  Video conferencing has become a popular mode of meeting even if it consumes
considerable communication resources. Conventional video compression causes
resolution reduction under limited bandwidth. Semantic video conferencing
maintains high resolution by transmitting some keypoints to represent motions
because the background is almost static, and the speakers do not change often.
However, the study on the impact of the transmission errors on keypoints is
limited. In this paper, we initially establish a basal semantic video
conferencing (SVC) network, which dramatically reduces transmission resources
while only losing detailed expressions. The transmission errors in SVC only
lead to a changed expression, whereas those in the conventional methods destroy
pixels directly. However, the conventional error detector, such as the cyclic
redundancy check, cannot reflect the degree of expression changes. To overcome
this issue, we develop an incremental redundancy hybrid automatic
repeat-request (IR-HARQ) framework for the varying channels (SVC-HARQ)
incorporating a novel semantic error detector. The SVC-HARQ has flexibility in
bit consumption and achieves good performance. In addition, SVC-CSI is designed
for channel state information (CSI) feedback to allocate the keypoint
transmission and enhance the performance dramatically. Simulation shows that
the proposed wireless semantic communication system can significantly improve
the transmission efficiency.This work has been submitted to the IEEE for
possible publication. Copyright may be transferred without notice, after which
this version may no longer be accessible
