Exact error floor for downlink MC-CDMA with maximal ratio combining in correlated Nakagami fading channels

Relying on the method of characteristic function (CF) and residue calculation, we obtained an exact and closed-form error floor for downlink multicarrier code-division multiple access (MC-CDMA) with maximal ratio combining (MRC) in correlated Nakagami (1960) fading channels. Analysis results show that orthogonal spreading sequences (Walsh and orthogonal Gold sequences) perform better than non-orthogonal sequences (Gold sequences) and Walsh codes are the best. We also find that downlink MC-CDMA can benefit from the correlation between subcarriers.