P2P Streaming Systems Research Articles

Stability-Optimal Grouping Strategy of Peer-to-Peer Systems

When applied in high-churn Internet environments, P2P systems face a dilemma: although most participants are too unstable, a P2P system requires sufficient stable peers to provide satisfactory core services. Thus, determining how to leverage unstable nodes seems to be the only choice. Our primary idea is to group unstable nodes together in order to form an adequate number of stable service groups. Focusing on this topic, our main findings are three-fold: 1) A general analytical model to investigate the grouping process of P2P systems is established, in which the stability-scalability trade-off problem is paid special attention to. 2) We formalize the target of grouping as the Maximum Stability Grouping (MSG) problem. It proves to be not only NP-hard, but also infeasible; therefore, we restrict it to a feasible Homogeneous MSG (H-MSG) problem and deduce its optimal solution under the stochastic model. 3) We propose a homogeneous grouping strategy to fulfill the optimal solution. Comprehensive simulations have been performed on generated data sets and real-world traces from a P2P storage system and a P2P streaming system. Results show that our grouping strategy effectively captures the stability-scalability trade-off: besides excellent stability, it gains much higher stable service capacity, with acceptable loss in scalability.

Viewing experience optimization based on adaptive requesting window adjustment in peer-to-peer media streaming

In the last few years, great achievements have been made in the field of peer-to-peer (P2P) streaming system. In mesh-based P2P streaming system, retrieving data from multiple parents simultaneously improves resilience of the streaming service. However, it also brings in playback lags. To improve users’ viewing experiences, we should consider both playback lags and resilience of the streaming service. However, it seems there is a natural trade-off between these two goals. In this paper we propose a viewing experience optimization algorithm which adjusts the position of the requesting window adaptively based on different requesting strategies. The novelty of the proposed method is that it utilizes heterogeneous real-time demands for different genres of videos, and can adjust requesting strategies adaptively. Under the condition of guaranteeing basic QoS (Quality of Service), the algorithm achieves a balance between playback lags and resilience. Finally, experiment results show the satisfactory performance of the proposed method.

On Dynamic Server Provisioning in Multichannel P2P Live Streaming

To guarantee the streaming quality in live peer-to-peer (P2P) streaming channels, it is preferable to provision adequate levels of upload capacities at dedicated streaming servers, compensating for peer instability and time-varying peer upload bandwidth availability. Most commercial P2P streaming systems have resorted to the practice of overprovisioning a fixed amount of upload capacity on streaming servers. In this paper, we have performed a detailed analysis on 10 months of run-time traces from UUSee, a commercial P2P streaming system, and observed that available server capacities are not able to keep up with the increasing demand by hundreds of channels. We propose a novel online server capacity provisioning algorithm that proactively adjusts server capacities available to each of the concurrent channels, such that the supply of server bandwidth in each channel dynamically adapts to the forecasted demand, taking into account the number of peers, the streaming quality, and the channel priority. The algorithm is able to learn over time, has full Internet service provider (ISP) awareness to maximally constrain P2P traffic within ISP boundaries, and can provide differentiated streaming qualities to different channels by manipulating their priorities. To evaluate its effectiveness, our experiments are based on an implementation of the algorithm, which replays real-world traces.

Efficient Algorithms for Multi-Sender Data Transmission in Swarm-Based Peer-to-Peer Streaming Systems

In mesh-based peer-to-peer (P2P) streaming systems, each video sequence is divided into segments, which are then streamed from multiple senders to a receiver. The receiver needs to coordinate the senders by specifying a transmission schedule for each of them. We consider the problem of scheduling segment transmission in P2P streaming systems, where different segments have different weights in terms of quality improvements to the received video. Our goal is to compute the transmission schedule for each receiver in order to maximize the perceived video quality. We first show that this scheduling problem is NP-Complete. We then present an integer linear programming (ILP) formulation for it, so that it can be solved with any ILP solver. This optimal solution, however, is computationally expensive and is not suitable for real-time P2P streaming systems. Thus, we propose two approximation algorithms to solve this segment scheduling problem. These algorithms provide theoretical guarantees on the worst-case performance. The first algorithm considers the weight of each video segment. The second algorithm is simpler and it assumes that segments carry equal weights. We analyze the performance and complexity of the two algorithms. In addition, we rigorously evaluate the proposed algorithms with simulations and experiments using a prototype implementation. Our simulation and experimental results show that the proposed algorithms outperform other algorithms that are commonly used in deployed P2P streaming systems and that have been recently proposed in the literature.

