Repository forw the Osmocom BTS implementation.
This code implementes the 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.
Right now, only one hardware and Layer1 are supported: The sysmocom
There is some experimental and way incomplete code to use a couple of
OsmocomBB phones and run them in the BTS. However, the required code
for the Calypso DSP code have not been written yet. This would still
require a lot of work.
Some additional work is being done in using some parts of the OpenBTS
L1FEC and glue it against omso-bts. This code is called osmo-trx and
requires the jolly/trx branch of this repository.
== Known Limitations ==
As of August 20, 2015, the following known limitations exist in this
=== 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
* No OML (TS 12.21) alarms yet (temperature, ...)
* Only single-TRX BTS at this point
* Will reject TS 12.21 STARTING TIME in SET BTS ATTR / SET CHAN ATTR
* No support for frequency hopping
* No reporting of interference levels as part of TS 08.58 RF RES IND
* No error reporting in case PAGING COMMAND fails due to queue overflow
* No use of TS 08.58 BS Power and MS Power parameters
* 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
* Doesn't yet include MAC address in Abis/IP Identity message
* 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.