"That's why it was so important that the new 5G mobile protocol be designed to foil IMSI catchers, and why the 3rd Generation Partnership Project, or 3GPP (the body standardizing 5G) updated the Authentication and Key Agreement (AKA) to resist IMSI catching techniques."
"A duo of researchers at the University of Waterloo and the University of Illinois Urbana-Champaign have turned this old assumption of impracticality on its head with their description of a Wi-Fi localization exploit they call Wi-Peep. They have outlined how an inconspicuous and inexpensive device can locate hidden Wi-Fi devices without their cooperation."