A Cooperative Caching Strategy In Mobile Ad Hoc Networks

The mobile ad hoc networks (MANET) is a temporary network without infrastructure support. Mobile nodes have wireless interface and act as a router, network communication is accomplished by forwarding data packets among intermediate nodes. Because of the mobility of nodes, network topology and disconnection of wireless channel change frequently. Most of the research in ad hoc networks focuses on data link layer and network layer, many routing protocols are adopted. However, the ultimate goal of using ad hoc networks is to provide information accessibility to customers. So how to maintain data accessibility to nodes and assure data usability in dynamic network environment is still a very important research area.Cooperative caching that is widely used in distributed environment can improve data accessibility greatly, it allows different nodes coordinate and share caching data in order to shorten query time. Cooperative caching must solve two basic problems: which data should be cached and how to find cache data. According to network topology and data access pattern in MANET, nodes can cache selective data. When network disconnects, the nodes which have cache data could act as data center temporarily, supply other nodes'with data query service and assure data availability. So MANET needs supply basic strategies to find these selective data, such as flooding, random walk et all, these strategies can reduce routing hops in forwarding process.In the process of selecting which data should be cached, the data mining knowledge can be used for reference. Clustering analyse can be used in nodes'forward data query message, the data that have high interest in other nodes will prefetch.. At the same time, routing table can be used for data location. So this strategy make cooperative caching be processed directively in MANET and increase adaptability in network disconnection environment.