Rate control of VBR H.261 video on frame relay networks

The H.261 video compression standard provides an efficient scheme for the transmission of low bit-rate video traffic over high-speed networks. We introduce a modified H.261 codec that produces variable bit-rate (VBR) output for transmission over an integrated services frame relay (FR) network. We show that the quality of service requirements of VBR video can be met in the presence of inter-LAN data traffic by making use of the backward explicit congestion notification (BECN) facility, in conjunction with a modified H.261 video codec whose rate is controlled by the congestion notifications. We also show that the performance of the control mechanism is significantly influenced by a subset of network threshold and codec control parameters which is identified using 2^k factorial analysis techniques. We obtain optimal ranges of values for these parameters using mean field annealing optimization methods. Finally, we show that variable quantization rate control is more effective for this purpose than variable frame rate control and that the improvement in performance over that of an uncontrolled network is significant