OFDM DA conversion problem

1. How is orthogonality achieved in OFDM?
2. What is role of orthogonal frequency division multiplexing in wireless communication?
3. How OFDM signal is generated?
4. How to calculate number of subcarriers in OFDM?

How is orthogonality achieved in OFDM?

With OFDM, the subchannel frequencies are close together and overlapping but are still orthogonal, or separate, in that they are carefully chosen and modulated so that the interference between the subchannels is canceled out.

What is role of orthogonal frequency division multiplexing in wireless communication?

In coded orthogonal frequency-division multiplexing (COFDM), forward error correction (convolutional coding) and time/frequency interleaving are applied to the signal being transmitted. This is done to overcome errors in mobile communication channels affected by multipath propagation and Doppler effects.

How OFDM signal is generated?

In OFDM the signal itself is first split into independent channels, modulated by data and then re-multiplexed to create the OFDM carrier. OFDM is a special case of Frequency Division Multiplex (FDM). As an analogy, a FDM channel is like water flow out of a faucet, in contrast the OFDM signal is like a shower.

How to calculate number of subcarriers in OFDM?

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.