The srsLTE project is evolving

Written by Paul Sutton - April 15, 2021

Early 2014 saw the first public release of what is now the srsLTE project. At that time, it was known as libLTE and the key developer, Ismael Gomez, had just partnered with his university research colleague (me) to build a tiny startup called Software Radio Systems (SRS).

First developed as a free and open-source SDR component library for 4G LTE, the project consisted of 11k lines of code and featured a simple LTE cell search application. In the 7 years since then, srsLTE has grown to almost a million lines of code with full-stack UE, eNodeB and EPC applications providing a complete end-to-end 4G network. Meanwhile, SRS has grown from a 2-man startup to a team of 17 with locations across Ireland, Spain and Germany.

With help from the European Space Agency, SRS built on that first cell search example in 2014 to release the first open-source full-stack UE application in November 2015. This was followed by our initial eNodeB and EPC applications in June 2017 and February 2018 respectively, with development supported by the EU H2020 program, the US National Institute of Standards and Technology (NIST) and our early commercial partners. Since these first releases, regular updates have brought improved stability and user experience as well as new features including MIMO, mobility, carrier aggregation, eMBMS, NB-IoT and C-V2X.

As srsLTE has grown, so too has its community of users. In July 2019 we launched as a focal point for the community, to help new users get started with srsLTE, to share research results and to highlight success stories. Our research page now lists over 200 peer-reviewed publications based on research work using srsLTE. With the world’s most reliable and accessible open-source SDR UE, we’ve seen significant adoption of srsLTE by the mobile wireless security community. Of the 19 Coordinated Vulnerability Disclosures (CVDs) listed on the GSMA mobile security hall of fame, 11 are based on work using srsLTE.

In late 2018, 3GPP delivered the final Release 15 specifications for 5G NR. Building upon the technical foundation of 4G LTE, 5G NR introduces more flexibility, higher bandwidths and support for new millimeter wave frequency bands. Since early 2020, the SRS team has been developing support for this new standard and with our 21.04 release, we have added support for our first complete 5G application, the NSA-mode UE. This will be followed by our gNodeB application, due for release in October of this year.

As we expand the focus of the project beyond 4G LTE and into 5G NR, our “srsLTE” naming no longer fits like it used to. So, coinciding with our 21.04 release, the srsLTE project has become the srsRAN project.

With srsRAN, we will add 5G UE and gNodeB support but we will of course continue to develop and improve our existing 4G solutions. Indeed, this year sees the first large-scale deployments of our LTE solutions in production networks in partnership with our commercial clients. From the very beginning, we have designed and developed our software for real-world deployment and this represents a huge milestone for our team and community.

We’re excited about this new chapter in our evolution and we look forward to continuing to support our community, providing the most trusted open-source software for 4G and 5G mobile wireless networks!

Paul and the SRS Team