Mobile WiMAX系統中節省即時通訊耗電之封包排程演算法

Abstract

在寬頻無線存取(Broadband Wireless Access, BWA)的系統中，為了減少行動裝置在網路閒置或使用時的耗電，通常提供了可以彈性利用的睡眠模式(Sleep Mode)。舉例來說，Mobile WiMAX，也就是IEEE 802.16e，便是其中之一。為了減少行動用戶端(Mobile Subscriber Station, MSS)的耗電，IEEE 802.16e在睡眠模式的運作上提供了數種省電類別(Power-Saving Class)，各自適合不同服務類型的網路連結(Connection)，以使網路連結的耗電能最小化。不過不幸地，在一個行動用戶端同時啟用多個即時(Real-Time)服務時，先前的研究並不能完全發揮睡眠模式的特性來讓該行動用戶端整體的耗電最佳化。因此在此篇文章中，提出了兩個在Mobile WiMAX系統中針對減少即時通訊耗電所設計的封包排程演算法。這兩個方法不但保證了即時通訊所要求的服務品質(Quality of Service, QoS)，同時也盡可能地減少了行動用戶端的耗電，而在模擬的結果中顯示所提出的兩個方法都明顯地勝過傳統的方法。

Broadband wireless access systems usually provide flexible sleep-mode operations for mobile stations to conserve their energy during idle or active mode. For example, Mobile WiMAX, i.e. the IEEE 802.16e, offers several power-saving classes that can be associated with different types of network connections to minimize power consumption of mobile subscriber stations (MSSs). Unfortunately, previous studies did not fully utilize the sleep-mode features to save the energy of an MSS with multiple real-time connections, and power consumption of an MSS is not yet optimized. In this work, two energy-efficient packet scheduling algorithms for real-time communications in a Mobile WiMAX system are proposed. The schemes not only guarantee the quality of services (QoSs) of real-time connections but also minimize power consumption of MSSs. Simulation results demonstrate that the proposed schemes outperform the traditional approach.