Cellular Network Infrastructure » Radio Access Network » OsmoBTS

In Downlink DTX, the BTS is muting some bursts/blocks during times with no voice activity in the downlink side towards the phone. This basically means that there are RTP SID frames (possibly at larger-than-20ms-intervals), which should trigger the muting of some bursts from the BTS.

• if we are on a secondary TRX (not TRX0 which carries the BCCH), and
• if DTXd is active, and
• we get a PH-RTS.ind from the PHY for the TCH (not SACCH!), but we do not have a valid codec frame with actual voice data (but rather no codec frame or a SID frame), then we chose to mute the transceiver for this burst, rather than sending a normal/dummy burst.

In terms of measurement reporting, the phone will perform the downlink rxqual and rxlev calculations for both FULL (all frames) and SUB (only sacch frames) and report this to the BTS, who will forward it in the RSL MEAS REP to the BSC. The BTS does not need to perform any processing here, as far as I know.

The patches are pushed to gerrit/users/max/dtx-test branch and are ready for review/testing. Note support is implemented for sysmoBTS and LC15 BTS models.

Note: testing require fix for libosmo-abis which is under review in gerrit: 217.

Support has been merged to master.