Bug #4966

osmo-pcu: gprs+egprs multiplex: Allow selecting original 8-PSK dl block during retransmission for GMSK-required DL block

Added by pespin 4 months ago. Updated 3 months ago.

Target version:
Start date:
Due date:
% Done:


Spec Reference:


DUring GPRS+EGPRS multiplexing on a PDCH, if a GPRS-only phone is using the PDCH, there a re some constraints that must be followed by the PCU scheduler so that they are able to receive the DL blocks. That is namely:
  • At least 1 GMSK block must be sent every 18th block
  • If USF targes the GPRS-only phone, GMSK must be used

That means, for instance, when the scheduler looks for a GMSK DL block candidate to sent (due to above restrictions), it skips selecting DL blocks for TBFs which are waiting for retransmission of 8PSK blocks (MCS>4), meaning it may end up sending a Dummy Block sometimes.

Under that circumstances, we should do a 2nd pass over the TBFs and downgrade the ready-to-be-transmitted 8PSK DL block to a MCS of the same family which is MCS <= 4), that is, in practice, splitting the data in 2 blocks containing same BSN but different SPB to identify first/second subblocks.

Related issues

Related to OsmoPCU - Feature #4544: concurrent operation of GPRS and EGPRS modeResolved05/12/2020


#1 Updated by pespin 4 months ago

  • Related to Feature #4544: concurrent operation of GPRS and EGPRS mode added

#2 Updated by pespin 4 months ago

This contains a summary of information related to this improvement:

#3 Updated by pespin 3 months ago

  • Description updated (diff)

Also available in: Atom PDF

Add picture from clipboard (Maximum size: 48.8 MB)