Performance study and simulation of cooperative communication systems

Abstract

The concept of multiple input multiple output (MIMO) technique improves the performance of the communication system, but it requires many antennas at the input and the output side. More antennas introduce space and power complexities in the system. Cooperative communication solves this problem by using the concept of virtual MIMO, wherein the nodes share the antennas with the neighbouring nodes that indirectly create the multiple antenna environments. It provides transmit diversity and spatial diversity. In this dissertation, we study the cooperative communication protocols and compare the performances of these protocols with the performance of traditional communication system over Additive White Gaussian Noise (AWGN) channel. Performances of cooperative protocols are studied under different fading conditions as well. Cooperative protocols are employed at the relay nodes and signals from different paths are combined at the receiver using some diversity combining techniques. In this dissertation, we have used the maximal ratio combining technique at the receiver since it gives the best performance. The performance metric considered in this project is bit error rate (BER) versus the signal-to-noise ratio (SNR). In the initial chapters, we have made a literature survey on various fading environments and different receiver combining schemes. Then we have analysed the performance of the amplify and forward (AF) and decode and forward (DF) protocols with the non-cooperative communication and the AWGN channel under different fading models. Then, we have analysed the multi-user environment and the protocols in the multiuser scenario. We have also analysed the performance of the cooperative communication system with increasing the number of relays. Through the simulation results, we can conclude that the cooperative communication has better performance than the traditional non-cooperative communication.