第三代Universal Mobile Telecommunications System (UMTS) 採用discontinuous reception (DRX) 機制減少Mobile Station (MS) 不必要的電量消耗，讓電池的電量能作更有效的利用。DRX機制允許閒置的MS暫時將無線接收端的電源關掉一段時間，然後再啟動電源以便接收由基地台送來的paging訊息。每個MS皆可藉由DRX的兩個參數inactivity timer和DRX cycle調整各自休眠及喚醒的排程。目前已有許多文獻針對DRX機制進行研究分析，但是這些文獻主要針對Poisson分佈的網路流量提出數學模型或是電腦模擬模型以分析DRX機制的效能。本篇論文針對bursty特性的網路流量提出新的semi-Markov process數學模型來分析UMTS DRX機制的效能。我們除了研究DRX的兩個參數對於省電效能和平均封包等待時間的影響之外，並且對於各種不同的網路流量提供選擇inactivity timer和DRX cycle的準則。

The universal mobile telecommunications system (UMTS) utilizes the discontinuous reception (DRX) mechanism to reduce the power consumption of mobile stations (MSs). DRX permits an idle MS to power off the radio receiver for a predefined sleep period, and then wake up to receive the next paging message. The sleep/wake-up scheduling of each MS is determined by two DRX parameters: the inactivity timer threshold and the DRX cycle. In the literature, analytic and simulation models have been developed to study the DRX performance mainly for Poisson traffic. In this paper, we propose a novel semi-Markov process to model the UMTS DRX with bursty packet data traffic. The analytic results are validated against simulation experiments. We investigate the effects of the two DRX parameters on output measures including the power saving factor and the mean packet waiting time. Our study provides inactivity timer and DRX cycle value selection guidelines for various packet traffic patterns.

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