Hi all,
During experimenting with RACH requests in my virtual Um-interface environment, I found an interesting issue in OpenBSC. According to the specifications, every RACH request should contain BSIC value of target base station, and if I understand correctly BSC (or BTS?) should ignore such requests, where rach_bsic != bts_bsic (Ghost RACH).
Meanwhile, when I send all-zero sequence (just for testing) on RACH lchan, BSC allocates me a channel despite bts_bsic != 0x00. It probably also explains the reason, why sometimes in a real OpenBSC + OsmoBTS setup I see channel requests, followed by channel allocation without any further response from MS side.
So, do we have any BSIC matching functionality implemented somewhere? If not, I could try to open an issue and implement it.
With best regards, Vadim Yanitskiy.