An Adaptive Group-Based Reputation System in Peer-to-Peer Networks

Abstract. As more and more P2P applications being popular in Inter-net, one of important problem to be solved is inspiring users to cooperate each other actively and honestly, the reputation mechanism which is a hot spot for P2P research has been proposed to conquer it. Because of the characters of virtuality and anonymous in the network, it is very easy for users with bad reputations to reenter the system with new identities to regain new reputations in the reputation systems. In order to get rid of the impact of whitewashers and improve the system performance and efficiency, we propose a new probability-based adaptive initial reputation mechanism. In this new mechanism, newcomers will be trusted based on system’s trust-probability which can be adjusted according to the actions of the newcomers. To avoid the system fluctuating for actions of a few whitewashers, we realize the new reputation mechanism in system with group-based architecture, which can localize the impact of whitewash-ers in their own groups. Both performance analysis and simulation show that this new adaptive reputation mechanism is more effective.

Friendly P2P: Application-level Congestion Control for Peer-to-Peer Applications

International audiencePeer-to-Peer (P2P) file sharing applications use multiple TCP connections between peers to transfer data. The aggressiveness and robustness of P2P technology remarkably improve transfer efficiency and network bandwidth utilization. However, while the network bottleneck link is congested, P2P applications tend to unfairly steal bandwidth from other traditional Internet applications (Client/Server mode), which deteriorates the performance of traditional Internet applications. The paper proposes a friendlyP2P system with new application-level approaches for congestion detection and avoidance to keep fairness between P2P traffic and traditional Internet traffic. friendlyP2P, which is friendly to ISPs, namely to Internet networks and traditional Internet traffic, detects network congestion via throughput measurements and alleviates network congestion by optimization of the number of P2P connections from the viewpoint of P2P users. friendlyP2P system requires neither network node support nor TCP modification, which makes it easy to deploy. Simulation experiments demonstrate that fairness and congestion avoidance can be achieved in presence of congestion, and network bandwidth can be effectively utilized in absence of congestion with friendlyP2P technology

Performance evaluation of sctp as a transport layer solution for wireless multi-access networks

Abstract – Future communication systems might be characterized by an integration of multiple access systems, and people are expecting excellent multi-access solutions for better services. However, currently proposed solutions in different layers are unable to completely fulfill the requirements. In this paper, we put forward the Stream Control Transport Protocol (SCTP) as a transport layer approach for multi-access, and propose an efficient SCTP load-sharing enhancement. The evaluation of performance has been investigated in the key multi-access scenarios with theoretical analyses, simulations in NS and some Linux-kernel experiments. Since SCTP supplies an effective multi-homing mechanism and the transport layer solutions for multi-access can quickly adapt to the fluctuating network conditions, our SCTP approach is able to bring more throughput for the simultaneous multi-access, perform seamless behavior during the vertical handover between heterogeneous access networks, and provide better robustness and connectivity than other solutions in the wireless multi-access scenarios

A relay-aided media access (RAMA) protocol in multirate wireless networks

The IEEE 802.11 standard inherently supports multiple data rates at the physical layer. Various rate adaptation mechanisms have been proposed to exploit this multirate capability by automatically adapting the transmission rate to best utilize the wireless spectrum. This study is primarily motivated by the observation that in a wireless network, a multihop high-rate path can potentially achieve better throughput and delay than using a single-hop low-rate path for transmission. Specifically, this paper introduces a relay-aided media access (RAMA) protocol by taking advantage of the existence of such multihop high-rate links. This is demonstrated by replacing one low-rate link with two high-rate links using a relay node. One of the key novelties in the proposed RAMA protocol is that the transmission from the immediate relay node to the destination node is free of contention. Results from analysis and simulations show that RAMA can significantly improve performances in terms of both throughput and delay