TDMA應用於實現遠端跳躍資料傳輸平臺之建立

Abstract

現今，為解決現代社會中所遭遇到各種天災、人禍，提高及時獲救的機率，降低死亡率，短距即時通訊成為目前世界各國所致力於發展目標。在解決交通問題上，利用DSRC IEEE 802.11p的規格，即時監控路面交通進行相對應調度，並針對交通事故即時處理。在另一方面，為解決橋梁、鐵路等建築因時間而造成結構崩壞、危害性命等問題，建構以Zigbee為基礎之IEEE 802.15.4 規格之無線感測網路(WSN)。一般來說，為求資料的即時性及完整性，短距即時通訊及無線感測網路所接收到及所感測到的資料，往往須即時送至後端資料庫或決策中心，以利資料的即時分析與決策，這樣的概念，在短距通訊平臺的建構上佔有極重要的地位。然而，無論是DSRC IEEE 802.11p規格亦或是無線感測網路之相關協定，均未對後端資料的傳輸規畫多做著墨。因此，本論文之研究目的為建構一遠端跳躍式波浪傳輸平臺，結合DSRC IEEE 802.11p及IEEE 802.15.4無線感測網路傳輸規格，以跳躍式的方式將各節點匯集整合至匯流排窗口，再統一利用有線網路或3G網路遠端傳送至後端資料庫及決策中心。本論文主要為建構遠端波浪式跳躍資料傳輸平臺為主，採取時間分割的方式，擷取ARM 核心中CPU 計數作為時間分割的基礎，制定各傳輸節點間時間同步機制，並根據系統的需求，結合DSRC IEEE 802.11p及 IEEE 802.15.4 無線感測網路傳輸規格及相關標準，設計出網路傳輸封包格式及通訊協定，並將相關傳輸協定實現於以linux為基礎之非即時性作業系統。基於本論文所建構之遠端跳躍資料傳輸平臺傳輸媒介可分為WiFi (IEEE 802.11a)規格及電力線網路，本論文亦設計了傳輸媒介間的交換機制，以提升系統資料傳輸之可靠度。最後，藉由各種相關實驗結果，驗證本論文所建構之遠端資料傳輸平臺之可行性和實用性。

DSRC (Dedicated Short Range Communication) which is being seriously considered as a prospective wireless technology for solving a variety of natural or man-made disasters was investigated by many researchers. According to previous study, IEEE 802.11p standard could solve the traffic problems in modern cities based on its in-time information response and monitoring. Furthermore, IEEE 802.15.4 spec for WSN (Wireless Sensing Network) protocols can be used to enhance the quality of monitoring man-made building state, such as bridge or railway. In fact, the reliability of DSRC communication builds on precise analysis and decision upon transmission of date between uploading date and back-end databases. However, uploading data or information to back-end databases, there is no detailed definition of protocols. Hence, developing a remote wave hop transmission platform with combination of IEEE 802.11p spec and WSN protocols is core concept of this study. This study realized the remote wave hop transmission by using TDMA (Time Division Multiple Access), taking the ARM-based CPU core clock as time division slot, and constructing the timer offset synchronization, as well as timer frequency synchronization mechanism between each hopping node. According to requirement of short range communication system, the hopping network packet transmission format and corresponding communication protocol which with either IEEE 802.11p spec or WSN protocols have been designed and implemented in embedded ARM-based board which exist non-real time Linux OS(Operating System) by the format of driver module. Energy efficiency in wireless communication is the other issue need to be considered. Base on the practical mathematic energy consumption model, selecting proper transmission power mechanisms have been designed in order to maintain both the minimum energy consumption, as well as transmission performance. This energy efficiency scheme has been designed and integrated to the original communication protocol. All the theories designed in this study will be verified by a variety of related experimental result.