System and method for communications beam recovery
A method for operating an access node includes generating a configuration message including information specifying a set of reference signals of a first reference signal type and a set of reference signals of a second reference signal type used to identify a new beam, and information specifying random access channel resources allocated for transmitting preamble sequences, wherein each random access channel resource is associated with a reference signal of the first reference signal type, sending, to one or more user equipments (UEs), the configuration message, receiving, from a UE, a preamble sequence on one of the random access channel resources, and determining an identity of the UE in accordance with the preamble sequence and the one of the random access channel resources.
1. A method comprising:
sending, by an access node, a radio resource configuration (RRC) message to one or more user equipments (UEs), the RRC message including beam recovery information specifying a set of synchronization signals and a set of channel state information reference signals (CSI-RSs) identifying candidate beams for beam failure recovery and specifying random access channel (RACH) resources for beam failure recovery, at least one CSI-RS in the set of CSI-RSs not being associated with any of the RACH resources for beam failure recovery; and
receiving, by the access node, at least one preamble sequence from the one or more UEs over the RACH resources for beam recovery specified by the beam recovery information in the RRC message.
2. The method of claim 1 , wherein each synchronization signal in the set of synchronization signals is associated with the RACH resources for beam failure recovery.
3. The method of claim 1 , wherein the beam recovery information specifying the RACH resources for beam failure recovery indicates a time-domain or frequency-domain location of the RACH resources.
4. The method of claim 1 , wherein beam recovery the information specifying the RACH resources for beam failure recovery indicates a preamble sequence for the RACH resources.
5. The method of claim 1 , wherein at least one synchronization signal in the set of synchronization signals is selected for transmitting a candidate beam during beam failure recovery when a signal quality of the at least one synchronization signal meets a first threshold.
6. The method of claim 1 , wherein the CSI-RS is selected for transmitting a candidate beam during beam failure recovery when a signal quality of the at least one CSI-RS meets a second threshold.
7. The method of claim 1 , further comprising:
determining, by the access node, an index of an identified reference signal as:
a first reference signal index in response to a preamble sequence being received on a first random access channel resource; or
a second reference signal index in response to the preamble sequence being received on a second random access channel resource; and
participating, by the access node, in a beam failure recovery procedure with a UE, in accordance with the index of the identified reference signal.
8. The method of claim 7 , wherein the beam failure recovery procedure comprises sending, by the access node to the UE, a beam failure recovery response on a control channel.
9. The method of claim 8 , wherein the control channel comprises a physical downlink control channel (PDCCH).
10. The method of claim 8 , wherein the control channel is quasi collocated with the identified reference signal.
11. An access node comprising:
a non-transitory memory storage comprising instructions; and
one or more processors in communication with the non-transitory memory storage, wherein the one or more processors execute the instructions to:
send a radio resource configuration (RRC) message to one or more user equipments (UEs), the RRC message including beam recovery information specifying a set of synchronization signals and a set of channel state information reference signals (CSI-RSs) identifying candidate beams for beam failure recovery and specifying random access channel (RACH) resources for beam failure recovery, at least one CSI-RS in the set of CSI-RSs not being associated with any of the RACH resources for beam failure recovery; and
receive at least one preamble sequence from the one or more UEs over the RACH resources for beam recovery specified by the beam recovery information in the RRC message.
12. The access node of claim 11 , wherein each synchronization signal in the set of synchronization signals is associated with the RACH resources for beam failure recovery.
13. The access node of claim 11 , wherein the beam recovery information specifying the RACH resources for beam failure recovery indicates a time-domain or frequency-domain location of the RACH resources.
14. The access node of claim 11 , wherein the beam recovery information specifying the RACH resources for beam failure recovery indicates a preamble sequence for the RACH resources.
15. The access node of claim 11 , wherein at least one synchronization signal in the set of synchronization signals is selected for transmitting a candidate beam during beam failure recovery when a signal quality of the at least one synchronization signal meets a first threshold.
16. The access node of claim 11 , wherein at least one CSI-RS in the set of CSI-RSs is selected for transmitting a candidate beam during beam failure recovery when a signal quality of the at least one CSI-RS meets a second threshold.
17. A method comprising:
receiving, by a user equipment (UE), a radio resource configuration (RRC) message from an access node, the RRC message including beam recovery information specifying a set of synchronization signals and a set of channel state information reference signals (CSI-RSs) identifying candidate beams for beam failure recovery and specifying random access channel (RACH) resources for beam failure recovery, at least one CSI-RS in the set of CSI-RSs not being associated with any of the RACH resources for beam failure recovery; and
sending, by the UE, at least one preamble sequence over at least one of the RACH resources for beam recovery specified by the beam recovery information in the RRC message.
18. The method of claim 17 , wherein each synchronization signal in the set of synchronization signals is associated with the RACH resources for beam failure recovery.
19. The method of claim 17 , wherein the beam recovery information specifying the RACH resources for beam failure recovery indicates a time-domain or frequency-domain location of the RACH resources.
20. The method of claim 17 , wherein the beam recovery information specifying the RACH resources for beam failure recovery indicates a preamble sequence for the RACH resources.
21. The method of claim 17 , further comprising selecting at least one synchronization signal from the set of synchronization signals for transmitting a candidate beam during beam failure recovery upon determining that a signal quality of the at least one synchronization signal meets a first threshold.
22. The method of claim 17 , further comprising selecting at least one CSI-RS from the set of CSI-RSs for transmitting a candidate beam during beam failure recovery upon determining a signal quality of the at least one CSI-RS meets a second threshold.
23. The method of claim 17 , wherein the at least one preamble sequence includes a beamformed reference signal.
24. A user equipment (UE) comprising:
a non-transitory memory storage comprising instructions; and
one or more processors in communication with the non-transitory memory storage, wherein the one or more processors execute the instructions to:
receive a radio resource configuration (RRC) message from an access node, the RRC message including beam recovery information specifying a set of synchronization signals and a set of channel state information reference signals (CSI-RSs) identifying candidate beams for beam failure recovery and specifying random access channel (RACH) resources for beam failure recovery, at least one CSI-RS in the set of CSI-RSs not being associated with any of the RACH resources for beam failure recovery; and
send at least one preamble sequence over at least one of the RACH resources for beam recovery specified by the beam recovery information in the RRC message.
25. The UE of claim 24 , wherein each synchronization signal in the set of synchronization signals is associated with the RACH resources for beam failure recovery.
26. The UE of claim 24 , wherein the beam recovery information specifying the RACH resources for beam failure recovery includes at least one of the following: time location information of the RACH resources, or frequency location information of the RACH resources.
27. The UE of claim 24 , wherein the beam recovery information specifying the RACH resources for beam failure recovery includes preamble sequence information of the RACH resources.
28. The UE of claim 24 , wherein the one or more processors further execute the instructions to select at least one synchronization signal from the set of synchronization signals for transmitting a candidate beam during beam failure recovery upon determining that a signal quality of the at least one synchronization signal meets a first threshold.
29. The UE of claim 24 , wherein the one or more processors further execute the instructions to select at least one CSI-RS from the set of CSI-RSs for transmitting a candidate beam during beam failure recovery upon determining a signal quality of the at least one CSI-RS meets a second threshold.