Antenna Characterization for Bluetooth-Based Travel Time Data Collection

Several approaches for travel time data collection based on the reading of time-stamped media access control addresses from Bluetooth-enabled devices have been reported in the literature recently. This new approach offers a number of advantages over more conventional methods, including lower costs of hardware and software, the volume of data that can be collected over time, and ease of implementation. A fundamental component that may affect the quantity and the quality of the travel time samples collected with a Bluetooth-based system is the antenna type utilized. Antenna characteristics such as polarization and gain must be matched to specific application environments to optimize the performance of a Bluetooth reader unit. However, experimental data that focuses on antenna characterization as it relates to the use of Bluetooth technology to assess the performance of transportation facilities is lacking. In this study, five different types of antennas were characterized to assess their suitability to support a Bluetooth-based travel time data collection system. The results indicate that vertically polarized antennas with gains between 9dBi and 12dBi are good candidates for travel time data collection. Also, different antenna types are better suited to different uses of the Bluetooth-based system. If the main focus is the collection of travel time data, then an antenna with a lower sampling rate may provide more accurate travel time samples.