Preventive flow control method for packet video

Broadband ISDN (B-ISDN) networks utilising asynchronous transfer mode (ATM) are expected to provide the transport infrastructure for broadband multiservice applications. A preventive flow control method suitable for video services within an ATM network is presented. In this method each video encoder employs a model of the aggregate traffic of all sources sharing the virtual path with the heaviest traffic. The aggregate traffic is modelled knowing the mean, peak-to-mean and the number of sources passing through the bottleneck link of the transmission path. Once the encoder´s estimate of the aggregate traffic has reached a certain level of the channel capacity, it adjusts its bit rate accordingly. The impact of self flow control on both coding and network performance is investigated. It is shown that both network performance and perceived image quality are optimised for a threshold level corresponding to an estimated traffic of 80% of the channel rate