Table of Contents Author Guidelines Submit a Manuscript
International Journal of Digital Multimedia Broadcasting
Volume 2010 (2010), Article ID 793591, 14 pages
Research Article

“Q-Feed”—An Effective Solution for the Free-Riding Problem in Unstructured P2P Networks

1Department of Computer Science and Engineering, L.B.S Institute of Technology for Women, Kerala 695012, India
2Department of Computer Engineering, National Institute of Technology Karnataka, Surathkal, Karnataka 575025, India

Received 2 July 2009; Revised 11 October 2009; Accepted 14 December 2009

Academic Editor: Yuanqiu Luo

Copyright © 2010 Sabu M. Thampi and Chandra Sekaran K. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper presents a solution for reducing the ill effects of free-riders in decentralised unstructured P2P networks. An autonomous replication scheme is proposed to improve the availability and enhance system performance. Q-learning is widely employed in different situations to improve the accuracy in decision making by each peer. Based on the performance of neighbours of a peer, every neighbour is awarded different levels of ranks. At the same time a low-performing node is allowed to improve its rank in different ways. Simulation results show that Q-learning-based free riding control mechanism effectively limits the services received by free-riders and also encourages the low-performing neighbours to improve their position. The popular files are autonomously replicated to nodes possessing required parameters. Due to this improvement of quantity of popular files, free riders are given opportunity to lift their position for active participation in the network for sharing files. Q-feed effectively manages queries from free riders and reduces network traffic significantly.