Adaptive Unbalanced Spectrum Usage and Power Allocation for Cognitive OFDM-Based Relay Networks

A cognitive OFDM-based relay network is considered in this paper. Communication between any node pair occurs on a spectrum pool of OFDM subcarriers where the subcarriers are not used by primary users. Therefore, the available spectrum for different transmitter-receiver pairs is distinct due to their location difference and so on. To satisfy different traffic demand and improve system performance, an adaptive unbalanced spectrum usage scheme is proposed. Moreover, to obtain the system maximum throughput, the optimal power allocation problem is formulated under the total power constraint based on the presented spectrum usage scheme. Simulation results show the proposed scheme is very effective.