A location system comprising: a location network comprising a plurality of reference nodes and at least one controller. Each reference node is operable to transmit a respective beaconing signal from which a respective measurement can be taken by a mobile device for use in determining a location of the mobile device. The at least one controller is configured to control whether and/or how often one or more signals of the location system are transmitted to be used in determining the location of the mobile device, the control being based on feedback from at least one determination of the location of the mobile device relative to the reference nodes.