A Model for Analyzing Delay in Mesh-Based P2P Streaming Networks

Though some algorithms about the minimum delay have been designed, there is no actual algorithm which could be used in a Mesh-based P2P streaming system without a set of specified neighbors as we know. The characters of delay in Mesh-based P2P streaming network need to be understood more thoroughly. Using capabilities model to reflect the relationship between nodes and chunks, we model the delay character in P2P streaming system to explain the tradeoff between delay and playback quality. Finally, we use a holes and repair approach to give a serial of principles about how to make the delay to be low enough with a high quality as a direction for future design of algorithm.

Enabling resilient P2P video streaming: survey and analysis

Peer-to-Peer (P2P) techniques for multimedia streaming have been shown to be a good enhancement to the traditional client/server methods when trying to reduce costs and increase robustness. Due to the fact that P2P systems are highly dynamic, the main challenge that has to be addressed remains supporting the general resilience of the system. Various challenges arise when building a resilient P2P streaming system, such as network failures and system dynamics. In this paper, we first classify the different challenges that face P2P streaming and then present and analyze the possible countermeasures. We classify resilience mechanisms as either core mechanisms, which are part of the system, or as cross-layer mechanisms that use information from different communication layers, which might inflict additional costs. We analyze and present resilience mechanisms from an engineering point of view, such that a system engineer can use our analysis as a guide to build a resilient P2P streaming system with different mechanisms and for various application scenarios.

High-Quality P2P Video Streaming System Considering the Cooperation of Constitution Information and Delivery Status

Recently, video streaming services using P2P (Peer-to-Peer) have attracted attention to solve the problem of load concentration on servers and to reduce large latency. Many P2P streaming systems, like Coolstreaming, however, take a complicated approach to control playback timing severely. This leads to less churn resiliency and less adaptability to fluctuation of network traffic. Therefore, we focus on a simple and robust approach to realize “pseudo” streaming with high quality, which is based on BitTorrent. In the existing methods with the simple approach, peers download pieces just closer to playback timing to decrease the playback discontinuity. However, these methods do not consider the constitution of video structure in sophisticated manner. P2P streaming system must consider several important metrics for high-quality and fair distribution. Therefore, in this paper, we propose a new P2P video streaming system considering the cooperation of three important metrics; video structure, playback timing, and piece dispersion on network. In this system, users vary three piece selections to suit the delivery status. Specifically, users preferentially download pieces which affect the video quality, which are closer to playback timing, and which improve the delivery efficiency. Moreover, we show the effectiveness of the proposed method by computer simulation.

A Survey and Synthesis of User Behavior Measurements in P2P Streaming Systems

In terms of scalability, cost and ease of deployment, the Peer-to-Peer (P2P) approach has emerged as a promising solution for video streaming applications. Its architecture enables end-hosts, called peers, to relay the video stream to each other. P2P systems are in fact networks of users who control peers. Thus, user behavior is crucial to the performance of these systems because it directly impacts the streaming flow. To understand user behavior, several measurement studies have been carried out over different video streaming systems. Each measurement analyzes a particular system focusing on specific metrics and presents insights. However, a single study based on a particular system and specific metrics is not sufficient to provide a complete model of user behavior considering all of its components and the impact of external factors on them. In this paper, we propose a comparison and a synthesis of these measurements. First of all, we review video streaming architectures, followed by a survey on the user behavior measurements in these architectures. Then, we gather insights revealed in these measurements and compare them for consensual and contrasting points. Finally, we extract components of user behavior, their external impacting factors and relationships among them. We also point out those aspects of user behavior which require further investigations.

User density sensitive P2P streaming in wireless mesh networks

Link rate allocation is very important for supporting high video playback rate in Peer-to-Peer video streaming. Although many studies can be found on resource allocation in P2P streaming in wired networks, very few studies have studied the problem in wireless networks, especially in Wireless multi-hop Mesh Networks (WMNs), which is still challenging. To maximize the users’ satisfaction of P2P streaming in WMNs, this paper focuses on link rate allocation problem and proposes a fully distributed algorithm to efficiently utilize the upload and download bandwidth of wireless mesh nodes. We first build an efficient P2P streaming system based on the experimental results from real deployment of our wireless mesh testbed. Then we design an efficient distributed algorithm based on the solution to a linear optimization model, which optimizes towards a user-density-related objective to decide the best streaming rates among peers. Our scheme is resilient to network dynamics that is characteristic in wireless multi-hop peer-to-peer networks. The simulation experiments demonstrate the significant performance enhancement by using the proposed rate allocation algorithm in WMNs.

