Matlab Based Testbench Implementation of Digital Communication over an Acoustic Channel using OFDM

Abstract

This paper presents the implementation of an Orthogonal Frequency Division Multiplexing (OFDM)-based system for the transmission of digital signals over an acoustic channel between a speaker and a microphone in MATLAB. The features of the OFDM modulation scheme, such as its robustness towards intersymbol interference and multipath interference at the receiver side, are also discussed. An analog signal converted into digital bits is sent from the transmitter, and the output is recorded at the receiver. The study investigates the quadrature amplitude modulation (QAM) constellation, which makes the system more resistant to noise and inter-symbol interference (ISI). Clipping at the receiver has been overcome by directly scaling the signal. The effect of the distance on the channel capacity has also been studied by changing the distance between the speaker and the microphone. The performance of the OFDM system with different Signal-to-Noise Ratio (SNR) and constellation points is presented.