Visualizing SCFDMA & OFDMA signal

[tarakapraveen]

Hi ,

Can someone explain me visualizing the differences between SC-FDMA and OFDMA signals?

Thanks,
TU

 

[albbg]

OFDMA (Orthogonal Frequency-Division Multiple Access) signal suffers an high peak-to-average ratio (PAPR) that leads to low efficiency of the amplifiers, that means high power consumption. SC-FDMA (Single Carrier-FDMA) is similar to OFDMA but, in transmission OFDM spreading if preceded by DFT coding and followed by IDFT (in reception the sequence is reversed). This allow the lowering of the PAPR, improving the global efficiency. WiMAX technology is based on OFDMA while LTE is based on SC-FDMA.

 

[sureshreddy]

n LTE OFDMA is used in Downlink.OFDMA having High PAPR.signals with high PAPR requires highly linear power amplifiers inorder to avoid excessive intermodulation distortion so,amplifiers must be operate with a large backoff from its peak value.High PAPR is particularly critical for uplink trasmissions because of power constraints at UE.

SC-FDMA is used in uplink.SC-FDMA having low PAPR.Because of low PAPR, SC-FDMA is well suited to uplink.