ONERA, the French Aerospace Lab, and CNES, the French Space Agency, are currently running a Ka-band propagation experiment at the Guiana Space Centre (CSG) in Kourou (French Guiana). A rain gauge and a beacon receiver able to record the 20.2 GHz beacon signal of the Amazonas 3 satellite have been deployed. The equipment is operational since January 1, 2017 and the duration of the experiment has been set to 3 years. This letter addresses some results of the first year of measurements (from January 2017 to December 2017). The annual and monthly Complementary Cumulative Distribution Functions of rainfall rate and rain attenuation are presented as well as a comparison with the rain attenuation prediction method recommended in ITU-R P.618-13.
This paper presents the use of a Numerical Weather Prediction model (the WRF US model from NCAR/NCEP) coupled with an electromagnetic module to create rain attenuation time series and statistical results in a tropical region. Simulated results are compared with experimental data collected within a CNES/ONERA sponsored propagation experiment near Kourou, in French Guiana. Both simulated and experimental Complementary Cumulative Distribution Functions of rain attenuation (CCDF) are presented in an annual and monthly basis. Finally, a brief granulometric study is detailed to better understand the impact of the rain drop size distribution (DSD) on the obtained results.
Free space optical communications systems have to deal with several impairments originating from the interaction of optical signals with the local environment and the atmosphere. These impairments include cloud blockage, aerosols scattering, molecules absorption and turbulence. In this paper, we focus on the impact of molecular absorption bands on the choice of uplink/downlink data wavelength division multiplexing grids (WDM) as well as uplink Pointing/Acquisition and Tracking (PAT) beacon wavelength.
This paper presents a comparison of different instances of advanced iterative receivers for the non linear satellite channel. A comparison of the performance and complexity of each of the selected receivers is drawn. It is shown that the frequency domain implementation of the linear equalizer achieves good performance complexity trade-off. The cost to pay for the frequency domain processing is the addition of a Cyclic Prefix (CP) to ensure the blocks orthogonality. The consequence is a channel dependent spectral efficiency loss. We thus investigate on the efficiency gain related to the CP omission for frequency domain equalizers for different block sizes and show that for large block sizes, the equalizer's performance is not much sacrificed.
OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 13122
To link to this article :Abstract-In this paper, iterative receiver analysis and design for non linear satellite channels is investigated. To do so, an EXtrinsic Information Transfer (EXIT) chart-based optimization is applied using two major assumptions: the equalizer outputs follow a Gaussian Mixture distribution since we use non-binary modulations and partial interleavers are used between the Low Density Parity Check (LDPC) code and the mapper. Achievable rates, performance and thresholds of the optimized receiver are analysed. The objective in fine is to answer the question: Is it worth optimizing an iterative receiver for non linear satellite channels?
This paper proposes neural networks-based turbo equalization (TEQ) applied to a non linear channel. Based on a Volterra model of the satellite non linear communication channel, we derive a soft input soft output (SISO) radial basis function (RBF) equalizer that can be used in an iterative equalization in order to improve the system performance. In particular, it is shown that the RBF-based TEQ is able to achieve its matched filter bound (MFB) within few iterations. The paper also proposes a blind implementation of the TEQ using a multilayer perceptron (MLP) as an adaptive model of the nonlinear channel. Asymptotic analysis as well as reduced complexity implementations are also presented and discussed.
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