隨著智慧型手機的普及與影音編碼技術的提升，隨時隨地提供多媒體視訊串流服務勢必廣受歡迎。另一方面，由於行動台（mobile station）大多是使用電池作為電力來源，因此省電的技術也就變得很重要。IEEE 802.16e（俗稱WiMAX）是目前無線都會網路（wireless metropolitan area network）的媒介存取控制國際標準。雖然802.16e建議了三種power saving classes，但主要都是針對unicast traffic。文獻方法SMBC-AMC採用以multicast superframe和logical broadcast channel為架構的省電多播排程（multicast scheduling）機制。然而，802.16e及SMBC-AMC皆無法支援即時性資料的傳輸。此外，SMBC-AMC還強制每個logical broadcast channel所包含的frames個數皆相同、強制每個mobile station在每個multicast superframe期間醒來的比例（duty cycle）皆相同、強制基地台在每個frame期間傳輸multicast data都必須使用相同的modulation，因此不但缺乏彈性，而且可能造成頻寬浪費，導致multicast energy throughput低落。為此，我們提出一個能善用適應性調變（adaptive modulation and coding）且具省電效果的多播排程，稱之為EEMS-AMC。EEMS-AMC採用cross-layer design的設計，結合application layer的SVC（scalable video coding）視訊編碼技術來讓整個網路的multicast energy throughput逼近最佳化的效果。更具體的來說，EEMS-AMC具有三項特點與優勢：（1）藉由限制multicast superframe的長度及執行admission control，EEMS-AMC保證admitted的視訊串流的base layer資料能在delay requirement內傳輸完畢。（2）EEMS-AMC針對視訊串流的base layer資料和enhancement layer資料採用不同的排程方式。由於所有admitted的視訊串流的base layer資料皆可順利傳輸，因此EEMS-AMC採用greedy的排程方式來使得所有admitted stations的醒來時間逼近最佳解。（3）對於視訊串流的enhancement layer資料，EEMS-AMC以potential multicast throughput為衡量標準來選擇modulation方式，以multicast energy throughput gain為衡量標準來做排程，使得整個網路的multicast energy throughput逼近最佳解。模擬實驗結果顯示，就average duty cycle、multicast energy throughput、multicast packet loss rate和normalized total utility來看，EEMS-AMC的效能遠高於SMBC-AMC。

One of the major applications driving wireless network services is video streaming, which is based on the ability to simultaneously multicast the same video contents to a group of users, thus reducing the bandwidth consumption. On the other hand, due to slow progress in battery technology, the investigation of power saving technologies becomes important. IEEE 802.16e (also known as Mobile WiMAX) is currently the international MAC (medium access control) standard for wireless metropolitan area networks. However, in 802.16e, the power saving class for multicast traffic is designed only for best-effort-based management operations. On the other hand, SMBC-AMC adopts the concepts of “multicast superframe” and “logical broadcast channel” to support push-based multicast applications. However, SMBC-AMC requires that (1) the number of frames in each logical broadcast channel must be equal, (2) all mobile stations must have the same duty cycle, and (3) the base station must use the same modulation to send data in a frame. These imply that SMBC-AMC is too inflexible to reach high multicast energy throughput. In this thesis, we propose cross-layer energy efficient multicast scheduling algorithms, called EEMS-AMC, for scalable video streaming. The goal of EEMS-AMC is to find a multicast data scheduling such that the multicast energy throughput of a WiMAX network is maximum. Specifically, EEMS-AMC has the following attractive features: (1) By means of admission control and the restriction of the multicast superframe length, EEMS-AMC ensures that the base layer data of all admitted video streams can be delivered to mobile stations in timeliness requirements. (2) EEMS-AMC adopts the greedy approach to schedule the base layer data such that the average duty cycle of all admitted stations can approach to the theoretical minimum. (3) EEMS-AMC uses the metric “potential multicast throughput” to find the proper modulation for each enhancement layer data and uses the metric “multicast energy throughput gain” to find the near-optimal enhancement layer data scheduling. Simulation results show that EEMS-AMC significantly outperforms SMBC-AMC in terms of average duty cycle, multicast energy throughput, multicast packet loss rate, and normalized total utility.

論文審定書 i
致謝 ii
中文摘要 iii
Abstract iv
圖次 vii
表次 xi
第一章 緒論 1
1.1 微波存取全球互通（WiMAX） 1
1.2 多播服務（Multicast Services） 1
1.3 適應性調變 2
1.4 電源管理 4
1.5 論文貢獻 5
第二章 國內外相關文獻 7
2.1 Multicast Superframe 7
2.2 Logical Broadcast Channel and Modulation Scheme 8
2.3 SMBC-AMC 9
2.4 SMBC-AMC的缺點 14
第三章 EEMS-AMC 17
3.1 Admission Control 17
3.2 EEMS-AMC演算法 21
3.2.1 Base Layer的適應性調變 21
3.2.2 Base Layer資料排程 23
3.2.3 Enhancement Layer的適應性調變 25
3.2.4 Enhancement Layer資料排程 26
第四章 模擬實驗 31
4.1 變化Stream數目的影響 34
4.2 變化Mobile Station對Stream需求機率的影響 43
4.3 變化Mobile Station個數的影響 52
4.4 變化Mobile Station移動速率的影響 60
4.5 各種Video Stream類型的需求機率不相同 66
第五章 結論 85

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