Performance Analysis Of Relay Selection With Decode And Forward Model

The primary challenge in communication over wireless networks, unlike wire line networks, is the existence of interference and channel variations (fading). Path loss and fading are unique features of wireless propagation, respectively referring to the rapid decay in the received signal envelop with distance and to the random fades present in the received signal power. Multi hopping and diversity are the corresponding countermeasures entailing the division of a longer link into shorter links and the provision of diversified information bearing signal replicas at the destinations. Taking advantage of this broadcasting nature in wireless transmission, the cooperating nodes act as relays and help the source node transmit its data to the destination.Relay selection is an important factor in cooperative communication. In this thesis the BER performance of relay selection with decode and forward using path loss model is analyzed. The bit error rate performance of Rayleigh fading channel is compared with Additive white Gaussian noise channel. Two parameters, distance and power are used for relay selection. The relay can be selected varying the distance and power between the source and the destination. The effect of power and distance of relay from the source is analyzed using free space path model.At the end the Shannon's capacity theorem is used to simulate the capacity of the channel. Increasing the power, the capacity of the system also increases and reached to optimal level. As by increasing the power the performance is better but the capacity cannot be increase after some specific value. But higher power can increase the signal coverage area.