【作者】 刘兵伟；

【导师】 沈明玉；

【作者基本信息】 合肥工业大学 ， 计算机应用技术， 2009， 硕士

【摘要】 介质访问控制(Medium Access Control,MAC)协议是Ad Hoc网络协议体系结构中的重要组成部分,主要用于协调节点访问共享信道,MAC协议能否高效地利用有限的无线资源对Ad Hoc网络的性能起决定性作用。另外随着各类多媒体业务和实时业务的普及和推广,要求网络在带宽、时延等方面提供保证,Ad Hoc网络的QoS问题已经成为当前研究的一个新的热点。在Ad Hoc网络中MAC层的功能是控制节点的报文传输,对无线媒体的占用,保证网络的整体性能,MAC子层处在协议栈的下层,是所有数据报文和控制消息在无线信道上进行发送和接收的直接控制者,它能否高效地使用无线信道是上层各种协议和机制所提供的QoS能否得到最终保障的一个关键因素。本文从Ad Hoc网络的MAC协议入手,分析各种不同的MAC协议在AdHoc网络上的表现,将双信道传输与改进的握手协议相结合,设计实现了一个适用于多跳Ad Hoc网络的双信道MAC协议(DCMAC)。节点根据收到的不同控制包,在控制信道和数据信道中采用三种不同的预留方法,不仅解决了隐藏接收终端在单信道网络中不能同时接收数据的问题,还解决了暴露发送终端不能同时发送数据的问题,实现了数据信道的同时传输。通过性能分析可以看出,DCMAC协议的吞吐量属性比基于RTS/CTS的协议明显提高。本文分析了现有的Ad Hoc网络MAC层的QoS保障机制,针对目前基于区分服务的方法,结合802.11e的EDCF机制和改进的退避方法,利用双信道解决QoS保障问题。仿真结果表明,该方案能有效提高吞吐量和实时业务的服务质量。更多还原

【Abstract】 Medium Access Control (MAC) protocol is an important part in the network protocol stack of Ad Hoc network, and it is mainly used to coordinate nodes to access the shared wireless channel. Whether MAC protocol can utilize the limited wireless resource plays a crucial role in Ad Hoc network performance. With the development of various multimedia services and real-time business, the network bandwidth and delay are required to provide a guarantee, the QoS has become a current research question as a new hot spot. At Ad Hoc network, the functions of MAC layer are that controlling node packet transmission, occupying wireless media and ensuring the overall performance of the network. MAC layer locates on the lower layer of protocol stack, controls packets to be sent and received in the channel, efficiently using the wireless channel is a key factor for that the upper range of protocol and mechanisms get Final protection.On the basis of the MAC protocol, the performance of a variety of MAC protocol is analyzed in this dissertation for Ad Hoc network, Dual-channel and improved handshakes are integrated, design a medium access control (MAC) protocol called DCMAC (dual-channel MAC) for ad hoc networks. Based on receiving control packets, nodes use 3 different network allocation vectors (NAV) in control channel or data channel. The hidden terminal can receive data simultaneously and the exposed terminal can also transmit data. As can be seen through the performance analysis, a comparison with a RTS/CTS based protocol is given. The results show that the DCMAC protocol can improve the throughput. A detailed analysis is proposed on how to guarantee the quality of service at MAC layer in Ad Hoc network. As the technique based on DiffServ, combined the EDCF mechanism of 802.11e and the improved backoff method, using dual-channel to solve the QoS guarantee problem. The result of simulation proves the scheme can improve the throughput of network and the quality of serve for real-time traffic.更多还原