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; 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，技术进步和带宽的可用性带来了新的多媒体和实时应用程序的网络，例如互联网电话，交互式电视，视频按需以及视频会议。这些应用在从教育和医疗保健到娱乐的广泛活动中具有重要用途。 他们的全部部署显然会对我们生活和整个社会的质量产生巨大影响。 但是，此类应用非常需要带宽，对拥堵非常敏感，需要实时和可靠的沟通。 尽管适当的协议，例如异步传输模式（ATM）协议和Internet的TCP/IP协议的增强版本（带有RSVP），但已经存在，服务质量（QOS）提供仍然是可靠地支持实时应用程序之前需要解决的基本开放问题之一。 如果不是一个选项，则限制网络中允许的用户数量成为保证QoS的极其有用的工具。这项研究的核心目标是设计这样的录取控制程序并在实践中测试其表现。 为了提供QoS保证，网络应防止拥塞，这会导致缓冲区溢出和过度延迟引起的数据包损失。 基于最坏情况的录取控制算法（分配给带宽等于其峰值速率的呼叫）导致网络资源的严重缺乏，因为流量通常是爆发的，即，长时间的峰值速率不会长期维持。为了实现更有效的利用资源，提出的方法将允许某些拥塞现象，这些现象将很少发生，以便提供统计QoS保证。更具体地说，希望在损失概率和过度延迟的概率和概率特别小（例如，按10^{ - 6}的顺序）中操作网络。实时应用程序许可可以忍受这种拥塞现象的小频率。 这项研究将借鉴在应用概率，优化和最佳控制理论中开发的方法，并将在必要时使用，延伸，这些想法是PI最近开发的许多想法。计算非平凡交通模型的拥塞概率特别困难。 因此，提出的工作将使用大偏差理论（应用概率的子字段）作为主要的分析工具求助于渐近结果。 将首先解决被认为是成功入学控制的先决条件的问题。其中拟议的研究将解决： - 交通建模。 目的是提出捕获与入学控制相关的流量统计特性的模型。 - 绩效分析。 目的是渐近地估计多类和多台网络环境中的拥塞概率。 拟议工作的最终产品将是一种录取控制算法，该算法提供统计QoS保证接收呼叫并具有以下特征： - 支持多个服务类别。 应用程序将根据其产生的流量的统计特征和QoS要求捆绑在服务类中。 - 充分利用可用带宽。 控制器将足够灵活地研究服务类之间的不同带宽分配策略，并且只有在没有可行的分配可以保证对所有连接呼叫的QoS保证的情况下才拒绝接受。 - 最终QoS保证。 实时实现。 有关此项目的更多信息，请访问http://ionia.bu.edu/。