da-fdma

The basic difference between OFDMA and SC-FDMA is that, there there is an additional block of N point DFT before the sub-channel mapping in SC-FDMA.

This will effectively reduce the PAPR, thus the power amplifier will have a lesser linear range in SC-FDMA when compared with OFDMA

single sideband full carrier

In CDMA all the stations can sends data simultaneously. But in FDMA only one channel occupies the entire bandwidth of the link so each channel can be assigned to only one user at a time. So CDMA is better than FDMA.

tdma and fdma