Robust beam failure recovery procedure for using non-serving cells

Abstract

In response to a beam failure being detected for a serving cell serving a user equipment, the UE determines whether a timer is running. The UE performs one of the following operations: a beam failure recovery procedure with a target non-serving cell in response to the timer running; or a beam failure recovery procedure with a serving cell in response to the timer not running. Methods, apparatus, computer programs, and computer program products are disclosed.

Description

Technical Field

[0001] The present invention generally relates to a mobility procedure for handover of a user equipment in a wireless network, and more particularly, to beam failure recovery of a non-serving cell. Background Art

[0002] This section is intended to provide a background or context for the invention disclosed below. The description herein may include concepts that may be pursued, but not necessarily concepts that have been previously conceived, implemented, or described. Therefore, unless otherwise expressly indicated herein, what is described in this section is not prior art to the description in this application and cannot be included in this section and admitted as prior art. The abbreviations that may be found in the specification and / or drawings are defined as follows, at the beginning of the detailed description section.

[0003] One of the main goals of the New Radio (NR) Work Item (WI) on Mobility Enhancements for Rel. 16 is to study and specify solutions for fast handover failure recovery. See RP-181351 "New WID: NR mobility enhancements" by Intel Corporation at 3GPP TSG RAN Meeting #80, May 21-25, 2018, La Jolla, USA. One of the goals of this WI is as follows:

[0004] “· Study solution(s) to improve reliability and robustness of HO / SCG changes, especially considering the challenges in high / mid frequencies, focusing on the solutions identified below, but not limited thereto.

[0005] oConditional switching

[0006] oFast switch failure recovery"

[0007] Therefore, solutions will be investigated to improve the Handover (HO) or Secondary Cell Group (SCG) change reliability and robustness. One area of ​​improvement is the triggering of the Beam Failure Recovery (BFR) procedure, which is initiated after the User Equipment (UE) detects a beam failure. Summary of the invention

[0008] This section is intended to include examples and is not intended to be limiting.

[0009] In an exemplary embodiment, a method is disclosed, the method comprising, by a user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, determining whether a timer is running. The method also comprises, by the user equipment, performing one of: a beam failure recovery procedure with a target non-serving cell in response to the timer running; or a beam failure recovery procedure with a serving cell in response to the timer not running.

[0010] Additional exemplary embodiments include a computer program comprising code for performing the method of the previous paragraph when the computer program is run on a processor. A computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer readable medium carrying computer program code embodied therein for use with a computer. Another example is a computer program according to this paragraph, wherein the program is directly loadable into an internal memory of a computer.

[0011] An exemplary apparatus includes one or more processors and one or more memories containing computer program code. The one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus to perform operations including: determining, by a user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, whether a timer is running; and performing, by the user equipment, one of the following operations: a beam failure recovery procedure with a target non-serving cell in response to the timer running; or a beam failure recovery procedure with a serving cell in response to the timer not running.

[0012] An exemplary computer program product includes a computer readable storage medium bearing computer program code embodied therein for use with a computer. The computer program code includes: code for determining, by a user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, whether a timer is running. And code for performing, by the user equipment, one of the following operations: a beam failure recovery procedure with a target non-serving cell in response to the timer running; or a beam failure recovery procedure with a serving cell in response to the timer not running.

[0013] In another exemplary embodiment, an apparatus includes: a component for determining, by a user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, whether a timer is running; and a component for performing, by the user equipment, one of the following operations: a beam failure recovery process with a target non-serving cell in response to the timer running; or a beam failure recovery process with a serving cell in response to the timer not running. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the attached picture:

[0015] Figure 1 is a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced;

[0016] Figure 2An exemplary signalling diagram depicting the situation where a beam failure has been detected while the timer T is running;

[0017] Figure 3 describes the case where a beam failure is detected when the entry conditions for a measurement event are being evaluated or even met by the UE but are not met during the TTT; and

[0018] Figure 4 is a logic flow diagram of an exemplary process performed by UE 110 for robust beam failure recovery using non-serving cells. DETAILED DESCRIPTION

[0019] The following abbreviations that may be found in the specification and / or drawings are defined as follows:

[0020] 3GPP Third Generation Partnership Project

[0021] 5G Fifth Generation

[0022] 5GC 5G Core Network

[0023] AMF Access and Mobility Management Function

[0024] BFD-RS Beam Fault Detection Reference Signal

[0025] BFR Beam Failure Recovery

[0026] BFRR Beam Failure Recovery Request

[0027] BFI beam failure example

[0028] BLER Block Error Rate

[0029] BS Base Station

[0030] CBRA Contention-based random access

[0031] CE control components

[0032] CFRA Contention-free random access

[0033] CORESET Control Resource Set

[0034] C-RNTI Cell Radio Network Temporary Identifier

[0035] CSI-RS Channel State Information - Reference Signal

[0036] CU Central Unit

[0037] DMRS Demodulation Reference Signal

[0038] DU Distributed Unit

[0039] eNB (or eNodeB) Evolved Node B (e.g., LTE base station)

[0040] EN-DC E-UTRA-NR Dual Connectivity

[0041] en-gNB or En-gNB provides NR user plane and control plane protocol termination to UE

[0042] A node that acts as a secondary node in EN-DC

[0043] E-UTRA Evolved Universal Terrestrial Radio Access, also known as LTE radio

[0044] Access Technology

[0045] gNB (or gNodeB) is a base station used for 5G / NR, which provides NR services to UE.

[0046] User plane and control plane protocols are terminated and passed to NG

[0047] Interface connected to 5GC node

[0048] MR measurement report

[0049] NS Not Service

[0050] HO Switchover

[0051] I / F Interface

[0052] Ll The first (e.g., lowest) layer in a protocol stack, e.g.

