Transfer Functions and Linear Distortions in Ultra-Wideband Channels Faded by Rain in GeoSurf Satellite Constellations

Abstract

Because of rain attenuation, the equivalent baseband transfer function of large bandwidth radio-links will not be ideal. We report the results concerning radio links to/from satellites orbiting in GeoSurf satellite constellations located at Spino d’Adda, Prague, Madrid, and Tampa, which are all sites in different climatic regions. By calculating rain attenuation and phase delay with the Synthetic Storm Technique, we have found that in a 10-GHz bandwidth centered at 80 GHz (W-Band)—to which we refer to as “ultra-wideband-, both direct and orthogonal channels will introduce significant amplitude and phase distortions, which increase with rain attenuation. Only “narrow-band” channels (100~200 MHz) will not be affected. The ratio between the probability of bit error with rain attenuation and the probability of bit error with no rain attenuation increases with rain attenuation. The estimated loss in the signal-to-noise ratio can reach 3~4 dB. All results depend on the site, Tampa being the worst. To confirm these findings, future work will need a full Monte Carlo digital simulation.

Improved Spread Spectrum Aloha Protocol and Beam-Hopping Approach for Return Channel in Satellite Internet of Things

“…However, it can be eased by changing the orbital inclination and turning off some satellite loads at high latitudes. In [ 28 ], the authors give the evaluation results on both the output of a direct channel and the interference coming from the orthogonal channel in a GeoSurf satellite constellation.…”

Feasibility of Ultra-Wideband Channels at Millimeter Wavelengths Faded by Rain in GeoSurf Satellite Constellations

“…In [4], we have estimated the slowly time-varying transfer function and linear distortions that are likely found in ultra-wideband radio links in GeoSurf constellations working at millimeter wavelengths. As a practical example, the bandwidth considered was 10 GHz wide, centered at 80 GHz (W-Band), because we think it might be used in future worldwide internet radio links using spread spectrum modulation and code division multiple access (CDMA) [5][6][7][8][9][10] with BPSK and QPSK modulation, once high-frequency large wideband technology-now developed at lower frequencies [11]-will also be available at W-band.…”

“…The literature on what today is defined as "wideband" communication does not refer to rain attenuation or to the ultra-wideband radio links studied here but instead refers only to radio links in clear-sky conditions (mainly multipath), both for terrestrial and satellite systems [5,[12][13][14][15][16]; therefore, we discuss these topics further, following work carried out by [4,17].…”

A Small Power Margin and Bandwidth Expansion Allow Data Transmission During Rainfall Despite Large Attenuation: Application to GeoSurf Satellite Constellations at mm–Waves

“…In designing satellite links above 10 GHz -frequency beyond which the attenuation due to rainfall is no longer neglible -the traditional approach is to consider the average (annual or worst month) probability distribution 𝑃(𝐴) of exceeding rain attenuation 𝐴 (dB) [1][2][3][4][5][6][7][8][9]. In the design, 𝑃(𝐴) is considered the outage probability and 𝐴 (dB) the required power margin necessary to maintain the link working, i.e.…”

“…Moreover, these particular sites are important study-cases because satellite ground stations of NASA and ESA are located there (Fucino, Madrid, White Sands), or because longterm radio propagation experiments were performed at the sites (Fucino, Gera Lario, Madrid, Spino d'Adda), or just because there are large cities (Prague, Norman, Tampa, Vancouver). Following our previous studies of the GeoSurf links [2][3][4][5]28], we simulate 𝐴(𝑡) at 80 GHz (mm-wave), circular polarization.…”