认知协作多址接入方法.pdfVIP

摘要 随着手持无线终端设备的广泛使用，人们对数据传输速率的要求越来越高， 对频谱资源的需求也越来越大，学者们认为发展认知网络可以解决频谱资源稀缺 的问题。在认知网络中，非授权次用户可以通过检测频谱空洞机会式的使用授权 的空闲频段，提高频谱利用率，而协作通信可以通过共享天线的方式提高无线传 输速率。可以看出，认知和协作技术有着天然的互补特性，次级用户使用协作通 信，通过缩短主用户的传输时间可以进一步提高主用户的服务质量，同时自身也 获得更多的信道使用机会，从而进一步提升了次级用户的服务质量。 本文将协作技术应用到认知无线网络中，设计了一种应用于MAC （Multiple Access Control ）层的认知协作多址接入方法，基本思想是次级用户通过中继主用 户的数据来提高主用户的传输性能，协作成功后，作为回报，主用户允许次用户 占用信道进行一次自身业务的传输，提高协作用户的服务质量，从而使得次级用 户能够承载更多的业务类型。最后利用OPNET 仿真软件对本方法进行了仿真，通 过仿真验证了该协议相比于其它协议带来的性能提升。 关键词：认知网络 协作通信 多址接入协议 Abstract With the widely used of wireless hand-held terminals, human has a huge and growing demand of data transmission rate and spectrum resource. The researchers consider that developing Cognitive Radio (CR) networks is a good method to address spectrum scarcity problem. In CR networks, by detecting particular spectrum holes and jumping into them rapidly, the CR users can share the spectrum with the primary user and improve the spectrum utilization significantly. Cooperative communication enables single antenna terminals to share their antennas to improve the data transmission rate. So, cognitive and cooperative technology can be combined perfectly. CR users use cooperation to reduce the transmission time to improve QoS of PUs and CR users can obtain the chance to use the channel in return. In this way, it can improve the QoS of CR users. In this paper, a Cognitive Cooperative Multiple Access method is proposed, which can be used in CR network. The basic idea is that the CR users relay PU data packets to improve the QoS of PUs. If the CR user plays a successful cooperation, the CR users can occupy channel to transmit its own data in return. In this way, it can improve the QoS of CR users. The OPNET simulation results show that the throughput and delay performance will be significantly improved via