A Saudi Arabian university has crunched the math to minimize the impact of 5G cellular signals on aircraft radar altimeters while keeping the data flowing to phones at or near airports. There’s no free lunch. Ensuring flight safety comes at a signal penalty for cellphone users, but the researchers at King Abdullah University have figured out the ideal shape and size of so-called exclusion zones around airports where the 5G signal is degraded. “We used stochastic geometry to analyze different exclusion zone shapes. We found that triangular zones around runways preserved the radio altimeter signal while keeping the area of the lost 5G performance as small as possible,” Safa Khemiri, a Ph.D. student working on the project, told TechXplore. “The zone is like closing a lane on a highway. The data still moves but not as quickly as outside the zone where all lanes are open.”
The 5G signals operate in a frequency band just below that used by radar altimeters. The higher frequencies in the 5G band can carry more data but are most at risk of causing interference. In the exclusion zones, telecom companies have agreed to operate at the lowest frequencies to mitigate interference, but the new math from the Saudi students promises to strike the balance more precisely. The FAA has also ordered operators of all affected aircraft to equip with radar altimeters that are hardened against signal interference.
That’s great, though I find it telling that this work was done by a Saudi student, rather than here in the US. We need to get back to a tech leadership position.