95 lines
2.9 KiB
Plaintext
95 lines
2.9 KiB
Plaintext
: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::{srcdir}/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::{srcdir}/abis/ipa.adoc[]
|
|
|
|
include::{srcdir}/abis/oml.adoc[]
|
|
|
|
include::{srcdir}/abis/rsl.adoc[]
|
|
|
|
include::{srcdir}/abis/rtp.adoc[]
|
|
|
|
include::./common/chapters/port_numbers.adoc[]
|
|
|
|
include::./common/chapters/bibliography.adoc[]
|
|
|
|
include::./common/chapters/glossary.adoc[]
|
|
|
|
include::./common/chapters/gfdl.adoc[]
|