认知中继网络的性能分析

发布时间：2019-04-12 19:59

【摘要】：近些年来,随着无线通信业务的发展,传统的固定频谱分配方法已经不能满足无线通信系统日益发展的需求。认知无线电(Cognitive Radio)作为一种革命性的智能频谱共享技术,可以保证通信系统的高可靠性和有效的频谱利用率,从而得到了快速发展和广泛关注。此外,由于协作传输技术可以保证系统获得近似于MIMO技术的系统性能,也得到了快速发展。当我们将协作传输技术应用在认知网络中时,一个崭新的网络——认知中继网络(Cognitive Relay Networks,CRN)随之诞生。该网络保持了认知无线电高效利用频谱的特性,以及中继传输技术的可靠性,可以在一定程度上有效地提高无线通信系统性能。本文在不同系统模型下对认知中继网络进行了系统的研究,主要取得的研究成果为：1.在共享频谱认知中继网络中,由于多中继节点的存在,系统可以获得更好的系统性能。但是,由于非理想频谱检测的存在,次级用户会对主用户的传输产生干扰。我们分别讨论了在集中式频谱检测和分布式频谱检测下,次级用户对主用户的干扰。此外我们推导了干扰概率的数学表达式。实验结果表明,在非理想频谱检测下,主用户的会受到次级用户较大的干扰。相比于分布式频谱检测而言,集中式频谱检测可以获得更好的系统性能。另外,通过增加中继节点的数量可以弥补由非理想频谱检测造成的系统性能损失。2.在频谱共享认知中继网络中,我们分别推导了非理想频谱检测和理想频谱检测下,次级用户端到端中断概率的闭式表达式。此外,我们提出中断概率差的概念去衡量两种情况下,次级用户中断概率的变化情况。实验结果表明,次级用户的中断概率会受到频谱检测的影响,但是当我们增加中继节点的数目时,可以提高系统性能。3.自适应技术可以针对系统参数的变化动态调整自身的调制方式,将自适应技术应用于认知中继网络中可以有效地提高系统的性能。我们研究了在发达转发中继策略下,在干扰受限系统中应用自适应调制技术的性能分析。我们推导了系统容量、中断概率、平均频谱效率和平均误比特率的数学表达式。实验结果表明,自适应技术可以提高系统的性能,可以有效地提高次级用户的频谱效率和降低次级用户的误比特率。
[Abstract]:In recent years, with the development of wireless communication services, the traditional fixed spectrum allocation method can no longer meet the growing needs of wireless communication systems. As a revolutionary intelligent spectrum sharing technology, cognitive radio (Cognitive Radio) can guarantee the high reliability and efficient spectrum efficiency of communication system, so it has gained rapid development and wide attention. In addition, the cooperative transmission technology can guarantee the system performance similar to that of MIMO technology, and it also has a rapid development. When we apply cooperative transmission technology to cognitive network, a brand-new network, cognitive relay network (Cognitive Relay Networks,CRN), is born. The network can improve the performance of wireless communication system to a certain extent by maintaining the characteristics of efficient spectrum utilization of cognitive radio and the reliability of relay transmission technology. In this paper, the cognitive relay network is systematically studied under different system models. The main research results are as follows: 1. In shared spectrum cognitive relay networks, due to the existence of multi-relay nodes, the system can achieve better system performance. However, due to the existence of non-ideal spectrum detection, secondary users will interfere with the transmission of primary users. We discuss the interference of secondary users to primary users under centralized spectrum detection and distributed spectrum detection respectively. In addition, we derive the mathematical expression of interference probability. The experimental results show that the primary user will be greatly disturbed by the secondary user under the non-ideal spectrum detection. Compared with distributed spectrum detection, centralized spectrum detection can achieve better system performance. In addition, the loss of system performance caused by non-ideal spectrum detection can be compensated by increasing the number of relay nodes. In spectrum sharing cognitive relay networks, closed expressions of end-to-end outage probability of secondary users under non-ideal spectrum detection and ideal spectrum detection are derived respectively. In addition, we propose the concept of outage probability difference to measure the variation of the interrupt probability of secondary users in both cases. The experimental results show that the interrupt probability of secondary users will be affected by spectrum detection, but when we increase the number of relay nodes, the system performance can be improved. 3. Adaptive technology can dynamically adjust its own modulation mode according to the change of system parameters. The application of adaptive technology to cognitive relay networks can effectively improve the performance of the system. In this paper, we study the performance analysis of adaptive modulation in interference-constrained systems under the developed forwarding relay strategy. The mathematical expressions of system capacity, interrupt probability, average spectral efficiency and average bit error rate are derived. The experimental results show that the adaptive technology can improve the performance of the system, improve the spectrum efficiency of the secondary users and reduce the bit error rate of the secondary users.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN925

【相似文献】