One of the fastest growing segments of Internet applications are real-time mul-timedia applications, like Voice over Internet Protocol (VoIP). Real-time multimediaapplications use the User Datagram Protocol (UDP) as the transport protocol becauseof the inherent conservative nature of the congestion avoidance schemes of Transmis-sion Control Protocol (TCP). The e?ects of uncontrolled ?ows on the Internet havenot yet been felt because UDP tra?c frequently constitutes only ? 20% of the totalInternet tra?c. It is pertinent that real-time multimedia applications become bettercitizens of the Internet, while at the same time deliver acceptable Quality of Service(QoS).Traditionally, packet losses and the increase in the end-to-end delay experiencedby some of the packets characterizes congestion in the network. These two signalshave been used to develop most known ?ow control schemes. The current researchconsiders the ?ow accumulation in the network as the signal for use in ?ow control.The most signi?cant contribution of the current research is to propose novel end-to-end ?ow control schemes for unicast real-time multimedia ?ows transmitting overbest-e?ort networks. These control schemes are based on predictive control of theaccumulation signal. The end-to-end control schemes available in the literature arebased on reactive control that do not take into account the feedback delay existingbetween the sender and the receiver nor the forward delay in the ?ow dynamics. The performance of the proposed control schemes has been evaluated using thens-2 simulation environment. The research concludes that active control of hard real-time ?ows delivers the same or somewhat better QoS as High Bit Rate (HBR, nocontrol), but with a lower average bit rate. Consequently, it helps reduce bandwidthuse of controlled real-time ?ows by anywhere between 31:43% to 43:96%. Proposedreactive control schemes deliver good QoS. However, they do not scale up as well asthe predictive control schemes. Proposed predictive control schemes are e?ective indelivering good quality QoS while using up less bandwidth than even the reactive con-trol schemes. They scale up well as more real-time multimedia ?ows start employingthem.
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