A Diversity-Multiplexing Tradeoff Optimal Low Complexity Zero Forcing Method Based on ZP-OFDM

Abstract

Due to the computational complexity of maximum-likelihood signal decoding, the equalizers with less complexity are considered in the literature. Employing the zero forcing (ZF) equalizer, zero-padded orthogonal frequency-division multiplexing (ZP-OFDM) is capable of benefiting the maximum available multipath diversity with the computational complexity of inverting a matrix of the size of data block length, which incurs an extra implementation cost relative to the fast Fourier transform-based OFDM decoder. In this paper, based on the ZP-OFDM encoding scheme, we propose a two-stage decoder that attains the maximum multipath diversity with lower computational complexity, as compared with the ZF ZP-OFDM and prove analytically that our proposed decoder is diversity-multiplexing tradeoff optimal. It has also been shown that by setting the decoder parameters, it can attain any arbitrary diversity gain smaller than the maximum multipath diversity. Moreover, the more the diversity gain is decreased the more the computational complexity is reduced.