The double-stage threshold-type foreground-background congestion control for the common-store queueing system with multiple nonpreemptive priority classes is proposed to improve the transient performance, where the numbers of accepted priority packets in both foreground and background stores are controlled under the double-stage threshold-type scheduling. In the double-stage threshold-type congestion control, the background store is used for any priority packets, and some parts of the background store are reserved for lower-priority packets to accommodate more lower-priority packets in the background store, whereas some parts of the foreground store are reserved for higher-priority packets to avoid the priority deadlock. First, we derive the general set of coupled differential equations describing the system-state, and the expressions for mean system occupancy, throughput and loss probability. Second, the transient behavior of system performance is evaluated from the time-dependent state probabilities by using the Runge-Kutta procedure. It is shown that when the particular traffic class becomes overloaded, high throughputs and low loss probabilities of other priority classes can be obtained.

A queueing model suitable for multimedia packets with Poisson and batch Poisson arrivals is studied. In the queueing model, priority is given to the packets with batch Poisson arrival, and the packets with Poisson arrival, accumulated in a buffer, are routed by utilizing intervals of the packets with priority. The queueing performance of the proposed model is evaluated by the mean system delay. We also consider the effect of batch size and the ratio of the traffic with batch Poisson arrival and the one with Poisson arrival on the mean system delay. It is found that the proposed queueing model is useful to reduce the mean system delay of the packets with Poisson arrival, while maintaining the means system delay of the packets with batch Poisson arrival.