Institute for Digital Communications University of Edinburgh Edinburgh, UK H.Luo@ed.ac.uk Abstract—QoS support in MANETs is challenging because of unfavourable conditions such as a dynamic topology, limited bandwidth and energy constraints. In the past decade, significant effort has been devoted to QoS routing design which fails to obtain a one-for-all solution for MANETs. The key reason, it is believed, is the application dependent nature of routing protocols. Moreover, few researchers consider the relative importance of QoS metrics. Last but not the least, performance metrics are compared independently without any conclusion indicating the optimal protocol in a given scenario. In this paper, a QoS based performance evaluation with analytic hierarch process (AHP) is proposed and the alternative protocols are ranked according to the relative importance of QoS metrics. Keywords- MANETs; QoS; AHP;Performance evaluation
Institute for Digital Communications University of Edinburgh Edinburgh, UK Dave.Laurenson@ed.ac.uk bandwidth, while satisfying QoS constrains of applications. In addition, devices in MANETs are often battery operated and thus energy consumption must be considered. Routing in MANETs, which must react efficiently to dynamic topology and support traditional IP services, is so crucial and complicated that an IETF working group was set up. Considerable effort, therefore, has been devoted which leads to the emergence of a number of QoS routing techniques . In spite of the tremendous effort devoted to QoS routing for MANETs, the relative importance of QoS metrics, to the author’s best knowledge, is seldom considered. However, there are some applications in which relative importance of QoS metrics have to be considered in reality. For example, live video traffic regards delay and jitter as more critical than packet delivery ratio, email applications rank packet delivery ratio higher than delay. In this paper we develop an evaluation algorithm which incorporates the relative importance of different QoS metrics. Generally speaking, there are three methods to evaluate the performance of a given scheme, namely practical implementation, mathematical derivation and simulation. Results achieved by practical implementation are credible but they are scenario related and can’t be repeated. Mathematical derivation is comprehensive, but it is complicated and assumptions in the mathematical model degrade the credibility. Simulation offers the ability to evaluate multiple systems in a number of scenarios in a repeatable manner. However, just as with mathematical modelling, modelling assumptions may decrease the credibility of the results. The proposed algorithm adopts the combination of mathematical derivation and simulation. For simulation, version 2.32 of the well-known open-source software NS-2 is used. III. SIMULATION CONFIGURATIONS
In the past decades mobile traffic generated by handsets, laptops and mobile broadband gateways has been growing rapidly. For example, according to a survey by Cisco, the data communicated by mobile devices in 2010 was triple the volume of the entire global Internet traffic in 2000. This rapid growth in mobile data is forecasted to continue for the next five years with an average annual growth of 92% . The main reasons for the traffic expansion includes wide usage of mobile devices such as smartphones, iphones, laptops, etc., and a speed increase of mobile connections. The first step of ubiquitous communication is to gain access to a gateway point via last-mile access technologies. There are already several last-mile access techniques available, one of which is a mobile ad hoc network (MANET). A MANET is an autonomous system of mobile nodes which are free to move about arbitrarily. It may operate in isolation, or may have gateways to and interface with a fixed network . The requirement of...