Wireless Semantic Communications for Video Conferencing

Video conferencing has become a popular mode of meeting despite consuming considerable communication resources. Conventional video compression causes resolution reduction under a limited bandwidth. Semantic video conferencing (SVC) maintains a high resolution by transmitting some keypoints to represent the motions because the background is almost static, and the speakers do not change often. However, the study on the influence of transmission errors on keypoints is limited. In this paper, an SVC network based on keypoint transmission is established, which dramatically reduces transmission resources while only losing detailed expressions. Transmission errors in SVC only lead to a changed expression, whereas those in the conventional methods directly destroy pixels. However, the conventional error detector, such as cyclic redundancy check, cannot reflect the degree of expression changes. To overcome this issue, an incremental redundancy hybrid automatic repeat-request framework for varying channels (SVC-HARQ) incorporating a novel semantic error detector is developed. SVC-HARQ has flexibility in bit consumption and achieves a good performance. In addition, SVC-channel state information (CSI) is designed for CSI feedback to allocate the keypoint transmission and enhance the performance dramatically. Simulation shows that the proposed wireless semantic communication system can remarkably improve transmission efficiency.