A Feedback Control Model for Managing Quality of Service in Multimedia Communications

Abstract

Advances in Internet Protocol (IP) multicasting provide a rich background for support of IP multipoint collaborative communications. IP multicast applications have traditionally been deployed over wired networks, however, new wireless technologies such as Local Multipoint Distribution Service (LMDS) are currently emerging as transport mechanisms for wireless video, voice, and application sharing environments. For multimedia wireless services to effectively evolve, management tools that can support Quality of Service (QoS) adaptation of increasingly complex network resources and customer application profiles are needed. In this paper, we present a control model which provides response time and bandwidth requirement adaptation of audio, video, and application sharing multipoint IP teleconferences for emerging wireless multimedia communications. Our study is innovative in that it integrates feedback controls between the application and network layers. Our model is based on revealing feedback controls for multimedia call preparation and subsequent real-time connection control. Case-based reasoning memory is used to match real-time congestion (connection) controls with call preparation controls and user profiles for improved QoS. Network agents are used to capture user and multimedia teleconference application call profiles at the application layer and transfer them to the case memory. Real Time Protocol (RTP) statistics are used to identify connection management feedback controls at the network layer. Receiver-based, real-time adaptation at the network layer and above is possible through the use of a hierarchical coding technique. The proposed adaptive management architecture is based upon a case memory representation of call preparation feedback controls, RTP feedback controls for providing audio stream bandwidth adaptation, and configuration descriptions for integrated experiments. We conclude that implementation of these techniques should lead to improved QoS of wireless IP multipoint teleconferences.