Effects of cell losses on picture quality in ATM networks
Satoru Iai, Nobuhiko Kitawaki · Electronics and Communications in Japan (Part I Communications) · 1992
Abstract Asynchronous transfer mode (ATM) is viewed as the technique that forms the basis of broadband integrated services digital networks (B‐ISDN). In ATM, the cell losses that accompany congestion during cell multiplexing are believed to cause a significant deterioration in quality. In this paper, we study the effects of cell losses on image quality from the standpoint of subjective evaluations. First, the impairment factors that cause deterioration in the received video are extracted for the various network and terminal configurations that are assumed. Next, with the impairment factors as the parameters, a computer simulation was created of the impairment that accompanies cell loss and the subjective quality was studied using a 320‐frame video signal. It was clearly shown that of all the impairment factors, the five major influences on quality are the number of lost cells, the number of picture elements (pels) in the impaired region, the amplitude distortion of the image in the impaired region, the shape of the impaired region, and the bursti‐ness of cell loss. In addition, when consecutive frames are inquired as a result of cell loss, except when only one segment is seen, the total number of impaired frames hardly affects subjective image quality. Finally, based on these evaluation results, we discuss cell loss quality in pulse code modulation (PCM) and provide guidelines for designing networks and terminals.