Cellular Network Infrastructure » Radio Access Network » OsmoBTS

h1. [[OsmoBTS]]

[[OsmoBTS]] is a software implementation of a GSM BTS(Base Transceiver Station). 

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:]] (e.g. RSL, OML, RTP) and [[OsmocomBB:]] (e.g. LAPDm).  The Abis/IP protocol staking is inspired by ip.access A-bis/IP, sometimes called IPA multiplex.

h2. OsmoBTS in the Osmocom architecture

h3. OsmoBTS in a GSM + GPRS/EDGE network using [[OsmoNITB:]]

{{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];

}

}}

h3. OsmoBTS in a GSM + GPRS/EDGE network using [[OsmoBSC:]] and [[OsmoMSC:]]

{{graphviz_link()

digraph G {

    rankdir = LR;

    OsmoTRX -> OsmoBTS [label="bursts over UDP"];

    sysmoPHY -> OsmoBTS [label="/dev/msgq/"];

    octPHY -> OsmoBTS [label="Raw Ethernet"];

    OsmoBTS -> OsmoBSC [label="Abis/IP"];

    OsmoBSC -> OsmoMSC [label="3GPP AoIP"];

    OsmoMSC -> OsmoHLR [label="GSUP"];

    OsmoBTS -> OsmoPCU [label="pcu_sock"];

    OsmoPCU -> OsmoSGSN [label="Gb/IP"];

    OsmoSGSN -> OsmoGGSN [label="Gp"];

    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 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]], the USRP family, etc.

** Multiple indoor and outdoor "fairwaves":https://fairwaves.co BTSs, like [[umtrx:UmDESK]] and [[umtrx: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.

{{graphviz_link()

graph G {

  OsmoBTS [color=red];

  sysmoBTS [label="sysmocom sysmoBTS\n(many models)", shape=box];

  LC15 [label="Nuran\nLitecell 1.5", shape=box];

  OCT [label="Octasic\nOCTBTS", shape=box];

  TRX [label="OsmoTRX"];

  OtherSDR [label="Other SDR HW", shape=box, style=dashed];

  OtherPHY [label="Other GSM PHY", shape=box, style=dashed];

  UmTRX [label="Fairwaves\nUmTRX", shape=box];

  USRP [label="Ettus USRP\nFamily", shape=box];

  OsmoBTS -- sysmoBTS [label="osmo-bts-sysmo"];

  OsmoBTS -- LC15 [label="osmo-bts-lc15"];

  OsmoBTS -- OCT [label="osmo-bts-octphy"];

  OsmoBTS -- TRX [label="osmo-bts-trx"];

  OsmoBTS -- OtherPHY [style=dashed];

  TRX -- USRP;

  TRX -- UmTRX;

  TRX -- OtherSDR [style=dashed];

  { rank=same; sysmoBTS LC15 OCT UmTRX }

}

}}

{{include(cellular-infrastructure:MacroBinaryPackages)}}

h2. Manuals

* User Manual: http://ftp.osmocom.org/docs/latest/osmobts-usermanual.pdf

* VTY Reference: http://ftp.osmocom.org/docs/latest/osmobsc-vty-reference.pdf

* Abis Protocol Manual: http://ftp.osmocom.org/docs/latest/osmobts-abis.pdf

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

<pre>

git clone git://git.osmocom.org/osmo-bts.git

</pre>

You can browse it via cgit: https://git.osmocom.org/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 his team at sysmocom.