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. 1. Introduction A P2P network serves the content among the associate nodes rather than focussing it at a single central server. The barriers to starting and growing such systems are low, since they usually do not require any special administrative or financial arrangements, unlike with centralised facilities. P2P systems recommend an approach to aggregate and make use of the incredible computation and storage resources that otherwise just sit idle on computers across the internet when they are unused. P2P systems are widely used for file-sharing. The fundamental idea of file sharing is to utilise the idle disk space for storage and the existing network bandwidth for search and download [1]. A major benefit of P2P file sharing is that these systems are fully scalable—each additional user brings extra capacity to the system. In a P2P system, participating nodes mark at least part of their resources as “shared”, allowing other contributing peers to access these resources. Thus, if node A publishes something and node B downloads it, then when node C asks for the same information, it can access it from either node A or node B. As a result, as new users access a particular file, the system’s capability to provide that file increases [2]. There are mainly three different architectures for P2P systems: centralized, decentralized structured, and decentralized unstructured. In the centralized model, such as Napster [3], central index servers are used to maintain a directory of shared files
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