車載網路中儲存攜帶轉送訊息傳遞延遲之穩態分析

Abstract

在車載網路(Vehicular Ad Hoc Networks, VANETs)中，當道路上發生意外時距離最近的車輛會傳送緊急訊息給後方車輛，由於稀疏的交通量或是很低的無線裝置市場滲透率會發生很多的網路斷開現象，當發生網路斷開的現象時可利用對向車輛使用儲存攜帶轉送(store-carry-forward)來修復，而使用儲存攜帶轉送來修復網路斷開則需花費延遲時間。

在本論文會利用嵌入的馬可夫鍊(Embedded Markov Chain, EMC)分析前一次網路斷開的狀態對此次網路斷開的影響，並且分為三種類型去做討論，以及計算出使用儲存攜帶轉送傳遞訊息的穩態機率以及延遲時間的平均值與變異數，而數值分析的結果呈現出我們的分析是高度準確的。

In vehicular ad hoc networks (VANETs), when accident occurs, the vehicles which is the nearest of incident place, sends an emergency message to rear vehicle. There may occur network disconnections because of low penetration of wireless devices or light vehicle traffic. When a network disconnection occurs, a store-carry-forward message delivery can be carried out by vehicles in the reverse direction to help restore the network connection, and it may have some delay time. In this paper, we use the Embedded Markov Chain (EMC) to analysis the previous network disconnection that have impact on the actual network disconnection. And the state will divide into three type to analysis. The steady state probability of a store-carry-forward message delivery, the mean of delay and the variance of delay are investigated. Numerical results show that our analysis is highly accurate.