Signaling of sidelink beam training reference signal and sidelink discovery message before beam training response

Abstract

Disclosed are techniques for wireless communication. In an aspect, an originator UE transmits a sidelink beam training (BT) reference signal (BTRS) a first number of times on each of a first set of beams, and a sidelink discovery message a second number of times on each of a second set of beams, wherein each beam from the second set of beams is associated with at least one beam from the first set of beams (e.g., 1:1 or N:1 mapping of first set of beams to second set of beams). At least one responder UE responds by transmitting, after the transmission of the sidelink BTRSs and the sidelink discovery messages, a BT response signal and a sidelink discovery response message on a beam corresponding to one of the first set of beams.

What is claimed is: 
     
         1 . A method of operating an initiator user equipment (UE), comprising:
 transmitting a sidelink beam training (BT) reference signal (BTRS) a first number of times on each of a first set of beams;   transmitting a sidelink discovery message a second number of times on each of a second set of beams, wherein each beam from the second set of beams is associated with at least one beam from the first set of beams; and   receiving, from at least one responder UE after the transmission of the sidelink BTRSs and the sidelink discovery messages, a BT response signal and a sidelink discovery response message on a beam corresponding to one of the first set of beams.   
     
     
         2 . The method of  claim 1 , wherein the transmission of the sidelink discovery messages follows the transmission of the sidelink BTRSs. 
     
     
         3 . The method of  claim 1 , wherein the transmission of the sidelink BTRSs follows the transmission of the sidelink discovery messages. 
     
     
         4 . The method of  claim 1 , wherein the first number of times is the same as the second number of times. 
     
     
         5 . The method of  claim 1 , wherein the first number of times is greater than the second number of times. 
     
     
         6 . The method of  claim 1 , wherein for each beam in the first set of beams there is a corresponding beam in the second set of beams. 
     
     
         7 . The method of  claim 1 , wherein two or more beams among the first set of beams correspond to a single beam among the second set of beams. 
     
     
         8 . The method of  claim 1 ,
 wherein the sidelink BTRSs are transmitted in order between successively adjacent beams among the first set of beams, or   wherein the sidelink discovery messages are transmitted in order between successively adjacent beams among the second set of beams, or   a combination thereof.   
     
     
         9 . The method of  claim 1 ,
 wherein the sidelink BTRSs are transmitted via unordered beam sweeping of the first set of beams, or   wherein the sidelink discovery messages are transmitted via unordered beam sweeping of the second set of beams, or   a combination thereof.   
     
     
         10 . The method of  claim 1 , wherein the BT response signal comprises a preamble or a message. 
     
     
         11 . The method of  claim 1 , wherein an overhead associated with transmission of the BTRS the first number of times on each of the first set of beams, transmission the sidelink discovery message the second number of times on each of the second set of beams, and reception of the BT response signal and the sidelink discovery response message is:
   N×M×BTRS+N×U×BT_Resp+N×DISC+V×DISC_Resp,
   wherein numbers of the first set of beams and the second set of beams are each equal to N,   wherein M is a number of receive beams associated with each responder UE,   wherein V is a number of UEs among the at least one responder UE,   BTRS is a number of resource blocks (RBs) occupied per BTRS,   DISC is a number of RBs occupied per sidelink discovery message,   BT_Resp is a number of RBs occupied per BT response signal, and   DISC_Resp is a number of RBs occupied per sidelink discovery response message.   
     
     
         12 . The method of  claim 1 , wherein an overhead associated with transmission of the BTRS the first number of times on each of the first set of beams, transmission the sidelink discovery message the second number of times on each of the second set of beams, and reception of the BT response signal and the sidelink discovery response message is:
   N×M×(BTRS+DISC)+N×V×BT_Resp+V×DISC_Resp,
   wherein numbers of the first set of beams and the second set of beams are each equal to N,   wherein M is a number of receive beams associated with each responder UE,   wherein V is a number of UEs among the at least one responder UE,   BTRS is a number of resource blocks (RBs) occupied per BTRS,   DISC is a number of RBs occupied per sidelink discovery message,   BT_Resp is a number of RBs occupied per BT response signal, and   DISC_Resp is a number of RBs occupied per sidelink discovery response message.   
     
     
         13 . The method of  claim 1 , wherein the first set of beams includes two or more beams, and the second set of beams includes two or more beams. 
     
     
         14 . A method of operating responder user equipment (UE), comprising:
 receiving, from an initiator UE, a sidelink beam training (BT) reference signal (BTRS) a first number of times on each of a first set of beams;   receiving, from the initiator UE, a sidelink discovery message a second number of times on each of a second set of beams, wherein each beam from the second set of beams is associated with at least one beam from the first set of beams; and   transmitting, to the initiator UE, a BT response signal and a sidelink discovery response message on a beam that corresponds to one of the first set of beams.   
     
