Origin Destination Estimation Carrying Over Rolling Proximity Identifiers with RSSI

Origin destination (OD) data describing passengers' flows is essential for improving bus route operational efficiency. Manual collection of OD data is still conducted, so automatic OD data acquisition using the internet of things (IoT) is desired. One method utilizes Bluetooth beacon identifiers to understand passengers' flows while considering their privacy. Still, while random MAC addresses can estimate the number of devices there, they are insufficient for generating ODs. In contrast, in response to the COVID-19 pandemic, the government promoted the exposure notification system to prevent secondary infection. The smartphone app exchanges short-term identifiers called Rolling Proximity Identifiers (RPIs), updated every 15 minutes. This research aims to realize tracking during bus rides with only a few RPIs carryovers, since bus rides are only about an hour long at most. We evaluated the system on a bus in Kyoto City and successfully tracked passengers for 55 minutes, the experiment's maximum length.