Hybrid Dissemination Based Scalable and Adaptive Context Delivery for Ubiquitous Computing

Context delivery is an inevitable issue for ubiquitous computing. Context-aware middlewares perform all the functions of context sensing, inferring and delivery to context-aware applications. But one of the major issues for these middlewares is to devise a context delivery scheme that is scalable as well as efficient. Pure unicast or pure broadcast based dissemination can not provide scalability as well as less average latency. In this paper we present a scalable context delivery mechanism for context-aware middlewares based on hybrid data dissemination technique where the most requested data are broadcasted and the rest are delivered through unicast. Our scheme is adaptive in the sense that it dynamically differentiates hot (most requested) and cold (less requested) data according to request rate and waiting time. Inclusion of lease mechanism and bandwidth division further allows us to reduce network traffic and average latency. We validated our claim through extensive simulation.