Determining the geographic location of a portable electronic device (100) in a radio communications network, by transmitting radio signals from a plurality of first network transmitters (200, 300, 400); receiving, in the network, a measurement signal from the portable electronic device, which measurement signal comprises, for each transmitted radio signal, a plurality of data samples obtained in the electronic device from the respective transmitted signal at different time points during a measurement period with movement of the portable electronic device (100), and local position data associated to each data sample obtained from a local positioning unit in the electronic device, so as to form a synthetic antenna array; obtaining, a direction measurement between the electronic device and the first network transmitter from the synthetic antenna array; obtaining geographic location data for the first network transmitter; and identifying geographic location data of the portable electronic device based on the direction measurement and the geographic location data for the first network transmitter.