osmo-bts - Osmocom BTS Implementation ==================================== This repository contains a C-language implementation of a GSM Base Transceiver Station (BTS). It is part of the [Osmocom](https://osmocom.org/) Open Source Mobile Communications project. 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 * OpenCellular 2G (OC-2G) * software-defined radio based osmo-bts-trx (e.g. USRP B210, UmTRX, LimeSDR) Homepage -------- The official homepage of the project is GIT Repository -------------- You can clone from the official osmo-bts.git repository using git clone https://gitea.osmocom.org/cellular-infrastructure/osmo-bts There is a web interface at Documentation ------------- User Manuals and VTY reference manuals are [optionally] built in PDF form as part of the build process. Pre-rendered PDF version of the current "master" can be found at [User Manual](https://ftp.osmocom.org/docs/latest/osmobts-usermanual.pdf) as well as the VTY reference manuals * [VTY Reference Manual for osmo-bts-sysmo](https://ftp.osmocom.org/docs/latest/osmobts-sysmo-vty-reference.pdf) * [VTY Reference Manual for osmo-bts-trx](https://ftp.osmocom.org/docs/latest/osmobts-trx-vty-reference.pdf) * [VTY Reference Manual for osmo-bts-lc15](https://ftp.osmocom.org/docs/latest/osmobts-lc15-vty-reference.pdf) * [VTY Reference Manual for osmo-bts-oc2g](https://ftp.osmocom.org/docs/latest/osmobts-oc2g-vty-reference.pdf) * [VTY Reference Manual for osmo-bts-octphy](https://ftp.osmocom.org/docs/latest/osmobts-octphy-vty-reference.pdf) There also is an [Abis reference Manual](https://ftp.osmocom.org/docs/latest/osmobts-abis.pdf) describing the OsmoBTS specific A-bis dialect. Forum ----- We welcome any osmo-bts related discussions in the [Cellular Network Infrastructure -> 2G RAN (GERAN)](https://discourse.osmocom.org/c/cni/geran) section of the osmocom discourse (web based Forum). Mailing List ------------ Discussions related to osmo-bts are happening on the openbsc@lists.osmocom.org mailing list, please see https://lists.osmocom.org/mailman/listinfo/openbsc for subscription options and the list archive. Please observe the [Osmocom Mailing List Rules](https://osmocom.org/projects/cellular-infrastructure/wiki/Mailing_List_Rules) when posting. Issue Tracker ------------- We use the [issue tracker of the osmo-bts project on osmocom.org](https://osmocom.org/projects/osmobts/issues) for tracking the state of bug reports and feature requests. Feel free to submit any issues you may find, or help us out by resolving existing issues. Contributing ------------ Our coding standards are described at https://osmocom.org/projects/cellular-infrastructure/wiki/Coding_standards We us a gerrit based patch submission/review process for managing contributions. Please see https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit for more details The current patch queue for osmo-bts can be seen at https://gerrit.osmocom.org/#/q/project:osmo-bts+status:open Known Limitations ================= As of January 2021, 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 * Will reject TS 12.21 STARTING TIME in SET BTS ATTR / SET CHAN ATTR * 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 * 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. osmo-bts-octphy --------------- * No support of EFR, HR voice codec (lack of PHY support?) * No re-transmission of PHY primitives in case of time-out * Link Quality / Measurement processing incomplete * impossible to modify encryption parameters using RSL MODE MODIFY * no clear indication of nominal transmit power, various power related computations are likely off * no OML attribute validation during bts_model_check_oml()