The condition of improving throughput both of high and low priority at the same time

There is a conservation law that states that the sum of the average queuing delays within a set of multiplexed flow is independent of priority control. However with reference to ARQ specifically, we can adopt the idea of "goodput" (normalized throughput) to evaluate the efficiency of the transmission. With this, we discover that there are cases when the goodput of high-prioritized and low-prioritized flows can both improve at the same time. To achieve this, we will need routers that are able to handle priority control adaptively. This is confirmed theoretically in this paper, which uses a simple go-back-N model as a basis for calculation.