In-band and out-band spectrum analysis of OFDM communication systems using ICI cancellation methods

This paper presents the in-band and out-band spectrum analysis of the previously proposed OFDM communication systems. The first part of the paper discusses the subcarrier spectrum of standard OFDM systems. It shows that the common understanding of the sinc(x) function OFDM spectrum is not relevant, and the OFDM spectrum should be represented as sinc(x)exp(-jπx). The second part of the paper studies the spectrum of OFDM systems using intercarrier interference (ICI) cancellation methods. The ICI cancellation methods, known as the ICI self-cancellation scheme and using correlative coding in the OFDM frequency domain, have been proposed previously. This paper gives in-band and out-band spectrum analysis of the systems. It concludes that the proposed ICI cancellation methods not only reduce the ICI, but also make out-band spectrum roll-off much faster than the standard OFDM systems