Method and apparatus for transmitting reception confirmation in wireless system
Provided are a method and an apparatus for transmitting a reception confirmation in a wireless system. A terminal determines at least one downlink sub-frame for ACK/NACK feedback from each of a plurality of serving cells and determines the number of ACK/NACK bits for the plurality of serving cells. The terminal generates bundled ACK/NACK bits by arraying the ACK/NACK bits in the ascending order of the cell index of the plurality of serving cells, and transmits the bundled ACK/NACK bits.
1. A method of transmitting a reception acknowledgement in a wireless communication system, comprising:
determining, by a user equipment (UE), a number of ACK/NACK bits for a plurality of serving cells and at least one downlink subframe for which the UE needs to feedback ACK/NACK in each of the plurality of serving cells;
generating, by the UE, combined ACK/NACK bits by arranging the ACK/NACK bits in ascending order of cell indexes of the plurality of serving cells;
generating, by the UE, encoded ACK/NACK bits by encoding the combined ACK/NACK bits;
generating, by the UE, ACK/NACK symbols by modulating the encoded ACK/NACK bits; and
transmitting, by the UE, the ACK/NACK symbols to a base station.
2. The method of claim 1 , wherein the step of generating the combined ACK/NACK bits includes:
generating the combined ACK/NACK bits by arranging ACK/NACK bits for a first serving cell having a lowest cell index; and
appending ACK/NACK bits for a second serving cell having a cell index next to the lowest cell index at the end of the combined ACK/NACK bits.
3. The method of claim 2 , wherein the lowest cell index is zero.
4. The method of claim 1 , further comprising:
determining whether the number of ACK/NACK bits is greater than a specific value.
5. The method of claim 4 , wherein if the number of ACK/NACK bits is greater than the specific value, spatial bundling in which a binary AND operation of ACK/NACK bits corresponding to at least two codewords in each subframe is performed is applied to all subframes in all serving cell.
6. The method of claim 1 , wherein the wireless communication system is a time division duplex system.
7. The method of claim 1 , wherein a number of bits for the encoded ACK/NACK bits is 48 and the encoded ACK/NACK bits are modulated by using quadrature phase shift keying (QPSK).
8. The method of claim 7 , wherein the step of transmitting the ACK/NACK symbols includes:
spreading the ACK/NACK symbols with orthogonal sequences; and
transmitting the spread ACK/NACK symbols.
9. A user equipment configured for transmitting a reception acknowledgement in a wireless communication system, comprising:
a radio frequency unit configured for transmitting a radio signal; and
a processor operatively coupled with the radio frequency unit and configured to:
determine a number of ACK/NACK bits for a plurality of serving cells and at least one downlink subframe for which the user equipment needs to feedback ACK/NACK in each of the plurality of serving cells;
generate combined ACK/NACK bits by arranging the ACK/NACK bits in ascending order of cell indexes of the plurality of serving cells;
generate encoded ACK/NACK bits by encoding the combined ACK/NACK bits;
generate ACK/NACK symbols by modulating the encoded ACK/NACK bits; and
transmit the ACK/NACK symbols to a base station.
10. The user equipment of claim 9 , wherein the processor is configured to generate the combined ACK/NACK bits by:
generating the combined ACK/NACK bits by arranging ACK/NACK bits for a first serving cell having a lowest cell index; and
appending ACK/NACK bits for a second serving cell having a cell index next to the lowest cell index at the end of the combined ACK/NACK bits.
11. The user equipment of claim 10 , wherein the lowest cell index is zero.
12. The user equipment of claim 9 , wherein the processor is configured to determine whether the number of ACK/NACK bits is greater than a specific value.
13. The user equipment of claim 12 , wherein if the number of ACK/NACK bits is greater than the specific value, spatial bundling in which a binary AND operation of ACK/NACK bits corresponding to at least two codewords in each subframe is performed is applied to all subframes in all serving cell.
14. The user equipment of claim 9 , wherein a number of bits for the encoded ACK/NACK bits is 48 and the encoded ACK/NACK bits are modulated by using quadrature phase shift keying (QPSK).
15. The user equipment of claim 14 , wherein the processor is configured to transmit the ACK/NACK symbols by:
spreading the ACK/NACK symbols with orthogonal sequences; and
transmitting the spread ACK/NACK symbols.