Selection of the spreading parameters for the downlink of coded OFDM-CDMA systems

This article presents a new method for the selection of the spreading parameters for the downlink of two dimensional (2D) OFDM-CDMA systems in the presence of channel coding. This new approach allows the determination of the spreading factor values in time (S
_T
) and in frequency (S
_F
) directions in order to find the most reliable 2D transmission scheme. The method is based on the exponential effective SNR mapping (EESM) technique applied to the asymptotic signal to interference plus noise ratio (SINR) computed at the output of the equalizer. Thanks to this asymptotic compressed SINR, we are also able to assess the performances of 2D OFDM-CDMA systems in terms of BER (bit error ratio) at the output of the channel decoder