Multiple Antennas Bluetooth System for RSSI Stabilization

In this paper we introduce a Bluetooth system which achieves an important improvement in the RSSI stability thanks to the use of multiple antennas. The main advantage of our system is that it reduces the effects produced by fading in the received signal power, that is obtained by the RSSI (received signal strength indicator). In most positioning systems the RSSI stability is very important, because it is the main reference for obtaining the desired positions. Using spatial diversity our system tries to stabilize this RSSI measurement. We present a study of this important improvement in which we compare different combination/selection techniques which use the RSSIs obtained from the received signals. We have carried out an empirical evaluation of this multiple antenna Bluetooth system, and we have verified how these spatial diversity techniques reduce the mean square error of the measured RSSI with respect to a theoretical propagation model.