A method and a Radio Signature Positioning Determining Entity (RS-PDE) are provided for maintaining the reliability of a location database of the RS-PDE. A Data Transfer Scheduler (DTS) of the RS-PDE receives new location data comprising signal strength measurements records, and the new location data is correlated by a Data Correlation Device (DCD) with existing location data of the location database. The correlated location data is uploaded by a Data Uploader (DU) into the location database. A Data Performance Monitor (DPM) detects if the RS-PDE provides better positioning results using that correlated data, and if so, the RS-PDE then uses the correlated data for mobile station positioning. The location data update cycle may be triggered by a configurable timer defining an update periodicity, or by a detection of insufficient positioning accuracy of the RS-PDE using the existing location data.