P2broadcast: a hierarchical clustering live video streaming system for P2P networks

This work describes a novel live video streaming system for P2P networks, referred to as P2broadcast. The video streaming service has bandwidth requirements to guarantee presentation quality. Therefore, a scalable strategy to quickly find a path from a media server to a client with abundant bandwidth is very important. A common approach in the literature is the bandwidth first (BF) scheme, which allows a newcomer to adopt a BF tree traversal scheme to find its parent peer on the P2P overlay tree to retrieve the media content. The BF scheme is likely to build a deep overlay tree, resulting in long start‐up latency as the number of peers on the overlay tree grows. P2broadcast reduces start‐up latency by organizing peers into hierarchical clusters and making the overlay tree become a ‘short‐and‐wide’ tree. The hierarchical clustering structure enables a newcomer to find its parent peer among the set of peers that are more likely to provide large available bandwidth only. Limiting the set of potential parent peers not only reduces start‐up latency but also improves the system availability. Additionally, unlike the BF scheme that only concerns available bandwidth, P2broadcast utilizes a cost function to evaluate the appropriateness of a potential parent peer. The cost function considers the depth of the newcomer on the overlay tree, making the overlay tree become a short‐and‐wide tree. In addition to start‐up latency reduction, the short‐and‐wide tree feature also alleviates the service interruption probability due to the leaving or failure of a peer. Our simulation results show that P2broadcast greatly outperforms the BF scheme in terms of system availability, and achieves around 66% savings in start‐up latency and 10% decrement in service interruption probability. Copyright © 2005 John Wiley & Sons, Ltd.     

基于P2P的可运营媒体内容分发网络的设计与实现

为在3TNet 上开展视频业务提供高喷量媒体内容的分发支持,实现高性价比的可运营内容分发服务,采用CDN与P2P结合的架构,实现了基于P2P的可运营媒体内容分发网络.系统采用了灵活的内容分发算法管理平台,方便根据需要采用各种合适的副本分发、内容缓存算法.系统具有节点、媒体内容和系统部署成本高度可控,运营质量高,运营成本低等特点.     

Game‐theoretic auction design for bandwidth sharing in helper‐assisted P2P streaming

Video traffic offloading through the helper peers can significantly alleviate the server workload and enhance users' quality of experience. In this paper, the complex interactions of a number of helpers seeking to trade their bandwidth surplus in a peer‐to‐peer market are studied using non‐cooperative game theory and double auction. In particular, a non‐cooperative game is formulated among the helpers in which each helper can make a decision on the maximum amount of upload bandwidth surplus that it is willing to sell so as to maximize its utility function that reflects the tradeoff between the benefits from bandwidth sharing and its associated costs. Then, the price governing the bandwidth trading market between the helpers and peers is determined via a truthful double auction mechanism. To solve the game, an algorithm based on the best response dynamics is proposed using which helpers can reach a Nash equilibrium point. Simulation results exhibit that the proposed algorithm achieves significant performance improvements in terms of utility per selling helpers. Copyright © 2015 John Wiley & Sons, Ltd.     

Replication schemes for peer‐to‐peer content in wireless mesh networks with infrastructure support

Many mobile devices (e.g., smart phones, PDAs, portable computers) and wireless routers (e.g., WiFi access points) nowadays are equipped with ad hoc transmission mode. In a dense environment such as a college/office campus, this creates the possibility of forming a wireless mesh network (WMN) in which mobile users communicate with each other through multiple wireless hops. This allows mobile users to exchange (share) files over the free access WMN rather than a carrier frequency such as 3G and WiMax. We consider a peer‐to‐peer (P2P) content sharing setting in a WMN, wherein the mesh network operator over‐provision a number of mesh routers in the network with additional storage capacity and P2P‐aware devices that are programmed to cache and store P2P content. Those mesh routers act as caches and participants in P2P content sharing. The aim of this setting is to both reduce the cost of communications between peers within the WMN (i.e., reduce bandwidth and energy that P2P traffic consumes in the network), and enhance the performance of P2P content sharing (i.e., reduce the average P2P content download delay). Our main contribution in this paper is an optimum P2P content replication strategy at the participating mesh routers. In particular, we determine the optimum number of replicas for every P2P file such that the average access cost of all files in the network is minimized. We propose a centralized algorithm that enables the participating mesh routers to implement the optimal strategy. We further propose a distributed (low cost) algorithm for P2P content replication at the participating mesh routers, and show that the distributed algorithm mimics the optimal strategy very well. The analytical and simulation results show that our replication strategy significantly reduces the average overall cost of accessing P2P files in the WMN as compared with other commonly used replication strategies. Copyright © 2013 John Wiley & Sons, Ltd.     

