Optimal Power Allocation Algorithm for OFDM-Based Decode-and-Forward Dual-Hop Cognitive Systems

Relayed transmission is a promising technique to increase coverage and achievable capacity of the communication systems. A cognitive OFDM-based decode-and-forward (DF) cooperative relay network is considered in this paper. The objective of the problem is to maximize the capacity of the cognitive radio (CR) system while guaranteeing that the interference introduced to the primary system is below the prescribed interference temperature limit. The optimal power allocation in the source and the relay is presented and a low computational complexity near-optimal algorithm is proposed. The simulation results confirm the efficiency of the proposed algorithm.