Method and apparatus of beam failure recovery executed by user equipment
The invention provides a method performed by user equipment and user equipment. The user equipment is configured in a discontinuous reception (DRX) mode. The method performed by user equipment comprising: initiating a random access (RA) procedure if a value of a beam failure instance (BFI) counter is greater than or equal to a threshold, the threshold being configured by an information element (IE) beamFailureInstanceMaxCount; transmitting a RA preamble; starting a RA response window, the RA response window being configured in an IE BeamFailureRecoveryConfig; and monitoring a PDCCH on a search space indicated by an IE RecoverySearchSpaceId while the RA response window is running. The user equipment can reliably complete a procedure to recover from beam failure even if the user equipment is configured in a DRX mode, thereby improving the overall reliability and communication efficiency of a communication system related to the user equipment.
1. A method performed by a user equipment (UE) for a beam failure recovery (BFR), the method comprising:
after determining that a value of a beam failure instance (BFI) counter is greater than or equal to a threshold that is configured by an information element (IE) beamFailureInstanceMaxCount:
determining whether a medium access control (MAC) entity of the UE is in an active time when the UE is configured in a discontinuous reception (DRX) mode;
in a case that the MAC entity of the UE is in the active time, initiating a random access (RA) procedure; and
in a case that the MAC entity of the UE is not in the active time, delaying initiating the RA procedure, wherein;
a length of the delay is determined by a length of a time window,
the length of the time window is determined by the UE based on a quality of a specific signal,
in a case that the quality of the specific signal is greater than a specific threshold, the length of the time window is set to a first value,
in a case that the quality of the specific signal is less than the specific threshold, the length of the time window is set to a second value, and
the RA procedure comprises:
transmitting an RA preamble;
starting an RA response window that is configured by an IE BeamFailureRecoveryConfig;
monitoring a physical downlink control channel (PDCCH) on a search space indicated by an IE Recovery SearchSpaceId while the RA response window is running; and
considering the RA procedure to be successfully completed when the PDCCH on the search space indicated by the IE Recovery SearchSpaceId is received.
2. The method of claim 1 , wherein the RA preamble is a contention-free RA preamble for a BFR request.
3. The method of claim 1 , wherein the PDCCH is identified by a cell-radio network temporary identifier (C-RNTI).
4. A user equipment (UE), the UE-comprising:
one or more processors; and
at least one non-transitory computer-readable medium coupled to the one or more processors and storing one or more computer-executable instructions that, when executed by the one or more processors, cause the UE to:
after determining that a value of a beam failure instance (BFI) counter is greater than or equal to a threshold that is configured by an information element (IE) beamFailureInstanceMaxCount:
determine whether a medium access control (MAC) entity of the UE is in an active time when the UE is configured in a discontinuous reception (DRX) mode;
in a case that the MAC entity of the UE is in the active time, initiate a random access (RA) procedure; and
in a case that the MAC entity of the UE is not in the active time, delay initiating the RA procedure, wherein:
a length of the delay is determined by a length of a time window,
the length of the time window is determined by the UE based on a quality of a specific signal,
in a case that the quality of the specific signal is greater than a specific threshold, the length of the time window is set to a first value,
in a case that the quality of the specific signal is less than the specific threshold, the length of the time window is set to a second value, and
the RA procedure comprises:
transmitting an RA preamble;
starting an RA response window that is configured by an IE BeamFailureRecoveryConfig;
monitoring a physical downlink control channel (PDCCH) on a search space indicated by an IE Recovery SearchSpaceId while the RA response window is running; and
considering the RA procedure to be successfully completed when the PDCCH on the search space indicated by the IE Recovery SearchSpaceId is received.
5. The UE of claim 4 , wherein the RA preamble is a contention-free RA preamble for a BFR request.
6. The UE of claim 4 , wherein the PDCCH is identified by a cell-radio network temporary identifier (C-RNTI).