In a mobile communication system (T1) a data transmission determining means (DTDM) located in a subscriber station (MS) estimates a predetermined time interval in which no-data transmission will be directed from the base transmitter station (RBS) to said subscriber station (MS). An IF measurement means (IFMM) performs inter-frequency measurements necessary for handover procedures in the predetermined time interval in which no data transmission takes place. The determination of the no-data transmission is done autonomously by the subscriber station (MS) without the need of exchanging signalling or other data with the network control means (RNC). The invention is particularly useful for CDMA, WCDMA and TDMA mobile radio communication systems.