximum counter value of the first counter and (ii) the second timer expires. In this way, the UE can clearly determine when it is necessary to use the BFR mechanism for one of the TRPs in the cell(s) individually.

[0031] In an exemplary embodiment of the second aspect, the first TRP and the second TRP are located in a single cell or in different cells, which makes the method according to the second aspect more flexible to use, since it can be applied in both intra-cell and inter-cell scenarios.

[0032] According to a third aspect, there is provided a computer program product comprising a computer readable medium having computer code stored therein, which when executed by at least one processor causes the at least one processor to perform a method according to the second aspect of the present disclosure, which may simplify implementation of the method according to the second aspect of the present disclosure in any wireless communication device, such as a UE according to the first aspect of the present disclosure.

[0033] According to a fourth aspect, a UE for wireless communication is provided. The UE includes a transceiver means, a storage means, and a processing means. The storage means is configured to store processor-executable instructions. When executed by the processing means, the processor-executable instructions cause the processing means to operate as follows. First, the processing means causes the transceiver means to perform wireless communication with a first TRP using at least one first serving beam, and to perform wireless communication with a second TRP using at least one second serving beam. Next, the processing means assigns a first counter and a first timer to the first TRP. The first counter is incremented by one each time a BFI for the first TRP occurs. The BFI for the first TRP means that at least one first serving beam cannot provide a predetermined communication quality. The first timer is triggered in response to the BFI for the first TRP, and the first counter is reset when the first timer expires. Next, the processing means assigns a second counter and a second timer to the second TRP. The second counter, like the first counter, is incremented by one each time a BFI for the second TRP occurs. The BFI for the second TRP means that at least one second serving beam cannot provide a predetermined communication quality. Like the first timer, the second timer is triggered in response to a BFI for the second TRP, and the second counter is reset when the second timer expires. The processing means then decides whether to initiate a BFR mechanism for at least one of the first TRP and the second TRP based on (i) the current counter value of each of the first counter and the second counter, or (ii) the current counter value of at least one of the first counter and the second counter and at least one of the first timer and the second timer. Such a configuration allows the UE to clearly determine when it is necessary to use the BFR mechanism for at least one TRP individually or when it is necessary to use the BFR mechanism for all TRPs in the cell(s) simultaneously.

[0034] Other features and advantages of the present disclosure will become apparent from reading the following detailed description and from reviewing the accompanying drawings. [Brief description of the drawings]

[0035] The present disclosure is described below with reference to the accompanying drawings. [Figure 1] FIG. 1 shows a block diagram of a wireless communication system in which a Beam Failure Recovery (BFR) mechanism is initiated in a single transmitting / receiving point (TRP) scenario. [Diagram 2] FIG. 2 illustrates a block diagram of a wireless communication system in which a BFR mechanism is initiated in a multiple TRP (mTRP) scenario. [Diagram 3] FIG. 3 illustrates an example of a Medium Access Control (MAC) Control Element (CE) (MAC CE) that can be used in the BFR mechanism of a secondary cell (SCell). [Figure 4] FIG. 4 is a schematic diagram illustrating the mTRP Beam Fault Detection (BFD) approach proposed in 3GPP Release 17. [Diagram 5] FIG. 5 illustrates a block diagram of a UE for wireless communication according to an example embodiment. [Figure 6] FIG. 6 illustrates a flow chart of a wireless communication method according to an exemplary embodiment. [Figure 7] FIG. 7 is a diagram illustrating one of the rules governing the UE shown in FIG. 1 to initiate a BFR mechanism for one of the TRPs in the mTRP scenario. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Various embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. However, the present disclosure may be embodied in many other forms and should not be construed as being limited to the specific structures or functions discussed in the following description. Rather, these embodiments are provided to make the description of the present disclosure thorough and complete.

[0037] According to the detailed description, it will be clear to those skilled in the art that the scope of the present disclosure encompasses any embodiment disclosed herein, regardless of whether the embodiment is implemented independently or in cooperation with other embodiments of the present disclosure. For example, the apparatus and method disclosed herein can be actually implemented using any number of the embodiments provided herein. Furthermore, it should be understood that any embodiment of the present disclosure can be implemented using one or more of the elements presented in the appended claims.

[0038] Unless expressly stated otherwise, any embodiment described herein as "exemplary embodiment" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0039] In this specification, numerical terms such as "first" and "second" may be used to describe various elements, but it should be understood that these elements should not be limited by these numerical terms. These numerical terms are used in this specification only to distinguish one element from another element. Thus, a first TRP, counter, or timer described below can be referred to as a second TRP, counter, or timer, respectively, without departing from the teachings of the present disclosure.

