A method for use in a user equipment, including transferring data to the base station of a first cell (A1); sending an uplink scheduling request to the base station of a second cell (A3) in dependence on the condition that the user equipment has sufficient transmission power for performing inter-site carrier aggregation (A2); receiving an uplink resource allocation message from the base station of the second cell (A5) if the load of the second cell satisfies predetermined conditions (A4); transferring data to the base stations of the first and second cells via carrier aggregation (A6).