多媒体传输的实时传输协议分析

一、概述 为了实现带有实时性质的数据(例如交互式的话音和视频数据)从端到端的网络传递业务,由Internet的音频-视频传输工作组提出了实时传输协议,它的主要设计目标是满足多参与者多媒体会议的技术需要,但其应用范围远不止于此。下面我们首先对它作一个概括性的介绍。RTP的基本特征 实时传输协议(Real-time Transport Protocol,简称RTP)很适合用于发送多媒体数据(如音频流或视频流)给一个接收者(单播)或多个接收者(多播)。数据通常单方向传送,接收方不给确认信息。 与RTP同时存在的另一个协议是实时传输控制协议(RTCP),它让接收者给RTP发送者一个反馈信息(以及反之)。例如,接收应用程序可以告诉发送应用程序减慢视频流的速度。当速度减慢后,视频图象仍然可以显示,但可能出现跳动或分辨率降低。RTCP规范中的准则可以帮     

基于QoS套接字的多媒体业务QoS保障的研究

列举了基于QoS套接字的两种多媒体业务，其中一种基于UDP协议，另一种基于TCP协议。实验结果表明，增加了QoS套接字后，两种多媒体业务的性能都得到了较大的改善，但是由于TCP和UDP本身特性的不同，两种多媒体业务性能改善的程度有所不同。最后对试验结果进行了讨论并得出了一些有意义的结论。     

基于3G无线网络视频传输的QoS实现

在现有TCP/IP协议栈基础上提出了一种新的应用层QoS控制机制,并对该控制机制在CDMA2000网络上的运用进行了实际测试,测试结果表明该QoS控制机制可以实现H.264视频流在3G无线网络上的实时流畅传输。     

基于IPv6的流媒体传输技术及其在校园网中的应用

讨论了IP网络的发展趋势,阐述了IPv6特有的流特性,从优化实时传输协议、改进流媒体传输路由机制和提高流媒体服务质量QoS三个方面探讨了IPv6网络中流媒体传输的解决方案.并提供了一种校园网流媒体服务系统的设计思路.     

基于门限思想1-out-n不经意传输协议

在一个1—out—n的不经意传输模型中。发送者提供n条消息给另一方接收者。但是接收者只能选择获取其中的1条消患，并且发送者不知道接收者获取的是哪一条消息。文章提出了一个基于门限思想并且可复用的1—out-n不经意传输协议。它在效率方面优于以往的Naor-Pinkas协议和Tzeng协议。     

Ad Hoc上的新协议——多流实时传输协议

在Ad Hoc网络中传输多媒体数据会受到网络拓扑变化和无线信道干扰的限制。多流实时传输协议MRTP（multi—flow real—time transport protocol）是一种可以分配和传输多个视频数据流的新协议。它结合多描述编码和多径传输。能提高无线对等网络上视频传输的效率和质量。     

IPTV传输机制和质量监测（一）

IPTV俗称网络电视,按照ITU—T的定义,它是在IP网络上传送电视、视频、音频文字图形和数据等、并具有QoS／QoE、安全性、可靠性和灵活性的多媒体业务。对于IPTV,各运营商仍有着不同的理解,本文讨论的IPTV是指基于IP的MPEG-2TS流的传输方式,即能够在IP网络上提供端到端广播质量的视音频业务,而不涉及在互联网上传输的、需要第三方解码器支持的流媒体业务。     

Ad Hoc上的新协议——流实时传输协议

在Ad Hoc网络中传输多媒体数据会受到网络拓扑变化和无线信道干扰的限制.多流实时传输协议MRTP(multi-flow real-time transport protocol)是一种可以分配和传输多个视频数据流的新协议.它结合多描述编码和多径传输,能提高无线对等网络上视频传输的效率和质量.     

多媒体远程教学系统实时传输解决方案

有效的传输机制是保障多媒体远程教学系统这样的分布式多媒体系统应用需求的关键。针对分布式多媒体应用,结合流媒体的传输控制协议,提出了一种远程教学系统实时传输解决方案:通过RTSP(实时流传输协议)建立和控制多媒体会话,RTP(实时传输协议)承载实时信息的传输,RTCP(实时传输控制协议)监控数据的传输状态,RSVP(资源预留协议)预约传输所需的Internet资源保证服务质量。该传输方案不仅适用于远程教学系统,也适用于其他基于Internet的实时多媒体应用系统。     

流媒体技术讲座 第4讲 多媒体流的分层传输

随着音频、视频和图像等多媒体业务在IP网上的应用越来越广泛,有关如何保障媒体流传输的服务质量（QoS）方面的研究也越来越多。一方面,不同业务和应用对QoS的期望值不同;另一方面,即使是同种应用,由于用户具备的网络带宽、终端设备能力等不同,不同的用户也会具有不同的QoS要求。本文首先回顾一些QoS的控制策略,然后根据多媒体业务的特点对它在IP网上的分层编码和传输进行分析和讨论。     

3GPP系统架构演进(SAE)中的QoS探讨

针对不同的接入网技术和越来越高的用户需求,在SAE中实现端到端QoS显得尤为重要.本文详细介绍了SAE中引入的增强型QoS、QoS参数设置、用户数据承载级的区分控制和SAE中QoS协商过程,并分析了SAE中实现QoS有待解决的问题.     

