OFDMA technique

Frequency Division Multiple Access (FDMA) techniques consist in assigning each satellite with a specific carrier frequency . The main advantage of FDMA when compared to CDMA is that it guarantees signal separation since each signal is transmitted in a dedicated frequency slot.

The most obvious difference between the two schemes is that OFDMA transmits the four QPSK data symbols in parallel, one per subcarrier, while SC-FDMA transmits the four QPSK data symbols in series at four times the rate , with each data symbol occupying a wider M x 15 kHz bandwidth.

Instead of the traditional analog modulation used in multiplexing, OFDMA uses carrier signal waves, called subcarriers, to move small bits of information in a more streamlined fashion .