Mobile Intelligence

5.4 THE PROPOSED CLUSTER-BASED ADAPTIVE COOPERATIVE CACHING SCHEME

In this scheme, we consider a MANET environment in which there is a data center (DC) and a number of MHs. In the following part of this chapter, they are also called nodes). DC, whose address is known to all other MHs, can be regarded as database servers, which store all data items needed by the whole MANET, or can be considered the gateways to the Internet and provide information service for other MHs in the MANET. The data items in DC are regular objects, such as text files and pictures, which have different sizes. All modifications to data items are performed by DC. MHs get data items from DC as they need them. ad-hoc on demand distance vector (AODV) routing protocol [6] is used in the implementation.

5.4.1 Overview of Cross-Layer Based COCA (COoperative CAching)

COCA, illustrated in Figure 5.1, is a cluster-based middleware that stays on top of the network layer and provides caching service for the upper applications. COCA includes information searching, cache management, and prefetching modules. Cross-layer design is exploited to optimize system performance and make the system more adaptive. The stack profile module is responsible for cross-layer-related functions. In the MANET, every MH has a certain amount of cache space for caching data items from DC or other MHs, and COCA and stack profile reside in every mobile host.

5.4.2 Descriptions of Proposed Modules

5.4.2.1 Clustering Architecture

Clustering is an ...