A method for providing, by a user equipment, feedback information of a retransmission protocol to a radio base station in a mobile communication system, wherein the user equipment is configured with at least two cells, and at least one cell bundling group is defined for the user equipment such that one of the at least one cell bundling group is associated with at least two out of the at least two cells, wherein the user equipment is in communication with the radio base station to receive downlink transmissions via at least one of the at least two cells, and the user equipment is configured to operate a retransmission protocol with the radio base station comprising the step of providing feedback information for the downlink communication via the at least two cells to the radio base station, the method comprising the following steps performed by the user equipment: for each cell bundling group, bundling feedback information generated in connection with those cells being associated with the respective cell bundling group so as to generate bundled feedback information per cell bundling group, transmitting the bundled feedback information of each cell bundling group to the radio base station, and characterized in that the user equipment is operating each of the at least two cells in accordance with one out of a plurality of Time Division Duplex, TDD, configurations defining for each radio frame the subframes of the radio frame as an uplink subframe, a downlink subframe, or special subframe, wherein for each of the plurality of TDD configurations pre-determined feedback timing information defines for each uplink subframe whether and for which previous downlink subframe or subframes feedback information is to be transmitted in the respective uplink subframe, the method comprising the following steps being performed for each uplink subframe of that cell via which the bundled feedback information is to be transmitted: for each cell, generating an item of feedback information for each of the previous downlink subframe or subframes as defined by the pre-determined feedback timing information for the respective uplink subframe, the step of bundling the feedback information for each cell bundling group comprises: bundling the generated feedback information items across those cells, that are associated with the respective cell bundling group, in a successive order of the feedback information items such that the feedback information items of the same order are bundled, so as to generate bundled feedback information items in the same successive order per uplink subframe, per cell bundling group and per order of feedback information items. for each cell bundling group, bundling feedback information generated in connection with those cells being associated with the respective cell bundling group so as to generate bundled feedback information per cell bundling group, transmitting the bundled feedback information of each cell bundling group to the radio base station, and characterized in that the user equipment is operating each of the at least two cells in accordance with one out of a plurality of Time Division Duplex, TDD, configurations defining for each radio frame the subframes of the radio frame as an uplink subframe, a downlink subframe, or special subframe, wherein for each of the plurality of TDD configurations pre-determined feedback timing information defines for each uplink subframe whether and for which previous downlink subframe or subframes feedback information is to be transmitted in the respective uplink subframe, the method comprising the following steps being performed for each uplink subframe of that cell via which the bundled feedback information is to be transmitted: for each cell, generating an item of feedback information for each of the previous downlink subframe or subframes as defined by the pre-determined feedback timing information for the respective uplink subframe, the step of bundling the feedback information for each cell bundling group comprises: bundling the generated feedback information items across those cells, that are associated with the respective cell bundling group, in a successive order of the feedback information items such that the feedback information items of the same order are bundled, so as to generate bundled feedback information items in the same successive order per uplink subframe, per cell bundling group and per order of feedback information items. for each cell, generating an item of feedback information for each of the previous downlink subframe or subframes as defined by the pre-determined feedback timing information for the respective uplink subframe, the step of bundling the feedback information for each cell bundling group comprises: bundling the generated feedback information items across those cells, that are associated with the respective cell bundling group, in a successive order of the feedback information items such that the feedback information items of the same order are bundled, bundling the generated feedback information items across those cells, that are associated with the respective cell bundling group, in a successive order of the feedback information items such that the feedback information items of the same order are bundled,