Sidelink discovery messages for beam training and onboarding of initiator user equipments to sidelink user equipment groups
Disclosed are techniques for wireless communication. In an aspect, a UE (e.g., an initiator UE) transmits sidelink discovery messages for beam training on a bandwidth associated with DMRS. One or more UEs (e.g., candidate responder UEs) select a beam to pair with a beam associated with one of the sidelink discovery messages, and transmit a sidelink discovery message on the selected beam. In another aspect, a UE (e.g., initiator UE) transmits a sidelink discovery message, which is forwarded to a UE, which may be a lead UE of a sidelink UE group. The lead UE adds the initiator UE to the sidelink UE group, and responds with a sidelink discovery response message and a group indication that at least indicates that the initiator UE now belongs to the sidelink UE group.
1. A first user equipment (UE), comprising:
a memory;
at least one transceiver; and
at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to:
determine a resource configuration for beam training, the resource configuration comprising a first set of resources associated with a first number of transmission repetitions for transmission of sidelink discovery messages by the first UE on each of a first number of beams on a bandwidth associated with a demodulation reference signal (DMRS) and a second set of resources associated with transmission opportunities for transmission of a second number of transmission repetitions of sidelink discovery response messages from one or more candidate UEs on one of a second number of beams available for transmission of the sidelink discovery response messages by the respective one or more candidate UEs, the first number of transmission repetitions corresponding to the second number of beams;
transmit, via the at least one transceiver, the sidelink discovery messages on the first set of resources in accordance with the resource configuration;
monitor the second set of resources for any sidelink discovery response messages from the one or more candidate UEs in accordance with the resource configuration; and
receive, via the at least one transceiver, from a second UE based on the monitoring, a sidelink discovery response message on a beam that corresponds to one of the second number of beams and is paired with one of the first number of beams.
2. The first UE of claim 1 , wherein the sidelink discovery messages are not transmitted in association with a separate beam training (BT) reference signal (BTRS).
3. The first UE of claim 1 , wherein the first number of transmission repetitions is at least two.
4. The first UE of claim 1 , wherein the second number of beams is at least two.
5. The first UE of claim 1 , wherein the first set of resources comprises a number of occupied resource blocks (RBs) that is based on the first number of beams, the first number of transmission repetitions, and a number of RBs per sidelink discovery message.
6. The first UE of claim 1 , wherein the second set of resources comprises a second number of occupied RBs that is based on the first number of beams, a number of the one or more candidate UEs that transmit a respective sidelink discovery response message, and a number of RBs per sidelink discovery response message.
7. A second user equipment (UE), comprising:
a memory;
at least one transceiver; and
at least one processor communicatively coupled to the memory and the at least one transceiver, the at least one processor configured to:
determine a resource configuration for beam training, the resource configuration comprising a first set of resources associated with a first number of transmission repetitions for transmission of sidelink discovery messages from a first UE on each of a first number of beams on a bandwidth associated with a demodulation reference signal (DMRS) and a second set of resources associated with transmission opportunities for transmission of a second number of transmission repetitions of sidelink discovery response messages from the second UE on one of a second number of beams that are available to the second UE for transmission of the sidelink discovery response messages, the first number of transmission repetitions corresponding to the second number of beams;
monitor the first set of resources for the sidelink discovery messages;
select one of the second number of beams to pair with one of the first number of beams based on the monitoring; and
transmit, via the at least one transceiver, to the first UE on a respective opportunity of the second set of resources associated with the selected beam, a sidelink discovery response message on the selected beam.
8. The second UE of claim 7 , wherein the sidelink discovery messages are not transmitted in association with a separate beam training (BT) reference signal (BTRS).
9. The second UE of claim 7 , wherein the first number of transmission repetitions is at least two.
10. The second UE of claim 7 , wherein the second number of beams is at least two.
11. The second UE of claim 7 , wherein the first set of resources comprises a first number of occupied resource blocks (RBs) that is based on the first number of beams, the first number of transmission repetitions, and a number of RBs per sidelink discovery message.
12. The second UE of claim 7 , wherein the second set of resources comprises a second number of occupied RBs that is based on the first number of beams, a number of candidate UEs that transmit a respective sidelink discovery response message, and a number of RBs per sidelink discovery response message.