由於無線網路技術的進步與車輛廠商希望透過車載隨意網路 (Vehicular Ad Hoc Networks，VANET) 提升本身車輛競爭力，因此VANET逐漸受到高度重視。然而在VANET的環境之下，因為車輛行駛速度相當快速的關係，造成車輛必須不斷的在不同的Access Point(AP)或Base Station(BS)進行換手 (Handoff) 的動作，所以為了確保在VANET環境中，資料封包傳輸的不中斷，車輛換手程序的延遲成為一個目前重要的議題。有鑑於此，本篇論文提出一個IP傳遞快速換手機制，讓即將離開AP通訊範圍的車輛，能夠將IP位址保留於AP中，這些IP位址將由AP傳遞給即將進入通訊範圍的車輛使用，可使得進入通訊範圍的車輛減少使用動態主機設定協定 (Dynamic Host Configuration Protocol，DHCP) 取得IP位址，因此車輛在不同的AP之間的換手延遲時間將縮小。模擬實驗的結果，本文提出的方法，確實有效減少換手所需的時間。

With the rapid development of wireless networks, motor companies hope that Vehicular Ad Hoc Networks (VANETs) would enhance the competitiveness of their vehicles, so VANETs has gained much attention. However, In VANETs, the rapid movement of vehicles lead to the frequently handoff in different access points or base stations. To ensure that the transmission of packets is not interrupted, how to reduce the delay of handoff is an important design issue. In view of this, we proposed a fast handoff mechanism. When vehicles leave the communication range of an AP, their IP addresses can be reserved in the AP. Then the AP passes the reserved IP addresses to the vehicles that enter the communication range of the AP. Therefore, it can reduce the use of DHCP to obtain IP addresses. Our simulation results show that the proposed fast handoff scheme can be used to effectively reduce the handoff time.

中文摘要 i
英文摘要 ii
誌謝 iii
目錄 iv
表目錄 vi
圖目錄 vii
一、緒論 1
1.1 研究背景與問題 1
1.2 研究動機與目的 4
1.3 論文架構 5
二、文獻探討 6
2.1 Dynamic Host Configuration Protocol 6
2.2 Mobile Internet Protocol 10
2.3 Handoff Schemes for VANET 12
2.4 IP Address Passing 17
三、研究設計 21
3.1 IP傳遞與暫存快速換手機制 21
3.2 IP位址保留模型之公式推導 28
3.2.1 Exit區域範圍 29
3.2.2 IP位址保留數量計算 30
四、模擬實驗 35
4.1 模擬環境與參數設定 35
4.2 實驗一：對於不同的車輛行駛速度的情形，比較IP address passing與本研究的保留機制對車輛換手延遲的影響。 37
4.3 實驗二：對於不同的時間點上車流量變化的情形，比較IP address passing與本研究的保留機制對車輛換手延遲的影響。 38
4.4 實驗三：對於不同IP位址保留數量變化的情形，觀察IP位址保留機制對車輛換手延遲的影響。 39
4.5 實驗四：對於不同Exit區域長度變化的情形，比較IP address passing與本研究的保留機制對車輛換手延遲的影響。 40
4.6 實驗五：對於不同平均車流量變化的情形，比較IP address passing與本研究的保留機制對車輛換手延遲的影響。 41
五、結論 42
參考文獻 43

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