Effect of relay locations in cooperative networks

Cooperative networks have been appreciated for their spatial diversity benefits in wireless communications. In this paper, we will explore the error performance of cooperative networks depending on the relay locations. Both decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols are considered with an arbitrary number of relays. To provide simple transceiver structure, differential modulation scheme is adopted for both protocols. The effect of relay locations is investigated by considering the number of relays and transmit energy including energy optimization. We show that there exists a common point where the error performance of both protocols coincides. Based on these results, we can achieve the improvement in error performance by choosing the relaying protocol depending on relay locations.