What is the importance of FFT in OFDM technology?
Implementation of OFDM deals with application of Fast Fourier Transform (FFT) to modulation and demodulation processes to generate carriers orthogonal to each other. In conventional system, IFFT (Inverse Fast Fourier Transform) is used at transmitter side and FFT is used in receiver side.
What are the main benefits of OFDM?
The main benefit of OFDM over single-carrier schemes is its ability to cope with severe channel conditions without complex equalization filters. It has improved the quality of long-distance communication by eliminating InterSymbol Interference (ISI) and improving Signal-to-Noise ratio (SNR).
Is the sample rate for OFDM equal to the FFT rate?
The sample rate for OFDM is exactly equal to the sample rate that the OFDM transmitter used when it inverse FFT’ed the data. No, the sample rate has nothing to do with the modulation types used inside the OFDM symbols (e.g. BPSK or QPSK).
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.
How is OFDM implemented in 802.11a WLAN modulation?
This topic discusses the basic concepts of OFDM and how OFDM is implemented in 802.11a WLAN modulation. The basic OFDM principles will be introduced using a simple analog OFDM implementation and then those concepts will be extended to the digital domain with a simple digital OFDM implementation which utilizes the FFT
How are the subcarriers of an OFDM signal orthogonal?
The subcarriers are orthogonal to each other, and 3. A guard interval is added to each symbol to minimize the channel delay spread and intersymbol interference. The following figure illustrates the main concepts of an OFDM signal and the inter-relationship between the frequency and time domains.