基于解码转发协议的认知中继网络物理层安全研究与应用

发布时间：2019-01-07 17:07

【摘要】：将协作通信网络与认知无线电组合成一类新型认知中继网络,不仅能够实现频谱共享,提高频谱利用率,而且能够拓宽无线覆盖区域、实现分级增益。协作通信中,解码转发技术是传输信号的重要手段之一。另外,为确保传输数据的可靠性,给通信系统中的终端设备提供传输路径是靠物理层实现的。然而,由于无线通信开放性以及广播性的特点,信息传输容易遭受窃听及干扰。因此,对于解码转发协议下,物理层上的认知中继网络的安全性能研究具有十分重要的意义。本文主要研究了三种不同解码转发认知中继网络系统的安全性能,并且就常见的小区通信环境出发分析其网络模型的实际应用。获得的部分研究成果如下:首先,考虑在两跳多中继解码转发认知网络中,研究了最大中继选择方案下系统的安全性能。具体而言,考虑直传链路的存在,选择合并技术被使用在信号接收端。此外,当所有的发送节点发送信号时,其发送功率受到授权用户的干扰。每一次信息传输,都能够被窃听者窃听。考虑所有信道都是经历Rayleigh衰弱,得到了安全中断概率以及非零安全容量概率。并且,求出了在高信噪比下的安全中断概率的渐近表达式来衡量系统的安全性能。分析的准确性是通过数值结果和仿真结果的比较得出的。所得结果对于优化和设计中继选择方案在认知中继网络中的应用具有指导意义。其次,在多跳解码转发认知中继网络中,研究该系统的安全性能是基于考虑主信道发射节点是多个天线且窃听者是单个天线的。具体而言,中继在单天线发射信息时,发射功率受到认知用户接收机的干扰温度影响,选择合并技术被使用在中继及信号接收端的多接收天线处。并且,窃听者能够窃听每一跳的信息。多跳系统中,只要任意一跳的信息传输发生中断,则整个系统就会发生中断。考虑所有的信道都是经历Nakagami-m衰弱,且相同的主信道、窃听信道、以及干扰信道都是独立同分布的。推导出了系统的安全中断概率,分析了中继数、天线数、以及Nakagami-m衰弱因子对系统安全中断概率的影响,以及中继数和天线数对非零安全容量概率的影响。分析的准确性是通过数值结果和仿真结果的比较得出的。所得结果对于优化多跳传输方案在认知中继网络中的应用具有指导意义。最后,对存在共信道干扰情况下的系统性能进行研究,是通过考虑中继处和多个用户处同时受到共信道干扰的影响。具体而言,机会式用户选择方案来选择出最佳用户,所有的发射节点都是配备单天线的,并且在传输信号时,其发射功率都会受到授权用户接收机的干扰影响。考虑所有信道都是经历Rayleigh衰弱,推导出了该系统模型下闭合形式的安全中断概率。分析的准确性是通过数值结果和仿真结果的比较得出的。所得结果对于优化和设计存在共信道干扰的认知中继网络的应用具有指导意义。
[Abstract]:The cooperative communication network and cognitive radio are combined into a new cognitive relay network, which can not only achieve spectrum sharing, improve spectrum efficiency, but also widen the wireless coverage area and achieve hierarchical gain. In cooperative communication, decoding and forwarding technology is one of the important means to transmit signals. In addition, in order to ensure the reliability of the data transmission, the physical layer is used to provide the transmission path to the terminal equipment in the communication system. However, due to the openness and broadcast of wireless communication, information transmission is vulnerable to eavesdropping and interference. Therefore, it is of great significance to study the security performance of cognitive relay networks in the physical layer under decoding and forwarding protocols. In this paper, the security performance of three different decoding and forwarding cognitive relay network systems is studied, and the practical application of the network model is analyzed based on the common cell communication environment. Some results obtained are as follows: firstly, the security performance of the system under the maximum relay selection scheme is studied in two-hop multi-relay decoding and forwarding cognitive networks. Specifically, considering the existence of direct link, the selective combining technique is used in the signal receiver. In addition, when all transmitting nodes transmit signals, their transmission power is interfered with by authorized users. Every transmission of information can be eavesdropped by eavesdroppers. Considering that all channels experience Rayleigh weakness, the probability of security outage and non-zero security capacity are obtained. Furthermore, the asymptotic expression of the security interruption probability in high SNR is obtained to evaluate the security performance of the system. The accuracy of the analysis is obtained by comparing the numerical results with the simulation results. The results can be used to optimize and design relay selection schemes in cognitive relay networks. Secondly, in multi-hop decoding forwarding cognitive relay networks, the security performance of the system is based on the consideration that the main channel transmitting node is multiple antennas and the eavesdropper is a single antenna. In particular, the transmission power is affected by the interference temperature of the cognitive user receiver when the relay transmits information with a single antenna, and the selection and combination technique is used at the multiple receiving antennas of the relay and the signal receiver. Moreover, eavesdroppers can eavesdrop on every hop of information. In multi-hop system, the whole system will be interrupted as long as any one-hop information transmission is interrupted. It is considered that all channels experience Nakagami-m debilitating, and the same primary channel, eavesdropping channel, and interference channel are independent and distributed. The security interrupt probability of the system is derived. The effects of relay number antenna number and Nakagami-m attenuation factor on the system security interrupt probability and the influence of relay number and antenna number on the non-zero safe capacity probability are analyzed. The accuracy of the analysis is obtained by comparing the numerical results with the simulation results. The results can be used to optimize the applications of multi-hop transmission schemes in cognitive relay networks. Finally, the performance of the system in the presence of co-channel interference is studied by considering that both relay and multiple users are affected by co-channel interference at the same time. In particular, the opportunistic user selects the best user. All transmit nodes are equipped with a single antenna, and the transmit power is affected by the interference of the authorized user receiver when transmitting the signal. Considering that all channels are subjected to Rayleigh debilitating, the closed form of the security interrupt probability is derived under the system model. The accuracy of the analysis is obtained by comparing the numerical results with the simulation results. The results are helpful to the optimization and design of cognitive relay networks with cochannel interference.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN925

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