The characteristics of the IEEE 802.16 wireless communication cause considerable difficulty in burst construction. The proposed BCO algorithm maximizes the throughput during downlink burst construction for each connection. BCO not only complies with the downlink burst structure specified in IEEE 802.16 standards, but also considers the issues of external fragmentation, internal fragmentation, and optimal block exploration. Compared to our previous work, which focused on constructing the uplink burst with a multi-rectangular shape [22], this study designs BCO for constructing the rectangular downlink burst, provides verification that BCO maintains united available bandwidth during burst construction, and compares it with other downlink burst construction algorithms in terms of total throughput, IUSR, and EUSR.
The simulation results confirm that BCO provides higher throughputs compared with eOCSA and WLFF. At the heavy load of 1 Mbps, BCO achieved 2 and 9 times the throughput achieved by WLFF and eOCSA, respectively. In addition, the improvement ratios achieved by BCO increased in conjunction with the requested bandwidth, as the number of connections decreased, and as the channel quality improved. In addition, the performance of BCO changed slightly when the channel quality between subchannels became more diverse, whereas that of WLFF and eOCSA decreased considerably, thereby causing an increase in the BCO improvement ratio.
This study used a two-phase bandwidth allocation architecture and focused on the phase of burst construction to maximize the throughput. However, the QoS violation ratio can be minimized if the burst constructor informs the flow scheduler of the results of burst construction, such as unused slots and unfulfilled requested
bandwidth. The feedback information will help the flow scheduler to assign an accurate number of slots for each connection. In the future, we will investigate a feedback mechanism for the burst constructer and the scheduling mechanism for the flow scheduler. In addition to maximizing the overall throughput, QoS support is also a crucial topic. Thus, enhancing BCO with supporting QoS is the focus of our future studies.
Reference
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“Towards a QoS-Aware IEEE 802.16 downlink sub-frame mapping scheme,” in Proc. IEEE GLOBECOM Workshops, Dec. 2010, pp. 1243-1247.
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行政院國家科學委員會補助國內專家學者出席國際學術會議報告 100 年 11 月 10 日 報告人姓
名 賴源正 服務機構
及職稱 台灣科技大學資訊管理系教授
會議 時間
地點
2011/10/09~2011/10/15 大陸上海、杭州
本會核定
補助文號 NSC99-2219-E-011-003 會議名稱 (中文) 2011 年 IEEE 無線及行動網路及通訊國際會議
(英文) WiMoB 2011(The 7th IEEE International Conference on Wireless and Mobile Networking and Communications)
(中文) 2011 年 IEEE 通訊及資訊技術國際研討會議
(英文) ISCIT 2011 (The 11th IEEE international Symposium on Communication sand Information Technologies)
一、參加會議經過
本人於十月十日至十月十二日間參加在中國上海舉行之 WiMoB 2011「The 7th IEEE International Conference on Wireless and Mobile Networking and Communications」 會議，並於十月十三日至十月十四日參加在中國杭州舉行之 ISCIT 2011 (The 11th IEEE international Symposium on Communication sand Information Technologies)，此二個會議皆為每年開一次會，主要參加者涵蓋全球 各大學或產業界從事資訊及通訊相關研究之學者或研究人員，在此領域是屬於 非常重要的國際會議。
本次行程簡述如下：十月九日搭機直飛杭州後並立即轉往上海，WiMoB 會 議於十月十日開幕，當天即辦理報到，第二天上午及笫三天上午為 Keynote Speech，會議共有 12 個場次、200 餘篇論文發表，同時也包括兩個 workshop。
參加完此會議後，於十月十二日晚間前往杭州，於次兩天參加於杭州舉行之 ISCIT，此會議的時間為十月十二日至十月十四日，但因十二日與 WiMoB 相衝 突，故僅參加後兩日的會議。本次參與此兩個會議，聆聽多篇論文發表並參與 討論，十月十四日會議結束後，於十月十五日搭機返回台灣。
二、與會心得
WiMoB 會議共有超過 200 篇論文發表，分成 12 個場次以口頭報告方式發 表，每一時段有二個場次並行，其重要主題如下：
* Vehicular Ad Hoc Networks
* Performance Analysis
* Routing
* Security and Privacy
* Localization & time synchronization
* MIMO
* Cooperative and Network Connectivity
* OFDM System
* Resource Allocation
* Mobile Applications
* Coding Techniques
* Routing in Wireless Networks
而 ISCIT 會議共有超過 300 篇論文發表，分成 20 個場次以口頭報告方式發 表，每一時段有三個場次並行，其重要主題如下：
* Coding and Decoding
* Cognitive Radio Networks
* Ultra-Wideband (UWB) Communications
* Energy-efficient Green Communications and Networking
* MIMO and Multiple-Channel Communications
* Signal Processing for Communications
* Spectrum Access, Power Control & Interference Management
* OFDM Communications
* Signal Processing for Communications
*Advanced Radio Access Techniques
* Routing, Traffic Management & Protocol Design
* Advanced Signal Processing
* Circuits, Devices and Testbed Implementation
* Networks Resource Management & Protocol Design
* Networks Applications
* Network Performance Management & Applications
* Information & Communications Techniques Applications
個人幸賴國科會補助得以參加此二個國際會議，從各場次論文報告中，個 人觀察到未來網路的重點有三：(1) OFDM Communications, (2) Energy Efficient Wireless Networks, (3) Cognitive Wireless Networks。本次與會除學術專業獲得充 電外，也認識一些國際同仁，對本人未來的研究助益頗大。
三、建議
(1) 參與會議之前，由於發表的論文眾多，且大多採並行方式同時進行，故 應先選定有興趣的論文，排定時程表，可以得到參與會議的最大收穫。
(2) 個人在聆聽論文時，發覺有些母語非英語的發表者，報告的並不是很理
想，這可能是一些沒留學過的學者之通病，建議國科會能多獎勵國內學 者的國外研究及補助，促使大家能有機會多多訓練英語發表。
(3) 此次會議，與各國學者討論，得知各國大學訓練資訊人員的人數都大幅 增加，以因應未來的趨勢，而國內在資訊領域的人才也是供不應求，而 通訊網路領域的人才更是欠缺，為了發展知識經濟，人才培育是非常重 要的課題，值得有關單位深思，並及早規劃。
最後，個人非常感謝國科會給予補助，參與此次會議，有機會與世界各國 的學者交換彼此的經驗及研究心得，對本人未來的研究助益頗大。
四、攜回資料名稱及內容 會議論文集之光碟兩片