Cooperative Caching Optimized Policy Research In MANET

With the rapid development of science and technology, the recent years have witnessed a rapid development of mobile computing and wireless communication techniques. At the same time, people have higher and higher demands for the mobile communication technologies. Currently, there are two different ways of configuring a mobile network:infrastructure-based and ad-hoc-based.Infrastructure-based wireless network uses fixed network access point interacting with mobile terminals. It is widely used in today's Wireless LANs and global wireless networks. But it has some limitations, such as it requires any mobile terminal be in the communication range of a base station, which is hard to scale to areas without any pre-existing infrastructures. However, Ad hoc networks, by enabling users to spontaneously form a dynamic communication system, are helpful in situations in which temporary network connectivity is needed, so they are often used in the battlefield and disaster recovery environments.But in MANET, most of the previous researches in ad hoc networks focus on the development of dynamic routing protocols. Although routing is an important issue in ad hoc networks, other issues such as data access are also very important since the ultimate goal of using ad hoc networks is to provide information access to mobile nodes. Cooperative caching is a very important technique for efficient data dissemination and sharing in MANET; However, due to the characteristics of MANET, such as wireless medium, multi-hop routes, dynamic topology, limited resources of mobile nodes, many cooperative caching techniques in the traditional wired networks and wireless networks can not be applied to MANET, thus we need to develop cooperative caching technology suiting MANET.In this paper, we first analyzed the characteristics of MANET, and then study some of the existing cooperative caching technology in MANET, finally we proposed a novel Cooperative Caching Optimized Policy (CCOP), and it can improve data availability and access efficiency by collaborating local resources of mobile nodes. CCOP addresses two basic problems of cooperative caching:cache resolution and cache management. To improve data availability and access efficiency, CCOP effectively make use of data locality and the commonality in users'interests. Mobile node discovers data sources which induce less communication overhead by utilizing cooperation zones, key node, and hop-by-hop resolution. For cache management, CCOP increases the effective capacity of cooperative caches by minimizing caching duplications within the cooperation zone and accommodating more data varieties.In order to verify the CCOP performance, we use the mathematical analysis and simulation of two ways. In mathematical analysis, we first move to build a mathematical model, and then analysis cache performance. And study the different factors inflorescence to the performance, such as distance from request node to data center, node density, and the data access pattern etc. In the simulation, we configure the parameters in the NS2 platform to build our simulation environment, and then compare CCOP with other existing cooperative caching strategy, such as SimpleCache and hop-by-hop, based on collaborative regional strategy, in the average response delay and average energy consumption. The mathematical analysis and simulation results demonstrate that CCOP can significantly reduce response delay and energy consumption when compared to other cooperative caching policies.