MPEG 2 Video Services for Wireless ATM Networks
Audio-visual and other multimedia services are seen as an important source of traffic for future telecommunications networks, including wireless networks. We examine the impact of the properties of a 50 Mb/s asynchronous transfer mode (ATM)-based wireless local-area network (WLAN) on Moving Picture Experts Group phase 2 (MPEG 2) compressed video traffic, with emphasis on the network's error characteristics. The paper includes a description of the WLAN system used and its loss characteristics, a brief discussion of relevant aspects of the MPEG 2 standards and the associated error resilience techniques for minimizing the effect of transmission errors, and a description of the method by which the video data is organized for transmission on the network. We show results on the effect of cell loss due to transmission errors on the quality of the decoded video at the receiver, and demonstrate how error resilience techniques in both the systems and video layers of MPEG 2 can be used to improve the quality of service. Situations where up to 1% of the data is lost due to network transmission errors are examined. Most important among the findings are that error resilience experiments that do not take into account the effect of the MPEG 2 systems layer will tend to significantly overestimate the quality of received video, and that the error resilience techniques provided within the MPEG 2 standard are not sufficient to provide acceptable quality with acceptable overheads, but that this quality can be significantly increased by the addition of a small number of simple techniques.