Beam failure recovery mechanism for multi-beam operation
A method of beam failure recovery for multi-beam operation in wireless communication systems with beamforming is proposed. Specifically, a four-step beam failure recovery procedure is proposed. In a first step of beam failure detection, UE detects a beam failure condition of the original serving beam pair link. In a second step of new candidate beam identification, UE performs measurements for candidate beam selection. In a third step of beam failure recovery request (BFRQ) transmission, UE transmits a BFRQ message to BS upon the triggering condition for BFRQ transmission is satisfied. In a fourth step of monitoring BS response, UE monitors BS response to decide the success or failure of the beam failure recovery.
1. A method comprising:
receiving beam failure recovery configuration from a base station by a user equipment (UE) over an established data connection using a serving beam pair link in a beamforming communication network;
monitoring a plurality of reference signals associated with different downlink beams based on the beam failure recovery configuration;
transmitting a beam failure recovery request (BFRQ) message indicating a UE-identified candidate beam pair link to the base station when a triggering condition for beam failure recovery is satisfied, wherein the triggering condition comprises detecting a beam failure of the serving beam pair link(s) for a predefined evaluation period and identifying a candidate beam pair link, wherein the beam failure is detected when a block error ratio (BLER) of the serving beam pair link is below a threshold; and
monitoring a response from the base station associated with the UE-identified candidate beam pair link.
2. The method of claim 1 , wherein the new candidate beam pair is identified when a reference signal received power (RSRP) of the candidate beam pair link is above a threshold.
3. The method of claim 1 , wherein the BFRQ message is sent over a physical random-access channel (PRACH), which is spatially associated with the UE-identified candidate beam pair link.
4. The method of claim 1 , wherein the BFRQ message is sent over a physical uplink control channel (PUCCH) associated with the UE-identified candidate beam pair link.
5. The method of claim 1 , wherein the UE retransmits the BFRQ message if the UE does not receive the response from the base station.
6. The method of claim 1 , wherein the beam failure recovery configuration comprises information on the triggering condition, information on transmitting the BFRQ message, and information on monitoring the response.
7. A user equipment (UE), comprising:
a radio frequency (RF) receiver that receives beam failure recovery configuration from a base station over an established data connection using a serving beam pair link in a beamforming communication network;
a beam monitor that monitors a plurality of reference signals associated with different downlink beams based on the beam failure recovery configuration;
a radio frequency (RF) transmitter that transmits a beam failure recovery request (BFRQ) message indicating a UE-identified candidate beam pair link to the base station when a triggering condition for beam failure recovery is satisfied, wherein the triggering condition comprises detecting a beam failure of the serving beam pair link(s) for a predefined evaluation period and identifying a candidate beam pair link, wherein the beam failure is detected when a block error ratio (BLER) of the serving beam pair link is below a threshold; and
the beam monitor that monitors a response from the base station associated with the UE-identified candidate beam pair link.
8. The UE of claim 7 , wherein the new candidate beam pair is identified when a reference signal received power (RSRP) of the candidate beam pair link is above a threshold.
9. The UE of claim 7 , wherein the BFRQ message is sent over a physical random-access channel (PRACH), which is spatially associated with the UE-identified candidate beam pair link.
10. The UE of claim 7 , wherein the BFRQ message is sent over a physical uplink control channel (PUCCH) associated with the UE-identified candidate beam pair link.
11. The UE of claim 7 , wherein the UE retransmits the BFRQ message if the UE does not receive the response from the base station.
12. The UE of claim 7 , wherein the beam failure recovery configuration comprises information on the triggering condition, information on transmitting the BFRQ message, and information on monitoring the response.
13. A method, comprising:
transmitting beam failure recovery configuration from a base station to a user equipment (UE) over an established data connection using a serving beam pair link in a beamforming communication network;
receiving a beam failure recovery request (BFRQ) message indicating UE-identified candidate beam pair link from the UE when a triggering condition for beam failure recovery is satisfied, wherein the triggering condition comprises detecting a beam failure of the serving beam pair link(s) for a predefined evaluation period and identifying a candidate beam pair link, wherein the beam failure is detected when a block error ratio (BLER) of the serving beam pair link is below a threshold; and
transmitting a response from the base station to the UE, wherein the response is associated with the UE-identified candidate beam pair link.
14. The method of claim 13 , wherein the beam failure recovery configuration comprises information on the triggering condition, information on transmitting the BFRQ message, and information on monitoring the response.
15. The method of claim 13 , wherein the BFRQ message is sent over a physical random-access channel (PRACH) associated with the UE-identified candidate beam pair link.
16. The method of claim 13 , wherein the BFRQ message is sent over a physical uplink control channel (PUCCH) associated with the UE-identified candidate beam pair link.
17. The method of claim 13 , wherein the response is transmitted by using a dedicated downlink transmission on the UE-identified candidate beam pair link.