生活中的无线设备日渐增多,且大都使用几个免费频道,它们之间产生的干扰已经成为一个不可避免的问题.认知技术的产生对于共享无线资源是重大的突破.采用这种技术,无线设备可以实时获得无线资源的使用情况,调整自身参数,以达到更好地利用无线资源,提高频谱利用率的目的.以CC1110作为无线收发站分别仿真测试了两种认知无线电协议.第一种是基于LBT(Listen before talk)策略的协议,该协议在碰撞率和信道利用率上均有不错的表现,但是只能支持单主单从的模式；第二种是基于门限策略的协议,它的碰撞率和信道利用率可以根据实际需要得到不同的性能,而且支持多主多从的模式.经过权衡,选用第二种协议作为系统实现的基础协议,并在此协议上做了一些实用性的优化,最终完成了一个带有认知功能的无线传感网的家庭健康监护系统.%Wireless applications are more and more common in our daily life. At the same time the interference among different applications becomes an inevitable problem. Cognitive radio (CR) technique is a great breakthrough in sharing wireless resources. With CR, wireless equipments can update the parameters according to real time information about the wireless resources in order to achieve higher efficiency. In this paper, use Matlab to simulate two different cognitive techniques. One is Probability-based, in which second user decides sending data packages or sensing the channel according to the prediction of the probability that the channel will be free. The other one is Time-based, which controls the time period second user used to send data packages. Then compare the utilities and collision probabilities , to find the more applicable one. After further modifications of the chosen technique, use it to build up a simple domestic medical system with CC1110.
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