[0040] In accordance with example embodiments disclosed herein, user equipment (or UE for short) may refer to a mobile device, a mobile station, a terminal, a subscriber unit, a mobile phone, a cellular phone, a smartphone, a cordless phone, a personal digital assistant (PDA), a wireless communication device, a desktop computer, a laptop computer, a tablet computer, a single board computer (SBC) (e.g., gaming devices, netbooks, smartbooks, ultrabooks, medical devices, biometric sensors, wearable devices (smart watches, smart glasses, smart wristbands, etc.), entertainment devices (audio players, video players, etc.), in-vehicle computers, etc.), and the like. A UE may refer to at least two co-located and interconnected UEs thus defined, such as at least two co-located and interconnected UEs, a smart meter / sensor, an unmanned vehicle (industrial robot, quadcopter, etc.) and its components (e.g., autonomous vehicle computers), industrial manufacturing equipment, Global Positioning System (GPS) equipment, Internet of Things (IoT) equipment, Industrial IoT (IIoT) equipment, Machine Type Communication (MTC) equipment, Massive IoT (MIoT) or Massive MTC (mMTC) equipment / sensor group, or any other suitable equipment configured to support wireless communication. In some embodiments, a UE may refer to at least two co-located and interconnected UEs thus defined.

[0041] According to example embodiments disclosed herein, a transmission / reception point (or TRP for short) may refer to a fixed communication point of a UE in a particular wireless communication network. A TRP may be implemented as a Radio Access Network (RAN) node, called a Base Transceiver Station (BTS) for 2G communication technology, a NodeB for 3G communication technology, an Evolved NodeB (eNodeB) for 4G communication technology, and a gNB for 5G New Radio (NR) communication technology. A RAN node may serve various cells, such as a macro cell, a micro cell, a pico cell, a femto cell, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., at least a few kilometers in radius). A micro cell may cover a geographic area, for example, less than 2 kilometers in radius. A pico cell may cover a relatively small geographic area, such as, for example, an office, a shopping mall, a train station, a stock exchange, etc. A femto cell may cover an even smaller geographic area (e.g., a home). Correspondingly, a RAN node serving a macro cell may be referred to as a macro node, a RAN node serving a micro cell may be referred to as a micro node, etc.

[0042] Each TRP may transmit multiple beams to the UE. From the multiple beams, a serving beam may be determined for providing wireless communication (i.e., wireless communication channel) between the TRP and the UE. Also, when a beam failure instance (BFI) occurs, for example, when the serving beam can no longer provide a desired communication quality, one or more candidate beams may be determined from the multiple beams for providing wireless communication. The one or more candidate beams may be determined by the UE and / or by the TRP. By determining and configuring the candidate beam, the UE and the TRP can continue wireless communication even when a BFI occurs in the serving beam.

[0043] The UE may use one or more reference signals (RSs) to measure the communication quality of a serving beam (i.e., a beam used in a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH). As the RSs for measuring the communication quality of the serving beam, one or more synchronization signal (SS) blocks (SSBs), one or more channel state information RS (CSI-RS) resources, and / or one or more demodulation RSs (DM-RSs) of a physical broadcast channel (PBCH) may be used. The communication quality of the serving beam may be based on at least one of an RS received power (RSRP) value, an RS received quality (RSRQ) value, and a CSI value measured on the RS resources. The TRP may provide such RS resources to the UE, for example, through dedicated radio resource control (RRC) signaling.

[0044] FIG. 1 illustrates a block diagram of a wireless communication system 100 in which a beam failure recovery (BFR) mechanism is initiated in a single TRP scenario. As illustrated in FIG. 1, the system 100 includes a single TRP 102 and a UE 104 implemented as a smartphone. As an example, the TRP 102 transmits a first beam 106 and a second beam 108 to the UE 104. A BFI may occur when the second beam 108 selected as a serving beam is blocked by a building 110 or other obstacle (e.g., a moving vehicle, a tree, a landscape element, or any object) and, as a result, is unable to provide a desired communication quality. In response to the BFI, the UE 104 may trigger a mechanism to recover from the beam failure, which is hereinafter referred to as a BFR mechanism.

[0045] FIG. 2 illustrates a block diagram of a wireless communication system 200 in which a BFR mechanism is initiated in a multiple TRP (mTRP) scenario. As illustrated in FIG. 2, the system 200 includes a TRP 202, a TRP 204, and a UE 206 implemented as a smartphone. Note that the mTRP scenario refers to an operation in which the UE 206 is served using all TRPs in the serving cell, i.e., both TRP 202 and TRP 204 in the example illustrated in FIG. 2. To provide such an operation, the TRP 202 transmits a serving beam 208 to the UE 206, and the TRP 204 transmits a serving beam 210 to the UE 206. Similar to the system 100, in the system 200, a BFI may occur, for example, when the serving beam 208 is blocked by a building 212 or other obstruction (e.g., a moving vehicle, a tree, a landscape element, or any object). In this case, the UE 206 may trigger a BFR mechanism when such a BFI occurs.

[0046] The BFR mechanism for the primary cell (PCell) was specified in 3GPP® Release 15 (later extended in 3GPP® Release 16). The BFR mechanism for one or more secondary cells (SCells) was specified in 3GPP® Release 16. In the SCell BFR mechanism, the UE performs Beam Failure Detection (BFD) for one or more configured SCells. The SCell BFD procedure is similar to that specified for PCells in 3GPP® Release 15, and for each configured SCell, the UE implicitly or explicitly determines a corresponding set of BFD resources (so-called set of BFD-RSs q0). In the implicit configuration, the UE determines the BFD-RS based on the RS indicated by the active Transmission Configuration Indicator (TCI) state of the PDCCH. In the explicit configuration, the UE performs the BFD procedure according to the RS configured by the TRP itself.

