Capacity increase in the downlink of spread spectrum systems through joint signal precoding

Two precoding schemes for the downlink of code division multiple access (CDMA) systems were proposed. The schemes reduced the multiuser interference by jointly precoding the transmitted signal based on the state of the downlink channel. A considerable increase in the capacity was achieved without the use of complex multiuser detectors at the mobile terminals. The scheme was found appropriate for time division duplex (TDD) systems.