# US 12,184,476 B2 · User equipment and beam failure recovery method

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- Number: US 12,184,476 B2
- Document ID: US12184476B2
- Status: Granted
- Kind: B2
- Application number: 17/044,668
- Filed: 2019-04-02
- Published: 2021-04-08
- Granted: 2024-12-31
- Earliest claimed: 2018-04-04
- Assignees: Sharp Kabushiki Kaisha
- Applicants: Sharp Kabushiki Kaisha
- Inventors: Chao Luo; Shohei Yamada; Renmao Liu
- Web page: https://patentgrep.com/patent/US12184476B2

## CPC

- H04L 41/0654: using network fault recovery (ring fault isolation or reconfiguration in loop networks without recovery actions by a network management system H04L12/437)
- H04W 76/19: Connection re-establishment
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04W 74/0833: Random access procedures, e.g. with 4-step access
- H04W 74/0838: using contention-free random access [CFRA]
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

The present invention provides user equipment (UE) and a beam failure recovery method. In the beam failure recovery method executed by UE, a physical layer entity of the UE measures a reference signal and indicates a beam failure instance to a MAC layer entity of the UE; each time the MAC layer entity receives the indication of the beam failure instance, the MAC layer entity starts a beam failure detection timer, determines whether the received beam failure instances are consecutively generated, and uses a beam failure instance counter to count the number of beam failure instances consecutively generated; when the counted number exceeds a preset threshold, it is determined that a beam failure has occurred; the UE initiates a random access procedure, and selects a contention-free random access resource or a contention-based random access resource in the random access procedure.

## Claims

### Claim 1

A method performed by a user equipment (UE), the method comprising:
receiving beam failure instance indication from lower layers;
starting or restarting a beamFailureDetectionTimer;
incrementing a BFI_COUNTER by 1, the BFI_COUNTER being a counter for a beam failure instance indication;
initiating a Random Access procedure for beam failure recovery on a basis of a value of the BFI COUNTER;
resetting the BFI_COUNTER to 0 in response to determining that the beamFailureDetectionTimer has expired;
resetting the BFI_COUNTER to 0 with regard to the Random Access procedure for beam failure recovery in response to determining that the Random Access procedure for beam failure recovery is successfully completed; and
forgoing resetting the BFI COUNTER to 0 with regard to the Random Access procedure for beam failure recovery in response to determining that the Random Access procedure for beam failure recovery is not successfully completed.

### Claim 2

A user equipment (UE), comprising:
at least one processor; and
at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the UE to:
receive beam failure instance indication from lower layers;
start or restart a beamFailureDetectionTimer;
increment a BFI COUNTER by 1, the BFI_COUNTER being a counter for a beam failure instance indication;
initiate a Random Access procedure for beam failure recovery on a basis of a value of the BFI COUNTER;
reset the BFI COUNTER to 0 in response to determining that the beamFailureDetectionTimer has expired;
reset the BFI COUNTER to 0 with regard to the Random Access procedure for beam failure recovery in response to determining that the Random Access procedure for beam failure recovery is successfully completed; and
forgo resetting the BFI COUNTER to 0 with regard to the Random Access procedure for beam failure recovery in response to determining that the Random Access procedure for beam failure recovery is not successfully completed.