What is oversampling in DSP?
In signal processing, oversampling is the process of sampling a signal at a sampling frequency significantly higher than the Nyquist rate. Theoretically, a bandwidth-limited signal can be perfectly reconstructed if sampled at the Nyquist rate or above it.
What is the channel spacing used for OFDM subcarriers?
Because of the 78.125 KHz spacing, an OFDMA 20 MHz channel consists of a total of 256 subcarriers (tones) as depicted in Figure 2.
What is the oversamplingrate of an OFDM symbol?
An OFDM symbol including guard interval consists of N c + N G samples each of which has duration 1 / f s, where N c is the number of subcarriers (equal to IDFT length) and N G is the number of guard interval samples. The “oversamplingrate” parameter in the source you referenced seems to be some additional oversampling factor of the transmit signal.
How is the symbol time calculated in OFDM?
An OFDM symbol is the time-domain representation of the symbols concurrently transmitted over all subcarriers. It consists of just as many samples as there are OFDM subcarriers since it is calculated as the IDFT of all subcarriers’ symbols. When adding the cyclic prefix, you add $N_G$ samples.
What makes a OFDM signal different from a normal signal?
OFDM is different because of the FFTs/IFFTs built into the signal. There is no advantage for the demodulator to do the FFT at higher than the symbol rate, so they don’t. The roll-off in OFDM is very minimal (an example of typical OFDM roll-off is shown below), though, so the sample rate is not much less than the bandwidth.
Which is the basic parameter of the OFDM system?
The basic parameter for ofdm system is the symbol time Tsy which is related to sub carrier frequency spacing deltaf. This time interval contains a number of samples equal to the total number of fft points comprising all the sub carriers whether it has a value or is nulled. Therefore for 256 subcarrires one has 256 samples.