許多新興的通信技術在近年被發展以支援無線都會區域網路(WMAN)，這些技術提供高速而可靠的服務的同時也提供了能源節省方法。為了提供WMAN服務，IEEE 802.16e標準被制訂以應用於固定和移動的寬頻無線系統，並對能源節省問題提出睡眠模式。本碩士論文中，我們將研究重點放在高訊務量或網路擁塞情況下IEEE 802.16e的節能問題，為了處理這個問題，在論文中我們提出一個排程式的節能機制。由於框架間隔非常短，所以當網路訊務量高甚至壅塞時，基地台不能在一個框架間隔中傳送它全部暫存的封包給行動式用戶站。這使得行動式用戶站浪費額外的能源等待傳送給它們的封包。為了解決高訊務量下的節能問題，我們提出了D-TIM (Delay-Tolerant Scheduling-Based TIM)方法，基地台能根據網路服務品質(QoS)所決定的延遲門檻值將兩種非即時性訊務的封包重排後，給定行動式用戶站一個醒來的數值，此數值表明行動式用戶站需要醒來的框架和流量指示訊息(TIM)之間的偏移量。以這種方法，行動式用戶站能在適當的框架中清醒而更有效地使用他們的能源並擁有較低的封包延遲時間，我們的模擬結果顯示D-TIM方法在能源效率以及封包延遲上能勝過其他文獻中的相關機制。此外我們對D-TIM提出兩個額外排程方法，以改善D-TIM方法對於即時性訊務的抖動(Jitter)影響，經過模擬後證明我們提出的兩種方法能解決即時性訊務的抖動問題，並且保持節能效果和較低的封包延遲。

Many emerging wireless communication technologies have been developed in recent years for the wireless metropolitan area network (WMAN), including techniques to provide high-speed and reliable services as well as techniques to conserve energy etc. For MANs, the IEEE 802.16e standard is designed for fixed and mobile wireless broadband systems. It also defines a sleep mode for energy conservation. In this thesis, we focus on the energy conservation issue for the IEEE 802.16e MAN when the system load is high or even the system is congested. To address this issue, a novel scheduling-based energy-conservative scheme is proposed in this thesis. When the system load is high or congestion occurs, a base station (BS) is not able to transmit all buffered packets to mobile stations (MSs) within a frame interval because of the short duration of the frame interval. This may result in extra energy consumption for MSs to wake up for receiving pending packets to be sent to them. To save energy for such a situation, we propose a delay-tolerant scheduling-based traffic indication message (D-TIM) to enable a BS to schedule queued packets for non-real-time polling service (nrtPS) and best effort (BE) using information of delay threshold (DT), which can be derived based on QoS parameters, and to determine the time offset between the frame in which an MS has to wake up and the frame containing a TIM message. By using the time offset, MSs are able to wake up more precisely so that energy can be efficiently saved and less packet delay can be reached. Through simulation, we finally demonstrate that the proposed scheme outperforms other related schemes in the literature in terms of energy efficiency and packet delay. Furthermore, two variants of D-TIM are also proposed to solve the problem of higher jitter caused by D-TIM to the unsolicited grant service (UGS). Again, we show the problem of higher jitter can be properly solved while maintaining good energy efficiency and less packet delay through simulation.

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