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

1. 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.

2. The method of claim 1 , wherein the acknowledgement information is generated at each of the TTIs.

3. The method of claim 1 , wherein a single reception result is generated by the UE, when the UE receives more than one data TB on a downlink data channel, and

wherein the single reception result indicates correct detection, if all of the data TBs were correctly detected, and indicates incorrect detection, if at least one of the data TBs was incorrectly detected by the UE.

4. The method of claim 1 , wherein when the UE does not detect a data TB or a control channel releasing transmission of the downlink data channel in a TTI, the UE generates a single reception result indicating the incorrect detection.

5. The method of claim 1 , wherein when the acknowledgement information is transmitted on uplink control channel, the acknowledgement information is generated by using bits indicating resources of the uplink control channel and bits indicating a constellation point of the uplink control channel.

6. The method of claim 1 , wherein the acknowledgement bits are encoded by Reed-Mueller (RM) encoding.

7. The method of claim 1 , wherein one of the state of reception results is represented as {NACK, any, any, any} and {NACK/DTX, any, any, any} for a first cell and a second cell of the two cells, respectively, by all acknowledgement information bits {0, 0, 0, 0}, if the first condition applies, and

wherein the ‘NACK’ indicates ‘Negative ACK’, the ‘DTX’ indicates ‘Discontinuous Transmission’ , and the ‘any’ indicates either ‘ACK’ or ‘NACK/DTX’.

8. A User Equipment (UE) for transmitting acknowledgement information in response to a plurality of data transport blocks (TBs) received in one or more downlink data channels over transmission time intervals (TTIs) in a time division duplex (TDD) communication system, the apparatus comprising:

a controller for 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; and

generating acknowledgement information respectively representing a reception result for each data TB by a corresponding acknowledgement bit, if a second condition applies;

an encoder for encoding the acknowledgement bits;

a multiplexer for multiplexing the encoded acknowledgement bits with uplink data; and

a transmitter for transmitting the multiplexed acknowledgement bits and the uplink data on information in 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.

9. The UE of claim 6 , wherein the acknowledgement information is generated at each of the TTIs.

10. The UE of claim 8 , wherein the controller generates a single reception result, when the UE receives more than one data TB on a downlink data channel, and

wherein the controller represents the single reception result to indicate correct detection, if all of the data TBs were correctly detected, and to indicate incorrect detection, if at least one of the data TBs was incorrectly detected.

11. The UE of claim 8 , wherein when the controller does not detect a data TB or a control channel releasing transmission of the downlink data channel in a TTI, the controller generates a single reception result indicating incorrect detection as the acknowledgement information.

12. The UE of claim 8 , wherein when the acknowledgement information is transmitted on an uplink control channel, the controller generates the acknowledgement information by using bits indicating resources of the uplink control channel and bits indicating a constellation point of the uplink control channel.

13. The UE of claim 8 , wherein the acknowledgement bits are encoded by Reed-Mueller (RM) encoding.

14. The UE of claim 8 , wherein one of the state of reception results is represented as {NACK, any, any, any} and {NACK/DTX, any, any, any} for a first cell and a second cell of the two cells, respectively, by all acknowledgement information bits {0, 0, 0, 0}, if the first condition applies, and

wherein the ‘NACK’ indicates ‘Negative ACK’, the ‘DTX’ indicates ‘Discontinuous Transmission’ , and the ‘any’ indicates either ‘ACK’ or ‘NACK/DTX’.