Number of samples in one period of subcarrier after IFFT

1. How do you calculate the number of subcarriers?
2. How many samples in a OFDM symbol?
3. What happens if number of subcarrier is increased?
4. How many time samples are in the useful part of an OFDM symbol?

How do you calculate the number of subcarriers?

If you divide the channel bandwidth (20 MHz) by the subcarrier bandwidth (312.5 kHz) you will see that 802.11a/g comprises 64 subcarriers. This is referred to as 64-point FFT/IFFT.

How many samples in a OFDM symbol?

An 802.11a OFDM carrier signal (burst type) is the sum of one or more OFDM symbols each comprised of 52 orthogonal subcarriers, with baseband data on each subcarrier being independently modulated using quadrature amplitude modulation (available formats: BPSK, QPSK, 16-QAM, or 64-QAM).

What happens if number of subcarrier is increased?

8.1.

The more subcarriers are used, the longer their symbol rate is, which means that the overall rate of information remains the same, but a longer symbol rate is useful for multipath mitigation (recall conditions when equalizers are required).

How many time samples are in the useful part of an OFDM symbol?

In 802.11, each OFDM symbol is 4 μs long. At 20 MSPS sampling rate, this means each OFDM symbol contains 80 samples.