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Abstract:A combined use of the ceIlular and high-speed "hot-spot" communications can provide higher-rate and more convenient network access services to mobile users on-board vehicles. The authors developed an experimental flexible access control system so as to indicate the technical feasibility of such services. The system consists of a set of QoS monitor and mobile router that monitors and selects the optimum wireless access media among the PacketOne, Dedicated Short Range Communication (DSRC) and wireless LAN. It also consists of a pair of flexible access processing module and gateway that provides a seamless data stream to the applications. A series of field experiments has been conducted at KDDI Training Centre, Saitama, Japan, where the access points of DSRC and wireless LAN and other network equipment were placed for the experiment. The experimental results showed that the flexible access control works wen for the optimum link selection and the flexible access buffer control provides a seamless streaming at the average throughput much higher than the cellular one.