A method, apparatus, and carrier medium carrying computer readable code. The apparatus includes a mobile robot arranged in operation to traverse an area, a first transceiver for a wireless network mounted on the robot and arranged in operation to communicate with a second transceiver to effect radio measurement operations for determining at each of a plurality of locations covering the area a measure indicative of the path loss between the first and second transceivers, and a location determining system at least a component of which is mounted on the robot and arranged in operation to determine the location of the first transceiver in the area.