Orthogonal Frequency Division Multiplexing is a scheme used in the area of high-data-rate mobile wireless communications such as cellular phones, satellite communications and digital audio broadcasting.
The Fourier transform, in essence, decomposes or separates a waveform or function into sinusoids of different frequencies which sum to the original waveform. It identifies or distinguishes the different frequency sinusoids and their respective amplitudes.
In many applications high-speed performance is required. For this purpose, conventional multi-carrier techniques are usually chosen, but this result in the lowering of spectrum efficiency. So, the principles of Orthogonal Frequency Division Multiplexing are used in such applications.
This paper gives the details of the development of IFFT & FFT algorithms to be used in OFDM systems based on the IEEE 802.11a standard for WLAN. This system consists of separate OFDM transmitter & receiver.
Actually, in the entire architecture of OFDM system, all the mathematical manipulations take place in these two blocks only, i.e. IFFT & FFT blocks while rest of the blocks convert the data from one format to another format. In this paper we have implemented FFT and IFFT blocks. The speed enhancement is the key contribution of the main processing blocks in OFDM system.
However, the advent of the Discrete Fourier Transform (DFT) made this transmission scheme more plausible. The Fast Fourier Transform (FFT) and the Inverse Fast Fourier Transform (IFFT) are the more efficient implementations of the DFT, are utilized for the base band OFDM modulation and demodulation process.
Simulation: ModelSim XE III 6.4b.
Synthesis: XiLinx ISE 10.1.