Method and apparatus for acknowledging SCell beam failure recovery request
A method for SCell BFR performed by a UE is provided. The method includes: transmitting, to a base station, a BFR MAC CE that includes a cell index of an SCell in which beam failure occurs and a new candidate beam index for the SCell, the transmission of the BFR MAC CE associated with a HARQ process having a HARQ process ID; and receiving, from the base station, a first DCI format that schedules a first PUSCH transmission with the HARQ process ID, the first DCI format indicating a toggled NDI value.
1. A user equipment (UE) for performing a Secondary Cell (SCell) Beam Failure Recovery (BFR) procedure, the UE comprising:
one or more non-transitory computer-readable media having computer-executable instructions embodied thereon; and
at least one processor coupled to the one or more non-transitory computer-readable media, the at least one processor configured to execute the computer-executable instructions to:
transmit, via uplink (UL), to a base station (BS), a BFR Medium Access Control (MAC) Control Element (CE) that includes a cell index of an Scell with beam failure detected and a reference signal index for the Scell, the UL transmission of the BFR MAC CE associated with a Hybrid Automatic Repeat Request (HARQ) process having a HARQ process identifier (ID);
receive, from the BS, Downlink Control Information (DCI) that schedules a Physical Uplink Shared Channel (PUSCH) transmission with the HARQ process ID of the HARQ process that is used for the UL transmission of the BFR MAC CE, the DCI indicating a toggled New Data Indicator (NDI) value;
determine, upon receiving the DCI, that the Scell BFR procedure is successfully completed; and
monitor, on the Scell, a Physical Downlink Control Channel (PDCCH) using antenna port quasi-colocation parameters associated with the reference signal index after receiving the DCI.
2. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
apply beam information indicated by the BS via at least one Transmission Configuration Indication (TCI) activation MAC CE to receive the DCI.
3. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
start, before receiving the DCI, a BFR timer; and
stop the BFR timer upon receipt of the DCI.
4. The UE of claim 3 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
start the BFR timer upon detection of a beam failure condition.
5. The UE of claim 3 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
stop the BFR timer when the Scell BFR procedure is determined as successfully completed.
6. The UE of claim 3 , wherein starting the BFR timer before receiving the DCI comprises starting the BFR timer when the BFR MAC CE is transmitted.
7. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
transmit a Scheduling Request (SR) for BFR.
8. The UE of claim 7 , wherein the SR requests a UL resource for transmitting the BFR MAC CE.
9. The UE of claim 1 , wherein:
the toggled NDI value is compared to an NDI value associated with the BFR MAC CE, and
the toggled NDI value is different from the NDI value associated with the BFR MAC CE.
10. A method for a Secondary Cell (Scell) Beam Failure Recovery (BFR) procedure performed by a User Equipment (UE), the method comprising:
transmitting, via uplink (UL), to a base station (BS), a BFR Medium Access Control (MAC) Control Element (CE) that includes a cell index of an S cell with beam failure detected and a reference signal index for the Scell, the UL transmission of the BFR MAC CE associated with a Hybrid Automatic Repeat Request (HARQ) process having a HARQ process identifier (ID);
receiving, from the BS, Downlink Control Information (DCI) that schedules Physical Uplink Shared Channel (PUSCH) transmission with the HARQ process ID of the HARQ process that is used for the UL transmission of the BFR MAC CE, the DCI indicating a toggled New Data Indicator (NDI) value;
determining, upon receiving the DCI, that the Scell BFR procedure is successfully completed; and
monitoring, on the Scell, a Physical Downlink Control Channel (PDCCH) using antenna port quasi-colocation parameters associated with the reference signal index after receiving the DCI.
11. The method of claim 10 , further comprising:
applying beam information indicated by the BS via at least one Transmission Configuration Indication (TCI) activation MAC CE to receive the DCI.
12. The method of claim 10 , further comprising:
starting, before receiving the DCI, a BFR timer; and
stopping the BFR timer upon receipt of the DCI.
13. The method of claim 12 , further comprising starting the BFR timer upon detection of a beam failure condition.
14. The method of claim 12 , further comprising:
stopping the BFR timer when the Scell BFR procedure is determined as successfully completed.
15. The method of claim 12 , further comprising starting the BFR timer before receiving the DCI comprises starting the BFR timer when the BFR MAC CE is transmitted.
16. The method of claim 10 , further comprising:
transmitting a Scheduling Request (SR) for BFR.
17. The method of claim 16 , wherein the SR requests a UL resource for transmitting the BFR MAC CE.
18. The method of claim 10 , wherein:
the toggled NDI value is compared to an NDI value associated with the BFR MAC CE, and the toggled NDI value is different from the NDI value associated with the BFR MAC CE.