臺灣博碩士論文加值系統

在無線車載網路中，緊急訊息如何有效地廣播一直以來是一個重要的議題。本篇論文提出一個動態分割協助廣播協定(DPAB)，透過調整車輛間控制封包回傳的訊號強度，藉以評估網路車輛密度以找尋最佳的代傳車輛，並減少干擾訊號，進而達到節省無線傳輸資源與提高封包成功傳輸率。最後透過數學分析與實驗模擬的方式驗證本論文；實驗結果也顯示，DPAB與其他作法比較下有較好的One Hop Delay與Packet Delivery Ratio。

Effectively broadcasting emergency messages in vehicular ad hoc networks (VANETs) is an important issue in VANETs. This paper proposes a Dynamic Partition Assisted Broadcast (DPAB) protocol to effectively broadcast emergency messages in VANETs. Adjusting the power level of control messages to estimate the network density and dynamically partition a transmission range into segments are the major techniques in DPAB. To do so can not only find the best vehicle in the furthest possible segment to relay the emergency messages in the network, but also can reduce the interference among vehicles to save the network resource and increase the packet delivery ratio. Based on the mathematical analyses and network simulations, the proposed protocol, DPAB, has a significant performance against the related work in one hop delay and packet delivery ratio.

目錄
第1章 緒論 1
1.1前言 1
1.2研究動機與目的 3
1.3研究方法 4
1.4論文架構 4
第2章 預備知識 6
2.1問題描述 6
2.2相關文獻 8
第3章 訊號感測 13
3.1訊號計算 13
3.2功率控制 14
第4章 動態分割協助廣播協定 17
4.1基本理念 17
4.2最遠代傳車輛 18
第5章 分析模型 25
5.1時間期望值 26
5.2One-hop Delay 28
第6章 網路效能模 30
6.1實驗場景及參數設定 30
6.2實驗結果及分析 31
第7章 結論 35
參考文獻 36
附錄 39

圖目錄
圖 1：鄰居車輛轉發資料。 3
圖 2：A、B兩車同時廣播緊急訊息造成碰撞。 7
圖 3：來源車輛蒐集鄰居資訊尋找代傳車輛。 7
圖 4：封包傳播延遲。 8
圖 5：UMB切割區域蒐集鄰居資訊。 10
圖 6：SB分割區域蒐集鄰居資訊。 10
圖 7：BPAB切割區域蒐集鄰居資訊。 11
圖 8：最遠車輛使用最大功率回傳訊號。 14
圖 9：車輛降低功率回傳訊號。 15
圖 10：來源車輛判斷車輛密度。 16
圖 11：來源車輛廣播控制封包。 18
圖 12：DPAB運作流程。(a)車輛稀疏。(b)車輛壅塞。 19
圖 13：不同傳輸範圍下車輛疏密值。 20
圖 14：道路分割為4個區域。 21
圖 15：車輛稀疏情況下訊號回傳順序。 22
圖 16：道路分割為16個區域。 23
圖 17：車輛壅塞情況下訊號回傳順序。 24
圖 18：車輛密度與時間期望值的比較。 31
圖 19：車輛密度與One-hop Delay的比較。 32
圖 20：車輛密度與訊息傳播速度的比較。 33
圖 21：車輛密度與封包成功接收率的比較。 34
圖 22：傳輸範圍與封包接收率的比較。 34

表目錄
表一 分析的數學符號設定。 25
表二 實驗的模擬參數設定。 30

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