The Research Of QoS Key Technologies On Mobile Ad Hoc Network

With the characteristic of node's movability, without infrastructure and self-organization, MANET is a complex distributed and flexible network and is attached more and more importance by the industry and scientific research field. Specifically, for extending the existing network covering area and decreasing signal fading, the combination of MANET and cellular mobile telecommunication network is an attractive research filed that many people devote to and is recognized as the future network development trend.However, for the limitation of radio frequency resources, data rate, battery energy and frequent movement, MANET faces up to various challenges to be spread wildly. In addition, with the rapid development of multi-media technology, it's urgent for MANET to support Quality of Service (QoS). Therefore, aiming at DiffServ model, multipath routing protocol, MPLS, this article puts forward to several key techniques to guarantee the QoS respectively and provides network simulation results based on OPNET simulation platform. This article includes six chapters, and they are: The first chapter introduces Ad Hoc network's basic knowledge, historical development, key technology and characteristic.The second chapter analyses the classification of QoS technology. The characteristic and applicable ranges of the available QoS models are also presented.Comparing with IntServ model and taking bandwidth and expansibility into account, the third chapter puts forward that DiffServ model is more compatible to Ad Hoc network. Therefore, based on classical IP layer DiffServ model of wired network, this chapter establishes the DiffServ model based on Ad Hoc network. Meanwhile, further research of wireless access algorithm found that transforming the relatively equal mechanism of MAC layer allocating resources can improve wireless DiffServ performance. The combination of two layers can guarantee some services with high priority more efficiently, such as voice and multimedia services and so on.In order to assure the bandwidth, the delay, the jittering of delay and the packet delivery, the existing QoS routing techniques always pay attention to local bandwidth estimation and resource reservation. However, for the reason of weakness of resource reservation on expansibility, it's not suitable to be applied in Ad Hoc network of which resources is extreme precious. Accordingly, from the viewpoint of improving route robust and decreasing delay, the fourth chapter advances multipath routing protocol to guarantee QoS parameters mentioned above.MPLS (multiple protocol label switching) is a outstanding technique used in wired network and enjoys the extreme advantage in fast forwarding, traffic engineering, QoS and VPN. The fifth chapter combines the MPLS of 2.5 layer and Ad Hoc technology, which could improve the shortage of the Ad Hoc network.Final chapter concludes this article and some future works are discussed.