There are many kits based on the SBC Raspberry Pi, or on the development board Arduino. From some destined to create your own retro consoles, even others for laptops, equipment hackable, etc. In the case of LibreCellular project they want to go further and join the era of mobile devices and high-speed wireless networks using free hardware and software.
LibreCellular aims to facilitate networking for mobile phones based on 4G LTE technology, using open source software and hardware. For this they are based on SDR (Software Defined Radio), a radiocommunication system where various components that are typically physically implemented are replaced by software.
The goal of LibreCellular
LibreCellular has another goal, not just that the implementation of your mobile data network works, but also that you can create it with low cost. On the other hand, they have also subjected this system to very rigorous tests to validate that it works properly, and they have provided it with the tools and documentation for developers that they will need.
All the elements of which this project will be composed will be under open source licenses, and more modules are expected to arrive to continue completing this work. Something that focuses all efforts on integration, testing, packaging and documentation to make it a reusable project and to create different solutions in a flexible way.
LibreCellular's first task will be to launch the continuous integration (CI) platform. That is, create a platform for development whereby developers can combine source code changes into a central repository and / or hardware revisions.
Efforts will also be made to complete the SDR base station for radio frequency and telecommunication of these networks, as well as to create the necessary test equipment, RF distribution network, and banks of LTE modems for connection. Once the entire infrastructure is operational, the focus will shift to the above - mobile stack integration, packaging, and documentation.
The LibreCellular project is made up of hardware and software parts, as I mentioned earlier. Everything you need to offer a basic LTE data service and support also for voice calls. For that to be possible, the following parts need to be integrated:
- Hardware CI platform: for base station with banks of LTE modems over a wired RF network, with RF measurement, control and reference clock distribution.
- Configuration and testing: will be made through the use of software OsmoGSMTester, and coverage will be extended as development evolves. In other words, it will go from a basic service where some subscriber mobile devices can be connected to a more complete service with VoLTE voice calling capacity thanks to an IP multimedia system (IMS).
- Software stack: all this hardware will be accompanied by software that allows communications to be carried out.
- Reference hardware platform- This will be a key goal, as it will save a lot of time to get new users up and running and will make troubleshooting hardware problems easier.
- Baseband processing: an SBC is used Intel NUC7i7DNBE to run the baseband and upper layers of the moving stack.
- SDR hardware: for which a plate has been selected LimeSDR-USB.
- RF interface: for radio frequency the project will be used LimeRFE which will provide a complete multiband RF front-ent with LNA, PA and duplexers. In addition, it provides a modulated output at 24 dBm in the moving bands 1, 2, 3, 4 and 5.
- Watch reference: for the reference clock that will be used by LimeSDR, a GPS Leo Bodnar Mini Precision to improve the stability and accuracy of the signal.
More information - Official Web