A cooperative spatial-aware cache for mobile environments

In many scenarios, particularly in military and emergency response operations, mobile nodes that are in close proximity to each other exhibit a high degree of data affinity. For example, all soldiers in the same region, regardless of their specialty, will want to know all nearby threats, as well as all friendly assets. Since relaying queries to a distant server is costly in terms of bandwidth and battery power, it would be ideal to use local resources that are only a hop away. In this paper we propose a shared spatial 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. We describe the analytical models that verify our claims and show the results of extensive simulations that validate our models under simulated but realistic conditions.