[0053] Physical layer PHY

[0054] L2 The second (higher) layer in the protocol stack, such as MAC, RLC

[0055] and / or PDCP

[0056] L3 The third (higher) layer in the protocol stack, such as RRC, non

[0057] Access layer and / or Internet Protocol

[0058] LTE Long Term Evolution

[0059] MAC Media Access Control, also a layer in the protocol stack

[0060] MME Mobility Management Entity

[0061] ng or NG Next Generation

[0062] ng-eNB or NG-eNB Next Generation eNB

[0063] NR New Radio

[0064] N / W or NW network

[0065] OOS Out of Synchronization

[0066] PCI Physical Cell Identity

[0067] PDCCH Physical Downlink Control Channel

[0068] PDCP Packet Data Convergence Protocol

[0069] PHY Physical Layer

[0070] PRACH Physical Random Access Channel

[0071] RAN Radio Access Network

[0072] QCL'd Quasi-Co-sited

[0073] RA-RNTI Random Access Radio Network Temporary Identifier

[0074] Rel version

[0075] RLC Radio Link Control

[0076] RLF Radio Link Failure

[0077] RRH Remote Radio Head

[0078] RRC Radio Resource Control

[0079] RS reference signal

[0080] RU Radio Unit

[0081] Rx or RX Receiver or Receiver

[0082] SCG Secondary Cell Group

[0083] SDAP Service Data Adaptation Protocol

[0084] SGW Service Gateway

[0085] SMF session management functions

[0086] SSB SS / PBCH block

[0087] SS / PBCH Synchronization Signal / Physical Broadcast Channel

[0088] TCI Transmission Configuration Indicator

[0089] TS Technical Specifications

[0090] TTT Trigger Time

[0091] Tx or TX Transmitter or Transmit

[0092] UE User Equipment (e.g., wireless, usually mobile device)

[0093] UPF User Plane Function

[0094] WI Work Item

[0095] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. All embodiments described in this detailed description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention, and do not limit the scope of the invention which is defined by the claims.

[0096] The exemplary embodiments herein describe a process for robust beam failure recovery using non-serving cells.Additional description of these techniques is presented after describing a system in which the exemplary embodiments may be used.

[0097] Steering Figure 1 , which shows a block diagram of one possible and non-limiting exemplary system in which exemplary embodiments may be practiced. A serving base station (BS) or cell 170-1, a target non-serving BS or cell 170-2, and (multiple) network elements 190 are illustrated as part of a wireless communication network 100. In Figure 1 In the embodiment, a user equipment (UE) 110 performs wireless communication with a wireless communication network 100 .

[0098] UE is a wireless, typically mobile device that can access a wireless communication network. UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected by one or more buses 127. Each of the one or more transceivers 130 includes a receiver Rx 132 and a transmitter Tx 133. The one or more buses 127 may be an address, data, or control bus, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, an optical fiber or other optical communication device, etc. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123.

[0099] UE 110 includes a mobility module 140, which includes a portion of one or both of 140-1 and / or 140-2, which can be implemented in a variety of ways. The mobility module 140 can be implemented in hardware as the mobility module 140-1, such as being implemented as a part of one or more processors 120. The mobility module 140-1 can also be implemented as an integrated circuit or by other hardware, such as a programmable gate array. In another example, the mobility module 140 can be implemented as a mobility module 140-2, which is implemented as a computer program code 123 and executed by one or more processors 120. For example, one or more memories 125 and the computer program code 123 can be configured to, together with one or more processors 120, cause the user equipment 110 to perform one or more operations as described herein. The UE 110 communicates with the serving BS / cell 170-1 via a wireless link 111-1 and communicates with the target non-serving BS / cell 170-2 via a wireless link 111-2.

[0100] Note that there may also be zero, one or more non-serving (NS) BSs / cells 171. If there are one or more non-serving BSs / cells, the set 172 of non-serving cells includes a target non-serving BS / cell 170-2 and X non-serving BSs / cells 171, where X is one or more. Target non-serving BS / cell 170 is a non-serving cell in the set 172 that satisfies the criteria for handover, for example.

[0101] A protocol stack 10 is also shown in the UE 110 and implemented in the computer program code 123 (although alternatively or additionally, the protocol stack 10 may also be implemented in one or more processors 120). The protocol stack 10 has a plurality of layers 20: L120-1, a first (e.g., lowest) layer, such as a physical layer (PHY); L2 20-2, a second (higher) layer, such as MAC, RLC and / or PDCP; L3 20-3, a third (higher) layer, such as RRC, non-access stratum and / or Internet Protocol; and (multiple) other layers. Protocol stacks 10 of this type are well known.

[0102] In general, various embodiments of user device 110 may include, but are not limited to, devices such as smart phones, tablet computers, personal digital assistants (PDAs) with wireless communication capabilities, portable computers with wireless communication capabilities, image capture devices such as digital cameras with wireless communication capabilities, gaming devices with wireless communication capabilities, music storage and playback devices with wireless communication capabilities, Internet appliances (including Internet of Things devices) that allow wireless Internet access and possible browsing, tablet computers with wireless communication capabilities, and portable units or terminals that include a combination of these functions.

[0103] Each BS / cell 170 provides access to the wireless communication network 100 through a wireless device such as UE 110. Each BS / cell 170 provides at least one cell and can provide multiple cells. The cell constitutes a part of a base station. That is, multiple cells can exist for each base station. For example, there can be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360-degree area so that the coverage area of ​​a single base station covers an approximate ellipse or circle. In addition, each cell can correspond to a single carrier and the base station can use multiple carriers. So if there are three 120-degree cells and two carriers for each carrier, the base station has a total of 6 cells. Therefore, when discussing serving BS / cell 170-1 and non-serving BS / cell 170-2, these can be two different cells from the same base station, or two different cells from two different base stations.

[0104] As used herein, a serving cell is a cell with which UE 110 is exchanging user data, ie, receiving / sending data from / to a cell. In contrast, a non-serving cell may be, for example, one of the following cells.

[0105] 1) A cell to which the UE is not connected and has not been prepared in advance, ie the cell has no UE context (relevant information about the UE regarding configuration, capabilities, history, etc.).

[0106] 2) A cell to which the UE is not connected but is prepared, i.e., the cell does have a UE context. Herein, the non-serving cell may be prepared in advance / actively by the serving cell.

[0107] 3) A cell to which the UE is connected but does not exchange any user data with it. This may correspond to a multi-connectivity scenario, where the UE is connected to multiple cells but is only served by one or a subset of them at a time.

[0108] It is assumed that the two BS / cells 170 are similar, and only an example of the circuit system in the serving BS / cell 170-1 will be described. The BS / cell 170 may be, for example, a base station for 5G, also known as New Radio (NR), which uses the term "RAN node" to refer to the base station. In 5G, the BS / cell 170 may be a NG-RAN node, which is defined as a gNB or ng-eNB. The gNB is a node that provides NR user plane and control plane protocol termination to the UE and is connected to the 5GC (e.g., (multiple) network elements 190) via an NG interface. The ng-eNB is a node that provides E-UTRA user plane and control plane protocol termination to the UE and is connected to the 5GC via an NG interface. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and (multiple) distributed units (DU) (gNB-DU), of which DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit (RU). The gNB-CU is a logical node that hosts the RRC, SDAP, and PDCP protocols of the gNB or the RRC and PDCP protocols of the en-gNB and controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected to the gNB-DU. The F1 interface is illustrated as reference numeral 198, although reference numeral 198 also illustrates the link between the remote elements of the BS / cell 170 and the centralized elements of the BS / cell 170, such as the link between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node that hosts the RLC, MAC, and PHY layers of the gNB or en-gNB, and its operation is partially controlled by the gNB-CU. One gNB-CU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface 198 connected to the gNB-CU. Note that DU 195 is considered to include transceiver 160, for example, as part of RU, but some examples of this may have transceiver 160 as part of a separate RU, for example, under the control of DU 195 and connected to DU 195. BS / cell 170 may also be an eNB (evolved Node B) base station for LTE (Long Term Evolution) or any other suitable base station. For eNB, this may use a remote radio head (RRH), also shown as reference numeral 195.

