Sensing Outage Probability of Space-Borne Passive Radiometry in Coexistence with an Active Terrestrial Network

We consider the uplink of a large-scale active terrestrial cellular network operating in the restricted L-band (1400–1427 MHz) with NASA's Soil Moisture Active Passive (SMAP) satellite. In our previous work, we used stochastic geometry to derive the statistical properties of radio frequency interference (RFI) at SMAP that originates from the terrestrial network. We demonstrated that, while it is crucial to prevent RFI from interfering with the main-lobe of SMAP's antenna, its low-gain side-lobe can tolerate the coexistence of a significant number of active devices on the same channel with low to moderate RFI impact on SMAP's measurements, ensuring minimal disruption to its sensing accuracy. In this paper, we extend our previous work by analyzing the Sensing Outage Probability (SOP), which is a novel metric that represents the probability of RFI exceeding the acceptable error threshold for a given passive remote sensing mission. We specifically assess the statistical characteristics, namely, the expected value and variance, of RFI induced on the SMAP satellite by clusters of 5G cellular User Equipment (UE), considering variations in the number of UEs and their transmission powers. Subsequently, we derive the SOP for each configuration and demonstrate that a significant number of UEs can operate co-channel with the passive remote sensor while ensuring that the induced RFI remains below a given threshold (in Kelvin) with high certainty.