減少手提式行動設備(Portable Device)的能源消耗一直是IEEE 802.11 無線區域網路(Wireless LAN)領域中的一個重要議題。這樣的議題在系統負載量(極)高的情況下必須特別小心的處理, 若存取點(Access Point, AP)佇列中累積的封包(Packet)量超過一個信標週期(Beacon Interval, BI)可傳送的量時, 則因封包暫存在AP而清醒的行動用戶(Station, STA)中可能會有部分行動用戶無法接受到服務的情況。根據這個觀察, 本論文中提出兩個應用在高交通量條件下有基礎架構無線區域網路的省電機制, 稱之為Partial Wake-up TIM (P-TIM)與Idle-less P-TIM (IP-TIM)。這兩個機制的概念主要是根據封包的延遲(Delay)時間決定服務的順序, 且僅喚醒最少所需清醒的行動用戶數, 並使部分有封包暫存在AP的行動用戶待在睡眠模式(Sleep Mode)達到省電。藉由模擬, 我們最後將呈現本論文所提出的省電機制在幾乎不影響封包延遲及流通量的情況下仍可節省可觀的電量。

Minimizing power consumption for portable devices is a significant research issue in IEEE 802.11 wireless LANs. In particular, this issue should be carefully addressed when the system load is (extremely) high. Note that some of stations waking up to receive pending packets may not be served if the total number of packets pending at the access point (AP) for these stations is larger than the amount of packets can be served within a beacon interval. Based on this observation, two scheduling-based power-saving mechanisms, namely, Partial Wake-up TIM (P-TIM) and Idle-less P-TIM (IP-TIM), for the infrastructure-based IEEE 802.11 wireless LAN under the high system load are proposed in this thesis. The idea for these two mechanisms mainly relies on the determination about the serving order of packets according to the packet delays, enabling the least awake stations necessary to wake up and power saving because some of stations with pending packets can be kept in the sleep mode. Through simulations, we finally show that the proposed mechanisms can save much power while keeping packet delay and throughput almost unchanged.

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