Optimizing of power allocation for two-hop DF relaying systems

This paper addresses the power allocation in two-hop decode and forward (DF) relaying systems under the total power constraint. The optimal solution is obtained by minimizing the end to end symbol error probability. A power allocation solution in a closed form is obtained by a first order Taylor development of the average error probability of each link. These results have been developed for some constellations of the modulator. This study is completed by considering the incremental (DF) relaying. To illustrate the accuracy of the proposed solution, numerical results have been carried out.