Spectrum Sharing Algorithm for Downlink Cognitive Radio Systems
认知无线电下行链路中的频谱共享算法

A spectrum sharing algorithm for downlink cognitive radio systems is proposed to maximize the system capacity under total transmission power and interference constraints. Interference to the licensed users is analyzed, and a method to set interference constraint is given accordingly. Based on the interference constraint, the maximum system capacity is achieved by two steps: first the optimal subcarrier allocation is derived by the maximum channel signal to interference plus noise ratio rule; then transmission power is optimally allocated by the proposed double water-filling method. Simulation results show this algorithm can provide significant capacity gain comparing with the conventional spectrum sharing algorithms.