Mobile Intelligence

5.3 COOPERATIVE CACHING APPROACHES IN MANETs

Simple and cooperative caching systems have been widely used in the Internet for improving Web service performance [23–30]. A detailed survey on Web caching can be found in Ref. [31]. In general, there are clients, caching proxies, and Web servers in a Web caching system. Caching proxies are placed between servers and clients and work cooperatively to provide caching for clients. When a client requests a Web page, it checks its own cache first. If that fails, it sends the page request to one of the caching proxies. If the requested page cannot be found in this proxy, it sends the request to its cooperative proxy. If the requested page cannot be found among these proxies, the request will be sent to the remote Web server to get the original page. Web caching systems lead to a decrease in bandwidth usage, Web server workload, and client query delay [31].

Web caching systems work well in improving the performance of Web services. However, this scheme cannot be directly used in the MANET environment due to the mobility and resource constraints of MANETs. In a MANET, all nodes are moving, and the network topology changes frequently, so it is impossible to place cache proxies in a MANET. Therefore, a different approach has to be used to implement a cooperative caching system in the MANET environment. Recently, several approaches have been presented for using cooperative caching in MANETs. In these approaches, every mobile node has a certain ...