Pii: S0140-3664(00)00199-7

The impact of ATM cell delays on multimedia application performance is studied through measurements using a broadband network analyser. A method is developed to measure the ATM cell delays of an application using the analyser. It is found that the cell delay distribution becomes continuous as the traf®c load on a connection becomes lighter. The effect of background traf®c on cell delay for a reference connection is studied. Though the cell delay of the reference connection is unaffected by the presence of background traf®c, 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. q 2000 Elsevier Science B.V. All rights reserved.