TR-IIS-01-007    pdffile

Wang, Chia-Hui, Jan-Ming Ho, Ray-I Chang, and Shun-Chin Hsu

Institute of Information Science, Academia Sinica, Nankang, Taipei, Taiwan

¡@

In this paper, based on the feedback of buffer occupancy (BO), a new control-theoretic flow control mechanism is proposed. Our mechanism applies feedback control to keep BO running to a given level to increase the time available for packet recovery without violating real-time requirements. It tightly couples gap-based loss detection and packet retransmission to provide effective and efficient error control. Therefore, reliable communications and optimized playback QoS can be achieved at a minimal cost. Moreover, our implicit prediction and prevention for buffer underflow and overflow can help clients with a limited buffer (such as set-top box, PDA and cellular phone) to achieve acceptable playback QoS. We have deployed the proposed mechanism into a true VOD service in an ADSL trial. Experiments show that the proposed mechanism outperforms the previous mechanisms. The proposed mechanism contributes an innovative way to resist the network uncertainty with minimal overhead.

Keywords: feedback control, buffer-occupancy, control theory, error control, video on demand.