RTCWeb Evolution

使用因特网进行综合音频和视频通信的情况正在大幅增加。目前，存在多种专有解决方案，例如Skype，Facetime或Google Hangouts。这些解决方案的一个重要限制是，它们需要安装专有软件，并且它们不能互操作。因此，IETF和W3C正在共同努力，以便开发Web浏览器的标准化扩展，从而能够在浏览器之间针对媒体（音频/视频）和非媒体（通用数据）应用数据进行直接实时通信。通信协议由IETF工作组RTCWeb定义，而编程接口（JavaScript API）由W3C工作组WebRTC开发。IETF目前指定的名为RTCWeb的协议栈必须为媒体和非媒体流提供NAT边界（网络地址转换）上的安全通信。为了实现这一点，已经存在的协议以新的方式组合。具有拥塞控制功能的传输协议SCTP（流控制传输协议）是RTCWeb架构的关键构建块之一，也是本项目的重点。RTCWeb环境中现有协议的新组合将在项目期间系统地进行评估，改进和扩展。特别的科学兴趣的问题是如何协调和控制各种媒体和非媒体流在RTCWeb上下文中考虑到他们的异构要求和属性，以提供预期的行为为用户。RTCWeb在一个应用程序中组合了各种流。这提供了以主动和目标导向的方式协调所涉及的机制（特别是拥塞控制）的机会。应制定和评估利用这一点的备选方案。项目合作伙伴的初步调查已经表明，SCTP的标准拥塞控制无法保护媒体流免受并发非媒体流的影响。因此，应在本项目中开发和评估替代拥堵控制。除了单独考虑SCTP拥塞控制之外，还应当考虑当前提出的关于媒体流的拥塞控制的方法以及接入路由器的主动队列管理机制。这些非常不同的机制目前是单独开发的，它们之间的相互作用是一个关键方面，尚未得到系统的评价。该项目的目标是通过有针对性的评估，结合协调拥塞控制的概念和机制的发展，实现整个系统的显着性能改善。

The use of the Internet for integrated audio and video communication is increasing substantially. At the moment, there exist multiple proprietary solutions, e.g. Skype, Facetime or Google Hangouts. A significant limitation of these solutions is that they require the installation of proprietary software and that they are not interoperable. Therefore, the IETF and the W3C are working together in order to develop a standardized extension of web browsers enabling a direct real-time communication between browsers for media (audio/video) and non-media (general data) application data. The communication protocols are defined by the IETF working group RTCWeb, whereas the programming interface (Javascript API) is developed by the W3C working group WebRTC. The protocol stack currently being specified by the IETF under the name RTCWeb has to provide a secure communication over NAT boundaries (Network Address Translation) for media as well as non-media streams. To achieve this, already existing protocols are combined in a new way. The transport protocol SCTP (Stream Control Transmission Protocol) with its congestion control feature is one of the key building blocks of the RTCWeb architecture and is in the focus of this project. The novel combination of existing protocols in the RTCWeb context will be evaluated, improved and extended systematically during the project. Of particular scientific interest is the question how to coordinate and control the various media and non-media streams in the RTCWeb context taking into account their heterogeneous requirements and properties in order to provide the expected behavior for the user. RTCWeb combines the various streams within one application. This provides the opportunity to coordinate the involved mechanisms - in particular congestion controls - in an active and target-oriented way. Options to exploit this shall be developed and evaluated. Initial investigations of the project partners have already shown that the standard congestion control of SCTP is not able to protect the media streams from concurrent non-media streams. Therefore, alternative congestion controls shall be developed and evaluated in the project. In addition to the consideration of the SCTP congestion control alone also the currently proposed methods with respect to congestion control for media streams as well as the active queue management mechanisms for access routers shall be taken into account. These very diverse mechanisms are currently developed separately and their interaction is a crucial aspect which has not yet been evaluated systematically. The goal of the project is to achieve a significant performance improvement of the overall system by means of targeted evaluations in combination with the development of concepts and mechanisms for coordinated congestion control.