An infrastructure-controller for an infrastructure. The infrastructure-controller configured to: send a ranging-scheduling-signal to a key, wherein the ranging-scheduling-signal comprises timing-information for a subsequent ranging operation; and activate one or more ranging nodes associated with the infrastructure, for receiving a key-ranging-signal from the key, at an infrastructure-node-start-ranging-time based on the timing-information. The ranging-scheduling-signal has a frequency in a first RF frequency range. The key-ranging-signal has a frequency in a second RF frequency range.