Power Allocation Based on Duality in a Cognitive System

In a cognitive radio network based on underlay, the secondary users need to ensure that the interference to the primary users does not exceed the maximum interference tolerance. In this paper, a new algorithm of power allocation is proposed by solving optimal problem according to the theory of duality. The algorithm proposed can satisfy both the limitation of interference tolerance and the requirement of maximum utility, while the requirement of rate can also be considered. Numerical results indicate that the proposed algorithm can limit the secondary users' interference under a predefined threshold while maintaining a maximum utility of the system.