A Community Based Mobility Model for Ad Hoc Networks Research

Validation of mobile ad hoc network protocols relies almost exclusively on simulation. The value of the validation is, therefore, highly dependent on how realistic the movement models used in the simulations are. Since there is a very limited number of available real traces in the public domain, synthetic models for movement pattern generation must be used. However, most widely used models are currently very simplistic, their focus being ease of implementation rather than soundness of foundation. As a consequence, simulation results of protocols are often based on randomly generated movement patterns and, therefore, they may differ considerably from those that can be obtained deploying the system in real scenarios. Movement is strongly affected by the needs of humans to socialise or cooperate, in one form or another. Fortunately, humans are known to associate in particular ways that can be mathematically modelled and that have been studied in social sciences for many years. It is in fact undeniable that social relationships definitely bias movement patterns. In this paper we propose a new mobility model that is founded on social network theory. The model allows collections of hosts to be grouped together in a way that is based on social relationships among the individuals. This grouping is only then mapped to a topographical space, with movements influenced by the strength of social ties that may change in different periods of the day. We have validated our model with real traces by showing that the generated mobility traces can be considered a very good approximation of human movement patterns. We have also run simulations of AODV and DSR using this mobility model and show how the delivery ratio is affected by this type of mobility.