Optimal energy allocation scheme for throughput enhancement in cooperative cognitive network

In this paper, a cognitive radio scenario is proposed, where secondary users are allowed to communicate concurrently with primary users provided that they do not create harmful interference to the licensed users. Here, we aim to improve the throughput of unlicensed system. For this aim, we propose a selective relay cooperative scheme to assist the secondary transmission. Moreover, an adaptive modulation is used in order to compensate the throughput loss due to the relaying. The main contribution of this work is to combine a selection scheme where only one “best” relay is chosen with an energy allocation scheme for source and relay nodes to maximize the achievable throughput under the system constraints. A variety of simulation results reveals that our proposed energy allocation method combined with adaptive modulation offers better performance compared with the classical cooperation scheme where energy resources are equally distributed over all nodes.