Implementation and evaluation of message delegation middleware for ITS application

There are many applications using communication between vehicles and systems on the fixed network in intelligent transportation systems (ITS). Although DSRC, wireless LAN, cellular phones, PHS, etc. can be used as communication media for vehicle-road communication, since characteristics, such as communicative area, transmission speed, communication cost, differ. The applications using vehicle-road communication need to have a function that selects one of these communication media by a certain standard. Moreover, the application also needs to have a reliable communication function, which sends a message only when the communication channel is available, since it is assumed that intermittence of a communication channel takes place frequently owing to the spot communication environment of DSRC and wireless LAN. To improve the development efficiency of applications in the DSRC network, so far, we have proposed middleware with a message delegation system that realizes reliable message delivery based on the information of the network status of the DSRC network. We describe implementation of the middleware and show the results of the middleware through evaluation.