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MAC CE - Buffer Status Report MAC CEs  


The functionality of BSR in NR is exactly sa the LTE BSR. For the BSR functionality, refer to LTE BSR page. The dfference is the structure of MAC CE and the length of Buffer Size Bit field. It is understandable that the length of the BSR bit field in NR would be longer than LTE BSR. Another difference is that NR BSR has explcit bit field for LCG as shown below whereas LTE BSR specifies LCG implcitely.



<  38.321-Figure Short BSR and Short Truncated BSR MAC CE >



<  38.321-Figure Long BSR and Long Truncated BSR MAC CE >



<  38.321-Table Buffer size levels (in bytes) for 5-bit Buffer Size field >



<  38.321-Table Buffer size levels (in bytes) for 8-bit Buffer Size field >




RRC Parameters for BSR



MAC-CellGroupConfig ::= SEQUENCE {

   drx-Config                   SetupRelease { DRX-Config } OPTIONAL, -- Need M

   schedulingRequestConfig      SchedulingRequestConfig OPTIONAL, -- Need M

   bsr-Config                   BSR-Config OPTIONAL, -- Need M

   tag-Config                   TAG-Config OPTIONAL, -- Need M

   phr-Config                   SetupRelease { PHR-Config } OPTIONAL, -- Need M

   skipUplinkTxDynamic          BOOLEAN,



   csi-Mask-v1530               BOOLEAN OPTIONAL , -- Need M

   dataInactivityTimer-v1530    SetupRelease { DataInactivityTimer } OPTIONAL -- Need






BSR-Config ::= SEQUENCE {

   periodicBSR-Timer              ENUMERATED { sf1, sf5, sf10, sf16, sf20, sf32, sf40, sf64,

                                               sf80, sf128, sf160, sf320, sf640, sf1280,

                                               sf2560, infinity },

   retxBSR-Timer                  ENUMERATED { sf10, sf20, sf40, sf80, sf160, sf320, sf640,

                                               sf1280, sf2560,sf5120, sf10240, spare5, spare4,

                                               spare3, spare2, spare1},

   logicalChannelSR-DelayTimer    ENUMERATED { sf20, sf40, sf64, sf128, sf512, sf1024,

                                               sf2560, spare1} OPTIONAL, -- Need R