ICI Reduction Through Shaped OFDM in Coded MIMO-OFDM Systems

Abstract—The default pulse shaping filter in the conventional multiple-input and multiple-output (MIMO) based orthogonal frequency division multiplexing (OFDM) system is a rectangular function, which unfortunately is highly sensitive to frequency synchronization errors and the Doppler spread. Shaped OFDM is able to considerably alleviate the effect of inter-carrier in-terference (ICI) as well as reduce the out-of-band frequency leak. In this paper, we study various pulse shaping functions and investigate their efficacy for reducing the ICI in the space-time block coded MIMO-OFDM system. We compare a new shaping pulse termed harris-Moerder pulse with several other popular Nyquist pulses such as the raised-cosine pulse and better than raised-cosine pulse. Our simulation results confirm that pulse shaping using a suitable shaping function other than the default rectangular one can alleviate ICI and thus achieve better bit error rate (BER) performance. Furthermore, it is demonstrated that the harris-Moerder shaping pulse is the most successful one in suppressing ICI. Index Terms—Pulse shaping, inter-carrier interference (ICI) reduction, orthogonal frequency-division multiplexing (OFDM), multiple-input and multiple-output (MIMO), space-time coding, Rayleigh fading channel. I