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Among the scheduling services, rtPS (real-time polling service) is designated for real-time applications. Among three packet delay intervals, performance effect on polling interval has been widely studied, but less on the intervals of scheduling and delivery. To evaluate the performance of delay-sensitive rtPS applications, instead of using continuous queueing model, a discrete-time GI-G-1 model, which considers intervals of polling, scheduling, and delivery, is proposed. By taking VoIP as a typical rtPS application, the transmission latency under different QoS settings, polling probability, and traffic load are presented. The latency is also compared among various codec schemes. The results indicate that when the codec rate is either fulfilled or dissatisfied by the promised bandwidth of service levels, the performance is highly dependent upon the polling probability, no matter what the traffic condition is. However, if the codec rate is in between the promised bandwidth of various service levels, the polling probability is a dominant factor in light traffic environment, while the settings on QoS parameters will strongly determine the performance in heavy traffic situation. In addition to the verification using simulation, the bandwidth utilization derived from the GI-G-1 model can be applied to improve the serving capacity of base stations. Copyright (c) 2011 John Wiley & Sons, Ltd

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