Beam failure recovery via relay node
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit a beam failure recovery (BFR) message regarding a failed link, wherein the failed link is one of an indirect link with a network node via a relay node or a direct link with the network node, wherein the BFR message is transmitted on one of the indirect link or the direct link that is not the failed link. The UE may receive an updated beam configuration for the failed link on a selected beam indicated by the BFR message. Numerous other aspects are described.
1 . A user equipment (UE) for wireless communication, comprising:
a memory; and
one or more processors, coupled to the memory, individually or collectively configured to:
transmit a beam failure recovery (BFR) message regarding a failed link, wherein the failed link is one of an indirect link with a network node via a relay node or a direct link with the network node, wherein the BFR message is transmitted on one of the indirect link or the direct link that is not the failed link;
wait a time period for a BFR response on the indirect link after transmitting the BFR message;
transmit a second BFR message on the direct link if no BFR response is received on the indirect link within the time period; and
receive an updated beam configuration for the failed link on a selected beam indicated by the BFR message.
2 . The UE of claim 1 , wherein the one or more processors are further individually or collectively configured to transmit a prior BFR message on the direct link before transmitting the BFR message on the indirect link.
3 . The UE of claim 2 , wherein the one or more processors are further individually or collectively configured to wait a time period for a BFR response on the direct link, and wherein the BFR message is on the indirect link as a result of no BFR response to the prior BFR message being within the time period.
4 . The UE of claim 1 , wherein the BFR message includes a first BFR message on the direct link and indicating a first beam and a second BFR message on the indirect link and indicating a second beam, wherein one of the first beam or the second beam is the selected beam.
5 . The UE of claim 4 , wherein the first BFR message and the second BFR message are in parallel.
6 . The UE of claim 4 , wherein at least one of the first BFR message or the second BFR message includes a time stamp.
7 . The UE of claim 6 , wherein the one or more processors are further individually or collectively configured to select, from one of the first beam or the second beam, the selected beam based at least in part on the time stamp.
8 . The UE of claim 4 , wherein the one or more processors are further individually or collectively configured to monitor, prior to receiving the updated beam configuration, the first beam and the second beam for communications from the network node.
9 . The UE of claim 8 , wherein the one or more processors, to monitor the first beam and the second beam, are configured to monitor the first beam and the second beam until the updated beam configuration from the network node is received on the selected beam.
10 . The UE of claim 4 , wherein the first BFR message and the second BFR message both indicate the selected beam.
11 . The UE of claim 1 , wherein the one or more processors are further individually or collectively configured to report, in each BFR message until a BFR procedure is complete, the selected beam.
12 . The UE of claim 1 , wherein the BFR message is on the indirect link via a sidelink communication.
13 . The UE of claim 1 , wherein the direct link is the failed link.
14 . The UE of claim 1 , wherein the BFR message is transmitted on the direct link via a random access channel (RACH) transmission.
15 . The UE of claim 1 , wherein the indirect link is the failed link.
16 . A network node for wireless communication, comprising:
a memory; and
one or more processors, coupled to the memory, individually or collectively configured to:
receive a beam failure recovery (BFR) message regarding a failed link, wherein the failed link is one of an indirect link with a remote user equipment (UE) via a relay node or a direct link with the remote UE, wherein the BFR message is received on one of the indirect link or the direct link that is not the failed link, wherein the BFR message is received on the direct link before receiving the BFR message on the indirect link; and
transmit an updated beam configuration for the failed link on a selected beam indicated by the BFR message.
17 . The network node of claim 16 , wherein the BFR message includes a first BFR message on the direct link and indicating a first beam and a second BFR message on the indirect link and indicating a second beam, wherein one of the first beam or the second beam is the selected beam.
18 . The network node of claim 17 , wherein at least one of the first BFR message or the second BFR message includes a time stamp.
19 . The network node of claim 18 , wherein the one or more processors are further individually or collectively configured to select, from one of the first beam or the second beam, the selected beam based at least in part on the time stamp.
20 . The network node of claim 17 , wherein the first BFR message and the second BFR message both indicate the selected beam.
21 . The network node of claim 17 , wherein the updated beam configuration is on the first beam and the second beam.
22 . The network node of claim 16 , wherein the one or more processors are further individually or collectively configured to respond to each BFR message from the remote UE until a BFR procedure is complete.
23 . The network node of claim 16 , wherein the BFR message is on the indirect link via a sidelink communication.
24 . The network node of claim 16 , wherein the direct link is the failed link.
25 . The network node of claim 16 , wherein the BFR message is received on the direct link via a random access channel (RACH) transmission.
26 . The network node of claim 16 , wherein the indirect link is the failed link.
27 . A method of wireless communication performed by a user equipment (UE), comprising:
transmitting a beam failure recovery (BFR) message regarding a failed link, wherein the failed link is one of an indirect link with a network node via a relay node or a direct link with the network node, wherein the BFR message is transmitted on one of the indirect link or the direct link that is not the failed link;
waiting a time period for a BFR response on the indirect link after transmitting the BFR message;
transmitting a second BFR message on the direct link if no BFR response is received on the indirect link within the time period; and
receiving an updated beam configuration for the failed link on a selected beam indicated by the BFR message.
28 . The method of claim 27 , further comprising:
reporting, in each BFR message until a BFR procedure is complete, the selected beam.
29 . The method of claim 27 , wherein the BFR message is transmitted on the direct link via a random access channel (RACH) transmission.