Incentive Mechanisms in P2P Media Streaming Systems

Free riding, whereby a peer utilizes network resources but doesn't contribute services, could have a huge impact on the efficacy of peer-to-peer media streaming systems, leading to scalability issues and service degradation. Here, the authors categorize, analyze, and compare a range of incentive mechanisms proposed for P2P streaming systems.

P2P (Peer-to-Peer) 비디오 스트리밍을 위한 다중 비디오 품질 인센티브 기법

인터넷 상에서의 비디오 스트리밍을 위한 대안으로서 P2P(Peer-to-Peer)가 관심을 받고 있다. P2P 시스템은 피어들의 대역폭 기여에 의존하고 있지만, 피어들은 자신의 대역폭을 제공하는 것을 꺼리는 경향이 있다. 본 논문에서 우리는 상향 대역폭 기여를 촉진하는 P2P 스트리밍 시스템을 제안한다. 제안 시스템에서 피어들 간의 공평성을 유지하고, 제어 가능한 방법으로 협력적인 피어와 이기적인 피어에게 다른 품질의 비디오를 제공한다. 제안 시스템은 기여한 상향 대역폭에 기초한 평가 기법으로 피어가 협력적인지 이기적인지를 결정하고, 협력적인 피어들에게는 인센티브로서 고품질의 비디오를 제공한다. 또한 제안시스템이 효과적으로 동작할 수 있도록 트리 재건조 알고리즘을 제안한다. 시뮬레이션을 통해, 트리 재건조 알고리즘이 효과적으로 동작하며, 인센티브 기법이 협력적인 피어에게 더 많은 하향 대역폭을 할당하고 이기적인 피어에게는 저품질 비디오를 제공함을 보인다. Peer-to-Peer (P2P) has attracted attention as an alternative way to enable streaming videos on the Internet. Although P2P systems depend on bandwidth contribution from peers, peers are likely to refuse to contribute their bandwidth. In this paper, we proposed a P2P streaming system that encourages peers to contribute their upstream bandwidth by maintaining fairness among peers and providing different video quality between cooperative peers and selfish peers with a manageable way. Our proposed system determines if peers are cooperative or selfish by a rating mechanism based on their contributed upstream bandwidth, and offers a high quality video to cooperative peers as an incentive. Also we propose a tree reconstruction algorithm to make the system work effectively. Through simulation, we show that the tree reconstruction algorithm works effectively, and our incentive mechanism allocates more downstream bandwidth to cooperative peers and punished selfish peers with low quality video.

Streamline: An Optimal Distribution Algorithm for Peer-to-Peer Real-Time Streaming

In this paper, we propose and evaluate an overlay distribution algorithm for P2P, chunk-based, streaming systems over forest-based topologies. In such systems, the stream is divided in chunks; chunks are delivered by each node in a store-and-forward way. A relaying node starts distributing a chunk only when it has completed its reception from another node. Peers are logically organized in a forest of trees, where each tree includes all peers. The source periodically distributes different chunks to each tree for their delivery. Our key idea consists in employing serial transmission: for each tree, and thus, for each chunk, the source node sends the chunk to its children in series; the same holds for each peer node of the tree, excluding the leaves. Besides this basic idea, the contributions of this paper are: 1) we demonstrate the feasibility of serial transmission over a forest of trees, which is not a trivial problem, unlike the case of parallel transmission; 2) we derive an analytical model to evaluate the system performance; 3) we derive a theoretical bound for the number of nodes reachable in a given time interval or equivalently for the time required to reach a given number of nodes; 4) we prove the optimality of our approach in terms of its capability to reach such bound; and 5) we develop a general simulation package for P2P streaming systems and use it to compare our solution to literature results. Finally, we stress that this paper is focused on the theoretical properties and performance understanding of the proposed distribution algorithm, rather than on its practical implementation in a real system. However, we also briefly describe a practical workable implementation of our algorithm.

