Robust Power Control Algorithm Based on Probabilistic Constraints in Cognitive Radio Networks

When the channel fading is assumed to be fast fading and the transient variation of the channel gain is considered, the signal-to-interference noise ratio (SINR, Signal to Interference plus Noise Ratio) of the secondary user changes with the channel gain. This will cause some secondary users to fail to get the SINR, required for normal communication if the secondary user transmit power is enhanced, although it meets the secondary user communication requirements, at the same time, the interference to the primary user exceeds the interference threshold. Affects the normal communication of the primary user. In order to solve this problem, a robust power control algorithm based on probabilistic constraints is proposed. In this paper, the average SINR model is transformed into the uncertain distribution model by introducing the uncertain parameters satisfying the exponential distribution. In this paper, the SINR probability density functions of primary and secondary users are given, and the probabilistic constraints are transformed into deterministic constraints. In order to solve the secondary user transmit power, the interference temperature of the primary user is taken as the constraint condition, and the complete iterative algorithm is used to realize the fast convergence of the secondary user transmit power. Since the protection of the primary user will lead to the damage of the interests of some secondary users, this chapter introduces the admission control, according to the highest degree of dissatisfaction first eliminate the mode of the sub-users who do not meet the requirements of communication to implement admission control. The number of secondary users meeting the communication condition in the system is increased. The simulation results show that the algorithm can quickly identify the secondary users who do not meet the communication conditions, and avoid the excessive elimination of the secondary users, increase the number of secondary users who can communicate normally, and increase the total throughput of the system.