Shoichi Nakabayashi

A complete simulator architecture for inter-vehicle communication intersection warning systems

This paper presents the complete simulator architecture of the intersection warning system (IWS) capable of evaluating different warning systems and communication protocols. In this simulator, the network layer, the physical layer, the driver behavior, and the vehicle traffic are modeled and simulated in detail. An optional repeater is utilized at the intersection to disseminate the position, the velocity, and the acceleration information of the approaching vehicles to the road segments shadowed by buildings. The simulation results show that IWS can significantly reduce both the vehicle collision percentage and the vehicle collision speed.

A study of real-time and autonomous decentralized DSRC system for inter-vehicle communications

To realize the inter-vehicle communications (IVC) system, the development of a real-time and autonomous decentralized dedicated short range communication (RAD-DSRC) is necessary. In this paper, the performance of a physical layer of the RAD-DSRC system is evaluated considering the influence of the radio propagation characteristic for the IVC system. The performance of a media access control layer is also evaluated with the PL (packet loss) performance of a CSMA (carrier sense multiple access). It is clarified that the improvement of the PL for the CSMA is possible to utilize the spread spectrum technology.

Dedicated Short-Range Communication System for Pedestrians and Vehicles During Right Turns

Many fatal accidents between pedestrians in crosswalks and right-turning vehicles occur every year in Japan, where vehicles travel on the left side of the road. The drivers failure to detect the pedestrian is often a primary cause of the collision. Drivers turning right need help to be more aware of risks associated with pedestrians in the crosswalk. This study investigated the capability of a dedicated short-range communications (DSRC) system (5.8 GHz) between pedestrians and right-turning vehicles in the crosswalk. One field observation was conducted of driver behavior for avoiding conflict with pedestrians in the crosswalk at an intersection, and two experiments measured the transmission performance of DSRC. The aim of the observation was to investigate the effective warning area for drivers facing potential collisions with pedestrians. The aim of the first experiment was to measure the transmission performance of DSRC between the pedestrian and the right-turning vehicle under dynamic conditions. The aim of the second experiment was to assess the influence of intersection size and presence of vehicles on the transmission performance of DSRC at the actual intersections. The two experiments showed that when the right-turning vehicle was run within the effective warning area, the packet arrival rates were mostly over the 80% required rate of Advanced Safety Vehicle 3. The study found that right-turning vehicles can communicate with pedestrians approaching from the right and left sides and that DSRC may contribute to the implementation of a system that assists drivers to avoid risks between right-turning vehicles and pedestrians in the crosswalk.