Impact of ATM cell delay on multimedia applications

Abstract

The impact of ATM cell delays on multimedia application performance is studied through measurements using a broadband network analyzer. A method is developed to measure the ATM cell delays of an application using the analyzer. It is found that the cell delay distribution becomes continuous as the traffic load on a connection becomes lighter. The effect of background traffic on cell delay for a reference connection is studied. Though the cell delay of the reference connection is unaffected by the presence of background traffic, the cell-delay auto-correlation is found to decrease. A gamma distribution is used to approximate the cell delay distribution. The measurement results closely match the delay prediction using the approximation. In a network with multiple ATM switches, the gamma distribution only slightly overestimates the delay. The frame level statistics and the cell delay performance of a video conferencing application based on motion JPEG are measured. Using the gamma cell delay distribution, the frame loss of an MPEG-I video source is predicted and compared against the measured values based on MPEG-I traces.