近年來，寬頻無線存取網路由於其頻寬與傳輸距離的提昇，使其變得越來越熱門。其中IEEE 802.16e標準(或稱Mobile WiMAX)是其中的一項技術可以提供固定式或是行動式的寬頻無線存取。在IEEE 802.16e標準下，由於所有的行動台(Mobile Stations, MSs)都是基於有限的電池電力下來運作的，因此在這種網路中，MS的電力節省就變成一個很重要的議題。雖然IEEE 802.16e標準有定義了睡眠模式的運作來提供電力節省的功能，且在睡眠模式的運作中有三個重要的參數：閒置門檻(Idle Threshold)、起始睡眠視窗(Initial Sleep Window)、最後睡眠視窗(Final Sleep Window)。這三個參數對於平均延遲與電力消耗有重大的影響，但是IEEE 802.16e標準並沒有定義任何機制來設定這些參數的值。 本篇論文提出了一個具電池壽命感知的電源節省機制來改善睡眠模式的能源效率。三個重要的睡眠模式參數將會根據每個用戶台不同的電池壽命情形來進行動態地調整，這樣的好處在於可以讓使用者在電力消耗與封包延遲之間取得一個平衡，而不是從頭到尾參數的值都是一樣的。所提機制能夠減少花在閒置的時間，也能降低平均的電力消耗，進而延長用戶台的總存活時間。透過電腦模擬的結果顯示，所提機制最多能比IEEE 802.16e標準讓用戶台提高30.08%的總存活時間，能夠作為睡眠模式運作在實作上的一個參考指南。 Recently, the broadband wireless access (BWA) network becomes more and more popular. The IEEE 802.16e is one of such technologies and has been standardized for fixed or mobile BWA systems. Because all mobile stations (MSs) operate on the limited battery power, power-saving for MSs in this network becomes a very important issue. Although the IEEE 802.16e standard adopts the sleep mode operation for power-saving and there are three parameters, the idle threshold, the initial sleep window, the final sleep window, it does not define any mechanism to setup these parameters. However, these parameters impose significant effect to average delay and average power consumption. Battery Lifetime-Aware Power Saving (BLAPS) mechanism is proposed in this thesis to improve the energy efficiency of the sleep mode. These three sleep mode operation parameters was adaptively setup by considering battery lifetime of each MS. Benefits of proposed mechanism are to reduce the idle time and the power consumption and to increase the total alive time of MSs. The proposed BLAPS mechanism was validated through computer simulation using QualNet 4.5. The simulation results show that the proposed BLAPS mechanism performs up to 30.08% better than the IEEE 802.16e standard in terms of average alive time of MSs. Our work may be a guideline for implementing the sleep mode operation.
