The capacity achievable with a broadband CDMA microcell underlay to an existing cellular macrosystem

The paper addresses whether the broadband-CDMA overlay concept can be applied to creating a CDMA microcell underlaying an existing analog macrocell. It is shown that indeed high capacity can be achieved in the microcell on both forward and reverse links, largely independently of the separation between microcell and macrocell bases. Furthermore, in the forward link the effect of neighboring base stations is shown to be negligible. In order to achieve maximum capacity it is found that transmit and receive notch filters at the microcell base station are invaluable at small separations between micro and macrocells