Sunday, 19 November 2017

Logical channel ID and Logical Channel group

Logical channel ID and Logical Channel group.
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To understand this, we need to understand little about bearer (SRB/DRB). A Radio bearer is a logical connection between the UE & eNodeB.
Except SRB 0, all RB's make use of dedicated resources assigned by eNodeB.
SRB 0 is used when there is no RRC connection exist.

==> In LTE system, there exists three SRB i.e. SRB0, SRB1 and SRB2 and corresponding logical channel identities are 0, 1 and 2 respectively. These identities are fixed as per specification.

==> In LTE system, there exists at max 8 DRB and corresponding logical channel identities are 3 to 10 respectively.

DRB & EPS bearer has one to one mapping, so it means there can at max 8 EPS bearer. An EPS bearer is logical connection between UE & P-GW.

==>  Logical channel ID = DRB ID + 2 as 0, 1 and 2 identity is used for SRB.

                                       




Logical channel Group - There are maximum 4 logical channel group and each logical channel belongs to some logical channel group.
Logical channel ID are aggregated in a logical channel group based on some parameters like similar QoS.
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5 comments:

  1. I understand UE can have upto 11 bearers (Dedicated + default) but LCID for logical channel(SRB + DRB)have 10 possible values... how does it work.. ?

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    Replies
    1. SRB0 is CCCH, it is common bear for all the UEs, LCID for SRB0 is just 0000.

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  2. LCID value 0,1,2 are used to SRB0, SRB1 and SRB2 respectively.
    And LCID 3 ~ 10 are used for DRB1 ~ DRB8 respectively.
    DRB1 means LCID 3
    DRB8 means LCID 10

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  3. LCID value 0 used to SRB0
    LCID value 1 used to SRB1
    LCID value 2 used to SRB2
    LCID value 3 used to DRB1
    LCID value 4 used to DRB2
    LCID value 5 used to DRB3
    LCID value 6 used to DRB4
    LCID value 7 used to DRB5
    LCID value 8 used to DRB6
    LCID value 9 used to DRB7
    LCID value 10 used to DRB8

    since group of LCID is mapped to one LCG. please help understanding which LCID's are grouped....

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  4. Please can you mention how many LCID clubbed as one LCGID
    ex:LCID0,LCID1,LCID2=LCGID0 like this

    ReplyDelete