From the Document: "Rogue base stations, also known as international mobile subscriber identity (IMSI) catchers, are devices that masquerade as cell phone towers, tricking cell phones within a certain radius into connecting to the device rather than a tower. During recent pilot tests conducted over the public airwaves, DHS detected anomalous activity that appeared to be consistent with rogue technology being used in proximity to sensitive facilities such as the White House. Some rogue base stations may have advanced features allowing interception and alteration of communication content. As a result of unknown capabilities, there is a need to detect rogue base stations in order to better protect the communication sector's critical infrastructure."
Cybersecurity and Infrastructure Security Agency: https://www.cisa.gov/