Packet video transmission in an ATM network using forced frame refreshment

We propose a method which enhances video transmission in an ATM network when congestion overload arise. In this method, in the event of loss of a cell which carries important information for the reconstruction of the frame, the decoder asks the encoder to employ an intraframe coding method to refresh the next frame. In order to prevent network from overloading, constraints are imposed on the maximum number of sources that refresh the whole picture simultaneously at the same video frame interval and the distance between two consecutive refreshments in each video connection. The rate of this refreshment depends on the network load and the number of connections sharing the network. It is shown that there is a minimum distance within two consecutive refreshments for each video connection where both network performance and perceived image quality are optimised