A method for attaching a first radio base station to a core network via a radio access network, wherein a forwarding of data within the radio access network is being controlled by a Software Defined Network, SDN, Controller, the radio access network comprising a plurality of further radio base stations (21, 23) being capable of providing radio connection to a plurality of user equipments, UEs (11, 12, 13), and being under the control of the SDN Controller, the method comprising the steps of: - selecting at least one UE from the plurality of UEs (11, 12, 13), wherein the selected at least one UE is located within an overlapping radio connectivity area of the first radio base station and one of the further radio base stations (21, 23), denoted as a second radio base station, wherein the at least one UE from the plurality of UEs (11, 12, 13) is selected by the second radio base station (21, 23), based on radio strength indicators applicable for each UE from the plurality of UEs (11, 12, 13) within the overlapping radio connectivity area, the radio strength indicators indicating radio strength between each UE from the plurality of UEs (11, 12, 13) and both the first radio base station and the second radio base station (21, 23), and wherein the at least one UE from the plurality of UEs (11, 12, 13) is selected if a movement speed relative to the first radio base station of said at least one UE (11, 12, 13) is below a pre-defined speed threshold, - activating, by the SDN Controller, control of the SDN Controller onto the at least one selected UE (11, 12, 13), - connecting, by the SDN Controller, the first radio base station to the second radio base station (21, 23) via the radio connections of the at least one selected UE (11, 12, 13), - enabling, by the SDN Controller, the forwarding of data between the first radio base station and the core network via the second radio base station (21, 23). - selecting at least one UE from the plurality of UEs (11, 12, 13), wherein the selected at least one UE is located within an overlapping radio connectivity area of the first radio base station and one of the further radio base stations (21, 23), denoted as a second radio base station, wherein the at least one UE from the plurality of UEs (11, 12, 13) is selected by the second radio base station (21, 23), based on radio strength indicators applicable for each UE from the plurality of UEs (11, 12, 13) within the overlapping radio connectivity area, the radio strength indicators indicating radio strength between each UE from the plurality of UEs (11, 12, 13) and both the first radio base station and the second radio base station (21, 23), and wherein the at least one UE from the plurality of UEs (11, 12, 13) is selected if a movement speed relative to the first radio base station of said at least one UE (11, 12, 13) is below a pre-defined speed threshold, - activating, by the SDN Controller, control of the SDN Controller onto the at least one selected UE (11, 12, 13), - connecting, by the SDN Controller, the first radio base station to the second radio base station (21, 23) via the radio connections of the at least one selected UE (11, 12, 13), - enabling, by the SDN Controller, the forwarding of data between the first radio base station and the core network via the second radio base station (21, 23).