[0047] Considering the Open System Interconnection (OSI) model, the physical layer or layer L1 decides whether to signal the BFI to the upper layer, i.e., the Medium Access Control (MAC) layer (which is a sublayer of layer L2), based on the downlink RSs (DL RSs), such as SSB / CSI-RSs, in the set q0. If all the RSs in the set q0 are in a failure state, i.e., the virtual PDCCH block error rate (BLER) estimated on the RSs is equal to or greater than a threshold (e.g., greater than 10%), the UE signals the BFI to the upper layer.

[0048] The MAC layer counts BFI notifications for each cell using a BFI counter and starts / trigger the BFR mechanism when it counts a predefined number of BFI instances notified from lower layers for the corresponding cell (P-cell / S-cell). The BFI counter is monitored by a BFD timer. Every time the UE receives a new BFI notification, the BFD timer is triggered (started or restarted) and the BFI counter is incremented. When the BFD timer expires, the BFI counter is reset. The BFI counter and the BFD timer can be configured per TRP, per BFD-RS set, or per serving beam or serving beam set. The serving beam may refer to a PDCCH or PDSCH beam. The value of the BFD timer duration may correspond to a Qout,LR reporting period of the Beam Failure Detection (BFD) Reference Signal (RS) (e.g., according to ETSI TS 38.331 V16.3.1, a value pbfd1 corresponds to 1 Qout,LR reporting period of BFD-RS, a value pbfd2 corresponds to 2 Qout,LR reporting periods of BFD-RS, etc.). The physical layer informs higher layers (BFI notification) when the radio link quality is worse than a threshold Qout,LR with a periodicity determined by the shortest period among the SS / PBCH blocks on the P-cell or primary S-cell (PS-cell) and / or periodic CSI-RS configurations in the set used by the UE to evaluate the radio link quality and a maximum between 2 ms and 1 ms.

[0049] FIG. 3 shows an example of a MAC Control Element (CE) (MAC CE) 300 that may be used in the SCell BFR mechanism. More specifically, when a BFI is detected in at least one SCell, the UE may indicate the beam failure and recover the failed SCell using the MAC CE 300. The MAC CE 300 communicates to the TRP the failed SCell index (via bits C1-C7), an indication of whether a candidate beam is available (via bits AC), and the candidate beam index (via bit field "Candidate RS ID"). The UE may indicate the candidate beams that are on the candidate beam list (i.e., a list of candidate beam indexes that are either SSB and / or CSI-RS indexes). The same MAC CE 300 that can indicate SCell failure / recovery information may also be used for the SCell BFR mechanism by setting the P-cell bit (SP) to indicate the failure.

[0050] In 3GPP Release 17, it is proposed to enhance the BFR mechanism to cover mTRP scenarios as shown in Figure 2. The mTRP scenario usually means operation based on single downlink control information (S-DCI) or multi-DCI (mDCI). In mDCI operation, a control resource set (CORESET) index value (e.g., CORESET pool index value) is used to group CORESETs under different groups. That is, if CORESETs share the same group ID or CORESET pool index value, they are considered to be in the same group. In S-DCI operation, different CORESETs are not grouped. That is, the same CORESET pool index value is set for all CORESETs.

[0051] When configured with one or more CORESET pool index values ​​(e.g., two CORESET sets are configured in mDCI operation), the UE is expected to simultaneously monitor DCI transmissions from CORESETs associated with different pool index values. Currently, up to two CORESET pool index values ​​(k=0, 1) can be configured. In the case of S-DCI (i.e., no pool index values ​​are available to determine set q0), the TRP can explicitly configure the UE by using BFD-RS for the corresponding CORESET set.

