A method, apparatus and computer program product are provided to improve the positioning performance of a positioning application. The method receives particular radio signal propagation information regarding received radio signal propagation parameter of a respective signal collected by a mobile device following transmission by a beacon on a sub-channel. The method also receives past radio signal propagation information regarding the received radio signal propagation parameter of signals previously transmitted by the beacon and collected by the mobile device on one or more sub-channels. Based on the particular radio signal propagation information and the past radio signal propagation information, the method determines a value for representing the respective signal that is different from the received radio signal propagation parameter of the respective signal. The method represents the respective signal with the value determined based on the particular radio signal propagation information and the past radio signal propagation information.