Design And Implementation Of Media Subsystem In WebRTC System

WebRTC is a real-time audio and video communication technology, which is natively supported by the browser and is not dependent on third-party plugins. As a new real-time communication pattern in web, WebRTC attracts widespread attention in the field of real-time communication due to the advantages of lower development and maintenance costs, higher user experience, characteristics of cross-platform and standardization. While bringing revolutions to real-time communication applications in internet, WebRTC brings opportunities to real-time communication services in telecommunications network. Achieving a combination of WebRTC technology and IMS, telecom operators can employ the advantages of WebRTC which include the huge potential user base, lower development and maintenance costs and rapid deployment in business of IMS. The combination can provide users with richer user experience, promote traditional users to migrate to the IMS network, and create tremendous business value.This paper designs and implements the media subsystem of WebRTC system to achieve audio and video communications based on WebRTC technology. The media subsystem has two scenarios, one is to achieve real-time communication between browsers in the internet architecture, and the other is to achieve the media intercommunications between browsers and terminals in IMS, attempting to combine WebRTC technology with the IMS. This paper analyzes functional requirements of media subsystem in signaling and media levels on the basis of research on relevant protocol specifications in the WebRTC standardization process and key technologies used in the WebRTC system. Based on the analysis, the paper gives a detailed description on the design and realization of media communications between browsers and intercommunications between browsers and terminals in the IMS network, and presents the network architecture and the business process of communications. In the intercommunications scenario, the paper highlights the key module in media intercommunications architecture, which is named as media gateway. The media gateway establishes communications in P2P mode with WebRTC clients and terminals in IMS network according to ICE, and completes the conversion of media transport protocol between heterogeneous networks to achieve media communications in relay mode. The test results evaluate the correctness and stability of the media subsystem.