Efficient data access using distributed cache network central location technique

Disruption tolerant networks are characterized by low node density, node mobility, and lack of global network information. Most of research efforts in DTNs focus on data forwarding, but only limited work has been done by an efficient data access to mobile consumers. A novel scheme to support cooperative caching in DTN and a novel sleep scheduling method to reduce the delay of alarm broadcasting from any sensor node in WSNs. we design two determined traffic paths for the transmission of alarm message. When a critical event occurs, an alarm is quickly transmitted along one of the traffic paths to a center node, and then as soon as, it broadcast by the center node along another path without collision, which enables the sharing and coordination of cached data among multiple nodes and reduces data log on delay. In network, the basic idea is to purposely cache data at a set of network central locations which can be easily accessed by other nodes. An efficient scheme that ensures appropriate NCL selection based on a probabilistic selection metric and coordinates multiple caching nodes to optimize the tradeoff between data accessibility and caching overhead.