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Quantitative Finance · Glossaire

Qu'est-ce que « Rain fade, link availability » ?

Aussi appelé : rain fade · link availability

Definition 14.5 Networks, Hardware and Trading Infrastructure · Chapitre 14 — Long-Haul Wireless

Rain fade is the attenuation of a radio signal by raindrops along its path, which grows with the rain rate and steeply with frequency. A link’s link availability is the fraction of time in which it carries traffic at its required error rate, usually stated per year.

Specific attenuation of rain against rain rate at four frequencies, horizontal polarisation, from the ITU-R P.838-3 coefficients. Data: fig_wireless.py; coefficients in code/firm/radiolink/data/p838_3.csv.
Figure 14.2. Specific attenuation of rain against rain rate at four frequencies, horizontal polarisation, from the ITU-R P.838-3 coefficients. Data: fig_wireless.py; coefficients in code/firm/radiolink/data/p838_3.csv.
FrequencyDish gainFree-space lossReceivedFade marginR∗R^*, whole hopR∗R^*, 10-km cell
(GHz)(dBi)(dB)(dBm)(dB)(mm/h)(mm/h)
638.9143.6−38.9-38.931.163.5196.0
1144.1148.8−33.6-33.636.418.480.4
1848.4153.1−29.3-29.340.78.142.3
8061.4166.1−16.4-16.453.60.78.5
Table 14.2. Link budget of a 60-kilometre hop with the model’s equipment (30 dBm, two 1.8-metre dishes at 60% efficiency, 3 dB3\,\mathrm{dB} of other losses, −70-70 dBm threshold), and the critical rain rate of Proposition 14.6 for rain along the whole hop and for a cell ten kilometres wide. Data: nw_wireless.budget_rows().
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