Abstract:The mobile peer-to-peer environment is easier to implement in location privacy preserving research. The mobile users cooperate through P2P multi-hop routing to blur their accurate locations into a spatial cloaking region, but most existing spatial cloaking algorithm cannot work well because of the high communication overhead, time consumption and the lower success rate. This paper proposes an algorithm that can recommend users privacy requirements by collecting users weighed density information in their neighborhood, and therefore help mobile users to find enough collaborative users quickly. The approach shows great anonymization success rate by 92% through extensive simulation experiments for a range of P2P environment scenarios. It achieves lower communication cost and less than 500ms of searching time at the same time.

Abstract:In unstructured P2P networks, the existing search protocols are effective for popular resources, but searching for scarce resources is inefficient. Improving copy rates of scarce resources is the main method to solve the search inefficiency. The query hit rates on scarce resources are lower as copies of scarce resources are small. So the existing passive copy replication strategies based on the success queries are not suitable for the improvement of rare resources popularity. To solve this problem, we propose an active replication and search strategy of scarce resources. In the search process, peers with scarce resources actively initiate the search for scarce resources. And local demand information is effectively obtained in the process of search, and then scarce resources are copied to the peers that have demands for the scarce resources. The method implements the on-demand replication of scarce resources to improve popularity and query hit rates of scarce resources. Based on local requirement information, we provide three different kinds of on-demand replication strategies and a rare resource search algorithm. Experimental results show that the active replication and search strategy of scarce resources can effectively increase copy rates of scarce resources with lower replication consumption and network overhead, and then improve the query hit rates of scarce resources.

Abstract:The construction of overlays is a crucial problem in the research of mobile peer-to-peer networks. The architecture of overlays determines the robustness, security and performance of MP2P networks. The paper first introduces the concept of mobile P2P overlays, including the definition, significance of the construction of overlays and the classification of them. Next, three kinds of overlays, distributed unstructured, distributed structured and semi distributed (hybrid) network, are described. The application of overlays in MANET, VANET and WMN is especially introduced. Furthermore, the aforementioned overlays are analyzed and compared. Finally, the paper concludes and presents the future research directions.

Abstract:Due to the limitation of own resource and the influence of subjective attitude, the nodes in mobile peer-to-peer networks often show selfish behavior. Detecting and stimulating selfish nodes to cooperate is becoming an important research topic recently. By allowing nodes to express their subjective forward attitude freely, the detection mechanism is implemented. Not only is the objective forwarding probability determined by its own resource, but subjective forwarding probability is also determined by selfish nodes that are considered. Therefore, choosing a routing path with the highest integrated forwarding probability can alleviate the influence of selfish nodes. To motivate the excessive selfish nodes to actively cooperate, an incentive and cooperation model based on punishment mechanism is presented. The selfish nodes are punished based on the damage degree of their selfish behavior. The monitor mechanism among nodes and strict punishment mechanism assure that the strategy proof is achieved. Simulation results show that the detection and incentive mechanism can not only discover appropriate routing in the condition of every rational and selfish node has limited resource, but also stimulate selfish nodes to actively cooperate when the degree of nodes’ selfishness is high.

Abstract:Reducing the network overhead generated during the search is important in the study of unstructured P2P network. Flooding and random walks are simple and easily implemented. However, a large number of redundant messages generated in the search process are the main reason of producing excessive network overhead. An effective limited search mechanism RFSA (restricted forward search algorithm) is proposed. The search path and redundant search path are defined. As the query messages reaching the node are received by introducing the local messages index caching mechanism, the repeat messages forwarding are eliminated. Using the real-time search path information carried in the search process, the neighbor notes that do not appear in the search path are selected to forward the query messages. Theoretically, the number of messages and network overhead generated by the RFSA. In the simulation, comparative analysis of the limited search mechanism and non-limited mechanism flooding and random walk algorithm is done in the network overhead, query hit rate, search coverage rate, and the number of redundant messages, etc. The results show that this method reduces the generation of a great number of redundant messages, and cuts down the network overload.

