A generalized CPM-SC-FDMA transmission scheme suitable for future aeronautical telemetry

In this paper, we propose CPM-SC-FDMA, a novel transmission scheme which combines many of the key characteristics of continuous phase modulation (CPM) with Single Carrier Frequency Division Multiple Access (SC-FDMA) in order to produce a power efficient, robust modulation scheme which is suitable for high-rate multiple-access aeronautical telemetry applications. The basis of our approach is found in the observation that the discrete-time samples from a CPM waveform constitute a constant envelope time domain sequence which can be DFT-pre-coded and subsequently mapped to a set of orthogonal subcarriers for an FDMA-style transmission. By a judicious selection of the subcarrier mapping scheme, we show that this new hybrid waveform retains the high power efficiency of CPM. Because it is based on CPM, it is compatible with existing telemetry signaling formats. In addition, it is characterized by a high spectral efficiency due to the concept of overlapping but mutually orthogonal narrowband subcarriers, thus allowing non-interfering multiple-access.