OFDM block diagram

In OFDM full form is basically two parts as transmitter and receiver.

In this system at the transmitter side error correction coding, interleaving process is done over the data stream. The data stream that is sent is in the form of a symbol that has undergone quadrature amplitude modulation. Then the symbol stream is assigned to one of the subcarriers with an assigned symbol. Every subscriber will operate at a particular frequency. 

In the frequency domain, the symbol frame is formed with a group of symbols from all subcarriers.

OFDM is a multi-carrier transmission technology. OFDM is used to obtain a higher data rate in the multipath fading environment of mobile communication.

The every symbol frame is transformed into a time frame with the help of N point "inverse Fourier transformation.

OFDM block diagram

The digital data stream is generated by this time of frames.

Finally, the signal is amplified and transmitted to the antenna side. Convolution coding method with CRC error detection is used to provide high data security for the system.

OFDM is sensitive to phase and frequency noise. To minimize its correct pulse shape needs to be selected.

OFDM is possible to use maximum likelihood decoding with reasonable complexity, so it is one types of OFDM advantages.

In OFDM receiver side the symbol frame received is detected. so it has to adjust automatic gain control to the desired level. A robust algorithm is to be used to withstand phase noise and also a frequency offset of the receiving unit that will interface with the synchronization process.