Wireless Relay-Aided Communication Coding And Precoding

This work focuses on the study and design of wireless relay-aided coding and precoding, which is a significant part of wireless relay-aided communication. A suc-cessful design of coding and cooperating strategy achieves higher cooperative diversity order gain, coding gain and band efficiency, hence leads to higher rate and quality of wireless relay-aided communication. Precoding, on the other hand, pre-equalizes the channel at the transmitting side instead of equalization at the receiver side. Hence, a successful design of precoding reduces the signal processing complexity at the receiver side, and at the same time, achieves higher diversity order and improves the reliability of broadcast communication.The introduction chapter investigates the back-ground knowledge of wireless relay-aided communication, and discusses relative works in the literature.In research on distributive coding, we firstly established the math model of relay cooperative system, based on which we studied the proposed distributive space-time block code:TCOSTS in detail. In TCOSTS, the two terminals transmit signals to each other simultaneously to double the transmission rate. By exploiting cyclotom-ic orthogonal space-time block code (COSTBC), this scheme achieves full rate, full diversity and low decoding complexity. Also, higher diversity order is available by employing more relay nodes. Benefiting from OFDM asynchronous system architec-ture, operations implemented at relay nodes are very simple, and the scheme is tolerant of delays between relay nodes.In research on MIMO-relay precoding, we firstly studied the basic knowledge of lattice-reduction(LR), and its application in MIMO communication. Then we proposed a lattice reduction (LR) aided joint precoding design for MIMO-relay broadcast com-munication with the average bit error rate (BER) criterion. We jointly designed the signal process flow at both the base station (BS), and the relay station (RS), using the reduced basis of two-stage channel matrices. We further modified the basic precoding design with a novel shift method and a modulo method to improve the power efficiency at the BS and the RS respectively. In addition, the MMSE-SIC algorithm is employed to improve the performance of precoding.Simulation results demonstrate that, the coding scheme TCOSTS achieves full diversity order, realizes full-duplex communication and can exploit more relay nodes. The series of LR-aided precoding achieves higher diversity order compared to tradi-tional precoding, and hence achieves higher communication reliability.