Study of User Activity in Peer to Peer Living Streaming System

understanding the characteristics of user activities make sense to various application designs, and consequently has impact on business benefit directly. In this paper, we present a study of a peer to peer (P2P) live streaming system based on measurement. We classify those channels into three types and study the statistical characteristics on user behaviors, such as user arriving and leaving, especially we conduct an in-depth analysis of their relations with program time point and time duration. We observe that users behave differently not only inside different type of channels but also different programs. We find that 1) peers watching time duration has no necessary relationship with peer interest; 2) peers watching time duration is enormously affected by program arrangement; 3) peers behavior is substantially active in the first 10min of a program. We also come up with a heuristic model about the number of online peers during a program and the watching time duration of one online user. Our study can be used as a reference for arranging the program resources and channel resources so as to attract more viewers to stay longer in the streaming system. This has important implications on not only the design and development of P2P streaming system and IPTV systems, but also the existing general TV system.

Security and privacy issues in P2P streaming systems: A survey

Streaming applications over Peer-To-Peer (P2P) systems have gained an enormous popularity. Success always implies increased concerns about security, protection, privacy and all the other ‘side’ properties that transform an experimental application into a service. Research on security for P2P streaming started to flourish, but no comprehensive security analysis over the current P2P solutions has yet been attempted. There are no best practices in system design, no (widely) accepted attack models, no measurement-based studies on security threats to P2P streaming, nor even general surveys investigating specific security aspects for these systems. This paper addresses this last aspect. Starting from existing analyses and security models in the related literature, we give an overview on security and privacy considerations for P2P streaming systems. Our analysis emphasizes two major facts: (i) the Byzantine–Altruistic–Rational (BAR) model offers stronger security guarantees compared to other approaches, at the cost of higher complexity and overhead; and (ii) the general perception (not necessarily the truth, but a commonplace belief) that it is necessary to sacrifice accuracy or performance in order to tolerate faults or misbehaviors, is not always true.

On the source switching problem of Peer-to-Peer streaming

Peer-to-Peer(P2P) streaming has been proved a popular and efficient paradigm of Internet media streaming. In some applications, such as an Internet video distance education system, there are multiple media sources which work alternately. A fundamental problem in designing such kind of P2P streaming system is how to achieve fast source switching so that the startup delay of the new source can be minimized. In this paper, we propose an efficient solution to this problem. We model the source switch process, formulate it into an optimization problem and derive its theoretical optimal solution. Then we propose a practical greedy algorithm, named fast source switch algorithm, which approximates the optimal solution by properly interleaving the data delivery of different media sources. The algorithm can adapt to the dynamics and heterogeneity of real Internet environments. We have carried out extensive simulations on various real-trace P2P overlay topologies to demonstrate the effectiveness of our model and algorithm. The simulation results show that our proposed algorithm outperforms the normal source switch algorithm by reducing the source switch time by 20%–30% without bringing extra communication overhead. The reduction in source switching time is more obvious as the network scale increases.

Research on Video on Demand Based on P2P Network

A P2P approaches to extend the ability of Video on Demand systems to serve more users. In the proposed system users share with each other the media data obtained and the media server is no longer the only source to get data from, thereby, the load on the media server could be greatly alleviated and the overall system capacity increases and more users could be served. The P2P streaming system introduces efficient searching; data transfer dynamically monitoring and initial buffering to maintain a high quality of playback. Its provider selection policy helps to reduce the load of the underlying network by avoiding remote data transfer.

Transmission Latency based Network Friendly Tree for Peer-to-Peer Streaming

In Peer-to-Peer(P2P) streaming system, the multicasting tree construction method influences considerably on network load. Under current available strategies, network resources are not used economically, or network resource friendship and the flexibility can't be approached thoroughly. With the increasing application of Internet, network infrastructure itself becomes a precious resource, which should be performed effectively. In our implementation, network transmission delay between the peers is detected, used as practical performance metrics of the P2P streaming system. Ac- cording to the metrics, network friendly tree is provided as overlay multicasting tree construction strategy for P2P streaming system. In this strategy, additional transmis- sion delays are minimized as new peers enter. The simulation experiment presents that the proposed strategy network friendly tree works better than other contrasts. And the transmission performance improves significantly at minor additional cost.

