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研究生:盧彥甫
研究生(外文):YenFu Lu
論文名稱:利用訊號變化與遮蔽效應之802.11 MAC碰撞避免協定
論文名稱(外文):Collision Avoidance 802.11 MAC Protocol with Signal Variation and Masking Effect
指導教授:陳青文陳青文引用關係
指導教授(外文):ChingWen Chen
口試委員:竇其仁黃秀芬
口試日期:2014-07-10
學位類別:碩士
校院名稱:逢甲大學
系所名稱:資訊工程學系
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2014
畢業學年度:102
語文別:中文
論文頁數:35
中文關鍵詞:IEEE 802.11DCF碰撞NAVSINR
外文關鍵詞:IEEE 802.11DCFcollisionNAVSINR
相關次數:
  • 被引用被引用:0
  • 點閱點閱:286
  • 評分評分:
  • 下載下載:33
  • 收藏至我的研究室書目清單書目收藏:1
在以IEEE 802.11 DCF為標準的多跳躍無線網路中,傳輸對的鄰居節點會進入NAV狀態,並且在傳輸對完成傳輸時結束NAV狀態以避免與傳輸中的節點發生碰撞。然而當一個節點在NAV狀態時,如果此時其鄰居開始進行資料傳輸,當此節點離開NAV狀態後,可能會與正在傳輸資料的節點產生碰撞而影響網路效能。這個狀況在Ad-Hoc Network和網路環境密度高的情況下更為嚴重。為了解決此種碰撞問題,在本篇論文中我們提出一個MAC層碰撞避免協定。主要分成三個部分,當某一節點處於NAV狀態時,1.如果可以收到其鄰居節點的控制訊號並且不會收到原傳輸對的訊號時,其要監聽其鄰居節點是否發出控制訊號來調整其NAV狀態時間以避免在NAV狀態結束後發生產生碰撞。2.如果節點同時會收到原傳輸對與其鄰居節點訊號時,並且鄰居節點的控制訊號強度比上原傳輸對訊號強度大於接收控制訊號的門檻值時,雖然節點處在同時收到兩者的訊號,但是根據遮蔽效應還是可以收到鄰居節點的控制訊號進而調整其NAV時間以避免碰撞發生。3.當節點會同時收到兩者訊號,並且接收的鄰居節點的控制訊號強度不足以遮蔽原通訊對的訊號而無法變遮蔽原通訊對的訊號而無法辨識時,此時利用偵測訊號強度變化來預測是否有鄰居節點傳輸對正在傳輸來改變NAV時間。實驗模擬結果顯示我們提出的協定碰撞發生比率較傳統802.11 DCF協定減少60%,同時比起其他的研究也減少約41%。除此之外,傳輸延遲以及重傳次數也能有較好的表現,整體網路輸出量也因此有所提昇。
IEEE 802.11 DCF is widely used and able to avoid the collisions of the hidden terminal problem in a wireless network. However, there may be collisions existing in the DCF MAC protocol. That is, when a node in NAV state does not receive any control signal, a collision may occur after the node ends the NAV period. In this paper, to solve this collision problem, a detailed analysis about the problem is given. Afterwards, according to the analysis, we utilize the “mask-ing effect” and the detection of signal variation to design the MAC collision avoidance protocol. With the received signal strength and the varia-tion of received signal strength of a node, the node can determine whether there are other transmissions occurring in the transmission range. Therefore, a node can determine whether the period of NAV state can be extended to avoid collisions. Simulation results show that our pro-posed MAC protocol can efficiently reduce 60% and 41% collisions than the IEEE 802.11 DCF protocol and OCS-MD. In addition, our pro-posed MAC protocol also shows shorter trans-mission delay and lower retransmissions than the 802.11 DCF and OCS-MD to have better network throughput.
摘要 3
目錄 5
圖目錄 6
第一章 緒論 8
1.1研究背景 8
1.2 802.11 DCF碰撞避免機制 8
1.3 研究動機 9
第二章 相關研究 11
2.1 傳輸功率控制 11
2.2 時間切割 12
第三章 提出的方法 14
3.1 分析碰撞問題的情況 14
3.2 節點收得到控制訊號的狀況 17
3.3 節點收不到控制訊號的狀況 17
3.3.1 分析傳輸距離與接收到的訊號強度關係 18
3.3.2 遮蔽效應 19
3.3.3 監聽訊號和訊號雜訊比的變化 22
3.4 利用訊號變化與遮蔽效應之802.11MAC碰撞避免協定 24
第四章 模擬結果與分析 27
4.1模擬環境 27
4.2 模擬結果 28
第五章 結論與未來工作 32
參考文獻 33
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[3]K.-P. Shih, Y.-D. Chen, and C.-C. Chang, &;quot;Adaptive Range-Based Power Control for Collision Avoidance in Wireless Ad Hoc Networks,&;quot; Proceedings of IEEE International Conference on Communications (ICC &;#39;07), pp. 3672-3677, Glasgow, Scotland, 24-28 June 2007.
[4] K.-P. Shih, C.-C. Chang, and Y.-D. Chen, &;quot;A Fragmentation-Based Data
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Conference (WCNC 2008), pp. 1786-1791, Las Vegas, Nevada,
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Power Control MAC Protocol for Wireless Ad Hoc Networks,&;quot; Proceedings of
IEEE Wireless Communications and Networking Conference (WCNC 2009), pp. 1-6, Budapest, Hungary, 5-8 April 2009
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