Abstract:The improvements of random walk search mainly depend on allocating weight for neighbor peers, which is always incurred on a high overhead and are not very helpful for rare items. This paper proposes a bidirectional random walk search mechanism (short for BRWS) for unstructured P2P network, according to the analysis of basic properties about random walk as well as the special property that random walk tends toward high degree nodes. The mechanism is proved theoretically in this paper, and can improve search success rate, including searching for rare items. It also has a high tolerance for churn. In the static and dynamic environment, comparisons were made among Random Walk, APS (adaptive probabilistic search), PQR (path-traceable query routing), P2PBSN (peer-to- peer based on social network) and BRWS based on three topologies: Random graph, scale free, small world. The experimental results show that BRWS can actually improve the search success rate with lower overhead even when searching rare resources. The method proposed in this paper can apply in P2P file sharing networks.

Abstract:To address the recommendation problems from malicious entities, a role separation based trust evaluation model (RSTrust) is proposed in this paper. In RSTrust, roles which entities act during trust evaluation are classified into transaction roles and recommendation roles. Trust on entity is therefore described as transaction trust and recommendation trust according to their associated roles, which leads to the separation of interference between different roles on different trusts. During the calculation of the global trust for an entity, the global recommendation trust of a recommender is used as a trust weight in RSTrust, and the disturbance of recommendation from malicious entities on global trust can be eliminated effectively. Analysis and simulation results demonstrate that RSTrust model has the fine feature of anti-malicious recommendation and good astringency.

Abstract:It is hard to optimize query latency, query hit, and query cost at the same time for the resource location of unstructured peer-to-peer network. For this problem, this paper presents a probabilistic routing algorithm called DCBF (data copying and Bloom Filter), which is based on data copying and a Bloom Filter technique. DCBF makes a few copies of each shared resource and places each copy on a random selected node, based on a directed random network. Each node forwards membership information to neighboring nodes with distributed declining Bloom Filters. Analysis and experimental results show that DCBF can make the most of the nodes, use the membership information of resource objects by making only a few copies, and forward membership information with distributed declining Bloom Filter to achieve high query hits with low cost and low latency.

Abstract:The rapid increase of P2P traffic worsens the congestion of network while P2P traffic identification becomes the basic technical support for network management. The types of P2P traffic and main challenges of traffic identification are introduced first. Next, the main techniques and research progresses of P2P traffic identification are summarized. Finally, the future trend is put forward.

Abstract:In order to gain insight on the topology characteristics of P2P IPTV systems and their online user behavior characteristics, This paper develop and deploys a multiprotocol P2P IPTV network crawler, called TVCrawler, which enables users to launch an in-depth measurement and comparative research for several well-known P2P IPTV systems, including PPLive, PPStream, and UUSee. This paper presents results from experiments and research efforts on these large-scale P2P IPTV overlay graphs. Major findings include 1) more than 50% of online users are unreachable because they lie behind NAT or firewall; 2) fluctuation range of churn increases with the increase of the population of channel, and there exists a power-law upper bound for fluctuation range of churn; 3) session length of peer follows a stretched exponential distribution; 4) while the in-degree of PPLive follows the power-law distribution with exponential cutoffs, the in-degree of PPStream appears to have multiple separate power-law regimes with different exponents, and the in-degree of UUSee approaches Weibull distribution. 5) All of measured P2P IPTV overlay graphs appear as a disassortative mixing; 6) small-world networks are ubiquitous in measured P2P IPTV systems. 7) the PPLive overlay graph is clustering, but the others are not; 8) all of measured P2P IPTV overlay graphs have robustness similar to that of a power-law graph, but PPLive is more vulnerable to malicious attacks and more robust to random failures than the other. These research and findings Will be good for designing and optimizing of P2P IPTV protocols, but also for monitoring, directing, and dominating the P2P IPTV system.