應用N-Fi系統於車間通訊及車載資通平台之研究

Abstract

智慧型運輸系統利用即時的資訊發佈以增進道路運輸與行車的效率，進而改善交通擁擠的程度，並提升交通安全。現今交通資訊發佈主要仍依靠CMS、廣播系統以及旅行前交通資訊查詢等方式，但用路人於交通中往往無法收到真正即時之交通資訊。有鑑於此，運用車間通訊技術於交通中成為各國智慧型運輸系統發展的主流之一。車間通訊網路可被視為行動隨意無線網路的特殊形式，也稱為VANET(Vehicle Ad-hoc Network)網路。 本研究將近場資訊系統及N-Fi系統應用於車間通訊概念，訂定相關之通訊協定以及研擬資訊發佈平台，利用IEEE802.15.4傳輸技術並提出一個類似雷達搜尋的廣播路由法，利用動態功率搜尋鄰近節點，使交通資訊能夠在無線隨意網路上有效率且即時地發佈，該路由特性具有無固定路由、免路由維護及有限轉傳等三大特色。本研究為了降低網路內的廣播封包數量，對於已接收過訊息之節點將不再接收相同資訊，也不參與轉傳，避免引起廣播風暴的問題。由於封包傳送過程並沒有特定路由，取而代之的是將轉傳任務交給距離發送端相對較遠的節點，因此節點之間並不需要交換大量的控制封包以決定轉傳節點。 本研究將車輛在道路上所需獲得的資料分類，並考量優先層級概念，依照資訊的重要性決定優先發佈順序；資訊發佈的來源可以是交控中心、路側單元、甚至是車輛本身，本研究於實驗中初步驗證所發展之系統能夠應用於轉傳資訊，可向前及向後發送，且具有極低失誤率，因此也可應用於需要高度可靠性之安全性訊息發佈。經實驗證明本系統已可達到車間通訊之基本功能。

Intelligent transport systems use real-time information dissemination to improve road transportation and traffic efficiency, and thereby alleviate the condition of traffic congestion and enhance safety. The current traffic information dissemination still relies on the CMS, broadcasting system and pre-trip travel imformation, however travelers are not often received the true real-time traffic information when they are on the road. In view of this, using vehicle-to-vehicle communication technologies in traffic become one of developmental mainstreams. Vehicle-to-vehicle communication network can be regarded as a special form of ad hoc wireless network, also known as the VANET (Vehicle Ad-hoc Network). This thesis uses Near Field Informatics system in vehicle-to-vehicle communication and set related protocol to the development of information dissemination platform. Moreover, this thesis uses IEEE 802.15.4 transmission technology and a similar radar-searching method, which utilizes dynamic power to search neighboring nodes, so that traffic information can be disseminated efficiently. The routing protocal has no fixed routing, without maintaining the routing and limited transmission of the three major characteristics. In order to reduce the number of packets, messages have been received for the node will no longer receive the same information, and don’t participate in transmission to avoid the problem of broadcast storm. As the packet transmission have no specific routing, the transmission task will give to the node which relative distance from the sending node, so nodes don’t have to exchange large numbers of control packets to determine the transmission node. This thesis classifies information which be required for vehicles on the road, and considers the priority level to decide the order of dissemination. Information dissemination can be a source of traffic management center, road side units and even a vehicle. The thesis in preliminary experiments to verify the system can be used in information dissemination, also can send forward and backward, and has a very low loss rate, therefore, requires a high degree of reliability can be applied to the safety message dissemination. Experiments have shown that this system can achieve the basic functions of vehicle-to-vehicle communication.