Mobile Ad Hoc Networks Swan And Diffserv Service Model

With the development of information technology, the needs of transmiting multimedia traffic in Ad Hoc Networks become more and more, how to provide QoS guarantees in Ad Hoc Networks become a hotspot. As a holistic frame of the entire networks, the design of QoS model is a stringent aim. We analyse existing QoS model, then proposed DSWAN model.DSWAN model we proposed is a fully distributed and stateless model, it can support multi class differentiated services, and adapt dynamiclly characters of Ad Hoc Networks, respond the dynamiclly changing in time. The model provide differentiated services which based PHB: treat a set of traffic which have similar demands as a same service class. Different service class traffic should be dealt differently according to different QoS demands.The model includes admission control, packet scheduling, rate control, queue management and congestion control mechanisms. The model uses distributed admission control for real-time traffic for guarantee QoS, it probe the status of networks, estimate it whether can satisfy the traffic's demand, then make a decision to admit the traffic or reject it. The chief aim of packet scheduling mechanism is provide different class traffics different QoS guarantees. Different priority traffics come into different queues, then they should be scheduled by packets scheduling mechanism. We adopt WF2Q scheduling algorithm. Rate control mechanism control the departure rate of packets, we use feedback mechanism to get the status of MAC layer, adjust departure rate to adapt dynamic changings of the networks, we ues AIMD algorithm. Queue management and congestion control mechanism are uesd to avoid congestion. The node should detect early congestion, then notify the source node to reduce traffic amount before discarding packets. Simulation results show that our QoS model can satisfy the different QoS demands of different class traffic, real- time traffic experiences low delay and high packet delivery ratio under various conditions.In this paper, Chapter 1 briefly introduces the basic characteristics and QoS support in ad hoc networks. Chapter 2 introduces several existing QoS models. Chapter 3 proposes our new QoS model. Chapter 4 discusses the method of building the simulation model. Chapter 5 has a deep discussion of the simulation results. Finally, summarizes our work and proposes the improvements.