Performance Analysis of OFDM-based System for Various Channels

Abstract: The demand for high-speed mobile wireless communications is rapidly growing. Orthogonal Frequency Division Multiplexing (OFDM) technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems in the near future. This paper investigates the performance of OFDM-based system over static and non-static or fading channels. In order to investigate this, a simulation model has been created and implemented using MATLAB. A comparison has also been made between the performances of coherent and differential modulation scheme over static and fading channels. In the fading channels, it has been found that OFDM-based system's performance depends severely on Doppler shift which in turn depends on the velocity of user. It has been found that performance degrades as Doppler shift increases, as expected. This paper also performs a comparative study of OFDM-based system's performance on different fading channels and it has been found that it performs better over Rician channel, as expected and system performance improves as the value of Rician factor increases, as expected. As a last task, a coding technique, Gray Coding, has been used to improve system performace and it is found that it improves system performance by reducing BER about 25-32 percent.