[Paper] Performance Improvement Technique for Windowed OFDM using Pre-Coding

Abstract

This paper discusses a side-lobe power reduction technique using window functions and a performance improvement scheme for use in windowed Orthogonal Frequency Division Multiplexing (OFDM) systems to enhance their spectrum usage. The windowed OFDM approach is effective for suppression of out-of-band emission. However, the communication performance using this method is degraded when compared with conventional schemes. To improve the performance of windowed OFDM in frequency-selective fading channels, a pre-coding method using a unitary transform is utilized. Furthermore, an additional coding scheme using pseudo-random code is proposed to improve its overall communication performance. The BER performance can be improved when compared with the conventional schemes, because the proposed coding scheme can reduce the noise variance in the demodulation process for the pre-coded windowed OFDM. The out-of-band emission power can be reduced and the notch depth can be increased when using the proposed scheme.