P2P流媒体网络中基于博弈理论的带宽请求分配策略

基于对等网(P2P)技术的视频流媒体系统以其较低的服务器开销和良好的可扩展性被广泛应用。但由于在这类系统中普遍存在节点的资源及视频播放位置的异构性,使得节点负载不均衡的问题极易发生,进而严重影响到节点的视频播放质量。该文重点研究面向节点负载均衡的节点带宽请求分配策略,将服务请求节点竞争服务提供节点带宽的行为建模为一个非协作博弈,通过寻求该博弈问题的 Nash 均衡解的方法确定优化的带宽请求分配(GBRA)策略。通过和典型的带宽请求分配策略进行实验对比,数值结果表明该文提出的GBRA 策略能有效改善P2P流媒体网络节点负载不均的问题并降低节点获取所需视频数据的平均延迟。     

一种应用于移动P2P网络的资源协作共享策略

移动P2P网络的移动节点设备资源短缺,网络动态多变,移动节点间的协作显得越发重要.本 文提出了一种灵活的移动节点间资源协作共享方案,为资源的请求者设计了基于可靠性理论 的请求资源预测算法.依据排队理论为资源的提供者,构建了层次型资源调度模型.数学分析 和仿真结果表明该预测算法提高了节点请求任务执行成功率,层次型资源调度模型则提高了 节点协作共享资源的服务能力,降低了资源请求丢失率.     

基于拍卖的P2P内容分发网络带宽分配机制

为了解决P2P内容分发网络中带宽资源稀缺且分配不合理这一突出问题,抑制节点的自私性行为,设计了一种基于拍卖的带宽分配机制。该机制通过上载带宽支付方式,迫使自私请求节点选择合适的带宽需求,使得整个P2P网络中的节点良性竞争带宽资源,避免了"公共地悲剧"的发生;且带宽分配算法在资源节点和请求节点并行执行,能很好适应P2P网络的分布式特性。仿真结果表明,该机制能够有效遏制搭便车行为,从而缩短P2P内容分发的平均完成时间,降低内容源服务器的上传数据比例。     

异构环境下P2P直播流媒体调度算法研究

对节点上行带宽异构环境下的P2P流媒体系统数据块调度算法进行了研究,具体包括系统模型及相关标识,基于带宽感知的数据块调度算法研究和性能评价。通过研究发现,在设计数据块调度算法时充分利用带宽异构性,优先选择高上行带宽的节点,能有效地降低平均块延时。     

基于蚁群优化的移动P2P网络路由选择算法

因为移动P2P网络具有动态性而且移动节点能量受限,提升移动P2P数据传输效率至关重要.利用蚁群优化算法,将蚂蚁的信息素与节点的能量和通信带宽结合起来,在蚁群选择路径时,减少其寻优路径上的信息素浓度,根据概率路由表中信息素的浓度对路由选择策略进行调整,避免网络拥塞和个别节点能量消耗过快,提出了一种移动P2P网络的多路径路由选择算法.实验结果表明,与EDSR路由协议相比,提出的算法能够降低节点的分组丢失率和端到端的平均时延,提高了网络的生存周期.     

基于P2P流媒体直播系统的数据传输策略

针对P2P模式下视频流媒体直播系统的数据传输策略用改进的模拟退火算法进行了优化。以全局规划的思想建立了P2P视频流媒体的数据传输策略数学模型VMDTSA-P2P,模型充分考虑了可用出口带宽和可用性时间对播放连续性的影响,把它们作为获取最优解的目标函数因子,并用改进后的模拟退火算法进行解的寻优,相比于传统的数据传输策略,在具有大量用户的情况下加快了新节点从伙伴节点中选择数据块提供节点的速度,并且保证得到近似最优的数据块提供节点组合,减少了视频流媒体直播系统播放的延迟,从而提高了播放的连续性、流畅性,保证了视频播放的质量。通过该算法在模拟P2P系统中的实现,验证了该算法在P2P系统中对数据传输的准确性和高效性。     

单码流场景下P2P流媒体直播数据调度方法

由于具有较高应对节点动态性的能力和较强的扩展性,Mesh-Pull P2P流媒体直播分发方法赢得了学术界和工业界的广泛青睐.提出了传统互联网单码流场景下Mesh-Pull P2P流媒体直播的数据调度算法.该算法采用TOPSIS方法来解决调度算法中数据块优先级的量化这一多属性决策问题,以降低节点的启动延迟.仿真实验表明,本算法可以在保证高视频播放质量的情况下降低用户观看视频的延迟.     

