Scenario simulator for smart antenna mobile radio systems

The smart antenna capability of base transceiver stations (BTSs) for mobile radio systems permits one to recognise the direction of arrival of the electromagnetic wave from the mobile radio units, in order to carry out a consequent spatial filtering in both radio paths. The adaptive array antenna architecture of the BTS achieves the digital beam forming using algorithms that iteratively adjust the weighting of the signals from the elements of an N-element array antenna. With this criterion it has been built an RF up-link scenario simulator of more user terminals that transmit from different azimuthal directions; the phasing and the amplitude of the N outputs of the RF scenario simulator are such as to cause their contributions to add constructively on a plane electromagnetic wave front at some chosen azimuthal angle, that can be varied by changing the phasing. This paper describes the architecture and the characteristics of the RF scenario simulator designed and implemented in our laboratories; the prototype has been used to test the performance of the algorithms of an experimental smart antenna BTS.