On the ICI Mitigation Techniques in High Mobility Mimo-OFDM Systems with Parallel ICI Cancellation Under Various Normalized Doppler Spreads

The signals of LF and VLF are rapidly alternated by the earth's surface; and there are various propagation models currently used by the wireless industry for signal transmission within the frequency range 150-1800 MHz. Hata-Okumura two rays model are one of them. This paper addresses the problem of Inter Carrier Interference (ICI) arising from the Doppler shift caused by the high mobility in areas covered by OFDM based systems via High Altitude Platforms (HAPs). The proposed scheme presented in this paper is for Doppler assisted channel estimation with the parallel interference cancellation with decision statistical combining scheme (PIC-DSC) for high mobility MIMO-OFDM systems to improve the ICI cancellation which is essential in enhancing the BER performance which induces a large frequency offset error. The simulation results shows that the outperforms convergence characteristic of channel estimation with the PIC-DSC interference cancellation scheme - under various normalized Doppler spreads (e.g., normalized Doppler spread of 0.1 and 0.025) at SNR 20dB and 30dB - has better symbol error rate (SER). The algorithm is efficiently mitigates ICI under Quadrature Phase Shift Keying (QPSK) modulation showing Bit Error Rate (BER) performance analysis and compared with other existing schemes.