隨著無線區域網路的普及與影音編碼技術的提昇，隨時隨地提供高品質的多媒體影音串流服務勢必廣受歡迎。由於多媒體影音串流的資料具有連續性、長時間與即時性，因此無線區域網路必須要有一套具有服務品質（quality-of-service）保證且提供高產率（throughput）的媒介存取控制（medium access control，簡寫成MAC）機制。從這個角度來看，無線區域網路裡頭配置有多波束（multi-beam）的基地台（access point，簡寫成AP）便成為很吸引人的解決方案之一，因為多波束基地台可以發揮空間再利用率（spatial reuse），將throughput大幅提昇。由於目前無線區域網路的國際標準IEEE 802.11不支援服務品質保證的功能，IEEE又增訂了802.11e國際標準，以支援多媒體資料的傳輸。然而若802.11/802.11e不做任何修改便直接套用至具多波束基地台的無線區域網路中，將面臨到許多問題。由於目前已知文獻皆透過修改802.11的DCF（distributed coordination function）機制來支援多波束的基地台，因此不具有服務品質保證的功能。
本論文以802.11e的HCCA（hybrid channel control access）為基礎，提出一套新的媒介存取控制協定，稱為MPCF（multi-beam AP-assisted point coordination function），不但適合具多波束基地台的無線區域網路，而且還提供non-reversal prioritization、time-bounded reservation、admission control、power management與cross-layer rate adaptation功能，以支援多媒體影音串流的服務。而且MPCF與傳統的802.11（即DCF）完全相容，能兼顧市場價值。模擬實驗結果顯示，就多媒體即時影音傳輸的表現來看，MPCF遠優於目前文獻已知支援multi-beam AP的MAC協定。

With the proliferation of mobile devices and the advance of audio/video coding technologies, there is an increasing demand to provide quality-of-service (QoS) guarantees for multimedia applications. A WLAN (wireless local are network) typically consists of an access point (AP) and a finite set of mobile stations. Since the AP is generally more powerful and less physical constraint than mobile stations, it is of great interest to consider the use of sectorized multi-beam antennas at the AP to boost the network throughput by exploiting the benefit of spatial reuse.
IEEE 802.11 is current the de facto standard for WLANs. However, if we directly apply 802.11 to the WLAN with multi-beam AP without any modification, we will encounter many challenging problems. Although existing solutions modify the 802.11 DCF (distributed coordination function) to solve these problems, yet DCF does not provide any QoS support.
On the basis of 802.11e HCCA (hybrid channel control access), in this thesis, we propose a novel MAC protocol, named MPCF (multi-beam AP-assisted point coordination function), which is not only backward compatible with DCF, but also supports QoS functionalities, including non-reversal prioritization, time-bounded reservation, admission control, and cross-layer rate adaptation for multimedia streaming.
Simulation results show that, in terms of throughput, frame delay dropped rate, and energy throughput, MPCF significantly outperforms existing protocols even in imperfect beam-forming and mobility environments.

論文審定書 i
誌謝 ii
中文摘要 iii
英文摘要 iv
圖次 vii
表次 ix
第一章 緒論 1
1.1 挑戰 2
1.2 文獻回顧 4
1.3 貢獻 6
第二章 MPCF協定 9
2.1 無線區域網路架構 9
2.2 Superframe結構 9
2.3 Prioritization Procedure 11
2.4 Collision Resolution Procedure 14
2.5 Polling Procedure and Energy-Conserving Scheduling 18
2.6 Rate Adaptation Procedure 23
2.7 Runtime Admission Control 27
2.8 Beam-Location Related Problems的處理 30
第三章 模擬器設計與實作 32
3.1 模擬程式的撰寫 32
3.2 MPCF模擬程式流程 37
3.3 比較對象模擬程式流程 50
3.4 Imperfect beam-forming判斷 58
3.5 Mobility model 59
3.6 模擬程式執行結果 64
第四章 模擬實驗結果 67
4.1 實驗參數設定 67
4.2 Wireless channel環境設定 68
4.3 Antenna model設定 69
4.4 實驗結果 70
第五章 結論 92
參考文獻 93
附錄 96

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