This paper puts the emphasis upon the array processing of the angular-spread signal which is called the generalized directionalsignal and aims to match this signal model in the energy sense.
So Mr O'Brien has been working on a ceiling-based system that tracks where a receiving device is, and then sends it a signal using several laser beams from a directional transmitter.
Smart antenna using digital signal process technique, produces space directional beam, and utilizes space filter ability for improving the performance of CDMA systems.