认知无线电系统中检测时间和检测周期的联合优化

Joint Optimization of Sensing Period and Sensing Interval in Cognitive Radio Networks

认知无线电中频谱感知是实现动态频谱接入的重要前提和核心环节,检测时间和检测周期是频谱感知算法中非常重要的两个参数,它们的取值直接影响了频谱空穴的检测概率和主次用户的碰撞概率。从最大化次用户的平均频谱利用率出发,在目标检测概率的限制下,提出了检测时间和检测周期联合优化的二维单目标最优化问题,基于能量检测,建立了联合优化的数学模型,并进行了理论推导和分析,找到了使认知系统频谱利用率最大的检测时间和检测周期求解方法。通过与仿真结果的比较,验证了理论推导的正确性。仿真结果表明,次用户频谱利用率分别随检测时间及检测周期的增加先增大后减小,存在使次用户频谱利用率最大的最优值。

Sensing/monitoring of spectrum-availability has been identified as a key requirement for dynamic spectrum allocation in cognitive radio networks（CRNs）.Sensing duration and sensing interval are two significant parameters associated with spectrum sensing,which directly affect the detection probability of available spectrum and the collision probability of the primary and secondary users.In this paper,a two-dimensional single-objective optimization problem of sensing period and sensing interval is proposed under the constraint that the primary users are sufficiently protected.Based on the energy detection sensing algorithm,the mathematical model of joint optimization is given.We present the approach of solving the sensing period and sensing interval optimization problem which makes the maximum utilization of spectrum for the secondary system.Simulation results show that the spectrum utilization increases at first and decreases then as the sensing interval and the sensing period increase.So there exists a set of optimal values of sensing interval and sensing period to maximize the spectrum utilization of the cognitive networks.