Beam failure recovery

1. A method of recovering from beam failure, comprising:

comparing an error rate of a last serving beam of a first cell to a threshold value;

determining occurrence of a beam failure in response to the error rate of the last serving beam of the first cell being below the threshold value for a predetermined number of times;

in response to determining occurrence of the beam failure, sending a beam failure recovery request message including information regarding beam failure recovery and information regarding a new candidate beam via a working beam of the first cell;

monitoring a response to the beam failure recovery request message via the new candidate beam of a second cell; and

receiving the response to the beam failure recovery request message via the new candidate beam from the second cell.

2. The method of claim 1 , wherein the beam failure recovery request message is sent via physical uplink shared channel or physical uplink control channel of the first cell.

3. The method of claim 2 , wherein the beam failure recovery request message is sent via physical uplink control channel of the second cell before it is sent via physical uplink shared channel or physical uplink control channel of the first cell.

4. The method of claim 1 , wherein the beam failure recovery request message is sent via one of physical uplink shared channel of the first cell, physical uplink control channel of the first cell and physical uplink control channel of the second cell.

5. The method of claim 1 , wherein the beam failure recovery request message is sent in a medium access control control element.

6. The method of claim 5 , wherein the medium access control control element is scheduled in a priority higher than other uplink transmissions.

7. The method of claim 1 , wherein the response is monitored via the same beam as the new candidate beam from sending the beam failure recovery request message for a predetermined time period.

8. The method of claim 1 , wherein physical downlink control channel is monitored in a predefined control resource set.

9. The method of claim 1 , further comprising receiving, via physical downlink shared channel, transmission configuration indicator state information in a radio resource control configuration message.

10. The method of claim 1 , wherein the response is a control resource set resource preconfigured for beam recovery sent via physical downlink control channel.

11. The method of claim 1 , wherein the first cell is primary cell or primary-secondary cell and the second cell is secondary cell.

12. The method of claim 1 , wherein the first cell is secondary cell and the second cell is primary cell or primary-secondary cell.

13. The method of claim 11 , before sending the beam failure recovery request message via the working beam of the primary cell or primary-secondary cell, further comprising:

sending a random access procedure signal via random access procedure resource of the primary cell or primary-secondary cell; and

configuring the working beam of the primary cell or primary-secondary cell.

14. A method comprising:

receiving a beam failure recovery request message including information regarding beam failure recovery and information regarding a new candidate beam in response to a determination of an occurrence of a beam failure, wherein the occurrence of the beam failure is determined in response to an error rate of a last serving beam of a first cell being below a threshold value for a predetermined number of times; and

sending a response to the beam failure recover request message via the new candidate beam.

15. The method of claim 14 , wherein the beam failure recovery request message is received via physical uplink shared channel or physical uplink control channel as a medium access control control element message.

16. The method of claim 14 , wherein the response is sent in a control resource set resource preconfigured for beam recovery via physical downlink control channel.

17. The method of claim 14 , wherein the beam failure recovery request message is received via a working beam of a first cell.

18. The method of claim 14 , wherein the beam failure recovery request message is received from another cell.

19. A method of recovering from beam failure, comprising:

receiving a beam management message including a carrier index and a reference signal in response to a determination of an occurrence of a beam failure, wherein the occurrence of the beam failure is determined in response to an error rate of a last serving beam of a first cell being below a threshold value for a predetermined number of times;

sending a random access procedure signal via random access procedure resource to the first cell, wherein the first cell is a primary cell;

configuring a working beam of the first cell; and

configuring the working beam of the first cell as a working beam of a second cell, wherein the second cell is a secondary cell, and the working beam is configured for the second cell without using random access channel resources.

20. The method of claim 19 , further comprising receiving a radio resource control configuration for transmission configuration indicator states for physical downlink shared channel and physical downlink control channel for the first cell and for the second cell.