Signal path optimization in software-defined radio systems

Growing requirements set upon communication transceivers lead to high sensitivity to nonidealities of analog components, especially in case of software-defined radio (SDR) systems. This paper deals with disturbances, mismatches, and the rejection of images that are caused by the front-end processing. A hybrid architecture comprehending advantages of homodyne and heterodyne receivers is proposed for an SDR system. Theoretical outcomes are discussed and backed by simulations. A fast Fourier transform (FFT)-based algorithm, the phase increment Kay algorithm, and two autocorrelation algorithms, i.e., Morelli-Mengali and Crozier-Moreland, used for frequency offset correction, are compared. The FFT algorithm turns out to be the best solution, both in terms of performance and ease of implementation. DC correction is then discussed and in-phase/quadrature imbalance compensation by means of a blind-source separation (BSS) algorithm and a hard-decision algorithm is performed. The latter algorithm displays implementation advantages, while BSS performs better.