认知中继网络性能优化研究

发布时间：2018-04-11 00:39

本文选题：协作频谱感知 + 能量效率　；参考：《南京邮电大学》2014年博士论文

【摘要】：随着无线通信业务的快速增长，低效的固定频谱分配方案已经无法满足需求。采用动态的频谱接入方案是解决频谱资源匮乏但利用率低的现状的有效方法之一，认知无线电技术被认为是解决频谱资源利用率低的最佳技术，即指认知用户在不影响主用户通信的前提下，能够和主用户共享频谱资源，从而有效地提高频谱资源的利用率。在认知无线电网络中采用协作技术不仅可有效提高频谱感知的准确性和数据传输的可靠性，而且可降低认知网络的能量损耗。本文针对认知无线电网络中的协作技术的性能优化进行了深入研究，主要研究内容和成果包括： (1)研究协作感知的性能优化问题，针对认知单中继网络提出了基于最小化网络中断概率的频谱感知和数据传输的联合优化方案。首先,分析协作感知的基本原理和性能；然后,将改进的中继协作传输方案应用到认知无线电网络中；最后，以最小化认知中继网络中断概率为目标，对感知时间、融合准则门限等参数进行优化，并给出认知单中继网络中断概率的近似表达式。数学分析和仿真结果表明，存在最佳的感知时间、最佳融合准则使认知中继网络的中断性能最优，且改进的认知中继协作传输方案的中断性能和容量均优于传统的认知中继协作传输方案。协作频谱感知可有效提高认知中继网络的中断性能。 (2)研究多中继协作传输网络的中断性能优化问题，提出了三种优化方案：中继节点功率分配优化方案、基于位置的中继节点优化选择方案和基于椭圆的功率-位置联合优化方案。首先，在总的发射功率受限和已知信道参数的情况下，提出最优功率分配(Optimal Power Allocation; OPA)方法，，并给出信源和中继的最优功率分配的最优解，仿真结果表明最优功率分配方案的中断性能优于等功率分配方案。其次，在等功率分配(Equal Power Allocation; EPA)方案下，提出基于位置的中继节点优化选择方法。理论分析和仿真结果都表明存在最佳的中继位置使多中继网络的中断性能最优，且最佳中继位置位于信源和目的端中间，距离该位置越远，多中继网络的性能越差。最后，基于椭圆模型，联合优化设计中继位置和功率分配比两个参数，从而使多中继网络的中断概率最小。 (3)研究认知多中继协作传输网络的中断性能优化问题，提出频谱感知和功率分配联合优化的方案。在认知信源和认知中继总发射功率受限、认知节点发射功率最大值受限和平均干扰功率受限的约束条件下，针对认知多中继网络进行优化设计和仿真验证，分析最优感知时间、最佳功率分配、最优中继位置、认知中继个数和协作频谱感知对认知多中继网络中断性能的影响。 (4)研究认知单中继网络的吞吐量和能量效率优化问题，针对认知中继协作传输方案建立认知网络的能量效率模型，提出认知中继网络能量效率优化方案。在总的发射功率一定的情况下，认知信源和认知中继采用等功率分配方案的基础上，研究认知中继网络的吞吐量和能量效率，分析感知时间、信噪比和k out of M准则对认知网络吞吐量和能量效率的影响。仿真结果验证存在最佳感知时间、最佳信噪比、最佳融合准则门限k和最佳协作感知用户数量M使认知网络的能量效率最优。采用协作技术可提高认知网络的能量效率。
[Abstract]:With the rapid growth of wireless communication service , the low - efficiency fixed frequency spectrum allocation scheme can ' t meet the demand . The dynamic spectrum access scheme is one of the most effective methods to solve the present situation of low spectrum resources and low utilization rate . Cognitive radio technology is regarded as the best technique to solve the problem of low utilization rate of spectrum resources , that is , the cognitive user can share spectrum resources with the main user without affecting the communication of the main user , thus effectively improving the utilization rate of the spectrum resources .

In the cognitive radio network , not only the accuracy of spectrum sensing and the reliability of the data transmission can be effectively improved , but also the energy loss of the cognitive network can be reduced . In this paper , the performance optimization of cooperative technology in cognitive radio network is studied . The main research contents and achievements include :

( 1 ) To study the performance optimization problem of cooperative awareness , and propose a joint optimization scheme based on minimizing network outage probability based on the cognitive single relay network . Firstly , the basic principle and performance of cooperative awareness are analyzed .
Then , the improved relay cooperative transmission scheme is applied to the cognitive radio network ;
Finally , the parameters such as perceived time , convergence criterion threshold and the like are optimized to minimize the probability of interruption of cognitive relay network , and the approximate expression of the interrupt probability of cognitive single relay network is given . The mathematical analysis and simulation results show that there is the best perception time , the best fusion criterion makes the interrupt performance of the cognitive relay network optimal , and the improved cognitive relay cooperative transmission scheme has better interrupting performance and capacity than the traditional cognitive relay cooperative transmission scheme .

( 2 ) To study the optimization of the interrupt performance of a multi - relay cooperative transmission network , three optimization schemes are proposed : the relay node power allocation optimization scheme , the location - based relay node optimization selection scheme and the ellipse - based power - position joint optimization scheme .

( 3 ) To study the optimization problem of the interrupt performance of cognitive multi - relay cooperative transmission network , and put forward the scheme of joint optimization of spectrum sensing and power distribution . Under the condition of limited total transmission power of cognitive source and cognitive relay , limited transmission power of cognitive node and limited average interference power , the influence of optimal sensing time , optimal power allocation , optimal relay location , cognitive relay number and cooperative spectrum perception on the interrupt performance of cognitive multi - relay network is analyzed .

( 4 ) To study the throughput and energy efficiency optimization problem of cognitive single relay networks , and to establish the energy efficiency model of cognitive network based on cognitive relay cooperative transmission scheme . The influence of the cognitive relay network on the throughput and energy efficiency is proposed . The simulation results show that the optimal sensing time , the optimal SNR , the best fusion criterion threshold k and the optimal cooperative perceived user number M make the energy efficiency of the cognitive network optimal . The energy efficiency of the cognitive network can be improved by using the cooperation technology .

【学位授予单位】：南京邮电大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN925

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