Enhanced Frame Preemption in Image and Video Transmission Over Time Sensitive Networks

Time Sensitive Network (TSN) is a set of protocols working at the data link layer, which provides a delay guarantee for different services through various traffic shaping protocols. In TSN, to avoid timeouts caused by urgent services being blocked by large-bandwidth services, the IEEE 802.1 Qbu frame preemption protocol was proposed, which allows high-priority frames to reduce the delay by preempting low-priority frames. However, this mechanism will increase the delay of low-priority frames. With a unique storage structure, image and video can tolerate a certain degree of byte loss, such as color bytes, which will reduce the quality of the image but will not affect video fluency. Combined with this feature, in this paper, we propose a frame preemption enhancement mechanism assisted by frame truncation, which properly discards non-important bytes of the Ethernet frame payload field to ensure the deadline constraints. To minimize the information loss of service caused by frame truncation, we propose a frame structure based on the current Ethernet frame, which adjusts the bytes arrangement order according to their importance. In this case, when frame truncation is applied for satisfying the delay requirement, it can ensure that the discarded bytes are of the lowest importance. Simulation results show that, compared with the standard frame preemption mechanism, our proposed mechanism can send more payload bytes to the receiver without increasing the delay and jitter of other services, and the switch memory usage peak is also reduced by 12.41%.