Time-Sensitive Networking (TSN) is a promising Ethernet protocol with time determinism, widely used in time-critical systems such as industrial automation, automotive networks, and avionics. By allocating dedicated time windows for time-sensitive flows, TSN enables deterministic transmission; however, as network traffic grows, multiple flows may contend for the same window, causing large delays. Frame aggregation can mitigate this by combining multiple small frames into a larger one, thereby reducing the number of frames and required time windows, but existing approaches typically handle only single-priority traffic and cannot fully utilize pre-allocated time windows. To address this limitation, we propose MCFS-2L, a mixed-criticality flow scheduling scheme with low delay and limited bandwidth usage. MCFS-2L first aggregates critical and non-critical frames with the same source and destination nodes and harmonic periods into a single frame, and then applies a dynamic reassembly and scheduling method that selectively disaggregates non-critical frames from unschedulable aggregated frames. Experimental results show that MCFS-2L increases the acceptance ratio of critical and non-critical flows by up to 4.78% and 8.58%, respectively, while reducing bandwidth utilization by up to 11.88%.

翻译：时间敏感网络（TSN）是一种具有时间确定性的以太网协议，广泛应用于工业自动化、车载网络和航空电子等时间关键系统。通过为时间敏感流分配专用时间窗口，TSN可实现确定性传输；然而，随着网络流量增长，多个流可能争用同一窗口，导致较大延迟。帧聚合可通过合并多个小帧为一个大帧来缓解此问题，从而减少帧数量和所需时间窗口，但现有方法通常仅处理单优先级流量，且无法充分利用预分配的时间窗口。为解决此局限，我们提出MCFS-2L——一种低延迟且有限带宽占用的混合关键性流调度方案。MCFS-2L首先将具有相同源/目的节点和谐波周期的关键帧与非关键帧聚合为单一帧，然后应用动态重组与调度方法，从不可调度的聚合帧中选择性地解聚合非关键帧。实验结果表明，MCFS-2L将关键流与非关键流的接受率分别提升最高达4.78%和8.58%，同时带宽利用率降低最高达11.88%。