A wireless node for use in a network of wireless nodes, for performing a localization to determine a location of a mobile device based on respective beacon signals transmitted wirelessly between the mobile device and each of a plurality of the wireless nodes. The first wireless node is configured to: wirelessly transmit or receive the respective beacon signal for use in determining the location of the mobile device; and wirelessly transmit information vouching for one or more others of the wireless nodes as being trusted for use in the localization. This information is transmitted to a device performing the localization (e.g. the mobile device), for use in identifying one or more rogue versions of said wireless nodes.