Interleaved Frequency Division Multiple Access (IFDMA) is a modulation scheme that achieves a frequency diversity gain and establishes a frequency orthogonal channel. In multicarrier modulation schemes such as orthogonal frequency division multiplexing (OFDM), a pilot signal is dispersed over the frequency and time domains and thus the estimated channel transfer function can track the fluctuations that occur in the time and frequency domains. This pilot signal is referred to as a scattered pilot signal. However, the scattered pilot signal has not yet been applied to IFDMA. In this paper, we propose a scattered pilot signal for IFDMA. The problem with the proposed scattered pilot signal is that it increases the peak to average power ratio of the transmitted signal. Therefore, we also propose three peak-to-average power ratio (PAPR) reduction schemes for the IFDMA symbols including the scattered pilot signal. A computer simulation shows that the proposed pilot signal achieves a highly accurate channel estimation under various channel conditions and that the proposed reduction shemes significantly reduce the PAPR.
2009 The Institute of Electronics, Information and Communication Engineers