     
         15 . The method of  claim 14 , wherein the reception of the sidelink discovery messages follows the reception of the sidelink BTRSs. 
     
     
         16 . The method of  claim 14 , wherein the reception of the sidelink BTRSs follows the reception of the sidelink discovery messages. 
     
     
         17 . The method of  claim 16 , wherein timing information or resource information or both associated with the sidelink BTRSs is known based on the reception of the sidelink discovery messages. 
     
     
         18 . The method of  claim 14 , wherein the first number of times is the same as the second number of times. 
     
     
         19 . The method of  claim 14 , wherein the first number of times is greater than the second number of times. 
     
     
         20 . The method of  claim 14 , wherein for each beam in the first set of beams there is a corresponding beam in the second set of beams. 
     
     
         21 . The method of  claim 14 ,
 wherein the sidelink BTRSs are received in order between successively adjacent beams among the first set of beams, or   wherein the sidelink discovery messages are received in order between successively adjacent beams among the second set of beams, or   a combination thereof.   
     
     
         22 . The method of  claim 14 ,
 wherein the sidelink BTRSs are received via unordered beam sweeping of the first set of beams, or   wherein the sidelink discovery messages are received via unordered beam sweeping of the second set of beams, or   a combination thereof.   
     
     
         23 . The method of  claim 14 , wherein the BT response signal comprises a preamble or a message. 
     
     
         24 . The method of  claim 14 , wherein an overhead associated with reception of the BTRS the first number of times on each of the first set of beams, reception the sidelink discovery message the second number of times on each of the second set of beams, and transmission of the BT response signal and the sidelink discovery response message is:
   N×M×BTRS+N×U×BT_Resp+N×DISC+V×DISC_Resp,
   wherein numbers of the first set of beams and the second set of beams are each equal to N,   wherein M is a number of receive beams associated with each responder UE,   wherein V is a number of UEs among the at least one responder UE,   BTRS is a number of resource blocks (RBs) occupied per BTRS,   DISC is a number of RBs occupied per sidelink discovery message,   BT_Resp is a number of RBs occupied per BT response signal, and   DISC_Resp is a number of RBs occupied per sidelink discovery response message.   
     
     
         25 . The method of  claim 14 , wherein an overhead associated with reception of the BTRS the first number of times on each of the first set of beams, reception the sidelink discovery message the second number of times on each of the second set of beams, and transmission of the BT response signal and the sidelink discovery response message is:
   N×M×(BTRS+DISC)+N×V×BT_Resp+V×DISC_Resp,
   wherein numbers of the first set of beams and the second set of beams are each equal to N,   wherein M is a number of receive beams associated with each responder UE,   wherein V is a number of UEs among the at least one responder UE,   BTRS is a number of resource blocks (RBs) occupied per BTRS,   DISC is a number of RBs occupied per sidelink discovery message,   BT_Resp is a number of RBs occupied per BT response signal, and   DISC_Resp is a number of RBs occupied per sidelink discovery response message.   
     
     
         26 . An initiator 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:   transmit, via the at least one transceiver, a sidelink beam training (BT) reference signal (BTRS) a first number of times on each of a first set of beams;   transmit, via the at least one transceiver, a sidelink discovery message a second number of times on each of a second set of beams, wherein each beam from the second set of beams is associated with at least one beam from the first set of beams; and   receive, via the at least one transceiver, from at least one responder UE after the transmission of the sidelink BTRSs and the sidelink discovery messages, a BT response signal and a sidelink discovery response message on a beam corresponding to one of the first set of beams.   
     
     
         27 . The initiator UE of  claim 26 ,
 wherein the sidelink BTRSs are transmitted in order between successively adjacent beams among the first set of beams, or   wherein the sidelink discovery messages are transmitted in order between successively adjacent beams among the second set of beams, or   wherein the sidelink BTRSs are transmitted via interleaving of the first set of beams, or   wherein the sidelink discovery messages are transmitted via interleaving of the second set of beams, or   a combination thereof.   
     
     
         28 . A responder 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:   receive, via the at least one transceiver, from an initiator UE, a sidelink beam training (BT) reference signal (BTRS) a first number of times on each of a first set of beams;   receive, via the at least one transceiver, from the initiator UE, a sidelink discovery message a second number of times on each of a second set of beams, wherein each beam from the second set of beams is associated with at least one beam from the first set of beams; and   transmit, via the at least one transceiver, to the initiator UE, a BT response signal and a sidelink discovery response message on a beam that corresponds to one of the first set of beams.   
     
     
         29 . The responder UE of  claim 28 ,
 wherein the sidelink BTRSs are received in order between successively adjacent beams among the first set of beams, or   wherein the sidelink discovery messages are received in order between successively adjacent beams among the second set of beams, or   wherein the sidelink BTRSs are received via interleaving of the first set of beams, or   wherein the sidelink discovery messages are received via interleaving of the second set of beams, or   a combination thereof.