OFDM Transmitter and Receiver with BPSK baseband, RF up-down conversion

A simple code to illustrate the operation of an OFDM based RF transmitter and Receiver

The objective of this code is to illustrate the process of generating an OFDM modulated base-band signal, addition of quantization noise, up-converting it to an RF carrier frequency, addition of AWGN, down-conversion of the RF carrier in the receiver to recover the OFDM base-band signal, its demodulation and estimation of bit error rate.
A simple code to illustrate the operation of a BPSK-OFDM Transmitter and Receiver including RF up-conversion and down-conversion is presented. The code also includes sections for addition of Additive White Gaussian Noise and Quantization Noise. Quantization noise is added to illustrate the impact of the resolution of the Digital to Analogue Converter that is generally employed to convert the digitally generated base band signal to analogue equivalent which in turn is up-converted to RF and transmitted.

The up-conversion is accomplished by the multiplication of each base band symbol with a sinusoidal carrier that is generated at the specified carrier frequency 'Fc'. The real part of the base band OFDM symbol is multiplied with the cosine component of the RF carrier and the imaginary part of the base band OFDM symbol is multiplied with the sine component of the RF carrier. The sine and co-sine components are added to yield a composite vector modulated RF carrier.

The down-conversion is accomplished by multiplying the modulated RF carrier with a sine and a cosine component of the Local Oscillator (at the carrier frequency) and performing numerical integration using trapezoidal rule over the symbol period.

Further impairments such as non-linearity of the transmitter's RF power amplifier, Doppler effect in the channel, multi-path fading effects, noise figure of the receiver's RF chain, adjacent channel interference, etc could be added based on the application of interest. Further enhancements such as higher modulation schemes such as 64 QAM for the sub-carriers may also be added depending on the application.

References: IEEE802.11 standards, Simulation of Digital communication systems with MATLAB by Mathuranathan Viswanathan.

Beginners in this field are advised to read the book "Simulation of Digital communication systems with MATLAB by Mathuranathan Viswanathan" for further information on the fundamentals of OFDM and other modulation schemes.