Multi-User SISO Precoding based on Generalized Multi-Unitary Decomposition for Single-carrier Transmission in Frequency Selective Channel

TL;DR

This paper introduces a novel multi-user precoding scheme for frequency selective channels using Generalized Multi-Unitary Decomposition, enhancing orthogonality and performance in multi-user single-carrier transmission.

Contribution

It proposes a new precoding method based on GMUD that offers multiple solutions for improved orthogonality and performance in multi-user frequency selective channels.

Findings

Achieves higher orthogonality between user beams.

Outperforms SVD-based precoding in simulations.

Provides multiple transmission beam options.

Abstract

In this paper, we propose to exploit the richly scattered multi-path nature of a frequency selective channel to provide additional degrees of freedom for desigining effective precoding schemes for multi-user communications. We design the precoding matrix for multi-user communications based on the Generalized Multi-Unitary Decomposition (GMUD), where the channel matrix H is transformed into P_i*R_r*Q_i^H. An advantage of GMUD is that multiple pairs of unitary matrices P_i and Q_i can be obtained with one single R_r. Since the column of Q_i can be used as the transmission beam of a particular user, multiple solutions of Q_i provide a large selection of transmission beams, which can be exploited to achieve high degrees of orthogonality between the multipaths, as well as between the interfering users. Hence the proposed precoding technique based on GMUD achieves better performance than precoding based on singular value decomposition.