A method (300; 1000; 1100) of aggregating radio resources of a cellular telecommunications network for radio communication with a User Equipment, UE, the method comprising the following steps performed by a master network node of the telecommunications network: sending (302; 200; 301) a message to the UE, the message configuring the UE to determine radio resources for radio aggregation out of a plurality of radio resources of the telecommunications network, wherein the message specifies that the determining includes measuring, by the UE, time offsets relative to a reference cell of the telecommunications network for the plurality of radio resources; receiving (304; 210; 305) from the UE a report indicative of a set of radio resources for radio resource aggregation and the time offsets measured for the radio resources; comparing (220; 310) the time offsets with an aggregation window assigned for the UE, wherein the aggregation window is the time window within which the UE can aggregate cells; deciding (230; 350) a new aggregation window and a new aggregation set according to one or more objectives, wherein the objectives include at least one of load considerations, service considerations, throughput considerations, and a Carrier Aggregation, CA, capability of one or more network nodes, and wherein the aggregation set consists of a Primary Cell, PCell, and one or more activated Secondary Cells, SCells, that the UE is receiving and decoding for radio resource aggregation; moving the aggregation window, wherein said moving leads to the new aggregation window, and wherein said moving is performed such that the new aggregation window contains a detected SCell which is found by the master network node to be more suitable to use by the UE than another SCell, according to the one or more objectives; and configuring (306; 290; 395) the UE for aggregating at least two of the radio resources indicated in the report for the radio communication according to the new aggregation set. sending (302; 200; 301) a message to the UE, the message configuring the UE to determine radio resources for radio aggregation out of a plurality of radio resources of the telecommunications network, wherein the message specifies that the determining includes measuring, by the UE, time offsets relative to a reference cell of the telecommunications network for the plurality of radio resources; receiving (304; 210; 305) from the UE a report indicative of a set of radio resources for radio resource aggregation and the time offsets measured for the radio resources; comparing (220; 310) the time offsets with an aggregation window assigned for the UE, wherein the aggregation window is the time window within which the UE can aggregate cells; deciding (230; 350) a new aggregation window and a new aggregation set according to one or more objectives, wherein the objectives include at least one of load considerations, service considerations, throughput considerations, and a Carrier Aggregation, CA, capability of one or more network nodes, and wherein the aggregation set consists of a Primary Cell, PCell, and one or more activated Secondary Cells, SCells, that the UE is receiving and decoding for radio resource aggregation; moving the aggregation window, wherein said moving leads to the new aggregation window, and wherein said moving is performed such that the new aggregation window contains a detected SCell which is found by the master network node to be more suitable to use by the UE than another SCell, according to the one or more objectives; and configuring (306; 290; 395) the UE for aggregating at least two of the radio resources indicated in the report for the radio communication according to the new aggregation set.