[0109] The BS / cell 170 includes one or more processors 152, one or more memories 155, one or more network interfaces ((multiple) N / WI / F) 161, and one or more transceivers 160 interconnected by one or more buses 157. Each of the one or more transceivers 160 includes a receiver Rx 162 and a transmitter Tx 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include (multiple) processors 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory / memories and (multiple) processors and / or other hardware, but these are not shown.

[0110] BS / cell 170 includes a mobility module 150, which includes one or both parts of 150-1 and / or 150-2, which can be implemented in a variety of ways. The mobility module 150 can be implemented in hardware as a mobility module 150-1, such as being implemented as a part of one or more processors 152. The mobility module 150-1 can also be implemented as an integrated circuit or through other hardware, such as a programmable gate array. In another example, the mobility module 150 can be implemented as a mobility module 150-2, which is implemented as a computer program code 153 and executed by one or more processors 152. For example, one or more memories 155 and computer program code 153 can be configured to, together with one or more processors 152, enable the BS / cell 170 to perform one or more operations as described herein. Note that the functionality of the mobility module 150 can be distributed, such as distributed in the NR between the DU 195 and the CU 196, or implemented only in the DU 195.

[0111] One or more network interfaces 161 communicate over a network, such as via links 176 and 131. Two or more RAN nodes 170 communicate using, for example, link 176. Link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interfaces for other standards.

[0112] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of wires on a motherboard or integrated circuit, optical fiber or other optical communication device, wireless channel, etc. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for a gNB implementation of 5G, other elements of the BS / cell 170 may be physically in a different location from the RRH / DU, and the one or more buses 157 may be partially implemented as, for example, a fiber optic cable or other suitable network connection to connect the other elements of the BS / cell 170 (e.g., central unit (CU), gNB-CU) to the RRH / DU 195. Reference 198 also indicates those suitable network link(s).

[0113] The wireless communication network 100 may include one or more network elements 190, which may include core network functions and provide connectivity to additional networks, such as a telephone network and / or a data communication network (e.g., the Internet), via one or more links 181. Such core network functions for 5G may include access and (multiple) mobility management functions ((multiple) AMFs) and / or user plane functions ((multiple) UPFs) and / or (multiple) session management functions ((multiple) SMFs). Such core network functions for LTE may include MME (mobile management entity) / SGW (serving gateway) functions. These are merely exemplary functions that may be supported by (multiple) network elements 190, and note that both 5G and LTE functions may be supported. BS / cell 170 is coupled to network element (or elements) 190 via link 131. Link 131 may be implemented, for example, as an NG interface for 5G, or an S1 interface for LTE, or other suitable interfaces for other standards. The network element(s) 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces ((multiple) N / WI / F) 180 interconnected by one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured to, together with the one or more processors 175, cause the network element 190 to perform one or more operations.

[0114] The wireless communication network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functions into a single, software-based managed entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks or portions of networks into virtual units, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities resulting from network virtualization are still implemented to some extent using hardware such as processors 152 or 175 and memories 155 and 171, and that such virtualized entities also produce technical effects.

[0115] Computer readable memories 125, 155, and 171 may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. Computer readable memories 125, 155, and 171 may be components for performing storage functions. As non-limiting examples, processors 120, 152, and 175 may be of any type suitable for the local technical environment and may include one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Processors 120, 152, and 175 may be components for performing functions, such as controlling UE 110, BS / cell 170, and other functions described herein.

[0116] Having thus introduced a suitable non-limiting technical background for the practice of exemplary embodiments of this invention, the exemplary embodiments will now be described in more detail.

[0117] The network configures UE 110 with a reference signal set for monitoring the quality of a radio link (e.g., wireless link 111). Note that "network" refers to at least the BS / cell 170 that interacts with UE 110 via wireless link 111, but may also include one or more network elements 190. The reference signal set may be referred to as q0 or beam fault detection reference signal (BFD-RS). Typically, (multiple) BFD-RS are configured to be quasi-co-located (QCL'd) with the PDCCH demodulation reference signal (DMRS) space, i.e., these reference signals correspond to the downlink beam used to send the PDCCH. The downlink beam is identified by a reference signal, an SS / PBCH block index, or a CSI-RS resource index. The network may configure the BFD-RS list using RRC signaling or using combined RRC+MAC control element (CE) signaling.

[0118] When the UE is not explicitly configured with a BFD-RS list, the UE explicitly determines the BFD-RS resources based on the configured / indicated / activated PDCCH-TCI state of each CORESET, i.e. the downlink reference signals (CSI-RS, SS / PBCH blocks) that are spatially QCL'd with the PDCCH DMRS (or in other words, the PDCCH beam).

[0119] The physical layer 20-1 periodically evaluates the quality of the radio link (based on the BFD-RS in the q0 set). The evaluation is performed for each BFD-RS, and when the radio link condition of each BFD-RS in the beam failure detection set is considered to be in a failure condition, for example, the hypothetical PDCCH BLER estimated using the reference signal (RS) is higher than the configured threshold, a beam failure instance (BFI) indication is provided to a higher layer (e.g., MAC layer 20-2). An example of a BLER threshold may be an out-of-sync (OOS) threshold for radio link monitoring, which corresponds to 10% BLER. The evaluation and indication are performed periodically.

[0120] In the case where at least one BFD-RS is not in a failure condition, no indication is provided to higher layers. At the same time, the MAC layer 20-2 implements a counter to count the BFI indications from the PHY layer, and if the BFI counter reaches a maximum value (configured by the network), a beam failure is declared. The counter can be configured to be supervised by a timer: each time the MAC layer receives a BFI indication from a lower layer, the timer is started. Once the timer expires, the BFI counter is reset (the counter value is set to zero).

