Methods and apparatuses are described for transmitting acknowledgement information in response to a plurality of data TBs received on one or more downlink data channels over TTIs by a UE in a TDD communication system. A method includes generating acknowledgement information comprising four acknowledgement bits, jointly representing a state of reception results for the plurality of data TBs, if a first condition applies, wherein a number of the data TBs is greater than a number of the acknowledgement bits; generating acknowledgement information respectively representing a reception result for each data TB by a corresponding acknowledgement bit, if a second condition applies; encoding the acknowledgement bits; multiplexing the encoded acknowledgement bits with uplink data; and transmitting the multiplexed acknowledgement bits and the uplink data on an uplink data channel.