This paper proposes a three-dimensional (3D) channel model for satellite communications at Q-band in a high latitude, including the path loss, shadowing, and small-scale fading. The shadowing effect is modelled by a Markov chain. The three states in the Markov chain are separated by the threshold of the received power level for the link budget and system optimization. The probability density function (PDF) of shadowing amplitude is modelled by a mixture of two Gaussian distributions with parameters obtained by the expectation-maximum (EM) algorithm. The small-scale fading is represented by a 3D geometry-based stochastic model (GBSM) where scatterers are located on the spherical surface of a hemisphere. The movement of the receiver and the Rician factor influenced by environment scattering are considered. Statistical properties including the local temporal autocorrelation function (ACF) and Wigner-Ville spectrum are derived. The satellite communication channel measurement at Q-band is conducted on the campus of Heriot-Watt University (HWU) in Edinburgh, UK. The parameters of our proposed channel model are estimated by the measurement data. Numerical and simulation results demonstrate that our proposed channel model has the ability to reproduce main statistical properties which are also consistent well with the corresponding theoretical and measurement results.
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