The performance for DS-CDMA and MC-CDMA systems for a single user is similar. However, as the number of users increases the performance of DSCDMA system declines rapidly (Fig 8).

MC-CDMA on the other hand exhibits a much better characteristic for BER vs SNR when the number of users increases from, say 1 to 64 (Fig 9). Hence, we can see that MC-CDMA is more suited towards multiuser environments.

Fig 8 BER vs SNR for DS-CDMA system

Fig 9 BER vs SNR for MC-CDMA system

5. CONCLUSION

In this paper, the need and theory for a new spreadspectrum technique i.e. Multicarrier CDMA was introduced and the three types of Multicarrier CDMA techniques were presented. The bit error rate for a Rayleigh fading dispersive channel was compared for the DS-CDMA scheme and the MC-CDMA scheme.
MC-CDMA combines the advantages of band spreading, code division and frequency diversity of DS-CDMA with the advantages of Multi-Carrier Modulation. Thus, Multicarrier CDMA needs more
attention for future implementation on wireless data transmission systems.