[0052] FIG. 4 shows a schematic diagram of the mTRP BFD approach proposed in 3GPP Release 17. According to this approach, the UE can be configured to determine the failure of DL RSs indicated by PDCCH TCI states composed of different sets q0. As an example, the UE may be configured to determine when a particular set q0 (e.g., either k=0 or k=1) is in a failure state. This may be referred to as TRP failure, e.g., set q0, k=0 refers to BFD-RSs of one TRP, and set q0, k=1 refers to BFD-RSs of another TRP. At the MAC layer, the UE performs BFD on set q0, and BFD depends on the count of BFI instances. More specifically, FIG. 4 shows an mTRP scenario in which two TRPs, namely TRP0 and TRP1, are used to serve the UE. Here, it is assumed that TRP0 transmits three beams (e.g., PDCCH) to the UE, and TRP1 transmits two beams (e.g., PDCCH) to the UE. The UE checks the communication quality of each beam from TRP0 and TRP1 by measuring the corresponding RS, i.e., RS#1, RS#2, RS#3 from TRP0, and RS#4, RS#5 from TRP1. The RS from TRP0 may be included in set q0_#0, and the RS from TRP0 may be included in set q0_#1. Alternatively, the RS from both TRP0 and TRP1 may be provided as a single set q0_. To perform BFD in multi-TRP communication in a specific manner in the BFD-RS set / set q0, it should be considered that for each of TRP0 and TRP1, an independent BFD procedure may be configured, and the DL RSs indicated by the TCI status of the PDCCH may be included in the respective set q0(#0,#1) based on the CORESET association with CORESET pool index (CPI) value k (k=0,1). CORESETs under the same CPI value can be considered as grouped for the purpose of failure detection. The CORESET is monitored for PDCCH transmissions based on the TCI state (indicating DL RS) activated for the CORESET.DL RSs indicated by TCI states may be included in the respective set q0 based on the CPI value set for CORESET. Alternatively, CORESET or BFD-RSs may be divided into groups or sets, respectively, based on any higher layer parameters or implicit decisions. Furthermore, independent BFD procedures for each of TRP0 and TRP1 may be configured according to sets q0_#0 and q0_#1 (for TRP0 and TRP1, respectively) or for a single set q0 (BFI counters for TRP0 and TRP1, respectively). As an example, counter values ​​of BFI counters at different times are shown in small boxes (black for TRP0 and grey for TRP1) in Fig. 4 (see "0", "1", "2", "3" in the small boxes). Thus, for TRP1 (or in other words, all BFD-RS beams from TRP1), a beam failure occurs / is detected when the corresponding BFI-counter reaches 3 (in this example, counter value 3 is the maximum counter value at which a beam failure is considered detected), meaning that each of the two beams from TRP1 is no longer able to provide the desired communication quality. This approach therefore allows the UE to determine when all beams from a TRP are in a failed state, hence it is called the mTRP BFD approach. Once such a failed TRP is determined, the UE can initiate a BFR mechanism for that failed TRP.

[0053] However, in the mTRP BFD approach shown in FIG. 4, the UE cannot know when multiple / all TRPs (e.g., both TRP0 and TRP1) in the serving cell are in a failure state (i.e., all of its beams cannot provide the desired communication quality). This is because the BFI counters of the TRPs are used independently of each other, so the UE cannot determine when the TRPs are in a failure state at the same time. Therefore, the UE cannot know when it is necessary to initiate a BFR mechanism (i.e., a cell-level BFR mechanism) for all TRPs in the serving cell. In other words, in the mTRP BFD approach shown in FIG. 4, the UE cannot select either the BFR mechanism for a specific TRP or the cell-level BFR mechanism.

[0054] Of course, a simultaneous failure (where multiple / all TRPs are considered to be in a failed state) can also be determined when the BFI counters of the TRPs reach their maximum value at the same time, however, even if we define a simultaneous failure in this way, the precise definition of "simultaneous" is open to interpretation.

[0055] The exemplary embodiments disclosed herein provide a technical solution that allows mitigating or even eliminating the above-mentioned drawbacks inherent in the prior art. In particular, the technical solution disclosed herein includes defining rules for the UE to determine whether the TRPs are considered to have failed simultaneously or individually in an mTRP scenario. Such rules are defined based on counter values ​​of BFI counters used by the UE for each of the TRPs. In some embodiments, the rules may additionally be defined based on the state of a timer monitoring the BFI counters. Using such defined rules, the UE can clearly determine when it is necessary to use the BFR mechanism for at least one of the TRPs individually or for all TRPs in one or more cells simultaneously.

[0056] FIG. 5 illustrates a block diagram of a UE 500 for wireless communication according to an exemplary embodiment. As shown in FIG. 5, the UE 500 includes the following components: a processor 502, a memory 504, and a transceiver 506. The memory 504 is coupled to the processor 502 and stores processor-executable instructions 508 that, when executed by the processor 502, cause the processor 502 to perform aspects of the present disclosure, as described below. It should be noted that the number, arrangement, and interconnection of the components constituting the UE 500 illustrated in FIG. 5 are not intended to limit the present disclosure, but are merely utilized to provide a general idea of ​​how the components may be implemented within the UE 500. In another exemplary embodiment, the transceiver 506 may be implemented as two separate devices, one for receiving operations and the other for transmitting operations. Regardless of the implementation, it is suggested that the transceiver 506 may perform various operations necessary to perform reception and transmission of various signals, such as, for example, signal modulation / demodulation.

[0057] The processor 502 may be implemented as a central processing unit (CPU), a general purpose processor, a special purpose processor, a microcontroller, a microprocessor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a complex programmable logic device, etc. It is also noted that the processor 502 may be implemented as any combination of one or more of the foregoing. As an example, the processor may be a combination of two or more microprocessors.

[0058] The storage unit 504 can be implemented as a non-volatile memory or a volatile memory used in modern electronic computers. By way of example, non-volatile memory includes read only memory (ROM), ferroelectric random access memory (RAM), programmable ROM (PROM), electrically erasable PROM (EEPROM), solid state drive (SSD), flash memory, magnetic disk storage (such as hard drives and magnetic tapes), optical disk storage (such as CDs, DVDs, and Blu-ray disks), etc. Volatile memory includes dynamic RAM, SDRAM (synchronous DRAM), DDR SDRAM (double data rate SDRAM), static RAM, etc.

