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h1. [[OsmoBTS]] [[OsmoBTS]] is a software implementation of Layer2/3 of a BTS. It implements the follwing protocols/interfaces: * LAPDm (GSM 04.06) * RTP * A-bis/IP in IPA multiplex * OML (GSM TS 12.21) * RSL (GSM TS 08.58) [[OsmoBTS]] is building up on work done previosuly for [[OpenBSC]] (RSL, OML, RTP) and "OsmocomBB":http://bb.osmocom.org (LAPDm). The Abis/IP protocol staking is inspired by ip.access A-bis/IP, sometimes called IPA multiplex. h2. OsmoBTS in the Osmocom architecture {{graphviz_link() digraph G { rankdir = LR; OsmoTRX -> OsmoBTS [label="bursts over UDP"]; sysmoPHY -> OsmoBTS [label="/dev/msgq/"]; octPHY -> OsmoBTS [label="Raw Ethernet"]; OsmoBTS -> OsmoNITB [label="Abis/IP"]; OsmoBTS -> OsmoPCU [label="pcu_sock"]; OsmoPCU -> OsmoSGSN [label="Gb/IP"]; OsmoBTS [color=red]; } }} h2. Backends / Hardware support [[OsmoBTS]] is modular and has support for multiple back-ends. A back-end talks to a specific L1/PHY implementation of the respective BTS hardware. Based on this architecture, it should be relatively easy to add a new back-end to support so-far unsupported GSM PHY/L1 and associated hardware. So far [[OsmoBTS]] has been integrated with several different L1/PHY and hardware systems. The backends are: * osmo-bts-sysmo ** Multiple indoor and outdoor BTS products called "sysmoBTS":http://www.sysmocom.de/products/sysmobts which is sold by "sysmocom":http://sysmocom.de/ * osmo-bts-trx ** Wideband SDR transceiver hardware supported by [[OpenBTS]] transceiver or [OsmoTRX] PHY layer software, including the [[umtrx:UmTRX]], [[UmTRX]], the USRP family, etc. ** Multiple indoor and outdoor "fairwaves":https://fairwaves.co BTSs, like [[umtrx:UmDESK]] [[UmDESK]] and [[umtrx:UmSITE]] [[UmSITE]] * osmo-bts-litecell15 * osmo-bts-octphy * osmo-bts-bb ** A pretty crazy experimental BTS hardware based on two [[OsmocomBB]] phones had originally been supported, but needs to be re-integrated with core code changes. h2. Status The source code includes a http://cgit.osmocom.org/cgit/osmo-bts/tree/README file with current status information h2. GPRS support In the GSM architecture, the BTS is an element in the circuit-switched domain only. For packet-switched support, OsmoBTS provides a socket interface towards [[OsmoPCU:]]. This adds GPRS and EDGE support to it. h2. Source code The source code is available from git.osmocom.org (module osmo-bts). Public read-only access is available via git clone git://git.osmocom.org/osmo-bts.git You can browse it via cgit: http://cgit.osmocom.org/cgit/osmo-bts/ h2. Authors / Credits [[OsmoBTS]] was originally developed in 2011 by Andreas Eversberg and Harald Welte. Today it is mostly maintained by Harald Welte and Holger Freyther at sysmocom. Exception is the osmo-bts-trx back-end which is maintained by Fairwaves.