Performance Analysis of OFDM Scheme with Channel Estimation and Doppler Shift Effects

Abstract

Future wireless communication systems will require robust technologies such as orthogonal frequency division multiplexing (OFDM) with multi-input multi-output (MIMO) to overcome the challenges of data communication over frequency-selective fading channels. This paper presents a simplified single-in single-out (SISO) transmission scheme for OFDM systems using low complexity zero-forcing (ZF) detection algorithm. The paper studies and evaluates the impact of the Doppler frequency shift caused by the relative movement between the transmitting and receiving antennas on the OFDMSISO system. Moreover, the paper investigates how the channel estimation using Pilot assessment and interpolation techniques impacts the performance of bit error rate (BER) and studies the mean square error (MSE) of the estimated channel on the OFDM system. Additionally, the effect of varying the pilots’ interval on system performance has been studied. Also, this work provides a comparative study of two different interpolation techniques that can be used for the channel estimation; linear interpolation and interpolation based on fast Fourier transform (FFT). The main results show that the Doppler frequency shift significantly and not linearly affects the BER performance of the system, especially at higher frequencies. On the contrary, the channel estimation performance does not change since the MSE of the estimated channel almost remains the same for different Doppler frequencies. Furthermore, the findings show that changing the Pilots’ interval will not significantly affect channel estimation since the MSE variation is small. However, data transmission rates will be strongly affected. Finally, the results reveal that the FFT-based interpolation technique outperforms the linear interpolation for estimating the wireless communication channel.