Research And Implementation Of Wireless Ad Hoc Networks QoS Service Model

With the rapid development of the network technology in mobil Ad Hoc network, its application areas and service models are expanding, so providing QoS in Ad Hoc network has become an important research subject. As a holistic frame of the entire networks, the design of QoS model is a key issue to solve. Recently, several QoS models for Ad Hoc networks have been designed out such as SWAN, DiffServ and FQMM. However, SWAN only divided the service types into best effort flow and real time flow. DiffServ does not involve the dynamics of wireless networks. At the same time, the Ad Hoc network is difficult to distinguish edge nodes and core nodes. FQMM model is only applicable to small-scale Ad Hoc Networks. we analyze several existing QoS models and design out a new QoS model――BSSM(Bandwidth-Sensing Service Model).BSSM model proposed in this paper can differentiate QoS services with multiple service types and priorities, and is able to adapt to the mobile Ad Hoc networks according to available bandwidth in time to adjust algorithms. BSSM model divided into eight priorities and four service types. Different priorities and different service type traffic can be treated distinguishing, to meet their different QoS requirements.BSSM model contains five basic modules: available bandwidth estimation module, admission control module, packet scheduling module, queue management module and congestion control module. Available bandwidth estimation module dynamic monitors the network status of node and neighbors, to estimate the available bandwidth. Admission control module judges whether real-time business services to meet the quality requirements and decide whether or not to permit admission of real-time business, by judging the available bandwidth provided by the available bandwidth estimation module. Packet scheduling module uses scheduling based on priority levels and service types, to meet the different QoS requirements of different priorities and different service type traffic. Queue management module and congestion control module try to avoid network congestion. When the source node detects the available bandwidth shortage, it can reduce rate of sending before the congestion aggravation. Through the result of the experiment, BSSM model has shown a good performance in a variety of experiment scenes and met the different QoS requirements of different priorities and different service type traffic.In this paper, Chapter 1 introduces the basic characteristics and QoS architecture in Ad Hoc networks. Chapter 1 also describes the difficulties of QoS in Ad Hoc network. Chapter 2 introduces and analyzes several typical QoS models and some basic algorithms in admission control, packet scheduling and queue management. Chapter 3 presents the new QoS model――BSSM in detail. Chapter 4 introduces the method and program module of implementation BSSM model in Linux system, as well as the HOOK function used in the procedures. Chapter 5 has a systematical analysis in the simulation results of the new QoS model. Finally, Chapter 6 concludes our work and proposes the improvements.