Bluetooth based collaborative crowd density estimation with mobile phones

We present a technique for estimating crowd density by using a mobile phone to scan the environment for Bluetooth devices. The paper builds on previous work directed to use Bluetooth scans to analyze social context and extends it with more advanced features, leveraging collaboration between close by devices, and the use of relative features that do not directly depend on the absolute number of devices in the environment. The method is evaluated on a data set from an experiment at the public viewing event in Kaiserslautern during the European soccer championship showing over 75% recognition accuracy on seven discrete classes.