An economic mechanism for request routing and resource allocation in hybrid CDN–P2P networks

Hybrid content delivery networks (HCDN) benefit from the complementary advantages of P2P (Peer to Peer) networks and CDNs (Content Delivery Network). In order to extend a traditional CDN and enable it to offer hybrid content delivery service, we have modified a traditional domain name system‐based request routing mechanism. The proposed scheme relies on an oligopolistic mechanism to balance the load on the edge servers and employs a truthful profit‐maximizing auction to maximize the contribution of users in the P2P content delivery. In particular, economics of content delivery in HCDNs is studied, and it is shown that through our request routing mechanism, it is possible to deliver higher quality of service to majority of end‐users, increase the net profit of the HCDN provider and decrease the content distribution cost at the same time. Copyright © 2015 John Wiley & Sons, Ltd.     

Exploring the accuracy of capturing snapshots in large‐scale P2P IPTV systems

With the growing maturity of peer‐to‐peer (P2P) technology, Internet protocol television (IPTV) applications based on that gained great success commercially and have attracted more and more attentions from both industry and academia. Currently, the active measurement method based on crawler technology is the most popular and effective one to study P2P IPTV systems. Existing measurement results revealed that accuracy of captured overlay snapshots depends on the crawling speed of crawler system. In order to capture more accurate overlay snapshots of P2P IPTV system, we developed a very fast and efficient distributed crawler system using the distributed architecture and peer degree‐rank mechanism. In this paper, we first introduce the architectures of PPTV channel‐list resource distribution and the whole system, which is the most popular and largest instance of P2P IPTV applications nowadays. Subsequently, this paper evaluates the crawling results of two dedicated crawlers capturing from peer‐list servers and ordinary peers, respectively. Finally, we propose a fast and accurate dedicated crawler system based on distributed architecture and peer degree rank for PPTV. The experiment results show that the performance of our distributed crawler system is much better than other existing crawler systems. Specifically, our distributed crawler can track a very popular channel with about 7200 online users in 30 s. It is also reasonable to believe that our distributed crawler system can capture complete overlay snapshots. To the best of our knowledge, our study work is the first to explore capturing accurate overlay snapshots of large‐scale P2P IPTV applications. Our crawler system can provide a good solution for capturing more accurate overlay snapshots of PPTV system and can also be used to help researchers to design crawler systems for other P2P IPTV systems. Copyright © 2015 John Wiley & Sons, Ltd.     

SeekStream: adapting to dynamic user behavior in P2P video‐on‐demand

In recent years, the users' perceived quality of experience (QoE) in streaming services has gained a lot of attention. Particularly, a number of research efforts have focused on providing live streaming and video‐on‐demand (VoD) services using peer‐to‐peer (P2P) architectures. However, in these proposed architectures, the heterogeneity of users and their dynamic behavior has not been sufficiently studied. In a real life scenario, where users have highly heterogeneous bandwidth resources (cable, DSL, 3G networks, etc) and can arbitrarily decide to perform a VCR function (stop, fast forward and seeking), ignoring this behavior can significantly deteriorate the system's efficiency and the perceived QoE. In this paper, we present SeekStream, a scalable P2P VoD architecture that ensures the stable delivery of the video stream to every participating user even in cases of high heterogeneity and frequent seeking operations. Specifically, SeekStream is a set of algorithms that optimize the P2P overlay dynamically and in a distributed fashion, making it adaptive to users dynamic behavior and bandwidth changes. The available bandwidth resources of the participating users are optimally exploited, keeping the contribution from the media server(s) to a minimal level. To illustrate the performance of the proposed algorithms, we are using a centralized overlay network manager that discovers the optimal network graph as a reference. We have developed an extensive P2P VoD simulator that shows the efficiency, scalability, and stability of our system under variant and dynamic conditions. The algorithms of our proposed system introduce less than 4% bandwidth overhead while we achieve high offloading of the media server(s). SeekStream guarantees a high block reception rate for the users, even under extreme seeking patterns. Copyright © 2016 John Wiley & Sons, Ltd.     

