srsRAN and Software Radio Systems

Products and offerings #

Who they are

This hub is for engineers who want to run a real LTE or 5G NR cell on a PC and a software-defined radio, or study a working protocol stack. Software Radio Systems (SRS) is a company registered in Ireland, based in Cork, with entities in Barcelona and Austin. According to its about page, it was founded by two former Trinity College Dublin postdoctoral researchers and has grown since 2014 through commercial licence sales and publicly funded programmes. The open-source code is the srsRAN family. The commercial products are srsRAN Enterprise 4G and 5G.

The big change in the last year is on the 5G side. The srsRAN Project README now says the project has become OCUDU, and that all development moved to a new repository in December 2025. The GitHub repository is now archived. Its last commit is dated 1 June 2026. OCUDU is hosted by the Linux Foundation’s OCUDU Ecosystem Foundation. Its LICENSE file still names SRS as the copyright holder.

Tooling and APIs

What you install. There are now three code bases to choose from:

• OCUDU, for new 5G NR work. Release 26.10 came out on 30 September 2026. According to SRS’s announcement, it adds 3GPP Release 17 non-terrestrial network support, 8T8R MIMO and multi-beam operation. See the satellite and NTN hub for what NTN means.
• srsRAN Project 25.10, the last release before the move. It is a 5G NR gNB split into CU-CP, CU-UP and DU, described in the feature list as 3GPP Release 17 aligned, with split 7.2 fronthaul through SRS’s own O-RAN fronthaul library.
• srsRAN 4G, which is still released (26.10 on 6 November 2026). It contains srsUE, srsENB and srsEPC. srsUE is the main reason many labs keep it: a software UE for LTE with prototype 5G features.

Licensing at the time of writing. We read the LICENSE files. srsRAN 4G and srsRAN Project are under the GNU Affero General Public License version 3. That matters if you offer a modified stack as a network service, because the AGPL extends source-sharing to network use. OCUDU is under the BSD 3-Clause Open MPI variant, a permissive licence. srsRAN Enterprise is sold under commercial terms with no public price list.

OS support. Linux only. The srsRAN Project installation guide requires a Linux-based OS and recommends Ubuntu 22.04 or later. The OCUDU guide asks for Linux with real-time kernel support. Neither guide mentions macOS or Windows. On a Mac, run it in a Linux machine or on a separate PC.

Language and build. C++17 with CMake. There is no Python API. You drive the gNB through a YAML configuration file and command-line options.

Radios. For the 5G code, the docs state that only UHD and ZeroMQ are supported, and only for split 8 deployments. That means a USRP such as the USRP B210 or USRP X310, or the ZeroMQ virtual radio for tests without RF. Split 7.2 uses an O-RAN radio unit over Ethernet. SoapySDR is not listed for the 5G code. srsRAN 4G is broader: its installation page lists UHD, SoapySDR, bladeRF and ZeroMQ, so a bladeRF 2.0 micro also works there. There is no GNU Radio integration in either stack. GNU Radio is useful alongside it to inspect captured IQ.

Pain points. The troubleshooting guide asks you to set the CPU governor to performance mode and to use USB 3.0 or Ethernet. Late samples and underflows show up as dropped UEs long before they show up as errors. The same guide warns that bad USRP time calibration can stop PRACH reception, so a UE never attaches.

Migration notes

• srsRAN Project to OCUDU. New fixes land only in OCUDU. Plan the move, and re-read your configuration against the OCUDU docs rather than assuming 25.10 files carry over unchanged. The licence change from AGPL to a BSD variant makes OCUDU easier to embed in products.
• Clocking. The run guide warns that a USRP’s on-board clock may not be accurate enough. Commercial phones need a cell that is close to its nominal frequency, so use a 10 MHz reference or GPSDO. See carrier frequency offset.
• Virtual first. Bring up gNB, core and UE over ZeroMQ before adding RF. It separates protocol bugs from radio bugs.
• From OpenAirInterface. Both stacks run on a USRP over UHD. Configuration formats, logging and the core network attachment differ. Compare with the OpenAirInterface hub.

Watch for

• Licence obligations. AGPL code in a hosted service carries source-sharing duties. Check which code base, and which version of it, you ship.
• Spectrum. Transmitting LTE or NR over the air needs a licence or a test permit from your national regulator. Use cables, attenuators or a shielded box in the lab. See spectrum, security and regulation.
• Stale guides. Many tutorials online still point at the archived srsRAN Project repository. The srsRAN 4G docs still recommend UHD 3.9.7 or 3.15, which are old.
• Feature claims. Release 17 alignment describes the target, not full coverage of the release. Check the feature list for what is implemented.