Iterative Source and Relay Precoder Design for Non-Regenerative MIMO Cognitive Relay Systems

• Published in: IEEE transactions on communications Vol. 63; no. 10; pp. 3497 - 3510
• Main Authors: Budhathoki, Krishna Ram, Maleki, Mehdi, Bahrami, Hamid Reza
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: achievable throughput; Antennas; Cognitive radio; Cognitive radio (CR); Design engineering; Frame relay; Interference constraints; Iterative methods; Joints; Mathematical models; multi-input multi-output (MIMO); non-regenerative relaying; Optimization; precoder design; Relay; Relay systems; Relaying; Relays; Resource management; Throughput; non-regenerative relaying; multi-input multi-output (MIMO); precoder design; achievable throughput; Cognitive radio (CR)
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2015.2402277

The problem of joint precoder design for the source and relay nodes of a cooperative cognitive radio (CR) system is investigated. We consider a non-regenerative relaying secondary CR system with underlay spectrum sharing methodology with the primary users. Based on an expression for the achievable throughput of secondary system, we develop an optimization problem to maximize the throughput subject to power constraints at the secondary source and relay, and an interference power constraint at the primary due to secondary source and relay transmission. First, we derive the structure of each of the relay and source precoding matrices separately assuming the other is known. Then, we propose an iterative technique to jointly design the source and relay precoding matrices. The results are also extended to the case where the direct source-destination link is available. Through simulation, we demonstrate the effectiveness of our proposed approach in improving the achievable throughput, and compare its performance with that of numerical optimization, source only precoding, relay only precoding, and a naive amplify-and-forward method.