Receiver-initiated resource renegotiation for VBR video transport

In this paper we address the important issue of providing QoS for VBR video communications in an efficient manner. We show that efficient transmission of VBR video with a high QoS is feasible when using a receiver-initiated resource renegotiation (RIR) scheme. The scheme for RIR is based on RTP and RSVP. RTP´s media specific header is used to send video source information to receivers. Receivers utilize this information to estimate the traffic descriptors. Renegotiations are triggered based on the receiver´s buffer status and RSVP is used to renegotiate flow parameters with the network. The performance of the proposed scheme is evaluated via simulations using several 20-minute-long MPEG-2 bit streams. Performance metrics considered are video quality and renegotiation overhead for different receiver buffer sizes and network delays. The results show that the proposed RIR scheme provides high video quality with an average renegotiation interval on the order of seconds, a 5-15 frames receiver buffer and network renegotiation delay below 300 msec. We also investigated call admission control (CAC) schemes for renegotiation VBR services. In particular, we studied the performance of the Central Limit Theorem based and the Chernoff bound based CAC algorithms, in terms of error in the calculation of the maximum number of admissible connections. Finally, to facilitate the scaling of the renegotiation scheme to large-scale networks, we studied how to reduce renegotiation overhead