ON THE IMPROVEMENT OF THE QUALITY OF SERVICE OF VIDEO SERVICES IN AN ASYNCHRONOUS TRANSFER MODE NETWORK USING FORCED FRAME REFRESHMENT

A method of improving the quality of service of video services in an a synchronous transfer mode network under congestion periods is consider ed. In the event of cell loss carrying intraframe coded data, the deco der asks the encoder to refresh the codec by intraframe coding the nex t frame. To prevent the network from overloading constraints are impos ed on the maximum number of sources that refresh the whole picture sim ultaneously at the same video frame interval and the distance between two consecutive refreshments in each video connection. The rate of thi s refreshment depends on the network load and the number of sources sh aring the network. It is shown that there is a minimum distance within two consecutive refreshments for each video connection where both net work performance and perceived image quality are optimized. (C) 1996 S PIE and IS&T.