Osmocom Base Transceiver Station (BTS) https://osmocom.org/projects/osmobts
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Vadim Yanitskiy d1f8f3429c l1sap: proper rate adaptation for CSD (RFC4040 'clearmode')
Since 95407f3f osmo-bts-trx supports scheduling all CSD specific
channel rates, however the rate adaptation was missing.

On the radio interface we deal with CSD-modified V.110 frames, which
need to be converted to normal 80-bit V.110 frames (RA1'/RA1), which
in turn need to be batched and sent in RFC4040 "clearmode" 160 octet
RTP payloads (RA1/RA2 as per I.460).

Note that this patch comments out TCH/F14.4 in bts_supports_cm_data(),
so that all channel allocations for this mode would be NACKed.  The
reason for this is that the rate adaptation functions for TCH/F14.4
are different than the RA1'/RA1 and the RA1/RA2.

For more information, see:

* 3GPP TS 44.021, section 8 (functions RA1'/RA1)
* ITU-T I.460, section 1.1 "Rate adaption of 8, 16 and 32 kbit/s streams"

Change-Id: I5e3701ad52d5d428fd02caff037881045f2d0a02
Related: OS#1572
2023-07-30 16:08:01 +07:00
contrib systemd: depend on networking-online.target 2023-05-26 14:10:44 +02:00
debian debian: set compat level to 10 2023-04-25 16:48:21 +02:00
doc osmo-bts-trx: visualize rx_tch[fh]_fn() functions 2023-07-13 03:42:29 +07:00
include l1sap: proper rate adaptation for CSD (RFC4040 'clearmode') 2023-07-30 16:08:01 +07:00
src l1sap: proper rate adaptation for CSD (RFC4040 'clearmode') 2023-07-30 16:08:01 +07:00
tests l1sap: proper rate adaptation for CSD (RFC4040 'clearmode') 2023-07-30 16:08:01 +07:00
.gitignore l1sap: proper rate adaptation for CSD (RFC4040 'clearmode') 2023-07-30 16:08:01 +07:00
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COPYING re-work original osmo-bts with support for sysmocom femtobts 2011-06-27 11:25:35 +02:00
Makefile.am Makefile.am: EXTRA_DIST: debian, contrib/*.spec.in 2020-05-22 13:37:41 +02:00
README.md update git URLs (git -> https; gitea) 2022-06-18 11:39:25 +02:00
TODO-RELEASE l1sap: use gsm0502_fn2ccch_block() from libosmogsm 2023-06-26 14:59:49 +00:00
configure.ac l1sap: proper rate adaptation for CSD (RFC4040 'clearmode') 2023-07-30 16:08:01 +07:00
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README.md

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 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 as well as the VTY reference manuals

There also is an Abis reference Manual 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 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()