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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
<https://osmocom.org/projects/osmobts/wiki>
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 <https://gitea.osmocom.org/cellular-infrastructure/osmo-bts>
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.
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.
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()
|