Distributed key management scheme for peer‐to‐peer live streaming services

Live media streaming over peer‐to‐peer (P2P) network structures is commonplace nowadays. However, with the large number of users in a typical P2P system, it is impractical to use the central server to process the key information update requests of all the users Accordingly, the present study proposes a distributed key management scheme in which the server is only required to transmit the key update information to a limited number of users. To further reduce the load on the server, the update information is distributed using a hop‐by‐hop approach. An effective method is proposed for protecting the key update information as it is propagated through the network. In addition, a technique is presented for ensuring the security of the certificates used in the system It is shown that the distributed key management scheme and authentication procedure ensure an efficient and secure P2P live streaming performance even in the event of high churn rates. Copyright © 2012 John Wiley & Sons, Ltd.     

Access control mechanism using flexible multi‐layer structure for mesh‐based P2P live streaming systems

When thousands of new peers seek to join the peer‐to‐peer (P2P) system within a very short time (i.e., the so‐called flash crowd event), most of the peers suffer a long startup delay as a result of peer over‐competition. Accordingly, recent studies have proposed a slot‐based user access control (UAC) mechanism, which periodically admits a certain number of new peers to the system, and a user batch join (UBJ) mechanism, which preconstructs the new peers into a fixed‐size tree structure before peer join process. However, in the UAC mechanism, it is difficult to determine the optimal time slot length; while in the UBJ mechanism, it is difficult to determine the optimal tree size. Accordingly, the present study proposes a structured access control (SAC) mechanism, in which the new‐arriving peers are preconstructed to a flexible multilayer structure to overcome the limitation of a fixed‐size tree structure, and the number of peers in each layer of the structure is determined based on a consideration of the remaining upload bandwidth of the P2P system. Based on the assumption of a heterogeneous upload bandwidth capability of the peers, an analytical model is derived to describe the growth behavior of a P2P system with access control. It is shown that the simulation results for the growth rate of a P2P system based on the SAC mechanism are in good agreement with those obtained from the analytical model. In addition, the simulation results show that the SAC mechanism outperforms the UAC and UBJ mechanisms in terms of a more rapid system growth and a shorter average startup delay. Copyright © 2016 John Wiley & Sons, Ltd.     

A robust and efficient dynamic identity‐based multi‐server authentication scheme using smart cards

In single‐server architecture, one service is maintained by one server. If a user wants to employ multiple services from different servers, he/she needs to register with these servers and to memorize numerous pairs of identities and passwords corresponding to each server. In order to improve user convenience, many authentication schemes have been provided for multi‐server environment with the property of single registration. In 2013, Li et al. provided an efficient multi‐server authentication scheme, which they contended that it could resist several attacks. Nevertheless, we find that their scheme is sensitive to the forgery attack and has a design flaw. This paper presents a more secure dynamic identity‐based multi‐server authentication scheme in order to solve the problem in the scheme by Li et al. Analyses show that the proposed scheme can preclude several attacks and support the revocation of anonymity to handle the malicious behavior of a legal user. Furthermore, our proposed scheme has a lower computation and communication costs, which make it is more suitable for practical applications. Copyright © 2014 John Wiley & Sons, Ltd.     

Structural‐based tunneling: preserving mutual anonymity for circular P2P networks

Many methods are suggested to preserve anonymity of users for peer‐to‐peer (P2P) networks. Most of these methods, by relying on established anonymous solutions on client/server applications, are presented for unstructured P2P networks. However, structured overlays, by using distributed hash tables for their routing, do not resemble traditional paradigms. Therefore, current anonymous methods cannot be implemented for them easily. In this paper, we introduce structural‐based tunneling (SBT) to provide mutual anonymity for circular P2P structures. In this method, we get help from inherited features of network infrastructure to establish a standard way for making tunnels. SBT introduces a flexible design that is able to manage different parts of the tunnels on current infrastructures. For this purpose, we incorporate SBT with Chord to show how such design can be managed for real‐world applications. The results of applied method with simulations show that by managing critical features of SBT, a trade‐off can be made between stronger security and performance of the network. Copyright © 2015 John Wiley & Sons, Ltd.     

基于P2P技术的时移电视系统方案

本文针对时移电视业务,提出了基于P2P技术的系统解决方案.时移电视系统由一个分片处理器和一个媒体定位器以及若干对等节点组成,直播媒体流经分片处理器处理后切分成媒体分段和分块,媒体定位器完成媒体分段的定位服务,对等节点以随机概率进行媒体录制和存储,节点之间直接进行媒体块传输.理论分析及实验结果表明,该系统方案具备良好的扩展性和业务体验质量.     

