An Effective Cooperative Cache Replacement Policy for Mobile P2P Environments

Recent researches in cooperative caching systems combined with P2P (peer-to-peer) web caching for mobile environments have been made quite actively owing to the advances in mobile technology. The hybrid cooperative caching technology in mobile environments enables P2P systems to achieve improved caching performance by utilizing the caches in neighbor peers. However, there is an important limitation of mobile caching system that the cache space of a mobile device is generally restricted. In this paper, we propose an effective cooperative cache replacement policy for mobile P2P environments that exploiting the sizes of objects in a system. The proposed replacement policy stores smaller objects in the local cache of each peer and stores larger objects in the local cache of its "idle" neighbor peer who has the least activity among its peers. The activity of a peer is determined by the request frequency and the latest request time. We compared the proposed replacement policy with the existing replacement policies for various mobile environments. The experiment results show that the proposed replacement policy achieves better performance than the existing replacement policies in terms of the hit ratio and the byte hit ratio. Especially when the cache size is reasonably small, the proposed replacement policy shows outstanding performance.