Admission Control in High Speed Multimedia Networks

高速多媒体网络中的准入控制

• 批准号: 9706148
• 负责人: Ioannis Paschalidis
• 金额: $ 20.01万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2001-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9706148&HistoricalAwards=false
• 关键词: Admission; Control; Speed; Multimedia; Networks

In recent years, technological advances and bandwidth availability have brought about a web of new multimedia and real-time applications, such as internet telephony, interactive TV, video-on-demand, and videoconferencing. These applications have important uses in a wide range of activities from education and health care to entertainment. Their full deployment will clearly have a huge impact on the quality of our lives and the society as a whole. Such applications, however, are very bandwidth demanding, very sensitive to congestion, and require real-time and reliable communication. Although appropriate protocols, such as the Asynchronous Transfer Mode (ATM) protocol and an enhanced version of Internet's TCP/IP protocol (with RSVP), already exist, Quality of Service (QoS) provisioning remains one of the fundamental open problems that need to be addressed before real-time applications can be reliably supported. If congestion is not an option, restricting the number of users that are allowed in the network becomes an extremely useful tool in guaranteeing QoS. The central goal of this research is to devise such an admission control procedure and test its performance in practice. To provide QoS guarantees the network should prevent congestion which causes packet losses due to buffer overflows and excessive delays. A worst case based admission control algorithm (which allocates to calls bandwidth equal to their peak rate) leads to significant underutilization of the network resources, since traffic is typically bursty, i.e., the peak rate is not sustained for long. To achieve more efficient use of the resources the proposed approach will permit some congestion phenomena which will be occurring infrequently enough to allow for the provision of statistical QoS guarantees. More specifically, it is desired to operate the network in a regime where loss probabilities and probabilities of excessive delays are particularly small (e.g., on the order of 10^{-6}). Real-time app lications can tolerate such small frequencies of congestion phenomena. This research will draw upon methods developed in applied probability, optimization, and optimal control theory, and will use, extending whenever necessary, many of the ideas developed recently by the PI. Calculating congestion probabilities for non-trivial traffic models is particularly hard. The proposed work will therefore resort to asymptotic results using large deviations theory (a subfield of applied probability) as the main analytical tool. Issues that are considered as prerequisites for successful admission control will be first resolved. Among them the proposed research will address: -Traffic Modeling. The aim is to propose models that capture the statistical properties of the traffic which are relevant to admission control. -Performance analysis. The goal is to asymptotically estimate congestion probabilities in a multiclass and multihop network environment. The final product of the proposed work will be an admission control algorithm that provides statistical QoS guarantees to admitted calls and possesses the following characteristics: -Support for multiple service classes. Applications will be bundled in service classes based on the statistical character of the traffic they generate and on their QoS requirements. -Full utilization of available bandwidth. The controller will be flexible enough to investigate different bandwidth allocation strategies among service classes and deny admission only when there is no feasible allocation that guarantees QoS to all connected calls. -End-to-End QoS guarantees. Real-time implementation. More information about this project can be obtained from the Web at http://ionia.bu.edu/

近年来，技术进步和带宽可用性带来了新的多媒体和实时应用网络，例如网络电话、交互式电视、视频点播和视频会议。这些应用程序在从教育、医疗保健到娱乐的广泛活动中具有重要用途。 它们的全面部署显然将对我们的生活质量和整个社会产生巨大影响。 然而，此类应用对带宽的要求非常高，对拥塞非常敏感，并且需要实时且可靠的通信。 尽管异步传输模式 (ATM) 协议和增强版 Internet TCP/IP 协议（​​带 RSVP）等适当的协议已经存在，但服务质量 (QoS) 供应仍然是在可靠支持实时应用程序之前需要解决的基本开放问题之一。 如果无法避免拥塞，那么限制网络中允许的用户数量就成为保证 QoS 的极其有用的工具。本研究的中心目标是设计这样的准入控制程序并在实践中测试其性能。 为了提供 QoS 保证，网络应防止拥塞，防止因缓冲区溢出和过度延迟而导致数据包丢失。 基于最坏情况的准入控制算法（分配给呼叫的带宽等于其峰值速率）会导致网络资源的严重利用不足，因为流量通常是突发性的，即峰值速率不会持续很长时间。为了更有效地利用资源，所提出的方法将允许一些不频繁发生的拥塞现象，以允许提供统计QoS保证。更具体地，希望在丢失概率和过度延迟的概率特别小的情况下操作网络（例如，大约10^{-6}）。实时应用程序可以容忍如此小的频率的拥塞现象。 这项研究将利用应用概率、优化和最优控制理论中开发的方法，并将在必要时使用 PI 最近开发的许多想法。计算重要流量模型的拥塞概率尤其困难。 因此，拟议的工作将诉诸使用大偏差理论（应用概率的子领域）作为主要分析工具的渐近结果。 被视为成功准入控制先决条件的问题将首先得到解决。其中拟议的研究将解决： - 流量建模。 目的是提出捕获与准入控制相关的流量统计特性的模型。 -性能分析。 目标是渐近估计多类和多跳网络环境中的拥塞概率。 拟议工作的最终产品将是一种准入控制算法，该算法为准入呼叫提供统计 QoS 保证，并具有以下特性： - 支持多个服务类别。 应用程序将根据其生成的流量的统计特征及其 QoS 要求被捆绑在服务类别中。 - 充分利用可用带宽。 控制器将足够灵活，以调查服务类别之间的不同带宽分配策略，并仅在没有可行的分配来保证所有连接呼叫的 QoS 时拒绝准入。 - 端到端的 QoS 保证。 实时执行。 有关该项目的更多信息可以从以下网站获取：http://ionia.bu.edu/