Avoiding out of order uplink data reception upon data radio bearer release, handover to another data radio bearer, or quality of service flow addition

Abstract

Certain aspects of the present disclosure provide techniques for avoiding out of order uplink data reception upon data radio bearer (DRB) release or quality of service (QoS) flow addition. An exemplary method that may be performed by a user equipment (UE), includes obtaining an indication that a first data radio bearer (DRB) is released or handed over to a second DRB, wherein a first mapping maps a first quality of service (QoS) flow to the first DRB; obtaining a second mapping that maps the first QoS flow to a second DRB; editing service data adaptation protocol (SDAP) headers of uplink protocol data units (PDUs) in an uplink transmission buffer associated with the first DRB, based on a difference between a first configuration of the first DRB and a second configuration of the second DRB; and transmitting the uplink PDUs via the second DRB.

What is claimed is: 
     
         1 . A method of wireless communications performed by a user equipment (UE), comprising:
 receiving a non-access stratum (NAS) protocol data unit (PDU) session modification command for a PDU session that adds a new quality of service (QoS) flow having a first QoS flow identifier (QFI);   determining that the UE does not have an uplink QoS flow to data radio bearer (DRB) mapping rule for the QoS flow having the first QFI; and   preventing, during a period subsequent to the determination, a service data adaptation protocol (SDAP) layer of the UE from processing and transmitting uplink data associated with the QoS flow having the first QFI.   
     
     
         2 . The method of  claim 1 , further comprising:
 receiving a QoS flow to DRB mapping rule for the QoS flow having the first QFI;   processing uplink data associated with the QoS flow having the first QFI using the received QoS flow to DRB mapping rule; and   transmitting the uplink data associated with the QoS flow having the first QFI using the received QoS flow to DRB mapping rule.   
     
     
         3 . The method of  claim 1 , further comprising:
 at the end of the period, determining a DRB mapping rule for the QoS flow having the first QFI.   
     
     
         4 . The method of  claim 3 , further comprising:
 starting a timer subsequent to the determination; and   determining that the period has ended when the timer expires.   
     
     
         5 . The method of  claim 3 , wherein the DRB mapping rule for the QoS flow having the first QFI is to map PDUs of the QoS flow having the first QFI to a default DRB of the PDU session. 
     
     
         6 . The method of  claim 3 , further comprising:
 determining that the PDU session does not have a default DRB, wherein:
 determining the DRB mapping rule for the QoS flow having the first QFI comprises determining to map PDUs of the QoS flow to a non-default DRB of the PDU session. 
   
     
     
         7 . A method of wireless communications, comprising:
 receiving a configuration of a protocol data unit (PDU) session, wherein the configuration does not identify a default data radio bearer (DRB) of the PDU session and a quality of service (QoS) flow of the PDU session does not have a QoS flow to DRB mapping rule configured;   subsequent to a period elapsing after receiving the configuration, determining if the configuration still holds;   when the configuration still holds:
 when a DRB of the PDU session that contains a QoS flow associated with a default QoS rule is configured to use uplink service data adaptation protocol (SDAP) headers, mapping the QoS flow to the DRB; and 
 when the DRB of the PDU session that contains the QoS flow associated with the default QoS rule is not configured to use uplink SDAP headers, mapping the QoS flow to another DRB that does not contain a guaranteed bit rate (GBR) QoS flow and is configured to use uplink SDAP headers. 
   
     
     
         8 . The method of  claim 7 , further comprising:
 determining a length of the period based on the configuration or another configuration received from a base station.   
     
     
         9 . The method of  claim 7 , further comprising:
 starting a timer subsequent to receiving the configuration; and   determining that the period has ended when the timer expires.   
     
     
         10 . An apparatus of wireless communications, comprising:
 a processor configured to:
 receive a non-access stratum (NAS) protocol data unit (PDU) session modification command for a PDU session that adds a new quality of service (QoS) flow having a first QoS flow identifier (QFI); 
 determine that the apparatus does not have an uplink QoS flow to data radio bearer (DRB) mapping rule for the QoS flow having the first QFI; and 
 prevent, during a period subsequent to the determination, a service data adaptation protocol (SDAP) layer of the apparatus from processing and transmitting uplink data associated with the QoS flow having the first QFI; and 
   a memory coupled with the processor.   
     
     
         11 . The apparatus of  claim 10 , wherein the processor is further configured to:
 receive a QoS flow to DRB mapping rule for the QoS flow having the first QFI;   process uplink data associated with the QoS flow having the first QFI using the received QoS flow to DRB mapping rule; and   transmit the uplink data associated with the QoS flow having the first QFI using the received QoS flow to DRB mapping rule.   
     
     
         12 . The apparatus of  claim 10 , wherein the processor is further configured to:
 at the end of the period, determine a DRB mapping rule for the QoS flow having the first QFI.   
     
     
         13 . The apparatus of  claim 12 , wherein the processor is further configured to:
 start a timer subsequent to the determination; and   determine that the period has ended when the timer expires.   
     
     
         14 . The apparatus of  claim 12 , wherein the DRB mapping rule for the QoS flow having the first QFI is to map PDUs of the QoS flow having the first QFI to a default DRB of the PDU session. 
     
     
         15 . The apparatus of  claim 12 , wherein the processor is further configured to:
 determine that the PDU session does not have a default DRB; and   determine the DRB mapping rule for the QoS flow having the first QFI by determining to map PDUs of the QoS flow to a non-default DRB of the PDU session.   
     
     
         16 . An apparatus for wireless communications, comprising:
 a processor configured to:
 receive a configuration of a protocol data unit (PDU) session, wherein the configuration does not identify a default data radio bearer (DRB) of the PDU session and a quality of service (QoS) flow of the PDU session does not have a QoS flow to DRB mapping rule configured; 
 determine if the configuration still holds subsequent to a period elapsing after receiving the configuration; 
 map the QoS flow to the DRB, when the configuration still holds and when a DRB of the PDU session that contains a QoS flow associated with a default QoS rule is configured to use uplink service data adaptation protocol (SDAP) headers; and 
 map the QoS flow to another DRB that does not contain a guaranteed bit rate (GBR) QoS flow and is configured to use uplink SDAP headers, when the configuration still holds and when the DRB of the PDU session that contains the QoS flow associated with the default QoS rule is not configured to use uplink SDAP headers; and 
   a memory coupled with the processor.   
     
     
         17 . The apparatus of  claim 16 , wherein the processor is further configured to:
 determine a length of the period based on the configuration or another configuration received from a base station.   
     
     
         18 . The apparatus of  claim 16 , wherein the processor is further configured to:
 start a timer subsequent to receiving the configuration; and   determine that the period has ended when the timer expires.