Distributed group-based cooperative caching in a mobile broadcast environment

Caching is a key technique for improving data retrieval performance of mobile clients. The emergence of state-of-theart peer-to-peer communication technologies now brings to reality what we call "cooperative caching" in which mobile clients not only can retrieve data items from mobile support stations, but also from the cache in their peers, thereby inducing a new dimension for mobile data caching. In this paper, we propose a distributed group-based cooperative caching scheme, in which we define the concept of a tightly-coupled group (TCG) by capturing the data affinity of individual peers and their mobility patterns, in a mobile broadcast environment. A distributed stable peer discovery protocol is proposed for discovering all TCGs dynamically. In addition, a cache signature scheme is adopted to provide hints for the mobile clients to determine whether their required data items are cached by their neighboring peers, and to perform cooperative cache replacement to increase overall data availability. Simulation studies are conducted to evaluate the effectiveness of our distributed group-based cooperative caching scheme.