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diff --git a/doc/manuals/osmobts-abis.adoc b/doc/manuals/osmobts-abis.adoc new file mode 100644 index 00000000..1e02414d --- /dev/null +++ b/doc/manuals/osmobts-abis.adoc @@ -0,0 +1,92 @@ +:gfdl-enabled: + +OsmoBTS Abis Protocol Specification +=================================== +Neels Hofmeyr <nhofmeyr@sysmocom.de> + +== Introduction + +This document describes the A-bis interface of *OsmoBTS*. Based on 3GPP TS +12.21 and 08.58, this document indicates which of the 3GPP specified A-bis +messages and IEs are implemented according to 3GPP specifications, which of +these are not or not fully implemented, as well as OsmoBTS-specific extensions +to the A-bis interface not specified by 3GPP. + +Extensions to the A-bis interface specific to OsmoBTS are detailed in this +document. For details on the messages and IEs that comply with above mentioned +3GPP specifications, please refer to those documents. + +.3GPP document versions referred to by this document +[cols="20%,80%"] +|=== +|3GPP TS 08.56 | version 8.0.1 Release 1999 +|3GPP TS 08.58 | version 8.6.0 Release 1999 +|3GPP TS 08.60 | version 8.2.1 Release 1999 +|3GPP TS 12.21 | version 8.0.0 Release 1999 +|=== + +.IETF documents referred to by his document +[cols="20%,80%"] +|=== +|IETF RFC 768 | User Datagram Protocol +|IETF RFC 791 | Internet Protocol +|IETF RFC 793 | Transmission Control Protocol +|IETF RFC 1889 | RTP: A Transport Protocol for Real-Time Applications +|IETF RFC 3551 | RTP Profle for Audio and Video Conferences with Minimal Control +|IETF RFC 4867 | RTP Payload Format and Files Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs +|IETF RFC 5993 | RTP Payload Format for Global Systems for Mobile Communications Half Rate (GSM-HR) +|=== + +== Overview + +The OsmoBTS A-bis interface consists of traffic management messages (RSL, Radio +Signalling Link) and network management messages (OML, Operation & Maintenance +Link), encapsulated in an IPA multiplex. + +OML and RSL each use a separate TCP connection. + +.TCP port numbers used by OsmoBTS Abis/IP +[options="header",width="50%",cols="35%,65%"] +|=== +|TCP Port Number|Usage +|3002|A-bis OML (inside IPA multiplex) +|3003|A-bis RSL (inside IPA multiplex) +|=== + +Both TCP connections for OML and RSL are established in the BTS -> BSC +direction, i.e. the BTS is running as a TCP client, while the BSC is +running as a TCP server. + +The BTS first establishes the TCP connection for OML. Via OML, the BSC +instructs the BTS to which IP address the RSL connection shall be +established. + +.Overview of A-bis connection establishment +["mscgen"] +---- +include::abis/abis-startup.msc[] +---- + +=== Identities + +The BTS is locally configured (via administrative means, out of band of +this specification) to have a Unit ID. The Unit ID consists of three +parts: + +* The Site Number +* The BTS number at the site +* The TRX number within the BTS + +include::abis/ipa.adoc[] + +include::abis/oml.adoc[] + +include::abis/rsl.adoc[] + +include::abis/rtp.adoc[] + +include::../common/chapters/port_numbers.adoc[] + +include::../common/chapters/glossary.adoc[] + +include::../common/chapters/gfdl.adoc[] |