What is a software defined radio?

Software Defined Radio (SDR) is a wireless device configurable with an FPGA to perform digital functions. SDR cards sold in e-commerce are capable of transmitting and receiving signals at different frequencies and adapt to wireless communications standards, from FM radios to Wi-Fi networks.

Software Defined Radio - the next generation wireless telecommunications platform

Presentation of the software radio

The software defined radio (SDR) is a configurable radiocommunication system using digital signal processing techniques on programmable digital circuits. Its flexibility allows it to adapt to different radiocommunication protocols, and to meet the growing need for performance and interoperability between systems. The objective of the software radio consists in a complete dematerialization of the radio interface. It participates in the global trend of the electronic circuits to become high integration density circuits.

Radiocommunications and their equipment have existed for more than a hundred years. The first architectures of radio equipment were mainly in analog technology. Since the 1980s, digital technology has gradually been installed in radiocommunications. Following this evolution, the word “software radio” or “software defined radio” has imposed itself.

Software radio: Operating principle

Software radios allow the use of multiple waveforms, possibly in different spectral bands, for different usages, or even simultaneously. In a software radio, the proprieties of the carrier frequency, the signal bandwidth, the modulation and the network access are defined by software. Therefore, they are intended to be portable on any platform. Modern software radios also implement error correction codes, voice, video or data encoding modules and cryptographic functions.

These devices are now proven and are part of your daily lives, whether it’s for the design of 3G+ modems in mobile devices or radio networks such as base stations.

Platforms and tests benches for software radios

Platforms and test benches of « free » software radio offer to the research workers and developers the ability to design their own software radio applications. In view of the increasing complexity of the systems to be designed, a prototyping platform is chosen according to multiple criteria: flexibility, speed of computation, communication between components and the presence of external interfaces. Although restricted software radio offers multiple benefits to the radio systems designers, there are still many opened questioned on how to implement and manage the flexibility in a wireless transmission system.