Hi Harald, I did a quick investigation, and it seems I found the problem:
https://git.osmocom.org/osmo-ttcn3-hacks/tree/bts/BTS_Tests.ttcn#n425 Since [1] we additionally filter Access Bursts by the link quality C/I in L1SAP, and since [2] we do provide the actual C/I values for osmo-bts-trx, as was received from the transceiver. [1] https://gerrit.osmocom.org/r/I893ec9c6c2ebad71ea68b2dc5f9f5094dfc43b78 [2] https://gerrit.osmocom.org/r/I8d86dec7ebc039cbfd038c4342ff328b11281865 The default minimum C/I for Access Bursts in OsmoBTS is 50 cB or 5 dB, while the TTCN-3 test cases configure fake_trx.py to send 0 cB, so of course such Access Bursts are getting dropped, as expected. I'll send a fix soon. For Normal Bursts, the minimum C/I value is -5 cB, so they pass without problems. With best regards, Vadim Yanitskiy.
