A framework for pervasively shared situational awareness in mobile ad hoc environments

Abstract

This dissertation presents a novel approach to sharing situational awareness among a group of geographically dispersed mobile networked devices. We divide our efforts into two parts: getting the information to the right places, and keeping it there. We start by introducing a stochastic approach to transporting geospatial messages that shows significantly better performance than the existing deterministic approaches, particularly in adverse network topologies. Under normal conditions, our model performs better than comparable existing approaches. Under pathological conditions, however, all other approaches fail while our model remains viable. Next, we introduce a novel cooperative spatial-aware cache that can be thought of as residing in a region rather than in any given node. Each node that participates in the cache holds an expendable part of the data, so that the loss of any node or small group of nodes can be tolerated with little or no degradation of service. The results of both our analysis and simulations show that our approach works significantly better than local caching alone both in terms of hit-ratios as well as cache survivability. In fact our shared spatial caches perform one order of magnitude better than local caches in terms of cache hit ratios.