Distributed beamforming in OFDM-based systems over frequency-selective channels

Abstract

Earlier publications on distributed beamforming have discussed only single carrier systems. Because orthogonal frequency division multiplexing has several advantages over single-carrier modulation in wideband systems, a logical direction of research is to investigate how such algorithm performs with OFDM. In this paper, we present a modified and further optimized version of a recently proposed distributed beamforming algorithm and incorporate it to a system using OFDM. The functionality of the algorithm is verified in simulations using realistic, frequency-selective channels. Based on extensive simulation studies, we recommend specific parameter values for the beamforming algorithm with the aims of maximizing the speed of convergence and asymptotic received power, and minimizing the amount of feedback required.