RF Fingerprinting for Contraband Wireless Devices Identification, Detection and Tracking in Correctional Facilities, Starkville, Mississippi, 2020-2022

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The growing use of contraband wireless devices, particularly cell phones, smuggled in correctional facilities, is a significant problem across the country. Inmates behind bars may use these devices to organize gang activities, run drug operations, and even plan escapes, which may threaten the safety and welfare of other inmates, prison employees and the general public. To combat the use of contraband cell phones, some radio-based technologies have been investigated, which primarily fall into the following three categories: radio jamming systems which disrupt the communication link between the wireless device and the transceiver outside of the prison by continuously transmitting on the same radio frequencies as the contraband wireless device, and thus make the device unusable behind bars; managed access systems (MAS) which build a private micro-cellular network over the whole facility in which all radio transmissions to carrier networks, e.g., calls or messages originating from inside or outside prisons, are captured, and only those authorized transmissions from and/or to a "white list" of preregistered wireless devices are allowed; and passive detection systems which identify and localize various sources of unapproved wireless transmissions from prisons. It has been known that a jamming system may interfere with authorized calls including public safety communications (e.g., 9-1-1 calls), particularly when multiple frequency bands are involved, and a MAS is usually prohibitively expensive in its installation and operation due to the needs of covering many different commercial networks and frequency bands with an optimized footprint. In contrast, the detection system offers a passive solution in that detection systems do not transmit any radio signals and thus do not interfere with other transmissions. Therefore, the overall objective of this project is to develop an effective and low-cost contraband interdiction system (CIS) for identifying, localizing, and tracking unauthorized wireless devices such as cell phones and WiFi devices in correctional facilities, through the use and development of advanced machine learning algorithms for fingerprinting radio frequency (RF) signals originating from an unauthorized wireless device.