Cellular Network Infrastructure » Radio Access Network » OsmoPCU

bts->n3101 is actually N3101_MAX, and it is provided via PCU socket from the BTS. So we already have a configurable N3101_MAX, but we have no actual per-USF/TBF counter and related mechanism.

The counter and timer are described in 3GPP TS 44.060 §13.2 and §13.4

This change is less trivial than initially anticipated: the problem is with TBF timeout handling in OsmoPCU - there's only single osmo_timer_list which is used for handling of all the timeouts. This in turn means that TBF cannot have 2 concurrent timers running at the same time - the moment we schedule new timer, we lose the information about any pending timer for this TBF. This is both counterintuitive and unnecessary fragile which makes it hard to test and modify.

Related gerrit 5109 has been merged, gerrit 5120 and 5158 are under review. Once it's merged we'll have generic infrastructure in place for handling TBF timers. Follow-up patches will convert remainig timers to use it (including T3169) which would allow use to properly integrate N3101 support.

Tested successfully with sysmoBTS, under review in gerrit 5158, 5182.

N3101 implementation has been merged, remaining patches to convert timer handling to the same infrastructure which is used for T3169 are under review.