Real-time Implementation of a DSP-based Algorithm on USRP for Mitigating Non-linear Distortions in the Receiver RF Front-end

With the commercial availability of flexible radios, the cognitive radio concept is moving out of textbooks and papers into real-world implementations. However, RF impairments in the front-end turn out to be a significant limitation in practice. The focus of this work is on non-linear distortions in wideband receivers, and their mitigation by means of digital signal processing. Mitigating distortions is essential for maintaining reliable and robust spectrum sensing or end-to-end communication. A feedforward algorithm in the digital domain is applied to clean the baseband signal from distortions. An embedded design on the commercially available software-defined radio platform USRP is presented. The obtained results show that the implemented algorithm successfully reduces intermodulation distortions in real-time, thereby increasing the effective linearity of the frontend.