Cross-Layer QoS Enabled SDN-Like Publish/Subscribe Communication Infrastructure for IoT

Publish/subscribe paradigm is often adopted to create the communication infrastructure of the Internet of Things(IoT)for many clients to access enormous real-time sensor data.However,most current publish/subscribe middlewares are based on traditional ossified IP networks,which are difficult to enable Quality of Service(QoS).How to design the next generation publish/subscribe middleware has become an urgent problem.The emerging Software Defined Networking(SDN)provides new opportunities to improve the QoS of publish/subscribe facilities for delivering events in IoT owing to its customized programmability and centralized control.We can encode event topics,priorities and security policies into flow entries of SDN-enabled switches to satisfy personalized QoS needs.In this paper,we propose a cross-layer QoS enabled SDN-like publish/subscribe communication infrastructure,aiming at building an IoT platform to seamlessly connect IoT services with SDN networks and improving the QoS of delivering events.We first present an SDN-like topic-oriented publish/subscribe middleware architecture with a cross-layer QoS control framework.Then we discuss prototype implementation,including topic management,topology maintenance,event routing and policy management.In the end,we use differentiated services and cross-layer access control as cross-layer QoS scenarios to verify the prototype.Experimental results show that our middleware is effective.     

QoS策略控制在Windows 2000中的实现

随着网络和多媒体业务的兴起,QoS技术显得越来越重要。而策略控制则是QoS技术发展的方向所在。首先介绍了QoS策略控制的基本思想,然后对策略控制系统进行了概述,接下来介绍了Windows 2000下的QoS策略控制系统架构,最后给出了一个实现方案,并进行了测试。通过测试结果表明,借助Windows 2000系统下的QoS组件,可以简单、有效地实现QoS策略控制。     

QoS support on fourth generation networks

The arrival of fourth generation mobile networks, based on IP core networks, lead us to the development of certain services, such as: Quality of service, mobility and AAA. This paper proposes architecture to supply quality of service support based in the differentiated services technique, known as Diffserv. In the same way we analyze the main components of this architecture: QoS Broker (central policy broker of quality of service, whose goal is the appropriate configuration of the routers in the network), Access Router (in charge of the management of the queuing system in order to provide QoS) and the AAA server (management of QoS user profiles).     

Call admission control and resource management issues for real-timeVBR traffic in ATM-satellite networks

In this paper, a novel strategy for handling ATM connections of different natures, traffic profile, and QoS requirements in enhanced satellite systems is proposed. The conducted research starts from early studies on resource management in integrated terrestrial-satellite environments and focuses on a combined connection admission control/traffic resource management strategy for QoS provisioning to both real-time and non-real-time constant and variable bit rate sources. The resulting connection handling policy is dynamic, and effectively exploits the system bandwidth through the statistical multiplexing of traffic sources and a preemptive policy over the satellite air interface. The proposed strategy is suited for a generic integrated ATM-satellite system, although its effectiveness has been assessed on a multimedia satellite platform, based on the Ka-band payload and on-board processing     

下一代网络QoS问题研究

分析了下一代网络的QoS要求和关键技术,论述了下一代网络端到端的QoS控制策略,并基于ITU-T建议,对下一代网络QoS控制策略的部署进行了讨论.     

分层循环调度算法初探

在综合现有的一些算法的基础上,提出了一种分层循环(LRR)的调度算法.LRR调度算法采用了两次循环调度,不仅能提供保证速率的服务,而且能提供区分类型的服务,对不同类型的流提供不同的迟延特性,在一定程度上能避免低迟延队列的迟延范围的扩大.     

An automated policy-based management framework for differentiated communication systems

This paper presents a novel paradigm to approach the issue of autonomous policy-based management of wired/wireless differentiated communication systems. In contrast to existing management approaches which require static a priori policy configurations, policies are created dynamically. The proposed framework addresses the management issue from a new perspective through posing it as a problem of learning from current system behavior, while creating new policies at runtime in response to changing requirements. A hierarchical policy model is used to capture users and administrators' higher level goals into network level objectives. Given sets of network objectives and constraints, policies are assembled at runtime. The new approach gives more flexibility to users and applications to dynamically change their quality-of-service (QoS) requirements while maintaining a smooth delivery of QoS through network monitors feedback. Simulation results demonstrate the performance of the proposed work.     

Adaptive Reservation Scheme for Hierarchical Admission Control in Mobile Cellular Networks

We propose an adaptive reservation scheme designed to operate in association with the Multiple Guard Channel (MGC) admission control policy. The scheme adjusts the MGC configuration parameters by continuously tracking the Quality of Service (QoS) perceived by users, adapting to any mix of aggregated traffic and enforcing a differentiated treatment among arrival streams during underload and overload episodes. We provide two implementations of the scheme. The performance evaluation carried out verifies that the QoS objective is met with an excellent precision and that it converges rapidly to new operating conditions. Other key features of our scheme are its simplicity, its oscillation-free behavior, and its integrated strategy to deal with multiservice scenarios.