Video transport in wireless ATM

Wireless ATM LANs have the potential to support multi-Mb/s bandwidths to mobile users with guaranteed quality of service. However, the lossy nature of the wireless medium will pose problems for loss-sensitive applications. Techniques to minimize the effect of these losses will therefore be required. In this paper, we examine the use of combined source and channel coding for MPEG video transport in a wireless ATM environment. Although forward error correction (FEC) provides protection against channel bit errors, the bandwidth overhead can become a significant drawback in a fixed bandwidth scenario. Additional protection against losses can be realized by using two-layer video coding. In this work, we compare the performance of a 1-layer main profile and 2-layer data partitioning and SNR scalable MPEG-2 encoders in a system with random channel errors and forward error correction. The results indicate that if the channel bit error rate is known an optimum FEC level can be chosen for the 1-layer case; However, at this fixed FEC level, if a critical bit error rate is exceeded then video quality degrades dramatically. The 2-layer cases appear to lead to more graceful degradation in quality at this critical bit error rates. In particular, SNR scalability may lead to better video quality over a larger range of bit error rates than a 1-layer approach