MobiStore: A system for efficient mobile P2P data sharing

MobiStore is a P2P data store for decentralized mobile computing, designed to achieve high availability and load balance. As P2P platforms, mobile devices connected to the Internet through WiFi or cellular networks are different from wired devices in two main aspects: (1) higher churn due to mobility, weak wireless signals, or battery constraints, and (2) significant variability in bandwidth and latency based on the point of attachment. These problems affect the stored content availability and skew the content serving load over the peers. MobiStore structures the mobile P2P network into clusters of redundant peers. The topology uses both algorithmically-defined and random edges among the peers of different clusters. The routing information is updated using a gossip-based protocol. Thus, MobiStore achieves, with high probability, O (1) lookup operations despite high churn and link variability. Inside the clusters, all peers replicate the content, which improves the content availability. Furthermore, based on the current load, MobiStore dynamically changes the number of peers inside the clusters and routes content request to randomly selected peers. These two dynamic techniques along with using consistent hashing to map content to peers balance the load over the peers. While some of these techniques are well known, the main contribution is on the novel ways of applying them to design and implement an efficient mobile P2P data store. Simulation results show MobiStore achieves an availability, i.e., lookup success rate, between 12–48 % higher than two baseline systems built over the MR-Chord and Chord P2P protocols; and it reduces the latency up to 9 times compared to these protocols. Finally, the results show MobiStore adapts to churn and workload to evenly distribute the requests across clusters and peers better than both baseline solutions.