Feedback-controlled traffic shaping for multimedia transmissions in a real-time client-server system

The number of applications requiring real-time transmission of multimedia streams over the existing network structure is increasing, Large amounts of digital video, audio and text data of continuous nature and with associated timing constraints are thus being exchanged, making network overloads more likely. Our paper presents a feedback-controlled solution for ensuring a continuous transmission and play-out of MPEG streams even in congested network conditions. A double-channel link (TCP and UDP) allows data to be sent from the server to the client, and control information describing the quality of the transmission to be sent between client and server. The control data is collected by a special unit located at the client which regularly inspects the receiver and driver buffers. The control data received from the client is processed by a feedback manager at the server which controls a transmission shaper. The latter can influence the transmission process by modifying parameters such as the transmission buffer size and the transmission frequency. Experimental results show improved behavior of the system in congested network conditions.