认知无线电网络中基于协作水平的协作门限与功率联合优化

Joint Optimization of Cooperative Threshold and Power Based on Cooperation Level in Cognitive Radio Networks

将协作传输技术用于认知无线电网络不仅增强了系统抗衰落能力,而且有效提高了频带利用率。但是,中继节点何时必须参与协助源节点传输信息是一个值得考虑的问题。该文提出一种基于协作水平的中继协作准则。首先给出协作水平的定义和表达式,并基于此式推导了系统平均带宽利用率和误符号率公式,然后由二者的折中得到关于协作门限和功率比的性能函数。为了使系统获得最优性能,文中采用粒子群优化算法联合优化协作门限和功率比。仿真结果表明,良好的源节点到目的节点的链路状态和尽量使用中继参与协作均有助于系统性能的最优化。

Cooperative transmission for cognitive radio networks not only enhances the anti-fading capability of the system, but also improves the bandwidth efficiency. But it’s really a worth considering issue when the relay node should assit the source node to transmit information. This paper proposes a cooperative guideline based on cooperative level. Firstly the notion of cooperative level is defined, then the expressions of system bandwidth utilization and the average symbol error rate are deduced, finally the system performance function is got through the compromise between the coorperative thresholds and power ratio. This paper also employs particle swarm optimization algorithm to solve optimal cooperative threshold and optimal power ratio. The simulation results verify the performance of the proposed scheme and show that good link state from source node to destination node and cooperative transmission by the relay node are both useful for optimizing the system performance.