Identifying and Protecting the RF Passive Bands Utilized by Meteorological Satellites from In-Band and Adjacent Band RF Interference Resulting from Increased Spectrum Use by Terrestrial Services

The meteorological community relies on remote sensing technologies for observations of weather and climate. These activities require access to uncontaminated passive bands that each provide essential information on specific phenomenology. To function, however, satellite-based passive sensors require radio frequency spectrum that is free of radio interference to ensure the usefulness and correctness of the measurements.

Under the World Radio-Communications (WRC)-19 agenda item 1.13, frequency bands between 24 GHz and 89 GHz (namely 24.25-27.5 GHz, 31.8-33.4 GHz, 37-40.5 GHz, 47.2-50.2 GHz, 50.4-52.6 GHz and 81-86 GHz) are being studied for the possible implementation of 5G mobile broadband. The mobile industry is applying significant pressure on policy makers worldwide to make this frequency spectrum available (even before WRC-19) for a fast implementation of 5G mobile (IMT-2020).

The consideration of these frequency bands targeted by the WRC-19 agenda item 1.13 involves allocated EESS (passive) bands used by passive microwave sensors on meteorological and Earth exploration satellites of space agencies from around the world.

Passive microwave techniques typically require an uncontaminated background free of radio interference on the specific frequencies that uniquely correspond to resonances of important atmospheric molecules. Because of these physical phenomena, the passive frequencies are fixed by nature and cannot be changed. The effect of this type of RF interference on the meteorological and EESS measurements is very difficult to predict and detect specifically as RF interference. It will also be difficult to detect early in deployment, as the level of interference will slowly rise over time with the increasing density of 5G deployment. The degradation of the measurements consequently will increase unnoticed until a point is reached at which the measured data in certain areas can no longer be considered adequate and will be rendered unusable in forecasting or in climate monitoring models. When such a level of interference is reached, the deployment of the interfering service - in this case 5G mobile systems - will be so far advanced that no realistic mitigation action could be applied to reduce the interference to acceptable levels.

It is critical that:

1. these effects be understood and identified;
2. appropriate measures be taken on future remote sensors to mitigate their susceptibility to this enhanced noise in the passive bands; and
3. international regulations constrain these unwanted emissions in the passive band.