以DSRC及3.5G網路共同支援車用通訊之可行性評估

Abstract

在未來，具無線通訊功能的車載系統是智慧型運輸系統必要的一環。它可用來避免交通意外的發生時所需要付出的社會成本，還可以用來控管車流量，來避免交通阻塞。現今發展的行動通訊系統，如3.5G的HSDPA(High Speed Downlink Packet Access)系統以及DSRC(Dedicated Short Range Communication)都可以用來實行，但由於不同的系統有不同的網路容量和服務範圍，因此有必要加以整合運用。 在現今3.5G網路覆蓋率高的情境下，本論文乃提出一種複合式系統，選擇在都市區佈建DSRC系統而在郊區使用原本已佈建3.5G系統。由於DSRC進入到HSDPA網路時，車子原本使用的應用服務會中斷，因為在連上HSDPA網路時，DSRC網路已中斷 。 因此本論文先去試算3.5G的網路瓶頸所在後，提供一套演算法去提升3.5G網路的最大服務車輛數目並使應用服務可以盡量完整使用，然後我們將去探討在兩系統交接的情形，並提出使用一個稱為D2H的可調式演算法提升3.5G網路的最大服務車輛數目。在此條件下我們去模擬不同的車速在不同的車流量下的系統交接情況，模擬結果包括平均換手的時間與換手失敗率，並可經由模擬結果去分析在8車道、6車道、4車道等不同交通環境下，車流量的大小會造成系統交接失敗率的影響。

In the future, a wireless vehicle communication system is necessary for intelligent transportation systems link. It can be used to avoid the occurrence of traffic accidents required to pay the social costs and be used for control traffic flow and also avoid traffic congestion. Current development of mobile communication systems such as 3.5G in the HSDPA (High Speed Downlink Packet Access) system and the DSRC (Dedicated Short Range Communication) can be used to implement, but because different systems have different network capacity and services, so the need to integrate. In today's 3.5G high network coverage environment of wireless network, this master thesis propose a hybrid system, select the deployment in urban areas using DSRC system and using 3.5G systems in rural area. Because of roaming form DSRC to HSPDA the application will be interrupted. Therefore this master thesis evaluates the bottleneck of 3.5G network’s capacity and provides an algorithm to improve the number of vehicle that 3.5G networks can serve and make full use of application as much as possible., then we're going to explore the transfer of the two systems situation, and proposes to use a adaptive algorithm called D2H to enhance the maximum number of service vehicles in 3.5G network. In this condition, we have the speed to simulate different traffic flow in the system under different transfer conditions, the simulation results including the average handoff time and the handoff failure rate, and can go through the simulation results of 8 Drive, 6 Drive, 4 Drive under various traffic conditions, traffic flow will cause the size of the handover failure rate of the system.