【作者】 李雪冰；

【导师】 秦阳；

【作者基本信息】 哈尔滨工业大学 ， 计算机科学与技术， 2010， 硕士

【摘要】 多输入多输出(MIMO)系统也叫多进多出系统被认为是下一代高速通信网络中的一个关键技术,它的最大特点是可以在不增加带宽的前提下成倍的提高网络吞吐量。对于多进多出系统的研究可以改变目前人们对无线接入速率低的问题,因此,对多进多出系统的研究逐渐成为了无线网络研究的热点。本文提出了一种新的适用于多天线系统的MAC层协议DACW(动态调整CTS等待时间)协议,该协议的主要特点是通过动态改变CTS的等待时间来改变CTS优先级,增加了RTS与CTS之间的竞争,使得时槽的使用手段变得更加灵活。DACW协议仍然沿用PRP协议的一部分思想,就是使传输请求是非独立的思想,并且在发送数据之前首先要发送RTS/CTS请求,请求成功以后才可以发送。改进后的协议在某些拓扑结构下对PRP协议的性能做出了改进,并且在PRP协议发生冲突的拓扑下进行了更正;在PRP协议性能较高的拓扑结构下保证与PRP协议一致。因此,经过改进以后,整体的吞吐量比PRP协议有所提高。提出改进方案以后,首先通过MATLAB对两种协议进行定量的比较,观察两种协议吞吐量曲线的趋势,看性能是否有所提高。接着,在QualNet上对MIMA、PRP和DACW三种协议进行仿真,通过搭建多种仿真的网络场景来测试协议的性能,并绘制出最终的吞吐量曲线并对比PRP协议和DACW协议的性能。性能评价方案主要是通过在网络层处理能力一定的前提下,不断地增加发包的间隔,使得MAC层达到饱和状态,通过这种饱和状态下的MAC层的发包数量来计算网络吞吐量。更多还原

【Abstract】 MIMO system is considered to be a key technology of high-speed communication networks of next generation. Its biggest feature is the premise of not increasing the bandwidth to improve network throughput under the double. Research of MIMO system can change the current rate of people on the problem of low access.Therefore, the multiple input and multiple output system has become a research hotspot in wireless networks. This paper presents a new MAC protocol which is adapt to multi-antenna system. DACW(Dynamic adjust CTS Waiting time) protocol, the main feature of this protocol is to change the priority of CTS dynamically which increase the contention between RTS and CTS, so that the usability of slot is more flexible. DACW protocol also uses part of the thought of PRP protocol that requirements are non-independent. It should transmit RTS first, if the requirement success then it can transmit data. After improved, throughput of the total network has increased.First we use MATLAB to simulate two protocols and then compare the performance curves. After that we use QualNet to simulate MIMA, PRP and DACW protocols. We also set up lots of scenarios to test the performance of the three protocols and compare the performance curves.Performance evaluation plan is that we assume that the network layer ability is not change. Then we continue to decrease the intervals of packet transmitting, making the MAC layer saturated, so that we can calculate the number of packet transmitting to compare the network throughput between the three protocols.更多还原