An apparatus of a user equipment, UE, the apparatus comprising: processing circuitry; and memory, the UE configured with more than one serving cell including a primary cell, Pcell, and at least one secondary cell, Scell, the UE further configured with a transmission mode supporting receipt of two transport blocks, TBs in at least one of the serving cells, the processing circuitry configured to: determine a number of HARQ- Acknowledgement, ACK, feedback bits to be transmitted in a subframe based on a downlink assignment index, DAI, wherein a value of the DAI in a downlink control information, DCI, format indicates an accumulative number of the serving cells with PDSCH transmissions associated with a PDCCH or an enhanced PDCCH, EPDCCH, and serving cells with the PDCCH or the EPDCCH indicating a downlink semi-persistent scheduling, SPS, release, up to a present serving cell in increasing order of serving cell index; calculate the HARQ-ACK feedback bits based on decoding of transport blocks of a received physical downlink shared channel, PDSCH, of the serving cells including the primary cell and the at least one secondary cell, wherein two HARQ-ACK bits are always generated for each PDSCH or SPS release according to the value of the DAI in each serving cell regardless of whether the UE is configured with a transmission mode supporting two TBs or one TB in the serving cell; and encode a PUCCH in accordance with the PUCCH format for transmission of uplink control information, UCI. processing circuitry; and memory, the UE configured with more than one serving cell including a primary cell, Pcell, and at least one secondary cell, Scell, the UE further configured with a transmission mode supporting receipt of two transport blocks, TBs in at least one of the serving cells, the processing circuitry configured to: determine a number of HARQ- Acknowledgement, ACK, feedback bits to be transmitted in a subframe based on a downlink assignment index, DAI, wherein a value of the DAI in a downlink control information, DCI, format indicates an accumulative number of the serving cells with PDSCH transmissions associated with a PDCCH or an enhanced PDCCH, EPDCCH, and serving cells with the PDCCH or the EPDCCH indicating a downlink semi-persistent scheduling, SPS, release, up to a present serving cell in increasing order of serving cell index; calculate the HARQ-ACK feedback bits based on decoding of transport blocks of a received physical downlink shared channel, PDSCH, of the serving cells including the primary cell and the at least one secondary cell, wherein two HARQ-ACK bits are always generated for each PDSCH or SPS release according to the value of the DAI in each serving cell regardless of whether the UE is configured with a transmission mode supporting two TBs or one TB in the serving cell; and encode a PUCCH in accordance with the PUCCH format for transmission of uplink control information, UCI. determine a number of HARQ- Acknowledgement, ACK, feedback bits to be transmitted in a subframe based on a downlink assignment index, DAI, wherein a value of the DAI in a downlink control information, DCI, format indicates an accumulative number of the serving cells with PDSCH transmissions associated with a PDCCH or an enhanced PDCCH, EPDCCH, and serving cells with the PDCCH or the EPDCCH indicating a downlink semi-persistent scheduling, SPS, release, up to a present serving cell in increasing order of serving cell index; calculate the HARQ-ACK feedback bits based on decoding of transport blocks of a received physical downlink shared channel, PDSCH, of the serving cells including the primary cell and the at least one secondary cell, wherein two HARQ-ACK bits are always generated for each PDSCH or SPS release according to the value of the DAI in each serving cell regardless of whether the UE is configured with a transmission mode supporting two TBs or one TB in the serving cell; and encode a PUCCH in accordance with the PUCCH format for transmission of uplink control information, UCI.