Configure OFDM Sample Rate and FFT Size

5G NR downlink and uplink transmissions use orthogonal frequency-division multiplexing (OFDM) modulation. You can perform OFDM modulation and OFDM demodulation by calling the nrOFDMModulate and nrOFDMDemodulate functions, respectively. You can also obtain dimensional information about the modulation by calling the nrOFDMInfo function.

These functions enable you to specify the OFDM sample rate and FFT size by using the SampleRate and Nfft name-value input arguments. When the specified sample rate and the nominal sample rate, corresponding to the FFT size, do not match, the OFDM functions resample the waveform. To learn more about the internal resampling filter, see Resampling Filter Design in OFDM Functions. To learn more about how the values you specify for the OFDM sample rate and FFT size influence the output of the nrOFDMInfo function, see Get OFDM Information.

If you do not specify the SampleRate and Nfft inputs, the functions set default values for these inputs.

To learn more about the various OFDM sample rate and FFT configuration options and their effect on the bandwidth occupancy, see these examples.

• The Use Default OFDM Sample Rate and Default FFT Size example plots the bandwidth occupancy for the default values.

• The Use Default OFDM Sample Rate and Custom FFT Size example plots the bandwidth occupancy for the default sample rate with the FFT size selected for maximum occupancy of 90%.

• The Use Custom OFDM Sample Rate and Default FFT Size example plots the FFT occupancy for a custom sample rate with a bandwidth occupancy of 75%.

• The Use Custom OFDM Sample Rate and Custom FFT Size example plots the FFT occupancy for a custom sample rate with a bandwidth occupancy of 90%.