Performance of relay-aided downlink MC-CDMA system using transmitter preprocessing

In this article, we investigate the performance of a relay-aided downlink (DL) multi-carrier code division multiple access (MC-CDMA) system with the aid of transmitter preprocessing (TP). In this contribution, we assume that each of the K user´s mobile station (MS) is aided by a group of MSs acting as relays to achieve relay diversity. In particular, we employ the preprocessing at the base station (BS) to mitigate the multi-user interference (MUI) at the relays that deters in achieving the relay diversity. Further, inter-relay interference (IRI) at the destination mobile stations (DMSs) is suppressed with the support of the preprocessing operated at the relays. To be specific, the preprocessing employed at the BS is based on the maximum-signal-to-interference-plus-noise ratio (MSINR) approach, and at the relays is based on transmit minimum-mean-square error (MMSE) principle. Our study demonstrates that TP-aided relay-assisted 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.