Adaptive AIMD rate control for smooth multimedia streaming

Internet applications use rate control algorithms, such as the additive-increase/multiplicative-decrease (AIMD) mechanism of the TCP protocol, to adjust transmission rates. An important design factor of rate control algorithms is the tradeoff between responsiveness and smoothness. In general, responding aggressively to changes in network conditions causes wide fluctuations in sending rates. In this paper, we address this tradeoff and develop an adaptive AIMD (ADAIMD) model that adjusts AIMD parameters dynamically. When the network condition is stable, an ADAIMD flow changes its sending rate in small steps to avoid rate fluctuations. When the network condition is changing significantly, the flow adjusts the additive and multiplicative coefficients of AIMD to accelerate rate changes. We will show that these goals can be achieved by applying the additive increase and multiplicative decrease rules to the additive coefficient of AIMD. Our simulation studies show that ADAIMD produces near constant bit rate (CBR), TCP-friendly flows with good responsiveness. Such a rate-control model forms the foundation of realtime transport protocols that provide exceedingly smooth streaming services to Internet multimedia applications.