A fractional-bits-per-symbol communication system for low-power satellites using N-Point PSK constellations

Abstract

Low-Earth orbiting satellites are becoming more common and transmit to ground stations through slowly fading radio channels. Radio links operating in this channel cannot operate efficiently with static communication systems making adaptive communication links critical. A fractional-bits-per-symbol communication system is presented as a possible improvement on current adaptive systems. Fractional-bits-per-symbols are realized by utilizing N-point PSK constellations and sequences. Sequences allow for N-point constellations to transmit whole numbers of bits over a number of grouped symbols called a waveform. Equations governing sequences and waveforms are presented. Mapping schemes are used to map bit-strings to waveforms and are shown to have an effect on the performance. Results of simulations using fractional-bits-per-symbols are presented. Theoretical data throughput is compared for low-Earth orbiting satellites using fractional and non-fractional-bits-per-symbol systems.