Transmit Processing Techniques Based on Switched Interleaving and Limited Feedback for Interference Mitigation in Multiantenna MC-CDMA Systems

In this paper, we propose transmit processing techniques based on novel switched interleaving, chipwise linear precoding, and limited feedback for both downlink and uplink multicarrier code-division multiple access (MC-CDMA) multiple-antenna systems. We develop transceiver structures with switched interleaving, linear precoding, and detectors for both uplink and downlink using limited-feedback techniques. In the proposed schemes, a set of possible chip interleavers is constructed and prestored at both the base station (BS) and mobile stations (MSs). For the downlink, a new hybrid transmit processing technique based on switched interleaving and chipwise precoding is proposed to suppress the multiuser interference. The BS and MSs are also equipped with another codebook of quantized downlink channel-state information (CSI). Each MS quantizes its own downlink CSI and feeds the index back to the BS through a low-rate feedback channel. Then, the selection function at the BS determines the optimum interleaver based on the CSI of all users. Moreover, a transmit processing technique for the uplink of multiple-antenna MC-CDMA systems, which requires a very low rate of feedback information, is also proposed. Codebook design methods for both interleavers and quantized CSI are also proposed. Simulation results show that the performance of the proposed techniques is significantly better than prior art.