Pre-Filtering Techniques Using Antenna Arrays for Downlink TDD MC-CDMA Systems

This paper deals with downlink time division duplex MC-CDMA system, and presents a space-frequency pre-filtering technique designed for two different receivers: a simple despread receiver without channel equalization and an EGC conventional receiver, where the base station is equipped with an antenna array. We show that the space-frequency pre-filtering approach proposed allows to format the transmitted signals so that the multiple access interference at mobile terminals is reduced allowing to transfer the most computational burden to the base station. Simulations results are carried out to demonstrate the effectiveness of the proposed pre-filtering schemes.