A system for measuring in an anonymous manner one or more spatial positions of one or more user devices within a region, wherein the system includes a wireless arrangement for receiving signals from the one or more user devices for determining the one or more spatial positions of the one or more user devices, wherein the wireless arrangement is operable to receive one or more user identification codes from the one or more user devices, wherein the one or more user identification codes include N bits; the system is operable to apply a mapping function to map the one or more user identification codes to form one or more corresponding secondary identification codes by decreasing an entropy of the one or more user identification codes by K bits; and the system is operable to modify the one or more corresponding secondary identification codes by increasing entropy of the one or more corresponding secondary identification codes by M bits.