[0121] The network may provide the UE with a list of candidate RSs for recovery that may be indicated using a dedicated signal. The candidate beam L1-RSRP measurement may be provided to the MAC layer, which performs the selection of new candidate beams and determines uplink resources to indicate the new candidates to the network. The network may configure the UE with candidate beam-specific dedicated signaling resources (e.g., PRACH resources). That is, the UE may indicate a new candidate beam by sending a preamble.

[0122] If the UE has declared a beam failure and the UE has detected one or more new candidate beams based on L1 measurements (e.g., L1-RSRP), a beam failure recovery procedure is initiated. A dedicated signal from the PRACH pool, which may be referred to as BFR resources or contention-free random access (CFRA) resources, is configured per candidate RS in the Candidate-Beam-RS-List, i.e., it must be noted that the beam recovery procedure is slightly different from the random access (RA) procedure when it comes to the response of the base station (e.g., gNB) to the preamble reception. A specific threshold may be configured so that the UE selects any new candidate (based on L1-RSRP measurements) above the threshold for beam failure recovery. In the absence of a beam above the configured threshold, the UE 110 indicates the new candidate using contention-based signaling, i.e., the contention-based random access (CBRA) preamble resources are mapped to a specific downlink RS.

[0123] UE 110 monitors the network response to a beam failure recovery request (BFRR) during a beam recovery window (similar to a RACH response window) using the same beam alignment used to send the recovery signal (i.e., the same beam direction used for TX as for RX). The UE expects the network to provide a response using a beam that is spatially QCL'd with the indicated downlink reference signal. Cases where this correspondence does not hold are not defined.

[0124] When CFRA is used for beam recovery purposes, the UE expects the network to respond using C-RNTI instead of RA-RNTI. In case CBRA resources are used, the UE expects a response from the network as it normally does in a RACH procedure.

[0125] Other considerations include the time to trigger (TTT). The LTE standard supports several parameters to trigger handover and select the target cell, such as hysteresis margin and TTT. When TTT is applied, handover is initiated only if the triggering requirements are met within the time interval defined by the TTT value. This parameter can reduce the number of unnecessary handovers and effectively avoid the ping-pong effect, but it can also delay handovers, thereby increasing the probability of handover failures.

[0126] As additional information about the handover, the source configures the UE to report measurements periodically or in an event-triggered manner (i.e., only when a condition is met within a certain duration). For inter-frequency handover, typically an A3 measurement event is configured, i.e., the UE triggers a report when a neighboring cell becomes more offset than the source / serving cell. See, e.g., 3GPP TS 38.331 or 3GPP TS 36.331.

[0127] Each measurement event has an entry condition and an exit condition. In the case of an A3 event:

[0128] Entry conditions: Mn+Ocn>Ms+Off+Hyst; and

[0129] Leaving conditions: Mn+Ocn <Ms+Off-Hyst,

[0130] in:

[0131] Ms: measurement of serving cell (L3 filtering);

[0132] Mn: Neighboring cell measurement (L3 filtering);

[0133] Ocn: cell-specific offset, which can be configured differently for different neighboring cells;

[0134] Off: Offset of switching; and

[0135] Hyst: hysteresis.

[0136] If the entry condition is met for the first time, the UE starts a timer with the TTT value. If the timer for TTT expires, the UE sends a measurement report to the source cell, and this may initiate the process leading to handover. The timer for TTT is stopped only when the exit condition is met. In this case, the UE does not send any measurement report because the timer for TTT has not expired.

[0137] A possible straightforward technique for the beam failure recovery problem that has been examined is for the UE to check the L1 beam measurements of the source cell and potential target non-serving cells. For example, in a co-frequency scenario (e.g., mobility between two different cells but within the same frequency in connected mode), if the strongest L1 beam measurement of the source cell is some offset weaker than that of the target cell, the UE triggers beam failure recovery to another non-serving cell.

[0138] This procedure can limit the cases where beam failure recovery is triggered in a non-serving cell, but does not necessarily reduce unnecessary serving eNB replacements or target cell access failures. This is because L1 measurements are subject to fast fading fluctuations and measurement errors and are not stable enough to make a reliable decision on triggering beam failure recovery on another serving cell. Therefore, this can lead to cell changes after fast fading and measurement errors. This needs to be avoided as it can lead to "false alarms" of fast handover back to the source cell or even failure of the target cell.

[0139] T312 has been introduced for declaring early RLF in L3 and initiating an RRC re-establishment procedure. The network can configure T312 for a certain measurement event X. If a measurement report is triggered from measurement event X while timer T310 is running, timer T312 starts. If timer T312 expires, the UE declares RLF and initiates an RRC re-establishment procedure. In the current 3GPP specification, timer T312 is started only when T310 is already running, but a proposal to start timer T312 independently of T310 with a triggered measurement report has been discussed.

[0140] The exemplary embodiments are based on the assumption that if the target cell is stable enough, it is likely that an RRC measurement event has been triggered shortly beforehand (e.g., but a report based on the measurement event may be lost). Otherwise, if no measurement report has been triggered beforehand, it is likely that the target cell is not stable enough and BFR to the neighbor is risky and may result in a failure or handover back to the serving cell.

[0141] As described above, TTT is used to trigger measurement reporting for handover. TTT is also used herein to allow beam failure recovery to another cell only when measurement reporting has been triggered using TTT. Therefore, there is an interaction between measurement reporting for L3 inter-cell mobility and beam failure recovery in non-serving cells herein.

[0142] The exemplary embodiments propose the following for triggering a beam failure recovery procedure in a non-serving cell.

[0143] 1) When a measurement event for which a timer T is configured triggers a measurement report, the timer T is started.

[0144] The entry conditions for the measurement reporting event may be evaluated using, for example, the L3 filtered cell quality of the target cell. This quality is currently derived as the average of the N strongest beam measurements above a threshold (or if no beam is above a threshold, the UE uses the best beam).

[0145] A measurement report may be triggered when an entry condition is met during a specific trigger time (TTT) or when a timer for TTT expires. That is, from an implementation point of view, a measurement report is sent only when a timer for TTT expires. This only happens if the entry condition has been met at least once and the exit condition has never been met since then, causing the timer TTT to expire.

[0146] 2) If beam failure has been detected while timer T is running, the UE is allowed to initiate beam failure recovery towards the strongest non-serving cell or any cell that has met the criteria for starting timer T. Otherwise, UE 110 should only perform beam failure recovery in the same serving cell.

[0147] In some embodiments, the UE may be provided with an alternative SSB / CSI-RS candidate set for BFR (including other configurations) applied when timer T is running. That is, the SSB / CSI-RS candidate set for BFR applied when timer T is running (e.g., including other configurations) may be different from the set that can be used by the UE before timer T is started. For example, before timer T is started, the SSB / CSI-RS candidate set for BFR only includes candidates from the serving cell, and when timer T is running, the set includes candidates from both the serving (e.g., source) and target cells. Alternatively, before timer T is started, the SSB / CSI-RS candidate set for BFR configuration may include candidates from both the source and target cells, and when timer T is running, the set only includes SSB / CSI-RS candidates from the target cell.