Double‐layer P2P networks supporting semantic search and keeping scalability

In peer‐to‐peer (P2P) networks, with the aim to support semantic search and keep scalability at the same time, a novel double‐layer P2P protocol is proposed. Firstly, keywords representing resource characteristics are compressed into bloom filters and structured P2P layer is constructed. Secondly, through analyzing one's bloom filters, each node extracts its interest, which is represented by a characteristic vector V. After obtaining common interest among nodes through comparing their Vs, a small‐world model is constructed, and another unstructured P2P layer is obtained. Consequently, on the basis of the decentralized architecture, a double‐layer semantic search P2P protocol is structured. When objective resource is being located, its similarity to local interest is used to determine whether it should be located in unstructured P2P semantic layer or structured layer adaptively, which not only improves search efficiency but also supports semantic location more widely. Copyright © 2013 John Wiley & Sons, Ltd.     

Modeling and application of moderate prefetching strategy based on video slicing for P2P VoD systems

In peer-to-peer (P2P) video-on-demand (VoD) streaming systems,each peer contributes a fixed amount of hard disk storage (usually 2 GB) to store viewed videos and then uploads them to other requesting p...     

一种基于C/S模式的中间件SDO的P2P平台的网络拓扑设计

为了解决异构数据间的共享问题,提供标准、统一、功能丰富的接口,对传统的SDO的数据集成做了改进,并在P2P上加上了对server的支持,提高了模块的复用程度,降低了通讯的复杂度,用户获取数据时既可以从peer那获取,也可以从cdn或其它服务器上获取。     

P2P技术应用于分布式数据库的研究探讨

文中论述了如下概念：基于P2P网络上保证在网络出现故障时,“顺利读取数据。基于数据安全,提出数据冗余的概念,包括在本地设置多个备份数据库服务器,在主服务器故障的时候,可以使用备份数据。还有在不同的地方,设置服务器。提出分布式系统后,就出现分布式数据库,这样只能保证在服务器端的数据库的数据完整性。但是,对于客户机是没有保证的,一旦与主机的连接出现问题的时,分布式数据库就发挥不出优势。现在,P2P的技术加上的分布式数据库的技术,就可以解决分布式数据库的网络与数据库的问题。     

GaMe‐PLive: a new game theoretic mechanism for P2P live video streaming

GaMe‐PLive is a game theoretical framework for peer‐to‐peer live video streaming. Prevention of free‐riding and minimization of loss rate in video data transmission are the important objectives of the proposed framework. GaMe‐PLive is also extremely evasive about overhead of extra control messages exchange. At first, a static game with complete information between peers is described, which models the peer's interactive decision process for acceptance/rejection of a video chunk request. All peers repeatedly play this game during video playback periodically. Afterwards, the proposed game is analyzed to obtain a Nash equilibrium, which determines a peer's best strategic response for participation in the video chunk distribution. It will be proved that by applying some simple and feasible conditions, the desired objectives can be reached. The experimental results reveal that the proposed system has been successful in detecting free‐riders with negligible false negative and false positive rate. Also, tolerable loss chunk percentage has been satisfied in all performed tests. Besides, an interesting social norm emerges in GaMe‐PLive: Less participation leads to more missing chunks. GaMe‐PLive will be proven to be quite resistant against cheating peers. The proposed framework displays high performance even if there is not a video server with high upload bandwidth. Copyright © 2015 John Wiley & Sons, Ltd.     

X‐Region: A framework for location privacy preservation in mobile peer‐to‐peer networks

While enjoying various LBS (location‐based services), users also face the threats of location privacy disclosure. This is because even if the communications between users and LBS providers can be encrypted and anonymized, the sensitive information inside LBS queries may disclose the exact location or even the identity of a user. The existing research on location privacy preservation in mobile peer‐to‐peer (P2P) networks assumed that users trust each other and directly share location information with each other. Nonetheless, this assumption is not practical for most of the mobile P2P scenarios, for example, an adversary can pretend to be a normal user and collect the locations of other users. Aiming at this issue, this paper presents x‐region as a solution to preserve the location privacy in a mobile P2P environment where no trust relationships are assumed amongst mobile users. The main idea is to allow users to share a blurred region known as x‐region instead of their exact locations so that one cannot distinguish any user from others inside the region. We propose a theoretical metric for measuring the anonymity property of x‐region, together with three algorithms for generating an x‐region, namely, benchmark algorithm, weighted expanding algorithm, and aggressive weighted expanding algorithm. These algorithms achieve the anonymity and QoS requirements with different strategies. Our experiments verify the performance of the algorithms against three key metrics. Copyright © 2013 John Wiley & Sons, Ltd.