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During probe‐to‐Earth superior conjunction, deep space communication channels will suffer from solar scintillation, leading to amplitude attenuation of received signals. This study aims to obtain the channel state information (CSI) on deep space channels affected by solar scintillation. Classical least squares (LS) and minimum mean squared error (MMSE) methods are adopted to perform channel estimation and compensate for the channel fading. Simulation results indicate that under the effect of solar scintillation, performing channel estimation technology can significantly improve bit error rate (BER) performance compared to systems without CSI, and the MMSE algorithm outperforms the LS for both BER and normalized mean squared error (NMSE). In addition, we also find that pilot density, geometric parameters, and the outer scale of solar wind turbulence has great influence on the estimation performance. Key Points: Performed channel estimation for deep space communications under solar scintillationLeast squares (LS) and minimum mean squared error (MMSE) methods were adopted for channel estimationSimulated the impact of pilot density, geometric parameters, and outer scale of solar wind turbulence on performance of channel estimation [ABSTRACT FROM AUTHOR]

Solar phase scintillation and solar amplitude scintillation are fundamentally important in deep space mission operations for designing a communication system capable of transmitting signals when the signal path is close to the Sun. The ESA's BepiColombo measurement data were analyzed in a previous paper in terms of the power spectral density of the solar phase scintillation, also with a comparison with Woo's solar phase scintillation theory, when X-band and Ka-band signals propagate close to the Sun with a small Sun-Earth-Probe (SEP) angle during the superior solar conjunction campaign in March 2021 in its cruise phase to Mercury. In this paper the solar amplitude scintillation is analyzed both by calculating the power spectral density and the scintillation index. The results of scintillation index, derived from these measurement data, fit the NASA JPL's scintillation index model. [ABSTRACT FROM AUTHOR]

Solar phase scintillation is of major interest in deep space mission operations for designing a communications system capable of transmitting signals when the path is close to the Sun, but also for improving the navigation under these conditions. The basis of this work is Woo's solar phase scintillation theory which reported a useful model for the spectral power density of phase scintillations of a signal traveling through a medium close to the Sun. In this paper, Woo's solar phase scintillation formula is used for the simulation of the spectral density of phase fluctuations induced by the Sun on coherent signals (uplink and downlink carriers are coherently related by a fractional ratio implemented by the spacecraft's transponder), for the two downlink frequency bands supported by the ESA deep space mission BepiColombo. In particular, the model has been compared to measurement data collected at low Sun Earth Probe (SEP) angles during the superior solar conjunction campaign in March 2021 (in its cruise phase to Mercury). The comparison shows a good match between the phase noise spectral densities of the modified formula and measurement data, therefore, confirming that the formula can be used for the planning and verification of the future near Sun measurements. [ABSTRACT FROM AUTHOR]

Summary: Deep space exploration missions require the modelling of deep space communication channels. Due to the turbulent nature of space channels, propagating electromagnetic waves suffer from fading‐induced turbulence. In particular, scintillation effects are imparted on the intensity of electromagnetic beam wave propagating through the solar corona. Thus, it is imperative to determine the wave intensity distribution. Often, distributions derived and verified for terrestrial channels are applied to wave propagation through deep space channels. However, this neglects the specific nature of the physical processes in the channel. For example, to incorporate the events of solar inferior and solar superior conjunctions, the introduced statistical distribution should be valid over a large‐range, spanning weak to strong, scintillation conditions. Moreover, the solar corona physical parameters should be clearly related to the distribution parameters. Such a theoretical model can be derived based on Rytov solution, the solar wind speed distribution and the space permeating plasma electron density variation. The resultant wave intensity distribution is compared with the Rician, the Nakagami and the inverse Gaussian–gamma distributions for different scintillation conditions. [ABSTRACT FROM AUTHOR]