Performance of cooperative communication aided MC-CDMA system using transmitter preprocessing based on vector quantized CSI

In this contribution, we investigate the performance of a cooperative communication aided downlink (DL) multi-carrier code division multiple access (MC-CDMA) system with the aid of transmitter preprocessing (TP) realized based on vector quantized (VQ) channel state information (CSI) acquired via feedback channels. In our work, we assume that each of the K destination mobile stations (DMS) is supported by a group of mobile stations (MSs) acting as relays to achieve the relay diversity. Specifically, we employ preprocessing at the base station (BS) to suppress the multi-user interference (MUI) at the relays that precludes in achieving the relay diversity. Further, inter-relay interference (IRI) at the destination mobile stations (DMSs) is mitigated with the support of the preprocessing operated at the relays. To be specific, the preprocessing operated at the BS is based on the maximum-signal-to-interference-plus-noise ratio (MSINR) approach, while that operated at the relays is based on the classical minimum-mean-square error principle. Both the preprocessing approaches are formulated based on the VQ-CSI acquired via feedback channels. Our study demonstrates that TP-aided cooperative DL MC-CDMA system results in better achievable bit-error-rate (BER) as the TP assists in achieving the relay diversity by eliminating the DL-MUI and IRI at the relays and the DMSs, respectively. Furthermore, our study reveals that the attainable BER of the VQ-CSI based TP remains close to that attained with the perfect CSI based TP.