Communication Method and Communications Apparatus

Abstract

Embodiments of this application provide a communication method and a communications apparatus. The method includes: receiving identification information of N beams of a target cell and random access channel configurations of M beams in the N beams, where N and M are positive integers; and determining a beam for accessing based on signal quality or signal strength of L beams in the N beams, the identification information of the N beams, and the random access channel configurations of the M beams, where L is a nonnegative integer.

What is claimed is: 
     
         1 . A method, comprising:
 receiving, by a terminal, random access channel configurations corresponding to M beams of a target cell, wherein M is a positive integer, and each random access channel configuration of the random access channel configurations of the M beams comprises a respective preamble index and a respective time-frequency resource configuration;   when the M beams comprise at least one beam whose signal strength is greater than or equal to a first beam signal strength threshold, determining, by the terminal, to use a first beam of the at least one beam for a random access procedure in the target cell; and   when a signal strength of each of the M beams is less than the first beam signal strength threshold, determining, by the terminal, to use a second beam of L beams for the random access procedure in the target cell, wherein a signal strength of the second beam is greater than or equal to the first beam signal strength threshold, L is a nonnegative integer, and the L beams are all beams whose signal strength is detected.   
     
     
         2 . The method according to  claim 1 , further comprising:
 receiving the first beam signal strength threshold.   
     
     
         3 . The method according to  claim 2 , wherein receiving the first beam signal strength threshold comprises:
 receiving the first beam signal strength threshold through a radio resource control (RRC) connection reconfiguration message.   
     
     
         4 . The method according to  claim 1 , further comprising:
 when a respective signal strength of each of the L beams and each of the M beams is less than the first beam signal strength threshold, or none of the M beams is found, performing the following:
 determining to use an earliest found beam for the random access procedure in the target cell; 
 determining to use a beam with a highest signal strength for the random access procedure in the target cell; 
 determining to use a randomly found beam for the random access procedure in the target cell; or 
 determining to use a beam with a highest priority for the random access procedure in the target cell. 
   
     
     
         5 . The method according to  claim 1 , wherein determining to use the first beam for the random access procedure in the target cell comprises:
 selecting the first beam based on a priority order of the at least one beam whose signal strength is greater than or equal to the first beam signal strength threshold.   
     
     
         6 . The method according to  claim 1 , wherein identification information of each beam comprises respective synchronization signal block identification information of the respective beam or respective channel state information-reference signal identification information of the respective beam. 
     
     
         7 . The method according to  claim 6 , wherein a priority of a beam that is used to transmit channel state information-reference signal identification information is higher than that of a beam that is used to transmit synchronization signal block identification information. 
     
     
         8 . An apparatus, comprising:
 a first circuitry, configured to:
 receive random access channel configurations corresponding to M beams of a target cell, wherein M is a positive integer, and each random access channel configuration of the random access channel configurations of the M beams comprises a respective preamble index and a respective time-frequency resource configuration; and 
   a second circuitry, configured to:
 when the M beams comprise at least one beam whose signal strength is greater than or equal to a first beam signal strength threshold, determine to use a first beam of the at least one beam for a random access procedure in the target cell; and 
 when a signal strength of each of the M beams is less than the first beam signal strength threshold, determine to use a second beam of L beams for the random access procedure in the target cell, wherein a signal strength of the second beam is greater than or equal to the first beam signal strength threshold, L is a nonnegative integer, and the L beams are all beams whose signal strength is detected. 
   
     
     
         9 . The apparatus according to  claim 8 , wherein the first circuitry is further configured to receive the first beam signal strength threshold. 
     
     
         10 . The apparatus according to  claim 9 , wherein the first beam signal strength threshold is carried in a radio resource control (RRC) connection reconfiguration message. 
     
     
         11 . The apparatus according to  claim 8 , wherein the second circuitry is further configured to:
 when a respective signal strength of each of the L beams and each of the M beams is less than the first beam signal strength threshold, or none of the M beams is found, perform the following:
 determine to use an earliest found beam for the random access procedure in the target cell; 
 determine to use a beam with a highest signal strength for the random access procedure in the target cell; 
 determine to use a randomly found beam for the random access procedure in the target cell; or 
 determine to use a beam with a highest priority for the random access procedure in the target cell. 
   
     
     
         12 . The apparatus according to  claim 8 , wherein the second circuitry is further configured to:
 select the first beam based on a priority order of the at least one beam whose signal strength is greater than or equal to the first beam signal strength threshold.   
     
     
         13 . The apparatus according to  claim 8 , wherein identification information of each beam comprises respective synchronization signal block identification information of the respective beam or respective channel state information-reference signal identification information of the respective beam. 
     
     
         14 . The apparatus according to  claim 13 , wherein a priority of a beam that is used to transmit channel state information-reference signal identification information is higher than that of a beam that is used to transmit synchronization signal block identification information. 
     
     
         15 . A non-transitory computer readable storage medium, wherein the non-transitory computer readable storage medium stores a program to be executed by a processor, the program including instructions for:
 receiving random access channel configurations corresponding to M beams of a target cell, wherein M is a positive integer, and each random access channel configuration of the random access channel configurations of the M beams comprises a respective preamble index and a respective time-frequency resource configuration;   when the M beams comprise at least one beam whose signal strength is greater than or equal to a first beam signal strength threshold, determining to use a first beam of the at least one beam for a random access procedure in the target cell; and   when a signal strength of each of the M beams is less than the first beam signal strength threshold, determining to use a second beam of L beams for the random access procedure in the target cell, wherein a signal strength of the second beam is greater than or equal to the first beam signal strength threshold, L is a nonnegative integer, and the L beams are all beams whose signal strength is detected.   
     
     
         16 . The medium according to  claim 15 , wherein the program further includes instructions for:
 receiving the first beam signal strength threshold.   
     
     
         17 . The medium according to  claim 15 , wherein the program further includes instructions for:
 when a respective signal strength of each of the L beams and each of the M beams is less than the first beam signal strength threshold, or none of the M beams is found, performing the following:
 determining to use an earliest found beam for the random access procedure in the target cell; 
 determining to use a beam with a highest signal strength for the random access procedure in the target cell; 
 determining to use a randomly found beam for the random access procedure in the target cell; or 
   determining to use a beam with a highest priority for the random access procedure in the target cell.   
     
     
         18 . The medium according to  claim 15 , wherein the program further includes instructions for:
 selecting the first beam based on a priority order of the at least one beam whose signal strength is greater than or equal to the first beam signal strength threshold.   
     
     
         19 . The medium according to  claim 15 , wherein identification information of each beam comprises respective synchronization signal block identification information of the respective beam or respective channel state information-reference signal identification information of the respective beam. 
     
     
         20 . The medium according to  claim 19 , wherein a priority of a beam that is used to transmit the channel state information-reference signal identification information is higher than that of a beam that is used to transmit the synchronization signal block identification information.