[0059] The processor-executable instructions 508 stored in the memory 504 may be configured as computer-executable code that causes the processor 502 to perform aspects of the disclosure. The computer-executable code for performing operations or steps for aspects of the disclosure may be written in any combination of one or more programming languages, such as Java, C++, etc. In some examples, the computer-executable code may be in the form of a high-level language, in a pre-compiled form, or generated on the fly by an interpreter (also pre-stored in the memory 504).

[0060] FIG. 6 shows a flow chart of a wireless communication method 600 according to an exemplary embodiment. Each step of the method 600 is intended to be executed by a corresponding one of the above-mentioned components constituting the UE 500. The method 600 starts at step S602, in which the processor 502 causes the transceiver 506 to communicate with the first TRP by using one or more first serving beams and to communicate with the second TRP by using one or more second serving beams. The first and second TRPs may be located either in the same cell or in two different cells. For example, the first TRP may be located in a serving cell, and the second TRP may be located in a non-serving cell, or in a cell configured for inter-cell mTRP, or in a cell configured for inter-cell communication. The method 600 then proceeds to step S604, in which the processor 502 assigns a first counter and a first timer to the first TRP. The first counter has a counter value that increments by one each time a BFI for the first TRP occurs. The BFI for the first TRP means that the first serving beam(s) can no longer provide a predetermined communication quality (e.g., the BFI for the first TRP may mean that all RSs included in the first set of RSs for beam failure detection can no longer provide a predetermined communication quality). The first timer is triggered in response to the BFI for the first TRP, and the first counter is reset when the first timer expires. Next, the method 600 proceeds to step S606, where the processor 502 assigns a second counter and a second timer to the second TRP. Similar to the first counter, the second counter has a counter value that is incremented by 1 each time the BFI for the second TRP occurs. The BFI for the second TRP means that the second serving beam can no longer provide a predetermined communication quality (e.g., the BFI for the second TRP may mean that all RSs included in the second set of RSs for beam failure detection can no longer provide a predetermined communication quality). Similar to the first timer, the second timer is triggered in response to a BFI for the second TRP, and the second counter is reset when the second timer expires.Steps S604 and S606 may be performed in parallel, as necessary and depending on the particular application. It should be noted that the BFI notification may be determined based on a set of DL RSs that identify the serving beam. The method 600 then proceeds to step S608, where the processor 502 decides whether to initiate a BFR mechanism for at least one of the first and second TRPs based on (i) the current counter values ​​of the first and second counters, or (ii) the current counter values ​​of at least one of the first and second counters and at least one of the first and second timers (i.e., the current timer state indicating whether the first and / or second timers have expired). Thus, the current counter values ​​and the current timer state define a particular selection rule for the processor 502.

[0061] For example, a BFR mechanism (i.e., a cell-level BFR mechanism) for both the first and second TRPs can be initiated, e.g., using a BFR MAC CE or a Contention-Free Beam Failure Recovery Request (RACH) (CFRA) / Contention-Based RACH (CBRA) recovery, as defined in 3GPP® Release 15 / Release 16. At the same time, a BFR for one of the first and second TRPs may be initiated, e.g., as currently agreed in 3GPP® Release 17, where the TRPs may be recovered individually in a TRP-specific manner.

[0062] It should be noted that the method 600 is not limited to the two TRP scenario, and in some other embodiments, it can be applied in other mTRP scenarios (i.e., more than two TRPs are involved) as well. In this specification, the two TRP scenario is selected for simplicity. Correspondingly, the total number of counters and the total number of timers depend on the total number of TRPs involved in the method 600.

[0063] As used in the embodiments disclosed herein, the indication "BFI for the first (second) TRP occurs" may refer to a failure of an RS in a BFD-RS set associated with a serving beam of the first (second) TRP. In other words, a TRP failure may refer to a failure of a BFD-RS set associated with a CORESET under a particular CPI value (e.g., #0 or #1 shown in FIG. 4). In this regard, each of the first and second counters refers to a counter configured to count BFI notifications for the BFD-RS set associated with the respective TRP.

[0064] In an exemplary embodiment, at least one of the first and second timers may be a BFD timer that monitors a respective counter. In some exemplary embodiments, the first and second timers (e.g., BFD timers) may be configured individually for the first and second TRPs, or the first and second timers may be configured as a common timer (e.g., a separate common BFD timer) for the first and second TRPs. In another exemplary embodiment, at least one of the first and second timers may be a timer that is explicitly set and assigned a value by the network in which the first and second TRPs are used.

[0065] As described above, in step S608, the processor 502 may determine whether to initiate a BFR mechanism for at least one of the first and second TRPs based on the current counter values ​​of the first and second counters and the timer states of the first and second timers. Therefore, the rules used by the processor 502 in step S608 can be conveniently divided into two groups, the first group including rules based only on the current counter values, and the second group including rules based on a combination of the current counter values ​​and the timer states. Each of the two groups will be described in detail below.

