Modelling and simulating Bluetooth-based moving observers

Bluetooth devices on board of traffic objects depict an easy way of detecting motions of persons and goods. However, the precondition is that one Bluetooth device (the observer) discovers another Bluetooth device - namely the on board device - within a very short time range. Device discovery in case of Bluetooth connection establishment is heavily dependent from the so called inquiry process which allows Bluetooth devices to look for each other and to exchange relevant information to build up a lasting connection. In this paper we give an analytical model of the time it takes a Bluetooth-based moving observer to discover a Bluetooth device within a floating traffic object by considering the specific behaviour of the inquiry procedure. Therefore, the analytical model refers to the inquiry process described in the official Bluetooth standard protocol version 1.2 and thus includes a specific mode - named interlaced scan mode-which was introduced to speed up discovery times. We show that, taking that kind of mode into account gives more reasonable results in terms of reflecting practical measurements by means of simulations. As a result, we can much better describe the observers behaviour concerning the probability of the first detection.