Communications Performance Based Specification of Phase Noise for SATCOM Systems

Phase noise plays a critical role in determining the performance of any satellite communications (SATCOM) system. This is true at every stage of the signal chain and its significance grows as SATCOM systems are tasked to support waveforms with increased spectral efficiency. Historically, phase noise specifications have been derived from physics based implementation considerations rather than waveform dependent communications performance thresholds. This paper introduces techniques for specifying phase noise performance based on the second approach. Waveform communications performance is considered in terms of threshold signal to noise ratio (SNR) and corresponding allowable degradation due to phase noise. From these, the paper proposes means for computing performance based phase noise thresholds and provides examples. This process is then applied to all relevant SATCOM link components. J oint optimization of link component phase noise thresholds is used to distribute the phase noise performance burden equitably over the various devices in the SATCOM signal chain. Life cycle growth trends in SATCOM waveform performance demand, such as greater spectral efficiency, are factored into the optimization process. When performance growth is projected, performance based phase noise thresholds that are adequate for the life of each component can be computed. The result is the ability to optimally specify phase noise thresholds, to do so equitably over the entire SATCOM link chain, and to do so adequately to satisfy demand growth over the lifetime of each component in the signal chain.