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Single-carrier FDMA (SC-FDMA) is a frequency-division multiple access scheme. Originally known as Carrier Interferometry , it is also called linearly precoded OFDMA ( LP-OFDMA ). Like other multiple access schemes (TDMA, FDMA, CDMA, OFDMA), it deals with the assignment of multiple users to a shared communication resource.
Frequency-division multiple access (FDMA) is a channel access method used in some multiple-access protocols. FDMA allows multiple users to send data through a single communication channel, such as a coaxial cable or microwave beam, by dividing the bandwidth of the channel into separate non-overlapping frequency sub-channels and allocating each sub-channel to a separate user.
The frequency-division multiple access (FDMA) channel-access scheme is the most standard analog system, based on the frequency-division multiplexing (FDM) scheme, which provides different frequency bands to different data streams.
At the source end, for each frequency channel, an electronic oscillator generates a carrier signal, a steady oscillating waveform at a single frequency that serves to "carry" information. The carrier is much higher in frequency than the baseband signal. The carrier signal and the baseband signal are combined in a modulator circuit.
The OFDM diversity gain and resistance to frequency-selective fading may partly be lost if very few sub-carriers are assigned to each user, and if the same carrier is used in every OFDM symbol. Adaptive sub-carrier assignment based on fast feedback information about the channel, or sub-carrier frequency hopping, is therefore desirable.
VOFDM replaces each scalar value in the conventional OFDM by a vector value and is a bridge between OFDM and the single carrier frequency domain equalizer (SC-FDE). When the vector size is 1 {\displaystyle 1} , it is OFDM and when the vector size is at least the channel length and the FFT size is 1 {\displaystyle 1} , it is SC-FDE.
In Fixed Channel Allocation or Fixed Channel Assignment (FCA) each cell is given a predetermined set of frequency channels. FCA requires manual frequency planning, which is an arduous task in time-division multiple access (TDMA) and frequency-division multiple access (FDMA) based systems since such systems are highly sensitive to co-channel interference from nearby cells that are reusing the ...
I will try to give the reasoning, and we need to edit the article one day. The explanation is suitable when we consider multiuser access as in OFDMA and SCFDMA. In OFDMA, each data symbol is carried by a single sub-carrier and single user is given multiple sub-carriers. In SC-FDMA, due to DFT the each data symbol is spread to multiple sub-carriers.