On the Performance of Spectrally Efficient DPM-OFDMA for Aeronautical Telemetry

Abstract

In this paper, we discuss CPM-OFDMA (Continuous Phase Modulation - Orthogonal Frequency Division Multiple Access) - a novel modulation that maps a discrete-time CPM into a spectrally efficient DFT-spread OFDMA transmission. Three CPM-OFDMA schemes are developed based on discrete-time variants of PCM/FM, SOQPSK-TG and ARTM-CPM telemetry modulations. Simulations reveal that spectrally efficient CPM-OFDMA schemes can outperform the conventionally defined telemetry schemes in the AWGN environment. For example, maximum likelihood sequence detection of conventional PCM/FM yields a BER of 10⁻⁵ at an E(b)/N(0) of 8:4 dB while the least complex CPM-OFDMA scheme that is based on sampling a PCM/FM waveform once per symbol interval achieves the same BER at an E(b)/N(0) of 7:8 dB. Finally, an extensive search to find a subset of the best performing binary schemes shows that there exist very low complexity schemes that can achieve a BER of 10⁻⁶ at an E(b)/N(0) of 7:8 dB, which is an order of magnitude improvement over the performance of PCM/FM at the same E(b)/N(0).