Distributed antipodal paraunitary precoders for OFDM systems

Antipodal paraunitary (APU) matrices have been shown to be useful with respect to bit error rate (BER) as linear precoders for OFDM systems, especially in a fast-varying channel environment. In this paper we study a broader class of paraunitary matrices, namely, the distributed antipodal paraunitary (DAPU) matrices, of which APU matrices are special cases. Systematic methods for recursively generating certain types of DAPU matrices as well as a fast algorithm to implement them in a system are presented. Simulation results show that under the same distribution length, DAPU precoded systems with longer precoders have a better BER performance than those with APU precoders, especially in mid- and high-SNR region.