一种基于轮询的认知无线网络频谱分配机制及性能分析

A polling based spectrum allocation mechanism in cognitive radio networks and performance evaluation

在认知无线网络中,认知用户机会式地占有授权用户暂时不使用的频谱,从而提高频谱的利用率。在采用集中式频谱分配机制时,认知用户对空闲频谱的使用由中央控制器协调和管理。由于授权用户对频谱的使用具有抢占优先权,使得认知用户的数据传输可能被中断。考虑认知用户对空闲频谱使用的公平性,提出一种基于纯限量轮询策略的频谱分配机制,并建立具有传输中断的离散时间纯限量多重休假排队模型。使用再生循环法,对所提出的频谱分配机制进行性能分析,给出平均响应时间、吞吐量、频谱切换率和频谱有效利用率的表达式。通过数值实验和系统仿真,分析系统性能指标对系统负载的依赖关系,并给出授权用户业务量的优化方案。

In cognitive radio networks,to improve the spectrum utility,the cognitive users use the spectrum unoccupied by the primary users to transmit packets.In a centralized spectrum allocation scheme,a central scheduler coordinates and manages the spectrum allocation.The primary users have the preemptive priority on using the spectrum,so the packet transmission of the cognitive radio users may be interrupted.Considering the fairness of spectrum usage,a novel spectrum allocation mechanism based on pure limited polling strategy is proposed,and a discrete-time pure limited queueing system with multiple vacations and interrupted service is built.By applying the recycling method,the performance of the proposed spectrum allocation mechanism is analyzed,and the formulas for the performance measures,such as the average response time,the throughput,the spectrum switching ratio and the spectrum utilization are given.Numerical results with analysis and simulation are provided to demonstrate the dependency relationships between the system performance measures and the traffic load of the cognitive radio users.Moreover,the optimal design for the traffic load of the primary users is given.