Delay comparison of automatic repeat request assisted Butterfly networks

The average burst delay and the standard deviation (SD) of burst delay in the context of the Butterfly networks are investigated and compared, when three types of automatic repeat request (ARQ) schemes, namely, the stop-and-wait ARQ (SW-ARQ), go-back-N ARQ (GBN-ARQ) and the selective-repeat ARQ (SR-ARQ), are considered. We assume that packets in a burst arrive at a constant rate and that the packet error rate (PER) is the same for all the links. Our studies show that, among the three ARQ schemes, the SW-ARQ scheme yields the highest average burst delay and also the highest SD of burst delay, while the SR-ARQ scheme is capable of attaining the lowest delay and also the lowest SD of burst delay. At very low PER, the GBN-ARQ may achieve a similar delay performance as the SR-ARQ. However, as the PER increases, the delay performance of the GBN-ARQ converges to that of the SW-ARQ.