On Multiple PRACH Preambles and Random Access Responses

Abstract

A method including, detecting, by a base station in a wireless communication system, within an RAR window, at least one of multiple first messages from a plurality of user equipments, wherein the plurality of user equipments is permitted to transmit multiple first messages within the RAR window, and wherein each first message includes a PRACH preamble; in response to receiving at least one PRACH preamble in the at least one of multiple first messages, transmitting at least one second message including an RAR downlink channel for each preamble received; receiving at least one third message, from at least one user equipment of the plurality of user equipments, including a beam connection request and transmitting at least one fourth message to the at least one user equipment on the requested beam.

What is claimed is: 
     
         1 . A method comprising:
 detecting, by a base station in a wireless communication system, within a random access response window, at least one of multiple first messages from a plurality of user equipments, wherein the plurality of user equipments is permitted to transmit multiple first messages within the random access response window, and wherein each first message comprises a physical random access channel preamble;   in response to receiving at least one physical random access channel preamble in the at least one of multiple first messages, transmitting at least one second message comprising a random access response downlink channel for each preamble received;   receiving at least one third message, from at least one user equipment of the plurality of user equipments, comprising a beam connection request and   transmitting at least one fourth message to the at least one user equipment on the requested beam.   
     
     
         2 . The method of  claim 1 , further comprising:
 after receiving the at least one third message, determining a preferred downlink beam for each user equipment of the plurality of user equipments; and   instead of transmitting the at least one fourth message to the at least one user equipment on the requested beam, transmitting only one fourth message to each user equipment on the preferred beam.   
     
     
         3 . The method of  claim 2 , wherein the determining is based on a difference between a number of second messages sent and a number of third messages received. 
     
     
         4 . The method of  claim 2 , wherein the determining is based on the at least one third message indicating the preferred beam. 
     
     
         5 . The method of  claim 2 , further comprising:
 based on the determining, shutting down other pending random access channel (RACH) procedures with each user equipment on non-preferred beams.   
     
     
         6 . The method of  claim 1 , wherein, in response to each at least one first message comprising physical random access channel (PRACH) preambles being grouped instead of comprising a PRACH preamble, the at least one second message comprises a random access response (RAR) for each PRACH preamble group. 
     
     
         7 . A method comprising:
 obtaining, by a user equipment in a wireless communications network, permission to transmit multiple first messages within a random access response window;   transmitting to a base station multiple first messages within the random access response window wherein each of the multiple first messages comprises a physical random access channel preamble;   receiving from the base station at least one second message, wherein each of the at least one second message comprises an RAR for each preamble; and   transmitting at least one third message comprising a beam connection request.   
     
     
         8 . The method of  claim 7 , wherein the at least one third message is only one message based on one received random access response (RAR) and omitting other random access responses (RARs) with an indication of the omitted RARs. 
     
     
         9 . The method of  claim 7 , wherein the at least one third message comprises a message corresponding to each received random access response (RAR), and identifying a preferred RAR for downlink. 
     
     
         10 - 20 . (canceled) 
     
     
         21 . A computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for controlling or performing the method of  claim 1 . 
     
     
         22 . A computer program product comprising a computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for controlling or performing the method of  claim 7 .