Joint power and rate control in cognitive network with external interference

In a cognitive network, secondary users can coexist with primary users by opportunistically exploiting the frequency bands of primary users. However, secondary users should constrain themselves to avoid interference to primary users based on the sensing technology. This paper investigates the method of increasing the spectrum efficiency in cognitive network within external interference. We consider the practical scenario with external interference, in which the wireless node can be treated as secondary users and the external interference can be considered as a primary user. Nevertheless, the ordinary relationship between the primary user and secondary users has been changed. We consider the spectrum resource allocation as a convex optimization problem which could obtain the optimal solution by adopting feasible direction method. Simulation results show that our algorithm could improve the overall throughput significantly.