Apparatus and method for transmitting acknowledgement information in a tdd communication system

A method for transmitting acknowledgement information in response to a plurality of data transport blocks (TBs) received on one or more downlink data channels over transmission time intervals (TTIs) by a user equipment (UE) in a time division duplex (TDD) communication system, the method comprising the steps of:

• 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,
• wherein the first condition includes the UE being configured for reception of the downlink data channels from two cells, and a number of the TTIs being three or four, and
• wherein the second condition includes the UE being configured for reception of the downlink data channels from a single cell, or the UE being configured for reception of the downlink data channels from two cells and a number of the TTIs being one or two.