A Complex Support Vector Machine Approach to OFDM Coherent Demodulation

Abstract

Most of the approaches to digital communication applications using support vector machines (SVMs) rely on the conventional classification and regression SVM algorithms. However, the introduction of complex algebra in the SVM formulation can provide us with a more flexible and natural framework when dealing with complex constellations and symbols. In this chapter, an SVM algorithm for coherent robust demodulation in orthogonal frequency division multiplexing (OFDM) systems is studied. We present a complex regression SVM formulation specifically adapted to a pilot-based OFDM signal, which provides us with a simpler scheme than an SVM multiclassification method. The feasibility of this approach is substantiated by computer simulation results obtained for Institute of Electrical and Electronic Engineers (IEEE) 802.16 broadband fixed wireless channel models. These experiments allow us to scrutinize the performance of the OFDM-SVM system and the suitability of the e-Huber cost function in the presence of non-Gaussian impulse noise interfering with OFDM pilot symbols.