WAVE車間無線通訊系統之移動管理研究

Abstract

由於Wireless Access in Vehicular Environments (WAVE) 無線通訊協定的制定，無線通訊技術能實際的應用於交通環境之中，交通工具之間透過此一通訊協定相互進行無接縫式(seamless)的資料傳輸。在WAVE通訊協定中，資料可以透過WAVE Short Message Protocol (WSMP)進行傳輸，但是在規格書中，針對WSMP僅只提供廣播(broadcast)服務，對於點播(unicast)及群播(multicast)並沒有相對應的處理機制。欲處理WSMP之點播(unicast)及群播(multicast)資料傳遞服務，必需建立移動管理(mobility management)的機制，方能紀錄每一個使用者/交通工具之位置，以達成資料傳遞之目的。本計畫中，我們提出一套’以預測位置為基礎之移動管理機制’，此一機制將有效的利用全球定位系統(Global Positioning System； GPS)所提供之位置資訊，大量的降低維持移動管理機制所需之資料傳輸量。在車流量大且行駛速度快的快速道路/高速公路上，基於相同的呼叫成本(paging cost)，我們所提出的’以預測位置為基礎之移動管理機制’可以大幅減少40%~90%的移動管理資料傳輸量。

The Wireless Access in Vehicular Environments (WAVE) provides seamless and interoperable services for vehicles. In WAVE, the WAVE Short Message Protocol (WSMP) provides broadcast services but does not define unicast/multicast services that require mobility management to track the locations of the vehicles. To resolve this issue, we will propose a prediction-based mobility management mechanism by utilizing positioning systems (e.g., GPS) for a WAVE system deployed in highway environment with a large volume of high-speed vehicles. Our study indicates that under the same paging cost, our approach can reduce 40%-90% of the network traffic as compared with the traditional cellular mobility management approach.