• 沒有找到結果。

且使用 The ONE 模擬器以及 OpenStreetMap 地圖的繪製軟體來進行模擬實驗,最後 將本論文提出的方向性路由機制 TPRP 和四種路由機制在模擬器上進行比較。

在第四章節路由機制比較項目有 Delivery Ratio (封包到達率)、Overhead (路 由開銷)、Latency (封包延遲時間)、Relayed (重傳)、HopCount (封包跳躍次數),

而使用方向性判斷路由機制 SD_MPAR 的 Delivery Ratio 平均約 90%,本論文提出的 方向性判斷路由機制 TPRP 的 Delivery Ratio 平均更是約 95%,說明了使用方向性判 斷是有效的提升封包到達率。在 Overhead 以及 Relayed 的數據可以看出 TPRP 都是最 低,而 Relayed 的數據和 Overhead 的數據是有相關性的,TPRP 在第一階段有街道傳 輸條件以及方向性判斷條件,第二階段也有嚴格判斷條件,所以 TPRP 的 Relayed 的 數據才會較低,影響著 TPRP 的 Overhead 也是較低。

在 Latency 數據中可以看出,有使用方向性判斷的路由機制都是較低的,可以使 封包是有效率的往目地車移動,降低 Latency。在 HopCunt 的數據中,明顯看出 TPRP 是最低的,說明了 TPRP 的方向性判斷篩選車輛是有效率的,而 VR 以及 SD_MPAR 使用 方向性判斷在 HopCunt 也是較低的,其中 VR 比較高是因為 VR 向性判斷路由機制是將 封包傳到沒有走過的路、使得可以遇到更多車輛來傳輸封包,所以 HopCunt 才會是方 向性判斷路由機制中最高的。

本論文提出的方向性路由機制 TPRP 在第一階段時是在路口判斷車輛行徑方向,

如果方向是封包最短路徑方向則代表有較快的機率可以遇到目的車,所以會複製一份 封包給此方向車輛,而當封包離目的車很短的距離時,封包距離目的車≦門檻值,TPRP 第二階段就能在所有街道進行判斷傳輸封包,可以更快速有效的使封包到達目的車。

在模擬數據比較中使用方向性判斷的路由機制都能有較好的效果,而本論文提出的路 由機制 TPRP 也是使用方向性判斷,使得路由機制 TPRP 可以有較佳的效能。第二階段 判斷篩選中,門檻值設定並沒有理論推導的過程,而是單純實驗過程中較佳的數值,

以及我們實驗中 Buffer 的空間設置較大,這是為了看出差異性,但也就無法比較我 們實驗中使用的 Buffer 管理方法,而我們路由判斷主要是在路口,當街道的路口數 量很少的話,我們的方法效能也會較差,這三點是希望在未來中可以改善的。

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