[0066] Rules based only on current counter values Assuming that each of the first counter and the second counter has a maximum counter value, the processor 502 performs the following in step S608: - if the current counter value of the first (second) counter is equal to the maximum counter value of the first (second) counter and the current counter value of the second (first) counter is equal to the maximum counter value of the second (first) counter or a predetermined counter value (the predetermined counter value may be provided by one of the TRPs and may be less than or equal to the maximum counter value of the second (first) counter), or - the sum of the current counter values ​​of the first counter and the second counter is equal to (i) the minimum or maximum of the maximum counter values ​​of the first counter and the second counter, or (ii) the sum of the maximum counter values ​​of the first counter and the second counter, or (iii) a predetermined threshold value; or if the current counter value of the first (second) counter reaches the maximum counter value of the first (second) counter at a certain time point and the current counter value of the second (first) counter reaches the maximum counter value of the second (first) counter within a predefined period from that time point (the period may be set in an explicit manner by one of the TRPs, e.g. in milliseconds or slots); In, it must decide to initiate a BFR mechanism (i.e., a cell-level BFR mechanism) for both the first TRP and the second TRP.

[0067] At the same time, the processor 502 performs the following in step S608: - if the current counter value of the first (second) counter is equal to the maximum counter value of the first (second) counter and the current counter value of the second (first) counter is equal to 0 (i.e. no BFI notification has been received for the second (first) counter), or - if the current counter value of the first (second) counter reaches the maximum counter value of the first (second) counter, while the current counter value of the second (first) counter is less than the maximum counter value of the second (first) counter or the predetermined counter value; In this case, it must be decided to initiate the BFR mechanism only for the first (second) TRP.

[0068] It should be noted that the maximum counter values ​​of the first and second counters may be set commonly (i.e., the first and second counters may have the same maximum counter value) or may be set independently (i.e., the first and second counters may have different maximum counter values).

[0069] Rules based on a combination of the current counter value and timer state If it is assumed that each of the first counter and the second counter has the maximum counter value, the processor 502 performs the following in step S608: - the current counter value of the first (second) counter is equal to the maximum counter value of the first (second) counter and a new BFI for the second (first) TRP occurs before the second (first) timer expires, and the new BFI causes the current counter value of the second (first) counter to be equal to the maximum counter value of the second (first) counter, or - if the current counter value of the first (second) counter is equal to the maximum counter value of the first (second) counter and a new BFI for the second (first) TRP occurs before the second (first) timer expires, the new BFI causing the current counter value of the second (first) counter to be equal to a predefined counter value (which may again be provided by one of the TRPs and may be less than or equal to the maximum counter value of the second (first) counter), or - if the current counter value of the first (second) counter is equal to the maximum counter value of the first (second) counter and a new BFI for the second (first) TRP occurs before the second (first) timer expires, or - if the current counter values ​​of the first and second counters are equal to the maximum counter values ​​of the first and second counters, respectively, and a new BFI for the first (second) TRP occurs before the second (first) timer expires; In, it must decide to initiate a BFR mechanism (i.e., a cell-level BFR mechanism) for both the first TRP and the second TRP.

[0070] At the same time, the processor 502 must decide in step S608 to start the BFR mechanism only for the first (second) TRP if the current counter value of the first (second) counter is equal to the maximum counter value of the first (second) counter and the second (first) timer expires (this rule is shown diagrammatically in FIG. 7, where the first TRP is shown as TRP#0, the second TRP as TRP#1, and the maximum counter value of the first counter is equal to 2 and is achieved upon expiry of the second timer (see “BFD timer expires” diagrammatically shown as the end of the corresponding arrow)).

[0071] It should again be noted that the maximum counter values ​​of the first and second counters may be set commonly (i.e., the first and second counters may have the same maximum counter value) or may be set independently (i.e., the first and second counters may have different maximum counter values).

[0072] Any of the embodiments disclosed herein are applicable to inter-cell mTRP communication. As an example, a first TRP may be associated with a serving cell (e.g., a PCell / Sp cell), and a second TRP may be associated with a non-serving cell. Both the serving cell and the non-serving cell may serve a UE in inter-cell mTRP communication.

[0073] Furthermore, the predetermined counter value and the predetermined threshold value used in the above-defined rules may refer to values ​​set by a network through which the UE 500 communicates with the first and second TRPs, or may refer to values ​​specified in a standard (e.g., 3GPP TS 38.331).