云辅助P2P-VoD系统中一种邻居选择算法

提出了一种邻居选择算法,包括节点选择和块选择2个子算法。前者保证请求节点能够以较低的被拒绝概率发现提供视频数据的邻居节点;后者为节点以何种方式下载数据块提供依据,保证系统中视频数据块的高可用性。实验结果表明,提出的算法能进一步降低服务器带宽开销和节点请求拒绝率,并提升节点的下载速率。     

基于市场机制的P2P流媒体网络节点选择算法

针对P2P流媒体网络中的节点选择问题,将移动代理引入P2P网络,建立起用于有效实现P2P网络节点的市场化节点选择模型.基于该模型,进一步提出了一种基于市场机制的自适应节点选择算法MANS:通过模拟市场经济中的价格机制适时调整节点的带宽价格,并动态划分节点角色,依据所建立的评价模型选择最优节点,进行数据服务.最后将该模型与MANS算法运用于直播场景,对仿真结果进行了分析并和静态选择算法进行了比较.     

一种基于响应度的P2P点播流媒体系统激励机制

针对P2P点播流媒体系统中的搭便车问题,提出了一个基于结点响应度的激励机制GBIM(Responsivity Based Incentive Mechanism).该机制根据结点对来自其它结点数据请求的响应度提供不同网络服务质量,从而激励邻居结点彼此协作,更多地贡献带宽资源,使系统效用最大化.仿真实验表明:GBIM机制促进了系统效用的增长,提高了系统的吞吐量,达到了激励节点参与资源共享的目的.     

Distributed upload bandwidth assigning algorithm in P2P VoD system

In a peer-to-peer(P2P) live streaming system,each peer uses greedy strategy to download chunks as many as possible so as to assure smooth playback and promote the chunk propagation.However,diversity of video playback rate,heterogeneity of peer downlink bandwidth and no prefetching limitation determine that greedy strategy is not the best strategy for P2P video-on-demand(VoD) system though this strategy performs well in P2P live system.To reasonably assign upload bandwidth among peers,we first present a stochastic model to relate expected downloading speed(EDS) with buffered data amount(BDA,the amount of data has been fetched in buffer,however has not been played yet by the peer),video playback rate and fluency(the probability of no interruption in a viewing process).On the base of this model,we design an equal fluency bandwidth assigning algorithm(EFBAA).In this algorithm,requesting peers compute EDS according to several local parameters(such as BDA,video playback rate and fluency) dynamically and independently and send the EDS to neighbor peers together with buffer map.Then the neighbor peer proportionally partitions and assigns its upload bandwidth to requesting peers according to their EDS.Extensive simulations demonstrate that EFBAA outperforms greedy strategy in terms of server load and startup latency.     

Scalable 3D video streaming over P2P networks with playback length changeable chunk segmentation

3D video distribution over P2P networks has been thought as a promising way for 3D video entering home. The convergence of scalable 3D video coding and P2P streaming can provide diverse 3D experiences for heterogeneous clients with high distribution efficiencies. However, the conventional chunk segmentation and scheduling algorithms originally aiming at the non-scalable 2D video streaming are not very efficient for scalable 3D video streaming over P2P networks due to the particular data characteristics of scalable 3D video. Based on this motivation, this paper first presents a playback length changeable 3D video chunk segmentation (PLC3DCS) algorithm to provide different error resilience strengths to video and depth as well as layers with different importance levels in the 3D video transmission. Then, a hybrid-priority based chunk scheduling (HPS) algorithm is proposed to be tied in with the proposed chunk segmentation algorithm to further promote the overall 3D video P2P streaming performance. The simulation results show that the proposed PLC3DCS algorithm with the corresponding HPS can increase the success delivery rates of chunks with more important levels, and further improve the user’s quality of 3D experience.     

