Abstract
Interleaved Frequency Division Multiplexing (IFDM) can achieve high diversity gain as well as establishing orthogonal frequency multiplexing by using a comb-shaped frequency spectrum. In IFDM, as the number of repeat transmissions of a modulated symbol is increased, the comb-shaped frequency spectrum should be narrowed, so that the frequency diversity gain is decreased. In addition, IFDM suffers from interpath interference imposed on the transmitted signal by multipath fading channel. In this paper, a novel frequency spectrum construction is proposed. In the proposed frequency spectrum construction, the comb-shaped frequency spectrum is frequency-shifted for every modulated symbol. As a result, the frequency spectrum of the frame composed of many modulated symbols is widely spread. In addition, the inter-path interference can be suppressed because the modulated symbol is orthogonal, in the frequency domain, to the following symbol. From the computer simulation, the frequency spectrum rotation can achieve better error rate performance thanks to the increase in frequency diversity gain and suppressing inter-path interference.