[0148] 3) If the timer T expires, the UE performs beam failure recovery in the same serving cell where the beam failure was detected.

[0149] In the latter case, it can no longer be assumed that the radio conditions of the target cell are sufficiently stable and / or will still meet the entry conditions for the measurement event triggering the report. This concludes the example of the method.

[0150] Unlike conventional techniques, in response to L3 conditions for RRC inter-cell mobility being met, the UE is allowed to initiate a MAC beam failure recovery procedure to a non-serving cell. This ensures that beam failure recovery is triggered when the radio link of the source cell is no longer sufficient and the radio link quality of the target non-serving cell is stable enough to continue serving the UE once the UE has been switched to the non-serving cell.

[0151] When the MAC layer (e.g., Figure 1 When a beam failure is detected by the MAC layer 20-2, the MAC layer 20-2 may trigger a failure indication to a higher layer (eg, layer 20-3) to indicate that the MAC layer 20-2 has detected a beam failure.

[0152] This enables the RRC layer 20-3 to check whether the timer T is running for any cell. If a beam failure indication is received while the timer T is running, the RRC layer 20-3 may instruct the MAC layer 20-2 to initiate beam failure recovery to a specific target cell that has satisfied the entry condition of the measurement event associated with the timer T. If the RRC layer 20-3 does not perform any action after receiving the indication from the MAC layer 20-2, the UE 110 performs beam recovery for the serving cell as normally performed according to the above.

[0153] In yet another option, the MAC layer 20-2 may indicate to higher layers (eg, 20-3) that a beam failure has been detected and that no serving cell CFRA candidates are above a threshold. This may delay the indication until the CFRA candidates are evaluated.

[0154] Figure 2 An exemplary signaling diagram is described for a situation where a beam failure has been detected while timer T is running. In this example, the serving BS / cell 170-1 signals a measurement configuration message 210, which includes a measurement report event associated with timer T. In box 220, the UE 110 determines that the entry conditions for the measurement event are met during the trigger time (TTT) or the timer for the TTT has expired. That is, the non-serving BS / cell 170-2 now meets the criteria that makes the cell a possible HO candidate. Note that the measurement configuration can have a whitelist or blacklist of cells to be considered in the measurement, and further, it can happen that more than one cell meets the criteria (although it is not a common case). If necessary, both situations can be considered simultaneously. The UE 110 starts the timer T and signals a measurement report 230. As described in box 235, the serving BS / cell 170-1 may or may not receive the measurement report (MR) 230. That is, Figure 2 It is shown that the measurement report is sent by the UE, but there is no indication whether the measurement report is successfully received by the source cell. Such measurement reports may be lost. In contrast to declaring a radio link failure after detecting a radio link failure, for example due to expiration of timer T310, UE 110 may perform beam failure recovery to another cell before expiration of timer T, such as Figure 2 For example, when the timer T is running, the UE 110 detects a beam failure in block 240. A beam failure recovery procedure 250 is performed between the UE 110 and the target non-serving BS / cell 170-2.

[0155] Figure 2 One of the examples described in the overview above is illustrated, where if the target cell is sufficiently stable, then it is likely that an RRC measurement event has been triggered shortly beforehand. It is assumed that the target non-serving BS / cell 170 - 2 is therefore suitable for the BFR procedure 250 .

[0156] Steering Figure 3, which depicts a situation where a beam failure is detected when timer T is not running. This may correspond to a situation where a beam failure is detected when the entry condition for the measurement is being evaluated by the UE or even met but is not met during the TTT. In this case, timer T is not started and the UE triggers beam failure recovery in the same serving cell. In this example, the serving BS / cell 170-1 signals a measurement configuration message 210 that includes a measurement reporting event associated with timer T. In box 320, the UE 110 determines that the entry condition for the measurement event has not been met during the TTT or the timer for the TTT has not expired. Therefore, timer T is not started. In box 330, the UE 110 detects a beam failure and a beam failure recovery procedure 350 is performed between the UE 110 and the serving BS / cell 170-1.

[0157] Figure 3 One of the examples described in the overview provided above is illustrated, where if no measurement report has been triggered beforehand, it is likely that the target cell is not stable enough and BFR to the neighbor is risky and may result in a failure or handover return. Assume that the target non-serving BS / cell 170-2 is therefore not suitable for the BFR process 250, and the BFR process 350 is instead returned to the serving BS / cell 170-1.

[0158] In one embodiment, the existing timer T312 may be reused for the proposed behavior. In an alternative embodiment, in response to the UE being allowed to perform recovery to the non-serving BS / cell 170-2, the timer / counter related to RLF detection or BFR is adjusted. That is, while the timer T is running, if a beam failure has been detected in the serving cell, the UE is allowed to perform beam failure recovery in another cell, and during this time period, the UE may apply a specific value for the timer / counter used for RLF detection or BFR in the target cell. For example, the number of random access trials during the BFR or RACH response window may be different for the serving and target cells.

[0159] Figure 4 is a logic flow diagram of an exemplary process performed by UE 110 for robust beam failure recovery using non-serving cells. The figure illustrates how a UE may implement Figure 2 and Figure 3 The figure further illustrates the operation of one or more exemplary methods according to the exemplary embodiments, the results of execution of computer program instructions embodied on a computer readable memory, the functions performed by logic implemented in hardware, and / or the interconnected components for performing the functions. For example, the mobility module 140 may include Figure 4A plurality of blocks in a block in which each of the included blocks is an interconnected component for performing the functions in the block. Assume Figure 4 The blocks in are performed by UE 110, for example, at least partially under the control of mobility module 140.

[0160] In block 405, the UE 110 receives a measurement configuration message 210, which includes a TTT and information for measurement reporting events and their corresponding association with a timer T. That is, the association is provided by the network. Note that only one block is shown here, but these can be configured separately, such as the TTT and information being configured at different times via different signaling. An example of a timer that can be used is timer T312 implemented as timer T. See block 410.

[0161] In block 415, the UE 110 determines whether the entry condition for the measurement is met during the TTT or whether the timer for the TTT has expired. If the entry condition is met or the timer for the TTT has expired (block 420=yes), the UE 110 starts the timer T in block 425 and sends the measurement report 230 in block 430, and the flow proceeds to block 435. Block 433 is an example of another alternative, where different timers / counters related to RLF detection or BFR are applied when the timer T is running, depending on the network configuration. Block 434 is an additional alternative, where when the timer T is running, the UE 110 can apply a different set of SSB / CSI-RS candidates for BFR (e.g., including other configurations) than used before the timer T was started.

