基于分簇结构的车联网认知频谱分配机制

Cognitive Spectrum Allocation Mechanism in Internet of Vehicles Based on Clustering Structure

目前的频谱分配机制主要采用固定分配模式,随着无线网络的快速发展,有限的频谱资源已经难以满足通信需求,因此采用认知无线电技术解决频谱资源短缺问题是一种有效的解决方案,而认知频谱的分配是提高频谱利用率的关键技术。文中基于车联网这个特定应用来研究认知频谱的分配机制,提出了一种基于分簇结构的三步式认知频谱分配机制,其中空闲频谱拥有者为授权用户,路口固定单元为簇首节点,认知车辆为簇内普通节点。该认知频谱分配机制的第一步是判断网络当前的负载状态,只有当重载或超重载时才启动认知频谱机制;第二步是采用基于交通拥堵优先级定价的频谱分配算法进行授权用户与簇首节点间的频谱分配,在授权用户获取一定收益的同时,保证簇首总频谱效用最大;第三步是采用基于消息优先级的均衡价格的频谱分配算法进行簇内用户的频谱分配,利用簇首与簇内不同节点的效用函数,推导簇内供求函数,同时结合市场均衡原理,求出最佳簇内频谱单价。从分配的频谱数和频谱收益两方面分析仿真结果可知,簇内采用的基于消息优先级的均衡价格的频谱分配算法优于无优先级的,簇间采用的基于交通拥堵优先级定价的频谱分配算法优于平均分配的。仿真结果充分表明,采用所提出的认知频谱分配机制分配的频谱数基本符合实际用户的频谱需求量,提高了频谱收益和频谱利用率,保证了安全消息的优先传输。

Nowadays,the spectrum allocation mechanism adopts a fixed allocation mode .With the rapid development of wireless network,it is difficult for limited spectrum resources to meet the communication requirements. Therefore,it is an effective solution to use cognitive radio technology to solve the shortage of spectrum resources.Cognitive spectrum allocation is a key technology to improve spectrum utilization.Based on the specific application of Internet of Vehicles,this paper studied the allocation mechanism of cognitive spectrum,and proposed a three-step cognitive spectrum allocation mechanism based on clustering structure,in which the idle spectrum owner is primary user,the intersection fixed unit is cluster head node,and the cognitive vehicle is intra-cluster ordinarynode .The first step of this mechanism is to judge the current load status of the network.Only when the network load status is overloaded or super heavy load,the cognitive spectrum mechanism will be activated.In the second step,the spectrum allocation algorithm based on traffic congestion priority pricing is adopted for the spectrum allocation between the primary user and the cluster head node,so as to ensure that the total spectrum utility of the cluster head is maximized while the primary user obtains certain income.In the third step,the equalization price spectrum allocation algorithm based on message priority is utilized for the spectrum allocation of the nodes in the cluster,the utility function of the cluster head and the nodes in the cluster is used to derive the supply and demand functions within the cluster,and the market equilibrium principle is used to find the optimal unit price of the spectrum within the cluster.The simulation results are analyzed in terms of the allocated spectrum number and spectrum benefit,and the results demonstrate that the spectrum allocation algorithm based on message priority is better than the non- priority,and the spectrum allocation algorithm based on traffic congestion priority pricing between clusters is better than the average allocation.The results also show that the proposed cognitive spectrum allocation mechanism basically meets the spectrum demands of actual users ,improves spectrum revenue and spectrum utilization,and ensures the priority transmission of security messages.