Some update on recent OsmoBTS changes
After quite some time of gradual bug fixing and improvement, there have been quite some significant changes being made in OsmoBTS over the last months.
Just a quick reminder: In Fall 2015 we finally merged the long-pending L1SAP changes originally developed by Jolly, introducing a new intermediate common interface between the generic part of OsmoBTS, and the hardware/PHY specific part. This enabled a clean structure between osmo-bts-sysmo (what we use on the sysmoBTS) and osmo-bts-trx (what people with general-purpose SDR hardware use).
The L1SAP changes had some fall-out that needed to be fixed, not a big surprise with any change that big.
More recently however, three larger changes were introduced:
phy_link / phy_instance abstraction
There now is the concept of a phy_link, each of which can have multiple phy_instances. Each instance represents one baseband transceiver, i.e. a software or hardware unit driving a TRX inside a BTS.
Every BTS model has been converted to use this new abstraction layer.
proper Multi-TRX support
Based on the above phy_link/phy_instance infrastructure, one can map each phy_instance to one TRX by means of the VTY / configuration file.
The core of OsmoBTS now supports any number of TRXs, leading to flexible Multi-TRX support.
OCTPHY support
A Canadian company called Octasic has been developing a custom GSM PHY for their custom multi-core DSP architecture (OCTDSP). Rather than re-inventing the wheel for everything on top of the PHY, they chose to integrate OsmoBTS on top of it. I've been working at sysmocom on integrating their initial code into OsmoBTS, rendering a new osmo-bts-octphy backend.
This back-end has also recently been ported to the phy_link/phy_instance API and is Multi-TRX ready. You can both run multiple TRX in one DSP, as well as have multiple DSPs in one BTS, paving the road for scalability.
osmo-bts-octphy is now part of OsmoBTS master.
Corresponding changes to OsmoPCU (for full GPRS support on OCTPHY) are currently been worked on by Max at sysmocom.
Litecell 1.5 PHY support
Another Canadian company (Nutaq/Nuran) has been building a new BTS called Litecell 1.5. They also implemented OsmoBTS support, based on the osmo-bts-sysmo code. We've been able to integrate that code with the above-mentioned phy_link/phy_interface in order to support the MultiTRX capability of this hardware.
Litecell 1.5 MultiTRX capability has also been integrated with OsmoPCU.
osmo-bts-litecell15 is now part of OsmoBTS master.
Summary
2016 starts as the OsmoBTS year of MultiTRX.
2016 also starts as a year of many more hardware choices for OsmoBTS
we see more commercial adoption of OsmoBTS outside of the traditional options of sysmocom and Fairwaves