International Journal of Computer Applications (0975 – 8887) Volume 43– No.8, April 2012 13 BSTRACT Mobile Ad hoc Networks are infrastructure less networks. Nodes themselves do routing and forwarding functions. Topology changes due to node movement. Frequent changes in topology leads to more route breaks. This in turn leads to reduction in Packet delivery Ratio (PDR). It is desired that routing protocols should select stable paths i.e. which are less likely to break. In this work, we have implemented one such protocol. Different mobility patterns lead to different performance of routing protocols. We have evaluated stable routing protocol under following mobility models: Random WayPoint, Manhattan Model, Reference Point Group Mobility and Gauss Markov Model. Performance measures of interest are Packet Delivery Ratio (PDR) and routing overhead. It is found that RPGM results in better PDR and lowest routing overhead compared to other models. Manhattan model results in lowest PDR and highest routing overhead. Keywords Mobile Ad-hoc Network, Topology, AODV 1. INTRODUCTION A mobile ad-hoc network (MANET) is an infrastructure-less network where mobile nodes move randomly and therefore topology of the network changes dynamically. The routing protocols should be able to cope with dynamic environment. In MANET, routing protocol is divided into two categories: (i) proactive protocols, where each node continuously maintains routes to all possible destinations. For e.g., DSDV (Destination Sequence Distance Vector) routing algorithm. (ii) Reactive routing protocols, where each node forms path only when it is needed. For e.g., DSR (Dynamic Source Routing), AODV (Ad hoc On Demand Distance Vector) [1] Routing. (iii) Hybrid Routing Algorithms like ZRP (Zone Routing Protocol). It is desirable that routes found should remain valid for longer duration. If routes break often, more packets are lost. Also router discovery exercise will be repeated frequently, leading to more routing overhead. Basic routing protocols don‟t find stable routes. They generally select routes based on hop count, but not expected lifetime of the route. In literature, many protocols are proposed which modify basic routing protocols to find stable routes. In [2], one such stable routing protocol is proposed. It modifies AODV protocol. In section VI, we have explained that protocol in detail. Mobility is the main cause of topology change. Change in topology has an impact on performance of routing protocol. Different application scenarios have different mobility patterns. For example group mobility in military environment. In city or urban environment, nodes move according to road map i.e. have geographical restrictions. Different mobility patterns have different impact on routing performance. Many authors have studied routing performance of basic routing under different mobility models. In this work, we aim to evaluate one stable protocol, under different mobility models. The paper is organized as follows. In section 2 gives idea of related work. Section 3 describes mobility models. Section 4 describes working of stable AODV routing protocol. Section 5 presents the simulation results and conclusion is presented in Section 6. References are listed at the end of paper. 1. 2. RELATED WORK To improve the performance of routing protocols in mobile ad-hoc network, many modified routing algorithms have been proposed by many authors. Earlier, routing algorithms stability was defined based on how link is modified between two nodes- called link stability based routing. To minimize route breakage, it is important to find out a route which endures longer lifetime. In [3], authors have studied the effect of node mobility on the performance of DSR and DSDV routing protocols. They have used following four mobility models: random way-point, group mobility, freeway model and manhattan models. Mohit Ranjan Panda, Manas Ranjan Mishra [4] have designed stable throughput and flow admission control routing algorithm to provide stable transmission of flow operations in mobile ad hoc networks. In [5], authors have proposed stability based routing. This algorithm finds stable route based on link expiration time. Using mobility information and updated value of link expiration time stable routes are determined. Mohamed Amine Abid and Abdelfettah Belghith have considered quality of service routing problem in [6]. They considered constraints to represent path length, number of hops and path stability. They proposed algorithm to solve quality of service problems. Xi Hu, Jinkuan Wang, Cuirong Wang have proposed their link stability prediction based routing algorithm in [7]. To determine stable link, their algorithm uses relative motion and distance between two neighbour nodes to determine mean link duration and based on that link stability is predicted. In [8], authors have shown effect of mobility patterns on the performance of AODV routing protocol. They have used following three mobility models: random way point, random walk with reflections and random walk with wrapping. In [9], link stability based algorithm is presented that performs well in condition of high or low mobility and high or low node density Performance Evaluation of Stable AODV Routing Protocol under Different Mobility Models Krunal Patel Department of Information Technology A. D. Patel Institute of Technology New V.V. Nagar, India Tejas Vasavada Department of Information Technology A. D. Patel Institute of Technology New V.V. Nagar, India