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In this paper, we present a WLAN-based automatic vehicle identification (AVI) technique. AVI, typically used for electronic toll collection, is a basic functional requirement for a smart car. The development of this technique is a subtask of building a WLAN-based multi-purpose vehicular terminal device providing various functions, such as AVI, car-to-car communication and vehicular internet access. The design and implementation of our WLAN-based AVI system was based on reducing the identification time in order to cover high-speed cars. As time is required to establish a network connection between a roadside access point and a car station, identifying a high-speed car by communicating through that network connection is not feasible. We utilize IEEE 802.11 management frame such as probe request frame in order to identify a station without establishing a network connection. We also control the timing of the scanning procedure in order to generate enough frames for reliable identification of high speed-cars. Based on the experimental results, our WLAN-based AVI system achieves an identification ratio of nearly 100% for various car speeds ranging from 40km/h to 100km/h, whereas, active RFID, one of the representative technologies for AVI, does not show reliable identification performance, especially at high-speeds. 1

This paper presents the efficient measurement method of radio resource by analyzing various medium occupied elements. The medium occupied time consists of 802.11 frames, wireless interference, and protocol waiting time from a wireless node on a current channel. And it is used to performance metric. Existing research is only measured partial occupied elements, and is lack of validation of measurement unit and scalability on various IEEE 802.11 radio. This paper presents the measurement method of classified occupied elements. To achieve this, we modified 802.11n based OpenHAL device driver to collect the register information of wireless chipset, and to analyze receiving frames in an virtual monitor mode. We conclude accurate medium occupied time measurement system from various validation methods.

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