[0162] If the entry condition is not met or the timer for TTT has not expired (block 420=No), the flow proceeds to block 435, where the UE 110 determines whether a beam failure is detected. If a beam failure is not detected (block 440=No), if the timer T has been started (block 440=No and the timer T has been started), the flow proceeds to block 435. Otherwise (block 440=No and the timer T has not been started), the flow proceeds to block 415.

[0163] If a beam failure is detected (block 440=yes), UE 110 determines in block 445 whether timer T is running. If timer T is running (block 450=yes), UE 110 performs a beam failure recovery procedure with target non-serving BS / cell 170-2 (block 455). Note that if there are multiple candidate target cells, the UE selects the strongest one. In contrast, if timer T is not running (block 450=no), UE 110 performs a beam failure recovery procedure with serving BS / cell 170-1 in block 460.

[0164] Additional examples are below.

[0165] Example 1. A method comprising:

[0166] determining, by the user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, whether a timer is running; and

[0167] The user device performs one of the following operations:

[0168] a beam failure recovery procedure with a target non-serving cell in response to a timer running; or

[0169] A beam failure recovery procedure with a serving cell in response to a timer not running.

[0170] Example 2. The method according to Example 1, further comprising:

[0171] Before determining whether the timer is running, do the following:

[0172] determining, by the user equipment, whether an entry condition of a measurement event is satisfied during a triggering time, or whether a timer for the triggering time has expired, wherein the measurement event is at least configured for the user equipment to measure one or more non-serving cells including a target non-serving cell; and

[0173] In response to the user equipment determining that an entry condition of the measurement event is satisfied during the trigger time, or a second timer for the trigger time has expired, the running of the timer is started.

[0174] Example 3. The method according to Example 2 also includes sending a measurement report in response to the user equipment determining that the entry conditions of the measurement event have been met during the trigger time, or the second timer for the trigger time has expired, the measurement report is sent to the serving cell and includes measurements of one or more non-serving cells.

[0175] Example 4. The method according to Example 1, further comprising:

[0176] Before determining whether the timer is running,

[0177] determining, by the user equipment, whether an entry condition of a measurement event is satisfied during a trigger time or a second timer for the trigger time expires, wherein the measurement event is configured for the user equipment to measure one or more non-serving cells including a target non-serving cell; and

[0178] In response to the user equipment determining that the entry condition of the measurement event is not satisfied during the trigger time or the second timer for the trigger time has not expired, the running of the timer is not started.

[0179] Example 5. The method of any one of Examples 2 to 4, wherein an entry condition for the measurement event being satisfied comprises an L3 condition for radio resource control inter-cell mobility being satisfied.

[0180] Example 6. The method of any one of Examples 1 to 5, wherein the timer is timer T312.

[0181] Example 7. The method according to any one of Examples 1 to 6, wherein the serving cell and the target non-serving cell are formed by the same base station.

[0182] Example 8. The method according to any one of Examples 1 to 7, wherein the serving cell and the target non-serving cell are formed by two different base stations.

[0183] Example 9. A method according to any one of Examples 1 to 8, wherein performing a beam failure recovery process with a service cell in response to a timer not running further includes: in response to expiration of the timer, in response to detecting a beam failure, performing a beam failure recovery process by a user device in the same service cell.

[0184] Example 10. A method according to any one of Examples 1 to 9, further comprising, while the timer is running, the user equipment applying a different set of synchronization signal / physical broadcast channel blocks, and / or channel state information-reference signal candidates for beam failure recovery than was used before the timer was started.

[0185] Example 11. The method according to any one of Examples 1 to 10 further includes, when the timer is running, the user equipment performing beam failure recovery on the target cell in response to detecting a beam failure in the serving cell, and during the time period during which the timer is running, the user equipment executes application-specific values ​​for one or more timers and / or counters used in radio link failure detection or beam failure recovery in the target cell.

[0186] Example 12. A computer program comprising code for performing a method according to any one of Examples 1 to 11 when the computer program is run on a computer.

[0187] Example 13. The computer program according to example 12, wherein the computer program is a computer program product comprising a computer readable medium carrying computer program code embodied therein for use with a computer.

[0188] Example 14. The computer program according to example 12, wherein the computer program is directly loadable into an internal memory of a computer.

[0189] Example 15. An apparatus comprising:

[0190] means for determining, by the user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, whether a timer is running; and

[0191] Means for performing one of the following operations by a user device:

[0192] means for performing a beam failure recovery procedure with a target non-serving cell in response to the timer running; or

[0193] Means for performing a beam failure recovery procedure with a serving cell in response to a timer not running.

[0194] Example 16. The apparatus according to Example 15, further comprising:

[0195] Since the component does the following before determining if the timer is running:

[0196] means for determining, by the user equipment, whether an entry condition of a measurement event is satisfied during a trigger time or whether a second timer for the trigger time has expired, wherein the measurement event is at least configured for the user equipment to measure one or more non-serving cells including a target non-serving cell; and

[0197] Means for initiating running of a timer in response to determining by the user equipment that an entry condition for the measurement event is satisfied during the triggering time or that a second timer for the triggering time has expired.

[0198] Example 17. The apparatus according to Example 16 further includes a component for sending a measurement report in response to a user equipment determining that an entry condition for a measurement event has been met during a trigger time or a second timer for the trigger time has expired, the measurement report being sent to a serving cell and including measurements of one or more non-serving cells.

[0199] Example 18. The apparatus according to Example 15, further comprising:

[0200] A component that does the following before determining if the timer is running:

[0201] for determining, by the user equipment, whether an entry condition of a measurement event is satisfied during a triggering time or a second timer for the triggering time expires, wherein the measurement event is configured for the user equipment to measure one or more non-serving cells including a target non-serving cell; and;

[0202] Means for not starting the running of the timer in response to determining by the user equipment that an entry condition for the measurement event is not satisfied during the triggering time or a second timer for the triggering time has not expired.

[0203] Example 19. The apparatus of any one of Examples 16 to 18, wherein an entry condition for the measurement event being satisfied comprises an L3 condition for radio resource control inter-cell mobility being satisfied.

[0204] Example 20. The apparatus of any one of Examples 15 to 19, wherein the timer is timer T312.

[0205] Example 21. An apparatus according to any one of Examples 15 to 20, wherein the serving cell and the target non-serving cell are formed by the same base station.