[0074] In step S608 of the method 600, when simultaneous or simultaneous failure of the first and second TRPs (or multiple / all TRPs) of a given cell or cells is determined, the UE may recover the TRPs using a cell-level BFR mechanism, or the UE may recover the TRPs individually using a separate BFR mechanism, or the UE may recover the TRPs individually using a single BFR mechanism. If the UE decides to trigger a cell-level BFR mechanism, it may provide a failure indication in a MAC CE, such as the MAC CE 300. The MAC CE may notify the failure (and recovery) of the serving cell. In the case of a separate BFR mechanism, the UE may provide a failure indication in the MAC CE, including at least information about the failed TRP (such as availability of candidate beams, identity (ID) of the candidate beam and / or failed TRP ID / BFD-RS set ID). In the case of a single BFR mechanism, the UE may provide a failure notification in the MAC CE including information about both (or all) failed TRPs (such as candidate beam availability, candidate beam ID, and / or failed TRP ID / BFD-RS set ID). In an exemplary embodiment, if the UE determines failure of both the first and second TRPs (simultaneously) according to the rules defined above, the UE may trigger a BFR mechanism to recover the TRPs. A TRP-specific BFR mechanism may include notifying the TRP failure for at least one of the first and second TRPs and providing the network with TRP-specific candidate beam information (which may include notification of the availability of the candidate beam and a candidate index value, if available).

[0075] In an example embodiment, the processor 502 may additionally check whether at least one of the first and second TRPs is a specific TRP in step S608 of the method 600. As used herein, a specific TRP may refer to a TRP that configures the UE 500 to perform monitoring of a specific CORESET (i.e., either the first or second TRP). If neither the first nor the second TRP is configured as a specific TRP and the first (second) counter reaches its maximum counter value, the UE 500 may initiate a BFR mechanism according to either one of the rules (either the first group or the second group) described above. However, if the first (second) TRP is configured as a specific TRP and the first (second) counter reaches its maximum counter value, the UE 500 may initiate a BFR mechanism for the failed first (second) TRP without considering the second (first) TRP (if the second (first) TRP also fails (e.g., a MAC CE such as MAC CE 300) while the UE 500 has triggered but not yet transmitted a Beam Failure Recovery Request (BFRQ), the UE 500 may switch to a cell-level BFR mechanism).

[0076] In an exemplary embodiment, the method 600 may include a further step after step S608, in which the processor 502 of the UE 500 encodes the BFR information into a BFRQ (e.g., a BFR MAC CE, such as the MAC CE 300, or a truncated BFR MAC CE, etc.). In an exemplary embodiment, the processor 502 may notify the TRPs that have failed for a particular serving cell by using a candidate beam reference signal ID (RS ID). For example, the processor 502 may notify that a beam failure has been detected on a serving cell or on a TRP, and may notify the particular TRPs where the beam failure has been detected based on the RS ID. In an exemplary embodiment, if a candidate beam is not available, e.g., based on a beam quality threshold (e.g., an RSRP threshold), the processor 502 may notify that a candidate beam is not available, and may notify the TRPs where the candidate beam is not available based on one of the candidate RS IDs configured in the TRP. For example, in such a case, the candidate beam RS ID may be the minimum / maximum index of the RS IDs configured in the given TRP.

[0077] In any of the embodiments disclosed herein, in step S608 of the method 600, the UE 500 may first determine whether a second (first) timer is running for the second (first) TRP when a beam failure (i.e., BFI) is detected for the first (second) TRP. If the second (first) timer (e.g., BFD timer) for the second (first) TRP is running, the UE 500 may determine whether to recover the first (second) TRP or recover both the first and second TRPs according to the rules defined above. If the second (first) timer (e.g., BFD timer) for the second (first) TRP is not running, the UE 500 may determine to recover the first (second) TRP.

[0078] It should be noted that each block or step of the method 600, or any combination of blocks or steps, may be implemented by various means, such as hardware, firmware, and / or software. By way of example, one or more of the above-described blocks or steps may be embodied by processor-executable instructions, data structures, program modules, and other suitable data representations. Furthermore, the processor-executable instructions embodying the above-described blocks or steps may be stored on a corresponding data carrier and executed by at least one processor to implement the functionality of the UE 500. The data carrier may be implemented as any computer-readable storage medium configured to be readable by the above-described at least one processor to execute the processor-executable instructions. Such computer-readable storage media may include both volatile and non-volatile media, removable and non-removable media. By way of example and not limitation, computer-readable media includes media implemented in any manner or technology suitable for storing information. More specifically, examples of computer readable media include, but are not limited to, information delivery media, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVDs), holographic media or other optical disk storage, magnetic tape, magnetic cassettes, magnetic disk storage, and other magnetic storage devices.

