Attention is currently required from: neels, pespin, dexter.

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3 comments:

• File include/osmocom/pcu/pcuif_proto.h:

  • Patch Set #19, Line 279: uint8_t pgroup;

    And AFAIR, yes, it can be bigger than 255.

    Here I meant the `IMSI % 1000`, not the actual paging group.

• File include/osmocom/pcu/pcuif_proto.h:

  • Patch Set #18, Line 43: PCU_IF_SAPI_PCH_DT

    Yes, its a bit ugly, but we need to stay backwards compatible at least until we updated OsmoBTS as w […]

    The patch for `osmo-bts.git` is already in Gerrit (currently WIP to avoid merging before this one). So I see no real need to stay backwards compatible anymore. Where we really need to stay backwards compatible is in `osmo-ttcn3-hacks.git`.

• File include/osmocom/pcu/pcuif_proto.h:

  • Patch Set #17, Line 280: uint8_t pgroup[3];

    Its indeed much simpler. Actually the paging group is only one byte in reality. […]

    As per 3GPP TS 45.002 section 6.5.2 it's defined as follows:

    ```
    CCCH_GROUP (0 .. BS_CC_CHANS-1) = ((IMSI mod 1000) mod (BS_CC_CHANS x N)) div N
    PAGING_GROUP (0 .. N-1) = ((IMSI mod 1000) mod (BS_CC_CHANS x N)) mod N
    ```

    so it can be in range `0 .. N-1`, where `N` is defined as:

    ```
    N = number of paging blocks "available" on one CCCH = (number of paging blocks "available" in a 51-multiframe on one CCCH) x BS_PA_MFRMS.
    ```

    We have defines for this, so `N(max) = MAX_PAGING_BLOCKS_CCCH * MAX_BS_PA_MFRMS = 81`, therefore the paging group can be in range `0..80`.

    But again, what we have in osmo-pcu **is not really a paging group**.

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