Method and apparatus for beam recovery in next generation wireless systems
A beam failure recovery procedure in a wireless communication system comprises receiving, from a base station (BS), at least one beam failure detection reference signal (RS) and at least one new candidate beam RS over a downlink channel; identifying a set of RS resources including an index for the at least one beam failure detection RS; identifying a set of RS resources including an index for the at least one new candidate beam RS; identifying a dedicated control-resource set (CORESET) received from the BS for a beam failure recovery request; transmitting, to the BS, the beam failure recovery request associated with a quality measurement of the at least one beam failure detection RS over a physical random access channel (PRACH); and receiving, from the BS, a beam failure response in response to the beam failure recovery request based on the dedicated CORESET indicated to the UE.
1. A user equipment (UE) in a wireless communication system, the UE comprising:
a transceiver; and
at least one processor coupled with the transceiver and configured to:
receive, from a base station (BS), configuration information including information associated with a set of preamble sequences for a beam failure recovery,
receive, from the BS, at least one first reference signal (RS) on a first RS resource, for detecting a beam failure, wherein the first RS resource is identified based on an RS index indicated by a transmission configuration indication (TCI) state of control resource sets (CORESETs), wherein the TCI state indicates quasi-collocation properties for receptions of physical control channels (PDCCHs) in the CORESET by the UE,
identify a beam failure based on a received power of the at least one first RS being smaller than a first threshold,
receive, from the BS, at least one second RS on a second RS resource, for identifying a candidate beam,
identify the candidate beam based on a received power of the at least one second RS being larger than a second threshold,
transmit, to the BS, a preamble sequence from the set of preamble sequences for requesting the beam failure recovery on a physical random access channel (PRACH), in case that the beam failure is identified, wherein the preamble sequence is identified from a set of preamble sequences for the beam failure recovery and is associated with the at least one second RS, and
receive, from the BS, a response of the preamble sequence.
2. The UE of claim 1 , wherein at least one RS index of the at least one first RS is spatially quasi co-located (QCL) with the RS index indicated by the TCI state.
3. The UE of claim 1 ,
wherein the set of the preamble sequences for the beam failure recovery is associated with the second RS resource for identifying the candidate beam, and
wherein the response comprises a downlink control information (DCI) that is scrambled by a cell radio network temporary identifier (C-RNTI) of the UE.
4. The UE of claim 1 , wherein the configuration information is received based on system information or radio resource control (RRC) signaling.
5. The UE of claim 1 , wherein the at least one processor is further configured to:
receive, from the BS, information associated with the second threshold for reference signal received power (RSRP) that is used to determine the candidate beam;
obtain at least one RSRP measurement by using the second RS resource; and
identify the candidate beam by determining that the at least one RSRP measurement is larger than the second threshold.
6. The UE of claim 1 , wherein the at least one processor is further configured to receive, from the BS, information associated with a window for monitoring the response and information associated with a CORESET, for monitoring the response, the CORESET being dedicated for the response for the beam failure recovery.
7. The UE of claim 1 ,
wherein the configuration information includes information on a time duration for the detecting the beam failure.
8. The UE of claim 1 , wherein the at least one processor is further configured to:
monitor the response according to quasi co-located parameter associated with the candidate beam.
9. A base station (BS) in a wireless communication system, the base station comprising:
a transceiver; and
at least one processor coupled with the transceiver and configured to:
transmit, to a user equipment (UE), configuration information including information associated with a set of preamble sequences for a beam failure recovery,
transmit, to the UE, at least one first reference signal (RS) on a first RS resource associated with a detection of a beam failure, wherein the first RS resource is identified based on an RS index indicated by a transmission configuration indication (TCI) state of control resource sets (CORESETs), wherein the TCI state indicates quasi-collocation properties for receptions of physical control channels (PDCCHs) in the CORESET by the UE, wherein a beam failure is identified based on a received power of the at least one first RS being smaller than a first threshold,
transmit, to the UE, at least one second RS on a second RS resource associated with an identification of a candidate beam, wherein the candidate beam is identified based on a received power of the at least one second RS being larger than a second threshold,
receive, from the UE, a preamble sequence from the set of preamble sequences associated with the beam failure recovery on a physical random access channel (PRACH) based on the identification of beam failure by the UE, wherein the preamble sequence corresponding to an RS resource associated with the candidate beam is associated with a preamble sequence in a set of preamble sequences for the beam failure recovery and with the at least one second RS, and
transmit, to the UE, a response of the preamble sequence associated with the beam failure recovery.
10. The base station of claim 9 ,
wherein the set of the preamble sequences for the beam failure recovery is associated with the second RS resource, and
wherein the response comprises a downlink control information (DCI) that is scrambled by a cell radio network temporary identifier (C-RNTI) for the base station.
11. The base station of claim 9 , wherein the at least one processor is further configured to:
transmit, to the UE, information associated with the second threshold for reference signal received power (RSRP) for the candidate beam.
12. The base station of claim 9 , wherein the at least one processor is further configured to transmit, to the UE, information associated with a window for the response and information associated with a CORESET for the response, the CORESET being dedicated for the response for the beam failure recovery.
13. The base station of claim 9 ,
wherein the configuration information includes information on a time duration for the detection of the beam failure.
14. A method performed by a user equipment (UE) in a wireless communication system, the method comprising:
receiving, from a base station (BS), configuration information including information associated with a set of preamble sequences for a beam failure recovery;
receiving, from the BS, at least one first reference signal (RS) on a first RS resource, for detecting a beam failure, wherein the first RS resource is identified based on an RS index indicated by a transmission configuration indication (TCI) state of control resource sets (CORESETs), wherein the TCI state indicates quasi-collocation properties for receptions of physical control channels (PDCCHs) in the CORESET by the UE;
identifying a beam failure based on a received power of the at least one first RS being smaller than a first threshold;
receiving, from the BS, at least one second RS on a second RS resource for identifying a candidate beam;
identifying the candidate beam based on a received power of the at least one second RS being larger than a second threshold;
transmitting, to the BS, a preamble sequence from the set of preamble sequences for requesting the beam failure recovery on a physical random access channel (PRACH) in case that the beam failure is identified, wherein the preamble sequence is identified from a set of preamble sequences for the beam failure recovery request and is associated with the at least one second RS; and
receiving, from the BS, a response of the preamble sequence.
15. A method performed by a base station in a wireless communication system, the method comprising:
transmitting, to a user equipment (UE), configuration information including information associated with a set of preamble sequences for a beam failure recovery;
transmitting, to the UE, at least one first reference signal (RS) on a first RS resource for a detection of a beam failure, wherein the first RS resource is identified based on an RS index indicated by a transmission configuration indication (TCI) state of control resource sets (CORESETs), wherein the TCI state indicates quasi-collocation properties for receptions of physical control channels (PDCCHs) in the CORESET by the UE, and wherein a beam failure is identified based on a first RS received power of the at least one first RS being smaller than a first threshold;
transmitting, to the UE, at least one second RS on a second RS resource associated with an identification of a candidate beam, wherein the candidate beam is identified based on a received power of the at least one second RS being larger than a second threshold;
receiving, from the UE, a preamble sequence associated with the beam failure recovery on a physical random access channel (PRACH) based on the identification of the beam failure, wherein the preamble sequence corresponding to an RS resource associated with the candidate beam is associated with a preamble sequence in a set of preamble sequences for the beam failure recovery and with the at least one second RS; and
transmitting, to the UE, a response of the preamble sequence associated with the beam failure recovery.