QoE optimization for HTTP adaptive streaming: Performance evaluation of MEC-assisted and client-based methods

Seamless streaming of high quality video under unstable network condition is a big challenge. HTTP adaptive streaming (HAS) provides a solution that adapts the video quality according to the network conditions. Traditionally, HAS algorithm runs at the client side while the clients are unaware of bottlenecks in the radio channel and competing clients. The traditional adaptation strategies do not explicitly coordinate between the clients, servers, and cellular networks. The lack of coordination has been shown to lead to suboptimal user experience. As a response, multi-access edge computing (MEC)-assisted adaptation techniques emerged to take advantage of computing and content storage capabilities in mobile networks. In this study, we investigate the performance of both MEC-assisted and client-side adaptation methods in a multi-client cellular environment. Evaluation and comparison are performed in terms of not only the video rate and dynamics of the playback buffer but also the fairness and bandwidth utilization. We conduct extensive experiments to evaluate the algorithms under varying client, server, dataset, and network settings. Results demonstrate that the MEC-assisted algorithms improve fairness and bandwidth utilization compared to the client-based algorithms for most settings. They also reveal that the buffer-based algorithms achieve significant quality of experience; however, these algorithms perform poorly compared with throughput-based algorithms in protecting the playback buffer under rapidly varying bandwidth fluctuations. In addition, we observe that the preparation of the representation sets affects the performance of the algorithms, as does the playback buffer size and segment duration. Finally, we provide suggestions based on the behaviors of the algorithms in a multi-client environment.     

面向固定移动融合环境的P2PSIP系统设计

全业务运营是电信市场继语音和宽带接入服务之后的下一个增长点,而基于IP的融合有线网络和无线网络的语音服务则是全业务的重点之一。本文通过分析现有VoIP网络存在的问题以及固定移动融合网络环境下VoIP的特点,提出一种新型双层重叠网架构的P2PSIP架构,并阐述了新型架构的优点及双层重叠网之间的通信机制。新型架构能有效提高系统的安全性、健壮性和用户节点资源利用效率,更好的满足固定移动融合网络环境下VoIP对带宽、网络质量和安全性的要求。     

基于P2P技术的网格资源发现中覆盖网络的构建

文章针对网格环境下的集中式资源发现机制的不足,设计了基于P2P技术的资源发现模型,并在分析典型P2P系统Gnutella覆盖网络构建方式的基础上,提出了网格环境下进行覆盖网络构建的新方式--定序方式.按照定序方式构建的覆盖网络可以保证资源发现的服务质量,同时定序方式以节点间的网络延时作为覆盖网络构建的依据,请求消息按照小的网络延时路径在覆盖网络上传播,从而可以提高资源发现的效率.     

Evolved data scheduling scheme based on layered P2P streaming in mobile network

To relieve the negative effect brought by the intricate wireless network environment and unstable user behavior in layered mobile peer-to peer(P2P) streaming service,an evolved layered P2P (E-LP2P) dat...     

Efficient Uplink Bandwidth Request with Delay Regulation for Real-Time Service in Mobile WiMAX Networks

The emerging broadband wireless access technology based on IEEE 802.16 is one of the most promising solutions to provide ubiquitous wireless access to the broadband service at low cost. This paper proposes an efficient uplink bandwidth request-allocation algorithm for real-time services in Mobile WiMAX networks based on IEEE 802.16e. In order to minimize bandwidth wastage without degrading quality of service (QoS), we introduce a notion of target delay and propose dual feedback architecture. The proposed algorithm calculates the amount of bandwidth request such that the delay is regulated around the desired level to minimize delay violation and delay jitter for real-time services. Also, it can increase utilization of wireless channel by making use of dual feedback, where the bandwidth request is adjusted based on the information about the backlogged amount of traffic in the queue and the rate mismatch between packet arrival and service rates. Due to the target delay and dual feedback, the proposed scheme can control delay and allocate bandwidth efficiently while satisfying QoS requirement. The stability of the proposed algorithm is analyzed from a control-theoretic viewpoint, and a simple design guideline is derived based on this analysis. By implementing the algorithm in OPNET simulator, its performance is evaluated in terms of queue regulation, optimal bandwidth allocation, delay controllability, and robustness to traffic characteristics.     

基于最长有效功能序列的服务功能链部署算法

服务功能链的服务性能取决于功能的部署位置和数据传输路径的选择。针对资源有限的网络中的服务功能链部署问题,该文设计了一种基于最长有效功能序列(LEFS)的服务功能链部署算法,以功能复用和带宽需求联合优化为目标,在控制路径长度的同时根据LEFS逐步搜索中继节点,直至满足服务请求。仿真结果表明,该算法能够均衡网络资源,同时优化网络的功能部署率和带宽利用率,与其他算法相比,网络资源利用率降低了10%,可以支持更多的服务请求,且算法计算复杂度低,可以实现对服务请求的快速响应。