在無線區域網路下省電排程方法的研究

Abstract

對無線區域網路之行動裝置而言，節約電源是決定系統運作壽命的關鍵因素，本篇論文提出一個具負載知覺之省電排程法，藉由有效的安排節點之甦醒時機，使得一個無線存取點下所服務的節點，在同一時槽(time slot)醒來的節點個數為最小，以減少競爭的節點數量。除此之外，我們提出避免競爭之流量排程法，讓節點依照不同的屬性來安排其存取順序，這些方法分別為單一節點存取、最小聯結代碼(AID)優先與最小暫存資料優先等。模擬結果顯示，具負載知覺之省電排程法與避免競爭之流量排程法兩者在電力節約上可以比原先無線區域網路標準定義的省電模式效果更好，同時也達到減少碰撞的目的。

Power saving is a significant problem for a battery-powered device, especially when it has an IEEE 802.11 wireless LAN communication module. In this thesis, we proposed a novel traffic scheduling algorithm for 802.11 WLANs, named Load-Aware Wakeup Scheduling (LAWS). LAWS lowers the amount of stations which contend for transmitting data by efficiently scheduling their wakeup time. This thesis also proposes another traffic scheduling mechanism, named Contention Avoidance Traffic Scheduling (CATS). The access sequence of mobile stations in CATS is scheduled via different parameters. They are classified into Multiple Wakeups Single Access (MWSA) and Smallest AID First (SAF) Smallest Queue Length First (SQLF). Simulation results showed that both LAWS and CATS outperform the original IEEE 802.11 standard in saving energy and have less packet collision.