Non-orthogonal relaying system for improving network coding performance in butterfly network

Abstract

In cooperative wireless communication, for the last decade, Network Coding has been emerging as a means to improve throughput, specifically in multicast scenarios. Many researchers have investigated technique for performance enhancement in Network Coding scheme. In this thesis, Non-Orthogonal Decode-and-Forward scheme as one solution is suggested in a butterfly network. Generally, conventional Network Coding in a butterfly network consists of the three phases. In first and second phase, two sources transmit both data to a relay and each destinations. In third phase, network-coded data is forwarded from relay to both destination I and destination II. However, both sources remain silent in the phase. Therefore, the Non-Orthogonal Decode-and-Forward scheme, utilizing the unused resource(both sources) in Network Coding scheme, is applied and analyzed to be effective for performance enhancement. In this thesis, average throughput of conventional Network Coding and proposed scheme is derived for analysis. Finally, Simulation results validate this analysis and shows that performance of the proposed scheme is better than the conventional Network Coding in high SNR region of direct links in terms of average throughput. The proposed scheme is analyzed by average throughput according to power allocation. And then, effect of loop interference in some specific power allocation of the proposed system is considered.