UTILITY BASED GREEDY CACHING (UGC) SCHEME FOR MANETs

Abstract

Mobile Adhoc Networks (MANETs) have received considerable attention due to their potential applications in battlefield, disaster recovery and outdoor assemblies. Research is being carried out to improve the efficiency of information access in MANETs. Data caching is an important technique to reduce access cost. If a node caches the data that is served by a faraway server, near by nodes can get data from the node that has cached the data. So if cache based data access is used then network bandwidth will be utilized efficiently, query delay will be less and the nodes will consume less power. A number of caching schemes have been proposed in the literature. There are two main problems in caching - cache resolution and cache management. Cache resolution involves the task of sending a query to a node that may have data. Cache management involves the task of adding a new data item into a cache and purging data item(s) from the cache when the cache has no space to add a new data item. In this work, a new scheme, Utility-based Greedy Caching (UGC) is proposed for cache based data access in Mobile Adhoc Networks. In the UGC scheme, every data item has a utility value which is calculated by considering various factors viz. access frequency, size, Time-to-Live value and the distance between the requesting client and the responding client. Every node in the UGC scheme caches the data items with maximum utility in a greedy manner. Simulation results show that the UGC scheme reduces average query delay and increases cache hit ratio as compared to the existing schemes — COOP, Zone Caching and HybridCache. Simulation results also show that the UGC scheme increases query success ratio as compared to COOP and Zone Caching. The number of messages injected into the system by the query process is less in UGC as compared to COOP and Zone Caching. The UGC scheme has been simulated using QualNet - 4.5 Simulator running on an Intel Pentium IV machine.