USMI: An Ultra-Node Selection Mechanism with Incentive in P2P Network

The performance of P2P networks have decreased severely because of the large number of free-riders. How to incentive nodes to provide service is an important factor to improve the performance of P2P networks. A novel ultra-node selection mechanism with incentive called USMI is presented in this paper. The main contributions of USMI are following: 1) any node in USMI has a value called utility. The utility integrates the parameters including physical capability, voluntary and anticipation to future, differing from the general ultra-node selection which is only based on physical capability and unconsidered free-riding. The ultra-nodes is selected based on the utility value; 2) the ultra-nodes are endow with supervising privilege and they can identify and prevent the free-riders through the parameter of voluntary; 3) the probability of supervising is calculated based on game theory. It´s been shown that USMI increases the total number of file shared, improves the file querying success rate, decreases the average querying hops, and ensures the cost is small at the same time in the Simulation experiments. The ultra-node overlay of USMI is steady and robust.