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中文論文名稱 一個在行動隨建即連網路下鏈結隨適之封包切割及速率對應之媒體存取控制協定
英文論文名稱 A Link-Adapted Fragment and Rate Matching (FaRM) MAC Protocol for Mobile Ad Hoc Networks
校院名稱 淡江大學
系所名稱(中) 資訊工程學系碩士班
系所名稱(英) Department of Computer Science and Information Engineering
學年度 94
學期 2
出版年 95
研究生中文姓名 鄭立傑
研究生英文姓名 Li-Jie Cheng
學號 693191354
學位類別 碩士
語文別 中文
第二語文別 英文
口試日期 2006-06-13
論文頁數 54頁
口試委員 指導教授-石貴平
委員-曾煜棋
委員-簡榮宏
委員-許健平
中文關鍵字 鏈結調適  媒體存取控制  封包切割  IEEE 802.11  多重速率  馬可夫鏈 
英文關鍵字 link adaptation  medium access control  fragment  IEEE 802.11  multi-rate  finite-state Markov chain 
學科別分類 學科別應用科學資訊工程
中文摘要 IEEE 802.11中提供了多種傳輸速率,但卻未針對如何選擇速率以及何時應調整速率詳細定義。多重的傳輸速率主要是藉著實體層針對訊號的調變方式而達成,但是不同的調變方式,對於環境中雜訊的抵抗能力也有著不同的表現。本論文提出FaRM(Fragment and Rate Matching)協定,利用即時偵測所得到的噪訊比(signal-noise-ratio,SNR),得知當下網路上通訊的品質,並藉著使用Finite State Markov Chain(FSMC)預測網路中訊號品質的波動,如此將比傳統使用SNR臨界值之方法,更能貼近網路品質狀況的真正表現。此外本論文採用動態分割訊框大小(dynamic fragmentation),以期能藉由縮短資料長度,達到較高的資料傳送可靠度,並依此選出最有利之傳輸速率與訊框長度之配對,縮短傳輸所佔用之網路時間,以提升網路產能及改善傳輸延遲時間。透過FaRM動態地選擇速率以及訊框長度,可獲得更理想的傳輸效能。實驗結果呈現出,FaRM考量未來網路品質變化,並快速地針對網路品質調整傳輸方式,可得到較好的網路效能,以及更高的傳輸可靠度,並同時降低資料傳輸的延遲時間。
英文摘要 In the wireless environment, the channel condition varies due to several factors, especially in mobile ad hoc networks. Previous researches use SNR thresholds to determine the channel condition. However, SNR thresholds may not be an accurate decision, especially in a quickly varied environment. This paper proposes a fragment and rate matching (FaRM) MAC protocol for mobile ad hoc networks. In FaRM, stations dynamically detect the current signal-noise-ratio (SNR) to present the channel quality through the control frame exchange. Then FaRM uses Finite State Markov Chain to predict the variation of the channel quality. FaRM therefore can get closer results of the error occurrence in the channel than previous researches. According to the results generated from Finite State Markov Chain, FaRM dynamically selects the transmission rate with an acceptable fragment length. FaRM not only gains better throughput through the selection of high rate, but also increases the reliability by fragmentation. Comparing to other researches, the simulation results show FaRM has better performance, higher transmission reliability and lower transmission delay time by fragmentation according to the prediction of the network.
論文目次 目錄
第一章、序論 1
第二章、問題分析與目標說明 3
2.1 品質多變頻道下之問題分析 3
2.2 相關文獻 5
2.2.1 多重速率規劃協定 5
2.2.2 資料分割協定 9
2.3 本論文欲達成之目標 10
第三章、協定規劃與演算法 12
3.1 基本概念 12
3.2 噪訊比與位元錯誤率之轉換 14
3.3 Finite-State Markov Chain模型 17
3.4 分段長度決策 21
3.5 演算法 25
3.5.1 封包交換機制 25
3.5.2 NAV設定 28
3.5.3 動態切割及速率調整 30
第四章、協定延伸強化 33
4.1 錯誤更正碼 33
4.2 搭配錯誤更正碼之分段長度 35
4.2.1 Frame control欄位修改 35
4.3 合併之演算法 37
第五章、模擬與分析 38
5.1 實驗環境及參數 38
5.2 數據結果分析 39
第六章、結論與未來發展 42
參考文獻 44

圖目錄
圖1 IEEE 802.11 fragment burst 示意圖 4
圖2 RBAR與OAR比較圖 8
圖3 頻道優劣示意圖 10
圖4 FaRM運作示意圖 12
圖5 IEEE 802.11調變方法之SNR vs. BER對照圖 16
圖6 頻道品質波動示意圖 17
圖7 BSC示意圖 20
圖8 連續傳送長度 vs. 成功機率對照圖 22
圖9 FaRM運作示意圖 26
圖10 FaRM之CTS/ACK欄位 27
圖11 FaRM之NAV宣告示意圖 28
圖12 速率與長度決策流程圖 30
圖13 延伸協定之CTS/ACK欄位修改 36
圖14 Throughput比較圖 39
圖15 Error frame計數比較圖 40
圖16 Delay time比較圖 41

表目錄
表格 1 IEEE 802.11b速率相對應之調變技術 14
參考文獻 [1] IEEE 802.11 Working Group, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” ANSI/IEEE Std. 802.11, Sept. 1999.
