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LCG(Logical Channel Group)

 

With just a little modification of 3GPP description, LCG can be defined as "A group of Logical Channel which buffer status is being reported." There are four LCGs being used in LTE and each of the group has it's own ID from 0 to 3. You can see how this LCG ID is being used in BSR (Buffer Status Report)

 

The LCD is usually used in the DRB settings as shown below. (The most common place for DRB setting is in RRC Connection Reconfiguration message). Refer to 6.3.2 Radio resource control information elements of TS36.331

 

              | +-drb-ToAddModList ::= SEQUENCE OF SIZE(1..maxDRB[11]) [1] OPTIONAL:Exist

              | | +-DRB-ToAddMod ::= SEQUENCE [11111]

              | |   +-eps-BearerIdentity ::= INTEGER (0..15) [5] OPTIONAL:Exist

              | |   +-drb-Identity ::= INTEGER (1..32) [1]

              | |   +-pdcp-Config ::= SEQUENCE [101] OPTIONAL:Exist

              | |   | +-discardTimer ::= ENUMERATED [infinity] OPTIONAL:Exist

              | |   | +-rlc-AM ::= SEQUENCE OPTIONAL:Omit

              | |   | +-rlc-UM ::= SEQUENCE OPTIONAL:Exist

              | |   | | +-pdcp-SN-Size ::= ENUMERATED [len12bits]

              | |   | +-headerCompression ::= CHOICE [notUsed]

              | |   |   +-notUsed ::= NULL

              | |   +-rlc-Config ::= CHOICE [um-Bi-Directional] OPTIONAL:Exist

              | |   | +-um-Bi-Directional ::= SEQUENCE

              | |   |   +-ul-UM-RLC ::= SEQUENCE

              | |   |   | +-sn-FieldLength ::= ENUMERATED [size10]

              | |   |   +-dl-UM-RLC ::= SEQUENCE

              | |   |     +-sn-FieldLength ::= ENUMERATED [size10]

              | |   |     +-t-Reordering ::= ENUMERATED [ms50]

              | |   +-logicalChannelIdentity ::= INTEGER (3..10) [3] OPTIONAL:Exist

              | |   +-logicalChannelConfig ::= SEQUENCE [1] OPTIONAL:Exist

              | |     +-ul-SpecificParameters ::= SEQUENCE [1] OPTIONAL:Exist

              | |       +-priority ::= INTEGER (1..16) [13]

              | |       +-prioritisedBitRate ::= ENUMERATED [infinity]

              | |       +-bucketSizeDuration ::= ENUMERATED [ms100]

              | |       +-logicalChannelGroup ::= INTEGER (0..3) [2] OPTIONAL:Exist