Transmission of video telephony images over wireless channels

In this paper, the effects of digital transmission errors on H. 263 codecs are analyzed and the transmission of H. 263 coded video over a TDMA radio link is investigated. The impact of channel coding and interleaving on video transmission quality is simulated for different channel conditions. Fading on radio channels causes significant transmission errors and H. 263 coded bit streams are very vulnerable to errors. Powerful Forward Error Correction (FEC) codes are therefore necessary to protect the data so that it can be successfully transmitted at acceptable signal power levels. FEC, however, imposes a high bandwidth overhead. In order to make best use of the available channel bandwidth and to alleviate the overall impact of errors on the video sequence, a two-layer data partitioning and unequal error protection scheme based on H. 263 is also studied. The scheme can tolerate more transmission errors and leads to more graceful degradation in quality when the channel SNR decreases. In lossy environments, it can improve the video transmission quality at no extra bandwidth cost.