IAM: An Effective and Robust Protocol for P2P Live Streaming System

The phenomenal success and popularity of peer-to-peer (p2p) streaming over the last decade took many providers, researchers, as well as the mass, by surprise. It would become the dominant type of traffic over the Internet in the very near future. The released Windows Vista contains its own P2P networking system. Though P2P streaming has become one of the most attractive network applications, it is still awaiting some technological breakthroughs. P2P streaming faces very different challenges from other P2P applications, such as file download. In live P2P streaming, the stringent real-time performance requirement in terms of bandwidth and latency is one of the challenges it faces. In addition, frequent joining and leaving of the autonomous end-hosts have more significant impact on the system performance. So the churn problem and reconstruction due to uncertainty are key challenges of P2P streaming. A number of solutions were proposed which did not take all the factors into account. This paper presents IAM (IP Address Matching), a novel protocol for P2P live streaming system. For overlay structure, neighbor selection algorithm-FAMM (Forward Address Maximum Matching), which allows the peer choose the close peers as neighbors, is proposed. In this mechanism peer selects neighbors by matching IP address in regular expression. IP address is assigned by area basically, so the closer the peers are, the more the same bits of IP address they have. Peer chooses the first m (m > 0) peers whose IP address has same bits with it as the neighbors. Meanwhile, the latency is generally low. FAMM just likes the DHT routing. As managing peer failures and proper recovery are of critical importance for a robust P2P streaming system, a new peer exception mechanism is also proposed which is the other central issue of the IAM. According to the different error information which the peer receives, it detects the departure or failure of the neighbor intelligently and recovers from an unstable state promptly. To evaluate the performance of the IAM, we have conducted extensive simulations and real-network experiment. The results indicate that IAM shortens the latency and is robust to the dynamic peers. It achieves superior comprehensive performance over Random scheme. It is proved effective in the real-network environment, and the latency of recovery is shortened significantly which is only 25% of that with the usual mechanism, as well.

An Empirical Study of the Coolstreaming+ System

In recent years, there has been significant interest in adopting the peer-to-peer (P2P) technology for Internet live video streaming. There are primarily two reasons behind this development: the elimination of infrastructure support and the self-scaling property of P2P systems. The success of our system Coolstreaming represented one of the earliest large-scale P2P video streaming experiments. Since then, there have been several large-scale commercial deployments. With desirable content, these systems have the potential to scale orders of magnitude beyond the existing academic P2P prototypes. However, to transform this potential into reality, we need to understand the key design trade-offs and principles, as well as the design limitations of these systems. There are two main design decisions in a P2P streaming system: (i) How to form an overlay, and (ii) How to deliver the content. Coolstreaming adopts a gossiping protocol for overlay construction, and a swarm-based protocol for content delivery. While these protocols provide excellent flexibility and effectiveness in dealing with system dynamics and random failure, their impact on the performance and the system scalability remain less known. This paper takes an inside look at a commercial system based on the Coolstreaming, called Coolstreaming+. We explore its design choices and the impact of these choices on streaming performance. Specifically, by using internal traces generated by recent live broadcast events, we study the workload, performance, and dynamics of the system. Based on these traces, we show that (1) the churn is the most critical factor that affects the overall performance of the system, and (2) there is a highly skew resource distribution in P2P streaming systems, which has significant impact on resource allocation. We further discuss the impact of these observations on the system properties, and present solutions to deal with various design challenges. In particular, we suggest solutions to deal with the excessive start-up time and high failure rates during flash crowd, which are two of the main challenges any streaming system needs to address.

An Alliance Based Peering Scheme for P2P Live Media Streaming

While recent measurement studies have shown the effectiveness of P2P network in media streaming, there have been questions raised about the quality of service (QoS), reliability of streaming services and sub optimal uplink utilization in particular. P2P streaming systems are inherently less reliable because of churn, internet dynamics, node heterogeneity and randomness in the swarm. We present a new model for P2P media streaming based on clustering of peers, called alliances. We show that alliance formation is a loosely coupled and an effective way to organize the peers. We show that our model maps to a ldquosmall-worldrdquo network, which form efficient overlay structures and are robust to network perturbations such as churn. We present a comparative simulation based study of our model with CoolStreaming/DONet and present a quantitative performance evaluation. Simulation results are promising and show that our model scales well under varying workloads and conditions, delivers near optimal levels of QoS, and for most cases, performs at par or even better than CoolStreaming/DONet.