= Repository for the Osmocom BTS implementation. = For most complete and accurate information, please refer to https://osmocom.org/projects/osmobts/wiki To submit patches, please refer to https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit (Note: github pull requests are rejected by a bot) == Summary == This code implements Layer 2 and higher of a more or less conventional GSM BTS (Base Transceiver Station) - however, using an Abis/IP interface, rather than the old-fashioned E1/T1. Specifically, this includes * BTS-side implementation of TS 08.58 (RSL) and TS 12.21 (OML) * BTS-side implementation of LAPDm (using libosmocore/libosmogsm) * A somewhat separated interface between those higher layer parts and the Layer1 interface. Several kinds of BTS hardware are supported: * sysmocom sysmoBTS * Octasic octphy * Nutaq litecell 1.5 * software-defined radio based osmo-bts-trx (e.g. B210) == Known Limitations == As of August 20, 2015, the following known limitations exist in this implementation: === Common Core === * No Extended BCCH support * System Information limited to 1,2,2bis,2ter,2quater,3,4,5,6,9,13 * No RATSCCH in AMR * No OML (TS 12.21) alarms yet (temperature, ...) * Only single-TRX BTS at this point * Will reject TS 12.21 STARTING TIME in SET BTS ATTR / SET CHAN ATTR * No support for frequency hopping * No reporting of interference levels as part of TS 08.58 RF RES IND * No error reporting in case PAGING COMMAND fails due to queue overflow * No use of TS 08.58 BS Power and MS Power parameters * No support of TS 08.58 MultiRate Control * No support of TS 08.58 Supported Codec Types * No support of Bter frame / ENHANCED MEASUREMENT REPORT === osmo-bts-sysmo === * No CSD / ECSD support (not planned) * GSM-R frequency band supported, but no NCH/ASCI/SoLSA * All timeslots on one TRX have to use same training sequence (TSC) * No multi-TRX support yet, though hardware+L1 support stacking * Makes no use of 12.21 Intave Parameters and Interference Level Boundaries * Doesn't yet include MAC address in Abis/IP Identity message * MphConfig.CNF can be returned to the wrong callback. E.g. with Tx Power and ciphering. The dispatch should take a look at the hLayer3.