Per-user frequency domain equalization for SC-CDMA asynchronous uplink transmission

An optimal linear FDE called per-user minimum-mean-square-error(PU-MMSE) FDE was derived for SC-CDMA uplink by equalizing all the virtual subcarriers jointly.After a short discussion on the PU-MMSE FDE,a low complexity block-diagonal PU-MMSE FDE was proposed by exploiting the inherent characteristics of the FDE matrix.By means of theoretical analysis and computer simulation,the conventional per-carrier MMSE(PC-MMSE) FDE,proposed PU-MMSE FDE and block diagonal PU-MMSE FDE were compared from the perspectives of complexity and performance.Results obtained show that the proposed PU-MMSE FDE significantly outperforms the conventional PC-MMSE FDE,particularly in asynchronous uplink with practical impairments including carrier frequency offset and near-far effect.Furthermore,owing to the low complexity block-diagonal PU-MMSE FDE,the number of symbols in each block can be carefully chosen to trade-off between system performance and complexity.