[2] IEEE 802.11 Working Group, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: Higher-speed Physical Layer Extension in the 2.4 GHz Band,” ANSI/IEEE Std. 802.11b-1999, 1999.
[3] IEEE 802.11 Working Group, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications High-speed Physical Layer in the 5 GHz Band,” ANSI/IEEE Std 802.11a-1999, 1999.
[4] IEEE 802.11 Working Group, “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 4: Further Higher Data Rate Extension in the 2.4 GHz Band,” ANSI/IEEE Std 802.11g-2003, 2003.
[5] A. Kamerman and L. Monteban, "WaveLAN-II: A High-performance Wireless LAN for the Unlicensed Band," Bell Labs Technical Journal, vol. 2, no. 3, pp. 118-133, 1997.
[6] G. Holland, N. Vaidya, and P. Bahl, "A Rate-adaptive MAC Protocol for Multi-hop Wireless Networks," in Proceedings of the 7th Annual International Conference on Mobile Computing and Networking (MOBICOM), pp. 236-251, July 2001.
[7] B. Sadeghi, V. Kanodia, A. Sabharwal, and E. Knightly, "OAR: An Opportunistic Auto-rate Media Access Protocol for Ad Hoc Networks," in Proceedings of the 8th Annual International Conference on Mobile Computing and Networking (MOBICOM), pp.24-35, Sep. 2002.
[8] R. Theodore, Wireless Communications: Principles and Practice, Prentice Hall, Upper Saddle River, N.J., 1996.
[9] E. N. Gilbert, “Capacity of a Burst-noise Channel,” Bell System Technical Journal, vol. 39, pp. 1253–1265, Sep. 1960.
[10] E. O. Elliott, “Estimates of Error Rates for Codes on Burst-noise Channels,” Bell System Technical Journal, vol. 42, pp. 1977–1997, Sep. 1963.
[11] B. Kim, Y. Fang, T. Wong and Y. Kwon, "Throughput Enhancement Through Dynamic Fragmentation in Wireless LANs," IEEE Trans. Veh. Technol., vol. 54, no. 4, pp. 1415-1425, July 2005.
[12] H. S. Wang and N. Moayeri, “Finite-state Markov Channel-A Useful Model for Radio Communication Channels,” IEEE Trans. Veh. Technol., vol.44, pp. 163-171, Feb. 1995.
[13] Q. Zhang and S. A. Kassam, “Finite-state Markov Model for Rayleigh Fading Channels,“ IEEE Trans. Commun., vol. 47, no. 11, pp. 1688-1692, Nov. 1999.
[14] J. Arauz and P. Krishnamurthy, "A Study of Different Partitioning Schemes in First Order Markovian Models for Rayleigh Fading Channels," in Proceedings of the 5th International Symposium on Wireless Personal Multimedia Communications, pp. 277-281, Oct. 2002.
[15] J. Kim, S. Kim, S. Choi, and D. Qiao, "CARA: Collision-aware Rate Adaptation for IEEE 802.11 WLANs," in Proceedings of the IEEE INFOCOM, Barcelona, Spain, April 23-29, 2006.
[16] P. Chevillat, J. Jelitto, and H.L. Truong, "Dynamic Data Rate and Transmit Power Adjustment in IEEE 802.11 WirelessLANs," International Journal of Wireless Information Networks, vol. 12, no. 3, July 2005.
[17] J.G. Proakis, Digital Communications. 4th ed. New York: McGraw-Hill, 2001.
[18] M. K. Simonand, M.-S. Alouini, Digital Communication Over Fading Channels. New York: Wiley, 2000.
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