A method performed by a radio node of a cellular network, the radio node being operable for radio communication of data with User Equipments, UEs, the method comprising: - applying a first carrier type to each subframe on a first frequency for sending downlink signals to legacy UEs and/or new UEs, and - applying a second carrier type to each subframe on a second frequency for sending downlink signals only to new UEs, wherein new UEs are UEs which are determined by the radio node to support both the first carrier type and the second carrier type, wherein legacy UEs are UEs which are determined by the radio node to support only the first carrier type, and said method being characterized by comprising, upon determining an event, the steps of: configuring a first set of measurement gaps (A1-AN) spanning a plurality of subframes on the first frequency for the legacy UEs and/or the new UEs which are determined by the radio node to support measurement gaps; and applying the first carrier type for sending downlink signals in said plurality of subframes on the second frequency, thereby allowing the legacy UEs and/or the new UEs supporting measurements gaps to perform signal measurements on the second frequency during the first set of measurement gaps, and selectively applying on a subframe basis one of the first carrier type and the second carrier type for sending downlink signals in subframes on the second frequency other than said plurality of subframes, and/or said method comprising, upon determining said event, the steps of: configuring a second set of time intervals (T2, T4,...) on the second frequency for the legacy UEs and/or the new UEs which are determined by the radio node not to support measurement gaps; and applying the first carrier type for sending downlink signals in the subframes within said second set of time intervals (T2, T4...), thereby allowing the legacy UEs and/or the new UEs not supporting measurement gaps to perform signal measurements on the second frequency during the second set of time intervals (T2, T4...); and selectively applying on a subframe basis one of the first carrier type and the second carrier type for sending downlink signals in subframes on the second frequency other than the subframes of said second set of time intervals. - applying a first carrier type to each subframe on a first frequency for sending downlink signals to legacy UEs and/or new UEs, and - applying a second carrier type to each subframe on a second frequency for sending downlink signals only to new UEs, configuring a first set of measurement gaps (A1-AN) spanning a plurality of subframes on the first frequency for the legacy UEs and/or the new UEs which are determined by the radio node to support measurement gaps; and applying the first carrier type for sending downlink signals in said plurality of subframes on the second frequency, thereby allowing the legacy UEs and/or the new UEs supporting measurements gaps to perform signal measurements on the second frequency during the first set of measurement gaps, and selectively applying on a subframe basis one of the first carrier type and the second carrier type for sending downlink signals in subframes on the second frequency other than said plurality of subframes, and/or said method comprising, upon determining said event, the steps of: configuring a second set of time intervals (T2, T4,...) on the second frequency for the legacy UEs and/or the new UEs which are determined by the radio node not to support measurement gaps; and applying the first carrier type for sending downlink signals in the subframes within said second set of time intervals (T2, T4...), thereby allowing the legacy UEs and/or the new UEs not supporting measurement gaps to perform signal measurements on the second frequency during the second set of time intervals (T2, T4...); and configuring a second set of time intervals (T2, T4,...) on the second frequency for the legacy UEs and/or the new UEs which are determined by the radio node not to support measurement gaps; and applying the first carrier type for sending downlink signals in the subframes within said second set of time intervals (T2, T4...), thereby allowing the legacy UEs and/or the new UEs not supporting measurement gaps to perform signal measurements on the second frequency during the second set of time intervals (T2, T4...); and selectively applying on a subframe basis one of the first carrier type and the second carrier type for sending downlink signals in subframes on the second frequency other than the subframes of said second set of time intervals.