Cooperative Beamforming in Cognitive Radio Relay Networks Using Amplify-and-Forward Relaying Technique

TL;DR

This paper introduces a novel relay beamforming method for cognitive radio networks using amplify-and-forward relaying, optimizing signal quality while limiting interference, and demonstrates its effectiveness through simulations.

Contribution

A new beamforming approach for AF relay networks in cognitive radio systems, formulated as an SOCP problem and solved efficiently with bisection search.

Findings

Performance improves with larger relay networks.

Optimized beamforming enhances secondary receiver SINR.

Interference constraints effectively protect primary receivers.

Abstract

In this work, we study the problem of relay beamforming for an underlay cognitive radio relay network using amplify-and-forward (AF) relaying technique. We consider a cognitive radio network consisting of single primary and multiple secondary transmitters/receivers. In addition, there are several relay nodes that help both primary and secondary networks. We propose a new beamforming method for relays' transmission, in which the beamforming weights at the relays are the solution of an optimization problem. The objective of the optimization problem is maximizing the worst case signal to interference plus noise ratio (SINR) at the secondary receivers (SU-RX) and the constraints are the interference power on the primary receiver (PU-RX) and the total transmitted power of the relay nodes. We show that the beamforming problem can be reformulated as a second order cone programming (SOCP) problem and solved by the bisection search method. Our simulation results show the performance improvement as a function of the size and the power of the relay network.