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Vadim Yanitskiy axilirator at gmail.comHi Harald, > Sounds like we need a DM_REL_REQ - and we actually have one. I would > normally expect that to be used to release dedicated mode? Oh, right! L1CTL_DM_REL_REQ magically slipped my mind. Of course, this one is used to release dedicated mode, and trxcon does support it already. Sorry for confusion. >> The main problem of this approach is that the new ARFCN the MS >> is requested to switch needs to be C0 (i.e. transmit both FCCH >> and BCCH). Otherwise L1CTL_FBSB_REQ would fail. > > You are referring to trxcon or calypso-layer1 here? [...] > >> That's a poor man's (I would even say ugly) approach, and as it >> turns out, there is L1CTL_DM_FREQ_REQ, which allows to schedule >> frequency change at the given TDMA frame number! But not the >> timeslot change :/ > > I actually think it's not ugly at all. You release the old > dedicated channel and establish a new one. Nevermind. This is a result of my delusion. See above. > Looking at layer23, it seems we have DM_REL_REQ, then RESET, > then a new DM_EST_REQ during assignment. Right. I am now wondering, wouldn't this intermediate L1CTL_RESET_REQ cause an additional delay for handover? >> So there is no warranty that the new dedicated channel would contain >> RACH slots, right? That's another limitation of trxcon: it can send >> RACH bursts on RACH slots only, and only on TS0. Fortunately, I found a work around, please see: https://gerrit.osmocom.org/#/c/osmocom-bb/+/14274/ I've just confirmed that trxcon properly sends Access Bursts on any (activated by L1CTL_DM_EST_REQ) time-slot, please see: https://gerrit.osmocom.org/#/c/osmo-ttcn3-hacks/+/14291/ ... and of course discovered a problem of OsmoBTS ;) In short, it doesn't detect handover RACH. The problem seems to be here: https://git.osmocom.org/osmo-bts/tree/src/common/scheduler.c#n986 An Access Burst is merely ignored if a logical channel is not active. King regards, Vadim Yanitskiy.