Performance analysis of Cooperative Communication System based on Decode and Forward Relay System and Adaptive Modulation

Signal fading is one of the major concerns in wireless communication. Many different ways had been opted till now to mitigate signal fading. There is still a lot of research left to be done on signal fading. Diversity is one of the many techniques that can be used to mitigate fading. It is a burning topic nowadays. Space diversity is one of them. Based on this space diversity, many types of relay network systems, MIMO systems etc. have been developed. In these mentioned systems, the data signal is conveyed to the receiver over multiple independently fading signal paths. and then, combining these signals at the receiver appropriately, helps in removing noise. In this paper, cooperative wireless system based on decode and forward(DAF) one-way relay technique and adaptive modulation(AM) has been proposed, where BRS(best relay selection) method has been implemented. EM (Exception Maximum) algorithm is used for BRS. The proposed system has been named as EM cooperative system. Performance evaluation has been done for the proposed system over independent Nakagami-m and Rayleigh channels in terms of bit error rate (BER). System performance has been compared with direct transmission, where no algorithm has been used and BRS-DAF cooperative system [7]. Simulation has been done using MATLAB. According to the results, the proposed EM cooperative system proves to be the superior one. EM cooperative system achieves higher spectral density and the desired BER at lower SNR values as compared to the direct transmission and BRS-DAF cooperative.