Transmitter-Based Filters for Interference Mitigation under Imperfect Channel Conditions for the Fdd/Ds-Cdma Systems

Precoding techniques reduce complexity, size and cost of the mobile stations, while achieving the same interference mitigation effects of receiver based methods for Direct Sequence Code Division Multiple Access (DS- CDMA) downlink. The technique is based on processing of signal before transmission relying on knowledge of the channel state information. In most of the previous works, this a priori information is assumed. In practice, there will be performance degradation due to time varying nature of the radio mobile channels and methods used for channel estimation/ prediction. In this paper, we will present the performance evaluation of transmitter-based filters as precoding elements for mitigating inter symbol interference and multiple access interference under imperfect channel conditions in frequency-division duplex mode for DS-CDMA downlink through analysis and computer simulations.