Search in mobile peer-to-peer file-sharing system

In the recent years peer-to-peer (P2P) file-sharing has become the killer application in fixed networks and might also be highly attractive for mobile networks. However, file search and locating is a difficult task in mobile networks which differ from wired networks by the limited capacity of the radio link and the mobility of the environment. In used of current index search mechanism, indices are periodically updated which often results in the invalidation and/or pretermission of query results. In this paper, we propose a novel file search mechanism in mobile P2P networks which is based on Efficient and Real-Time Updates (ERTU) inverted index. Our ERTU index consists of dominant inverted index, temporary inverted index, deleted files list and cache index which enables highly efficient searching for popular resources. Based on ERTU index, the real-time updates (incremental and removed) of shared files can be reported to index server without re-indexing and the index can be queried even updates are being done to it. Simulations show that in mobile P2P environment ERTU index can enhance the precision and recall, and improve the searching and locating performance significantly.