Method and apparatus for selecting beam for preconfigured uplink resources in a wireless communication system

Abstract

Methods and apparatuses for selecting beam for preconfigured uplink resources in a wireless communication system are disclosed herein. In one method, a user equipment (UE) receives, from a network node, a signaling to configure at least one Preconfigured Uplink Resource (PUR) associated with one or more beams from multiple beams. The UE selects a first beam from the multiple beams and performs a transmission of data in RRC_INACTIVE state using the at least one PUR via the first beam if the first beam fulfills at least one condition, wherein the at least one condition comprises that the first beam is associated with the at least one PUR and Reference Symbol Received Power (RSRP) of the first beam is better than a first threshold. The UE initiates a Random Access (RA) procedure and performs the transmission during the RA procedure if no beam of the multiple beams fulfills the at least one condition.

What is claimed is: 
     
         1 . A method for a User Equipment (UE), comprising:
 configuring at least one Preconfigured Uplink Resource (PUR) associated with multiple Synchronization Signal/Physical Broadcast Channel Blocks (SSBs);   selecting a first SSB from the multiple SSBs and performing a transmission of data using the at least one PUR via a first beam associated with the first SSB if the first SSB fulfills at least one condition where Reference Symbol Received Power (RSRP) of the first SSB is above a threshold; and   initiating a Random Access (RA) procedure and performing the transmission during the RA procedure if no SSB of the multiple SSBs fulfills the at least one condition.   
     
     
         2 . The method of  claim 1 , wherein the transmission of data is performed in a RRC_IDLE or a RRC_INACTIVE state. 
     
     
         3 . The method of  claim 1 , wherein the first SSB is randomly selected from a subset of the multiple SSBs. 
     
     
         4 . The method of  claim 3 , wherein the subset includes more than one SSB that fulfills the at least one condition. 
     
     
         5 . The method of  claim 1 , wherein the first SSB is selected due to a highest measured RSRP among a subset of the multiple SSBs if the subset includes more than one SSB that fulfills the at least one condition. 
     
     
         6 . The method of  claim 1 , wherein the at least one condition further comprises a valid Timing Advance (TA) associated with the first beam. 
     
     
         7 . The method of  claim 1 , further including receiving signaling in a RRC_CONNECTED state to configure the at least one PUR associated with multiple SSBs. 
     
     
         8 . The method of  claim 1 , further comprising:
 determining whether the first beam becomes unsuitable based on the RSRP of the first SSB if the transmission using the at least one PUR is not successful;   selecting a second SSB from the multiple SSBs to perform a retransmission of the data if the UE determines that the first beam is unsuitable and the second SSB fulfills the at least one condition; and   performing the retransmission using the at least one PUR via a second beam associated with the second SSB.   
     
     
         9 . The method of  claim 8 , wherein the UE considers a TA associated with the first beam as invalid if the first beam becomes unsuitable. 
     
     
         10 . The method of  claim 8 , further comprising initiating the RA procedure and performing the retransmission during the RA procedure if no SSB of the multiple SSBs fulfills the at least one condition. 
     
     
         11 . The method of  claim 8 , further comprising determining that the first beam becomes unsuitable if the RSRP of the first SSB is less than the first threshold. 
     
     
         12 . The method of  claim 8 , further comprising determining that the transmission using the at least one PUR is not successful if the UE does not receive a response of the transmission. 
     
     
         13 . A User Equipment (UE), comprising:
 a memory; and   a processor operatively coupled to the memory, wherein the processor is configured to execute a program code to:
 configure at least one Preconfigured Uplink Resource (PUR) associated with multiple Synchronization Signal/Physical Broadcast Channel Blocks (SSBs); 
 select a first SSB from the multiple SSBs and perform a transmission of data using the at least one PUR via a first beam associated with the first SSB if the first SSB fulfills at least one condition where Reference Symbol Received Power (RSRP) of the first SSB is above a threshold; and 
 initiate a Random Access (RA) procedure and perform the transmission during the RA procedure if no SSB of the multiple SSBs fulfills the at least one condition. 
   
     
     
         14 . The UE of  claim 13 , wherein the transmission of data is performed in a RRC_IDLE or a RRC_INACTIVE state. 
     
     
         15 . The UE of  claim 13 , wherein the first SSB is randomly selected by the UE from a subset of the multiple SSBs, and wherein the subset includes more than one SSB that fulfills the at least one condition. 
     
     
         16 . The UE of  claim 13 , wherein the first SSB is selected due to a highest measured RSRP among a subset of the multiple SSBs if the subset includes more than one SSB that fulfills the at least one condition. 
     
     
         17 . The UE of  claim 13 , wherein the at least one condition further comprises a valid Timing Advance (TA) associated with the first beam. 
     
     
         18 . The UE of  claim 13 , wherein the UE receives signaling in a RRC_CONNECTED state to configure the at least one PUR associated with multiple SSBs. 
     
     
         19 . The UE of  claim 13 , wherein the processor is further configured to execute the program code to:
 determine whether the first beam becomes unsuitable based on the RSRP of the first SSB if the transmission using the at least one PUR is not successful;   select a second SSB from the multiple SSBs to perform a retransmission of the data if the UE determines that the first beam is unsuitable and the second SSB fulfills the at least one condition; and   perform the retransmission using the at least one PUR via a second beam associated with the second SSB.   
     
     
         20 . The UE of  claim 19 , wherein the processor is further configured to execute the program code to:
 initiate the RA procedure and perform the retransmission during the RA procedure if no SSB of the multiple SSBs fulfills the at least one condition; and/or   determine that the first beam becomes unsuitable if the RSRP of the first SSB is less than the first threshold; and/or   determine that the transmission using the at least one PUR is not successful if the UE does not receive a response of the transmission.