Cooperative communication over fading channel with multiple relays

The aim of this thesisis to analyze and develop cooperative communication techniques over fading channel with the aid of multiple relays. The initial researchin this studyis the performance evaluation of cooperation schemes based one way relaying network for amplify and forward (AF) and decode and forward (DF) methods. For multiple relays, cooperation schemes areanalyzed for fading channels. It is shown that cooperation scheme which has multiple relays has better performance than the scheme has single relay.The second research in this studyis the performance evaluation of on the two way relaying network and optimal beamforming schemes based two way relaying network for AF and DF methods. We propose an opportunistic relaying for fading channels and relay selection algorithms for AF and DF methods at the same time. In the proposed schemes, firstly optimal beamforming values are founded and compared with a single best relayselected by different algorithms. Results depictthat beamforming achieves a better performance compared to the opportunistic beamforming.The finalresearch directionis on applying relay stations (RS) with multiple antennasto provide communication between two nodesintheorthogonal frequency division multiplexing (OFDM) based two way relay channel. This scheme entails the channel state information only at RS.In this study, it is aimed to Spatial filtering isimplemented at the RS using ZF criterion. Simulations are realized in presence of frequency selective environment. The simulation results show that using of multiple RS is better than using of single RSfor DF method.Keywords:Cooperative communications, two-way relaying, relay selection, beamforming, opportunistic relaying