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Unformatted text preview: Chapter 2 THE IMPORTANT FRAMEWORK for Analyzing and Modeling the Impact of Mobility in Wireless Adhoc Networks Fan Bai and Ahmed Helmy University of Southern California,U.S.A Abstract: To study the impact of mobility on performance of Mobile Ad Hoc Network (MANET) protocols in a systematic way, we propose the IMPORTANT framework. This framework aims to evaluate the effect of different mobility models on the performance of MANET routing protocols. We propose various protocol independent metrics to capture interesting mobility characteristics of the mobility space, including spatial and temporal dependence, relative speed, geographic restrictions, link duration and path duration. In addition, a rich set of parameterized mobility models is discussed including Random Waypoint, Group Mobility, Freeway and Manhattan models. Based on these models several 'test-suite' scenarios are chosen carefully to span the mobility metric space. We demonstrate the utility of our test-suite by evaluating various MANET routing protocols, including DSR, AODV and DSDV. Our results show that the protocol performance may vary drastically across mobility models and performance rankings of protocols may vary with the mobility models used. This effect can be explained by the interaction of the mobility characteristics with the connectivity graph properties. Finally, we attempt to decompose the reactive routing protocols into mechanistic ``building blocks'' to gain a deeper insight into the performance variations across protocols in the face of mobility. Key words: mobility; modeling and analysis; routing protocols; performance evaluation; building block. 1. INTRODUCTION Mobility pattern of the Mobile Ad Hoc Network, in many previous studies, was assumed to be Random Waypoint because of its relatively simple implementation and analysis. However, in the future, MANETs are 2 Chapter 2 expected to be deployed in various different scenarios and applications having complex node mobility and connectivity dynamics. For example, in a MANET on a battlefield, the movement of the soldiers will be influenced by the commander. In a city-wide MANET, the node movement is restricted by obstacles or maps. The node mobility characteristics are very application specific. Widely varying mobility characteristics are expected to have a significant impact on the performance of the routing protocols like DSR, DSDV and AODV. As observed in the previous chapter, Random Waypoint model is a well-designed and commonly used mobility model, but we find it is insufficient to capture those characteristics including Spatial Dependence of movement among nodes, Temporal Dependence of movement of a node over time and the Geographic Restriction ....
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This note was uploaded on 05/27/2011 for the course CIS 4930 taught by Professor Staff during the Spring '08 term at University of Florida.
- Spring '08