Contents
What is OFDM demodulation?
OFDM Demodulation An OFDM demodulator demultiplexes a multi-subcarrier time-domain signal using orthogonal frequency division modulation. An OFDM demodulator consists of a bank of N correlators, with one correlator assigned to each OFDM subcarrier, followed by a parallel-to-serial conversion.
What is OFDM symbol time?
802.11ax introduces a longer OFDM symbol time of 12.8 μs, which is four times longer than the legacy symbol time of 3.2 μs. Subcarrier spacing is equal to the reciprocal of the symbol time. As a result of the longer symbol time, the subcarrier size and spacing decreases from 312.5 KHz to 78.125 KHz.
How is OFDM symbol duration calculated?
The sub-carrier frequency spacing delta_f =1/Ts= 1/(Td * N), Ts is the OFDM symbol duration,Td is the sampling symbol duration and equal to the smapling time interval。 Thus Td=1/fs, fs is the DAC sampling rate. Then we can calculate the bandwidth of the fignal.
Why OFDM is efficient?
Why OFDM Is Efficient? OFDM, like FDM, separates the channel bandwidth into multiple narrow-band subcarriers to carry the information. This not only permits the removal of the guard bands, but since the subcarriers are completely unrelated, they can even overlap each other. This is why OFDM is so bandwidth efficient.
How is subcarrier spacing calculated in OFDM?
Choosing the first subcarrier to have a frequency such that it has an integer number of cycles in a symbol period, and setting the spacing between adjacent subcarriers (subcarrier bandwidth) to be BSC = B/L, where B is the nominal bandwidth (equal to data rate), and L is the number of subcarriers, ensures that all …
How does an OFDM demodulator demultiplexes a time domain signal?
An OFDM demodulator demultiplexes a multi-subcarrier time-domain signal using orthogonal frequency division modulation. The OFDM demodulation uses an FFT operation that results in N parallel data streams. An OFDM demodulator consists of a bank of N correlators]
What kind of FFT operation is used in OFDM?
The OFDM demodulation uses an FFT operation that results in N parallel data streams. An OFDM demodulator consists of a bank of N correlators, with one correlator assigned to each OFDM subcarrier, followed by a parallel-to-serial conversion. Subcarrier Allocation and Guard Bands
How to demodulate time domain signal using MATLAB?
For this syntax, the symbol sampling offset is applied to each OFDM symbol and the number of rows in the output is nfft – length (nullidx), which accounts for the removal of null subcarriers. Use null subcarriers to account for guard bands and DC subcarriers.
How to calculate the number of OFDM symbols per antenna?
NSym is the number of OFDM symbols per antenna. NR is the number of receive antennas. The function assumes that the pilot subcarrier locations are the same across each OFDM symbol and transmit antenna. Use the comm.OFDMDemodulator to vary pilot subcarrier locations across OFDM symbols or antennas.