EVM based rate maximized relay selection for cooperative cognitive radio networks

Abstract

Cooperative relaying being a novel technique in cognitive radio (CR) communications promises enhanced performance for secondary users (SU) by exploiting spatial diversity. This paper proposes a cooperative framework for the rate maximized relay selection (RRS) based on error vector magnitude (EVM). EVM is the measure of error vector between received constellation points to the ideal ones. The problem is transformed to convex optimization (CO) problem for maximizing the capacity for both primary user (PU) and SU network in a interweave communication model. Simulation result reveals that PU can achieve higher capacity with cooperative relaying compared to the direct transmission and energy constraint of the cognitive radio network (CRN) is met by implementing RRS algorithm. Energy efficiency is improved up to 19% more than the conventional schemes. Furthermore, PU provides the opportunistic time gain (OTG) for those SU’s that act as relay for its transmission.