[0206] Example 22. The apparatus of any one of Examples 15 to 21, wherein the serving cell and the target non-serving cell are formed by two different base stations.

[0207] Example 23. An apparatus according to any one of Examples 15 to 22, wherein the component for performing a beam failure recovery process with a serving cell in response to a timer not running further comprises: a component for performing a beam failure recovery process by a user device in the same serving cell in response to expiration of a timer and in response to detection of a beam failure.

[0208] Example 24. An apparatus according to any one of Examples 15 to 23, further comprising a component for: while the timer is running, the user equipment applies a different set of synchronization signal / physical broadcast channel blocks, and / or channel state information-reference signal candidates for beam failure recovery than was used before the timer was started.

[0209] Example 25. An apparatus according to any one of Examples 15 to 24, further comprising a component for causing the user equipment to perform beam failure recovery on a target cell in response to detecting a beam failure in a serving cell while the timer is running, and a component for causing the user equipment to execute application-specific values ​​for one or more timers and / or counters used in radio link failure detection or beam failure recovery in the target cell during a time period during which the timer is running.

[0210] Example 26. An apparatus comprising:

[0211] one or more processors; and

[0212] one or more memories including computer program code,

[0213] The one or more memories and the computer program code are configured to, together with the one or more processors, cause the apparatus to perform the following operations, including:

[0214] determining, by the user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, whether a timer is running; and

[0215] The user device performs one of the following operations:

[0216] performing a beam failure recovery procedure with a target non-serving cell in response to the timer running; or

[0217] In response to the timer not running, performing a beam failure recovery procedure with the serving cell.

[0218] Example 27. The apparatus of Example 26, wherein the one or more memories and the computer program code are further configured to, with the one or more processors, cause the apparatus to perform operations comprising:

[0219] Before determining whether the timer is running, do the following:

[0220] determining, by the user equipment, whether an entry condition of a measurement event is satisfied during a triggering time, or whether a timer for the triggering time has expired, wherein the measurement event is at least configured for the user equipment to measure one or more non-serving cells including a target non-serving cell; and

[0221] In response to the user equipment determining that an entry condition of the measurement event is satisfied during the trigger time, or a second timer for the trigger time has expired, the running of the timer is started.

[0222] Example 28. An apparatus according to Example 27, wherein the one or more memories and the computer program codes are also configured to, together with one or more processors, cause the apparatus to perform the following operations, including: sending a measurement report in response to a user equipment determining that an entry condition for a measurement event has been met during a trigger time, or that a second timer for the trigger time has expired, the measurement report being sent to a serving cell and including measurements of one or more non-serving cells.

[0223] Example 29. The apparatus of Example 26, wherein the one or more memories and the computer program code are further configured to, with the one or more processors, cause the apparatus to perform operations comprising:

[0224] Before determining whether the timer is running, do the following:

[0225] determining, by the user equipment, whether an entry condition of a measurement event is satisfied during a trigger time or a second timer for the trigger time expires, wherein the measurement event is configured for the user equipment to measure one or more non-serving cells including a target non-serving cell; and

[0226] In response to the user equipment determining that the entry condition of the measurement event is not satisfied during the trigger time or the second timer for the trigger time has not expired, the running of the timer is not started.

[0227] Example 30. The apparatus of any one of Examples 27 to 29, wherein an entry condition for the measurement event being satisfied comprises an L3 condition for radio resource control inter-cell mobility being satisfied.

[0228] Example 31. An apparatus according to any one of Examples 26 to 30, wherein the timer is timer T312.

[0229] Example 32. An apparatus according to any one of Examples 26 to 31, wherein the serving cell and the target non-serving cell are formed by the same base station.

[0230] Example 33. An apparatus according to any one of Examples 26 to 32, wherein the serving cell and the target non-serving cell are formed by two different base stations.

[0231] Example 34. An apparatus according to any one of Examples 26 to 33, wherein performing a beam failure recovery process with a serving cell in response to a timer not running further comprises: in response to expiration of the timer, in response to detecting a beam failure, performing a beam failure recovery process by a user device in the same serving cell.

[0232] Example 35. An apparatus according to any one of Examples 26 to 34, wherein the one or more memories and the computer program codes are also configured to, together with the one or more processors, cause the apparatus to perform the following operations, including: while the timer is running, the user equipment applies a different set of synchronization signal / physical broadcast channel blocks, and / or channel state information-reference signal candidates for beam failure recovery than was used before the timer was started.

[0233] Example 36. An apparatus according to any one of Examples 26 to 35, wherein the one or more memories and the computer program codes are also configured to, together with the one or more processors, cause the apparatus to perform the following operations, including: while the timer is running, the user equipment performs beam failure recovery on the target cell in response to having detected a beam failure in the serving cell, and during the time period while the timer is running, the user equipment applies specific values ​​to one or more timers and / or counters used in radio link failure detection or beam failure in the target cell.

[0234] Example 37. A computer program product comprising a computer readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

[0235] code for determining, by a user equipment and in response to beam failure being detected for a serving cell serving the user equipment, whether a timer is running; and

[0236] Code for the user device to do one of the following:

[0237] code for performing a beam failure recovery procedure with a target non-serving cell in response to a timer running; or

[0238] Code for performing a serving cell beam failure recovery procedure in response to a timer not running.

[0239] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0240] (a) hardware circuit implementation only (such as implementation only in analog and / or digital circuitry) and

[0241] (b) a combination of hardware circuitry and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuitry and software / firmware and (ii) any portion of hardware processor(s) with software (including digital signal processor(s), software and memory(s) working together to enable a device (such as a mobile phone or server) to perform various functions and

[0242] (c) Hardware circuits and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) for operation, but in which the software may not be present when not required for operation.

[0243] This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to a particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0244] The embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., application specific integrated circuits), or a combination of software and hardware. In example embodiments, the software (e.g., application logic, instruction sets) is maintained on any of a variety of conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any medium or component that can contain, store, communicate, propagate, or transport instructions for use by or in conjunction with an instruction execution system, apparatus, or device, such as a computer, for example, in a computer program product. Figure 1An example of a computer described and depicted in . Computer-readable media may include computer-readable storage media (e.g., memory 125, 155, 171 or other devices), which may be any medium or component that can contain, store and / or transmit instructions for use by or in conjunction with an instruction execution system, apparatus or device, such as a computer. Computer-readable storage media do not include propagated signals.

[0245] If desired, the different functions discussed herein may be performed in different orders and / or simultaneously with each other. In addition, if desired, one or more of the above functions may be optional or may be combined.