[0079] Although exemplary embodiments of the present disclosure have been described herein, it should be noted that any various changes and modifications can be made in the embodiments of the present disclosure without departing from the scope of legal protection defined by the appended claims. In the appended claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A transmitting / receiving unit; a memory configured to store processor-executable instructions; at least one processor coupled to the memory unit, the processor-executable instructions executing The transceiver unit is caused to perform wireless communication with a first transceiver point (TRP) using at least one first serving beam, and to perform wireless communication with a second transceiver point (TRP) using at least one second serving beam; Allocating a first counter and a first timer to the first TRP, incrementing a counter value of the first counter by 1 each time a beam failure instance (BFI) for the first TRP occurs, the BFI for the first TRP meaning that the at least one first serving beam is unable to provide a predetermined communication quality, triggering the first timer in response to the BFI for the first TRP, and resetting the first counter when the first timer expires; assigning a second counter and a second timer to the second TRP, incrementing a counter value of the second counter by 1 each time the BFI for the second TRP occurs, the BFI for the second TRP meaning that the at least one second serving beam will no longer be able to provide a predetermined communication quality, triggering the second timer in response to the BFI for the second TRP, and resetting the second counter when the second timer expires; At least one processor configured to Equipped with Each of the first counter and the second counter has a maximum counter value, and the at least one processor is further configured to initiate a beam failure recovery (BFR) mechanism for both the first TRP and the second TRP when a current counter value of the first counter is equal to the maximum counter value of the first counter, and when a current counter value of the second counter is equal to a predetermined counter value and the predetermined counter value is less than or equal to the maximum counter value of the second counter; Initiating said BFR mechanism by triggering a Contention Based Random Access (CBRA) procedure; providing a medium access control element (MAC CE) for notifying a serving primary cell failure, and candidate beam index and availability for both the first TRP and the second TRP; The MAC CE further includes identification information of a first beam failure detection-reference signal (BFD-RS) set of the first TRP and identification information of a second BFD-RS set of the second TRP. User Equipment (UE) for wireless communication.

2. The UE of claim 1, wherein the at least one processor is further configured to start the BFR mechanism for both the first TRP and the second TRP when, at a certain point in time, the current counter value of the first counter reaches the maximum counter value of the first counter and when, within a predetermined period from the point in time, the current counter value of the second counter reaches the maximum counter value of the second counter.

3. The UE of claim 1, wherein the at least one processor is further configured to start the BFR mechanism for both the first TRP and the second TRP when the current counter value of the first counter is equal to the maximum counter value of the first counter and when a new BFI for the second TRP occurs before the second timer expires and the new BFI causes the current counter value of the second counter to be equal to the maximum counter value of the second counter.

4. 2. The UE of claim 1, wherein the at least one processor is further configured to start the BFR mechanism for both the first TRP and the second TRP when the current counter value of the first counter is equal to the maximum counter value of the first counter and when a new BFI for the second TRP occurs before the second timer expires, the new BFI causing the current counter value of the second counter to be equal to a predetermined counter value.

5. The UE of claim 1 , wherein the first TRP and the second TRP are located within a single cell.

6. 1. A method for wireless communication, comprising: A method for communicating with a user equipment (UE) using at least one first serving beam with a first transmission / reception point (TRP) and at least one second serving beam with a second TRP; Allocating a first counter and a first timer to the first TRP, incrementing a counter value of the first counter by 1 each time a beam failure instance (BFI) for the first TRP occurs, the BFI for the first TRP meaning that the at least one first serving beam is unable to provide a predetermined communication quality, triggering the first timer in response to the BFI for the first TRP, and resetting the first counter when the first timer expires; Allocating a second counter and a second timer to the second TRP, the second counter having a counter value that is incremented by one each time a BFI for the second TRP occurs, the BFI for the second TRP meaning that the at least one second serving beam will no longer be able to provide the predetermined communication quality, the second timer being triggered in response to the BFI for the second TRP, and the second counter being reset when the second timer expires; Including, Each of the first counter and the second counter has a maximum counter value, and the method further includes initiating a beam failure recovery (BFR) mechanism for both the first TRP and the second TRP when a current counter value of the first counter is equal to the maximum counter value of the first counter and when a current counter value of the second counter is equal to a predetermined counter value and the predetermined counter value is less than or equal to the maximum counter value of the second counter; initiating said BFR mechanism by triggering a contention-based random access (CBRA) procedure; providing a medium access control element (MAC CE) notifying a serving primary cell failure, and candidate beam index and availability for both the first TRP and the second TRP; Including, The MAC CE further includes identification information of a first beam failure detection-reference signal (BFD-RS) set of the first TRP and identification information of a second BFD-RS set of the second TRP. method.

7. 7. The method of claim 6, further comprising starting the BFR mechanism for both the first TRP and the second TRP if, at a certain point in time, the current counter value of the first counter reaches the maximum counter value of the first counter, and if, within a predetermined period from the point in time, the current counter value of the second counter reaches the maximum counter value of the second counter.

8. 7. The method of claim 6, further comprising initiating a pre-BFR procedure for both the first TRP and the second TRP when the current counter value of the first counter is equal to the maximum counter value of the first counter and when a new BFI for the second TRP occurs before the second timer expires and the new BFI makes the current counter value of the second counter equal to the maximum counter value of the second counter.

9. 7. The method of claim 6, further comprising starting the BFR mechanism for both the first TRP and the second TRP when the current counter value of the first counter is equal to the maximum counter value of the first counter, and when a new BFI for the second TRP occurs before the second timer expires and the new BFI causes the current counter value of the second counter to be equal to the predetermined counter value.

10. The method of claim 6 , wherein the first TRP and the second TRP are located within a single cell.

11. 11. A computer readable medium storing computer code, the computer code being configured, when executed by at least one processor, to cause the at least one processor to perform a method according to any one of claims 6 to 10.

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