Abstract: It is presented a method arranged to assist a determination of mobile devices being candidates for handover. The method is performed in a radio traffic detector and comprises: measuring a received signal strength value on a predetermined frequency band; repeating the measuring during a time period; generating a message comprising a timestamp associated with the time period, and a plurality of message elements, wherein each message element is based on a respective received signal strength value for respectively different time instances within the time period; and transmitting the message to a network node to assist the determination of mobile devices being candidates for handover. By using measured received signal strength, uplink traffic can be detected without the need to decode the signals. Corresponding radio traffic device, network node and method are also presented.