Dual radio based cooperative caching for wireless sensor networks

In this paper, we propose a caching scheme for wireless sensor networks which exploits cooperation among various sensor nodes in a zone formed around few sensor nodes. Zones are created by using dual radio mode of sensor nodes i.e. high and low power transmission ranges define zone size. In order to realize much larger cumulative cache, a node along with its own storage utilizes storage of sensor nodes in zone formed around it. Zone size is taken such that all nodes in a zone communicate with each other in single-hop using low power radio and hence conserves energy in cumulative cache management. Considering multiple and mobile sinks in sensor field, we develop unique token based cache admission control, cache discovery and least importance based item replacement policy. Proposed caching scheme is applied to two-tier data dissemination (TTDD) approach and newly proposed dual radio based data dissemination (DRDD) approach. Simulation results show significant gains in energy efficiency when cooperative caching is used in both approaches as compared to scenarios when these dissemination schemes do not employ caching.