Design and Performance of a Multiple Access CPM-SC-FDMA Transmission Scheme

This paper presents a novel modulation schemewhich combines key characteristics of Single Carrier Frequency Division Multiple Access (SC-FDMA) with Continuous Phase Modulation (CPM) to increase the power amplifier efficiency of SC-FDMA transmissions. CPM-SC-FDMA is developed based upon the observation that the samples from a CPM waveform – which are always constant modulus – may be treated as ‘data symbols’ and then DFT-spread for an SC-FDMA style transmission. The result is a new SC-FDMA waveform which generally retains much of the power efficiency of CPM. In particular, we show that two samples per symbol interval of the underlying CPM waveform are adequate to achieve good bit error rate performance. Also, trellis-terminated CPM-SC-FDMA has a low dynamic range in its envelope fluctuations and there is a gain of 6 dB in the peak-to-average power of 4-ary CPM-SC-FDMA relative to QPSK-SC-FDMA