Systems and methods for passive proximity detection of wireless devices in a cellular communications network are disclosed. In one embodiment, a supporting radio access node in a cellular communications network including one or more coverage radio access nodes in a coverage layer and one or more supporting radio access nodes in a supporting layer is disclosed. In this embodiment, the supporting radio access node detects a ranging signal transmitted by a wireless device while passively listening for a ranging signal. The supporting radio access node receives ranging assistance information from an anchor radio access node of the wireless device in the coverage layer and determines a range estimate for a range between the wireless device and the supporting radio access node based on the ranging signal transmitted by the wireless device and detected by the supporting radio access node and the ranging assistance information.