[0246] Although various aspects of the invention are set out in the independent claims, further aspects of the invention comprise other combinations of features from the described embodiments and / or the dependent claims with features of the independent claims, not just those explicitly stated in these combined claims.

[0247] It is also noted herein that although the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, numerous changes and modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A method for communication, comprising: determining, by the user equipment, whether an entry condition of a measurement event is met during a triggering time, or whether a second timer for the triggering time has expired, so as to send a measurement report to a serving cell, wherein the measurement event is at least configured for the user equipment to measure one or more non-serving cells including a target non-serving cell, and the triggering time is used to trigger a measurement report for handover; as well as In response to determining by the user equipment that the entry condition of the measurement event is satisfied during the trigger time, or the second timer for the trigger time has expired, starting the running of a timer; determining, by the user equipment and in response to beam failure being detected for a serving cell serving the user equipment, whether the timer is running; and The user equipment performs one of the following operations: a beam failure recovery procedure with the target non-serving cell in response to the timer running; or A beam failure recovery procedure with the serving cell in response to the timer not running.

2. The method according to claim 1 further includes sending a measurement report in response to the user equipment determining that the entry condition of the measurement event has been met during the trigger time, or the second timer for the trigger time has expired, the measurement report being sent to the serving cell and including measurements of the one or more non-serving cells.

3. The method according to claim 1, further comprising: Before determining whether the timer is running, determining, by the user equipment, whether an entry condition of a measurement event is satisfied during a triggering time or whether a second timer for the triggering time has expired, wherein the measurement event is configured for the user equipment to measure one or more non-serving cells including the target non-serving cell; as well as In response to the user equipment determining that the entry condition of the measurement event is not satisfied during the trigger time, or the second timer for the trigger time has not expired, the running of the timer is not started. 4 . The method of claim 1 , wherein the entry condition of the measurement event being satisfied comprises an L3 condition for radio resource control inter-cell mobility being satisfied. The method according to claim 1 , wherein the timer comprises a timer T312 . The method according to claim 1 , wherein the serving cell and the target non-serving cell are formed by the same base station. 7 . The method according to claim 1 , wherein the serving cell and the target non-serving cell are formed by two different base stations.

8. The method of claim 1, wherein in response to the timer not running, performing a beam failure recovery procedure with the serving cell further comprises: In response to the timer expiring, in response to detecting the beam failure, performing the beam failure recovery procedure by the user equipment in the same serving cell.

9. The method according to claim 1 also includes, while the timer is running, the user equipment applying a different set of synchronization signal / physical broadcast channel blocks, and / or channel state information-reference signal candidates for beam failure recovery compared to those used before the timer was started.

10. The method according to any one of claims 1 to 9 further includes, during the time period while the timer is running, the user equipment applying specific values ​​to one or more timers and / or counters used in radio link failure detection or beam failure in the target cell.

11. An apparatus for communication, comprising: one or more processors; as well as one or more memories including computer program code, wherein the one or more memories and the computer program code are configured to, together with the one or more processors, cause the apparatus to: determining whether an entry condition of a measurement event is satisfied during a triggering time, or a second timer for the triggering time has expired, to send a measurement report to a serving cell, wherein the measurement event is at least configured for the apparatus to measure one or more non-serving cells including a target non-serving cell, and the triggering time is used to trigger a measurement report for handover; as well as In response to determining that the entry condition of the measurement event is satisfied during the trigger time, or the second timer for the trigger time has expired, starting the running of a timer; in response to a beam failure being detected for a serving cell serving the apparatus, determining whether the timer is running; as well as Do one of the following: a beam failure recovery procedure with the target non-serving cell in response to the timer running; or A beam failure recovery procedure with the serving cell in response to the timer not running.

12. The apparatus of claim 11, wherein the one or more memories and the computer program code are further configured to, together with the one or more processors, cause the apparatus to: send a measurement report in response to determining that the entry condition for the measurement event has been met during a trigger time, or that the second timer for the trigger time has expired, the measurement report being sent to the serving cell and including measurements of the one or more non-serving cells.

13. The apparatus of claim 11, wherein the one or more memories and the computer program code are further configured to, together with one or more processors, cause the apparatus to: Before determining whether the timer is running, determining whether an entry condition of a measurement event is satisfied during a trigger time or whether a second timer for the trigger time has expired, wherein the measurement event is configured for the apparatus to measure one or more non-serving cells including the target non-serving cell; and In response to determining that the entry condition of the measurement event is not satisfied during the trigger time, or the second timer for the trigger time has not expired, the running of the timer is not initiated.

14. The apparatus of claim 11, wherein the entry condition for the measurement event being satisfied comprises an L3 condition for radio resource control inter-cell mobility being satisfied.

15. The apparatus of claim 11, wherein the timer comprises a timer T312.

16. The apparatus according to claim 11, wherein the serving cell and the target non-serving cell are formed by the same base station.

17. The apparatus according to claim 11, wherein the serving cell and the target non-serving cell are formed by two different base stations.

18. An apparatus according to claim 11, wherein, when performing a beam failure recovery process with the service cell in response to the timer not running, the one or more memories and the computer program code are also configured to, together with the one or more processors, cause the apparatus to: in response to expiration of the timer, in response to detecting the beam failure, perform the beam failure recovery process in the same service cell.

19. An apparatus according to claim 11, wherein the one or more memories and the computer program code are also configured to, together with the one or more processors, cause the apparatus to: while the timer is running, apply a different set of synchronization signal / physical broadcast channel blocks, and / or channel state information-reference signal candidates for beam failure recovery than was used before the timer was started.

20. An apparatus according to any one of claims 11 to 19, wherein the one or more memories and the computer program code are also configured to, together with the one or more processors, enable the apparatus to: apply specific values ​​to one or more timers and / or counters used in radio link failure detection or beam failure in the target cell during a time period in which the timer is running.

21. A computer readable medium comprising computer program instructions for performing at least the following operations: determining, by the user equipment, whether an entry condition of a measurement event is met during a triggering time, or whether a second timer for the triggering time has expired, so as to send a measurement report to a serving cell, wherein the measurement event is at least configured for the user equipment to measure one or more non-serving cells including a target non-serving cell, and the triggering time is used to trigger a measurement report for handover; as well as In response to determining by the user equipment that the entry condition of the measurement event is satisfied during the trigger time, or the second timer for the trigger time has expired, starting the running of a timer; code for determining, by the user equipment and in response to a beam failure being detected for a serving cell serving the user equipment, whether a timer is running; as well as Code for performing, by the user device, one of the following operations: a beam failure recovery procedure with the target non-serving cell in response to the timer running; or A beam failure recovery procedure with the serving cell in response to the timer not running.

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