MOBILITY MODELS FOR DELAY TOLERANT NETWORK : A SURVEY <s> Shortest Path-Based Map Mobility Model (SPBMM) <s> A mobile ad hoc network (MANET) is a collection of wireless mobile nodes forming a temporary network without using any existing infrastructure. Since not many MANETs are currently deployed, research in this area is mostly simulation based. Random waypoint is the commonly used mobility model in these simulations. Random waypoint is a simple model that may be applicable to some scenarios. However, we believe that it is not sufficient to capture some important mobility characteristics of scenarios in which MANETs may be deployed. Our framework aims to evaluate the impact of different mobility models on the performance of MANET routing protocols. We propose various protocol independent metrics to capture interesting mobility characteristics, including spatial and temporal dependence and geographic restrictions. In addition, a rich set of parameterized mobility models is introduced including random waypoint, group mobility, freeway and Manhattan models. Based on these models several 'test-suite' scenarios are chosen carefully to span the 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 routing protocols into mechanistic "building blocks" to gain a deeper insight into the performance variations across protocols in the face of mobility. <s> BIB001 </s> MOBILITY MODELS FOR DELAY TOLERANT NETWORK : A SURVEY <s> Shortest Path-Based Map Mobility Model (SPBMM) <s> Spatio-temporal preferences and encounter statistics provide realistic measures to understand mobile user's behavioral preferences and transfer opportunities in Delay Tolerant Networks (DTNs). The time dependent behavior and periodic reappearances at specific locations can approximate future online presence while encounter statistics can aid to forward the routing decisions. It is theoretically shown that such characteristics heavily affect the performance of routing protocols. Therefore, mobility models demonstrating such characteristics are also expected to show identical routing performance. However, we argue models despite capturing these properties deviate from their expected routing performance. We use realistic traces to validate this observation on two mobility models. Our empirical results for epidemic routing show those models' largely differ (delay 67% & reachability 79%) from the observed values. This in-turn call for two important activities: (i) Analogous to routing, explore structural properties on a Global scale (ii) Design new mobility models that capture them. <s> BIB002
The improved version of MBM is the Shortest Path-Based Map Mobility Model. This model also initially places the nodes in random places of map area. However, all nodes travel to a certain destination in the map and follow Dijkstra's shortest path algorithm BIB002 to discover the shortest path to the destination. When nodes have reached the destination, they have to wait for a while and select a new destination. All the places in the map usually have same probability to be chosen as the next destination, but the map data can also contain Points of Interest (POIs). These POIs are divided into several POI groups. Every node group can have configurable probability for choosing POI in certain group as the next destination. POIs have advantages for modelling places where people tend to gather e.g. restaurants, supermarkets and tourist attractions  . SPBMM is found easy to understand and competent to use in simulations, but it does not assure inter-contact time and contact time distributions that match real world traces when small number of nodes is used in the simulation BIB001 .