Development and performance analysis of algorithms for wireless relay and limited-feedback communications systems

Abstract

This thesis proposes algorithms for wireless relay and limited-feedback communication systems, and analyzes the performance of them. As two of the promising technologies used to dramatically increase the achievable rate and the reliability of wireless communication systems, we address MIMO and two-way relaying methods. Specifically, in the first part of this thesis, the MIMO system with a \textit{linear detector} is considered in pursuit of guaranteeing the feasibility of the proposed scheme. To achieve near-maximum likelihood (ML) performance with a linear detector, we consider the lattice reduction (LR)-aided precoding. It is assumed that the feedback bits are limited to a few bits. Under these constraints, we propose a new LR-aided precoding method with limited feedback, based on a statistically-designed codebook. The proposed LR-aided precoding takes advantage of the fact that it is enough for the transmitter to have only a part of the information of the precoding matrix, because the receiver has the full information of the precoding matrix as well as the channel matrix. Within the proposed LR-aided precoding scheme, the number of feedback bits is further reduced from that for representing a binary matrix in the conventional LR-aided precoding. More noticeable thing is that the proposed scheme can be applied under any given number of feedback bits, while, in the conventional LR-aided precoding, the number of feedback bits is not a design option but a fixed value that is determined by the number of transmit antennas. As a result, the proposed LR-aided precoding provides a nice compromise between the number of feedback bits and the performance. In the second part of this thesis, new two-way relaying (TWR) methods are proposed for the purpose of reducing the computational complexity and increasing the achievable rate of wireless communication systems. To implement the physical-layer network coding with pulse amplitude modulation (PAM) higher than binary phas...