A computer-implemented method and a server for device positioning. The computer-implemented method includes sending a control message to a detector. The control message indicates a set of channels associated with an area and time periods for monitoring the set of channels. A measurement of a signal from a device for the area and a target device is received from the detector. Position of the target device with respect to the area is determined based on a measurement and a radio map. The radio map indicates signal strength corresponding to positions in the area.