Method and apparatus for transmitting ACK/NACK in a wireless communication system based on TDD

Abstract

Provided is a method of transmitting ACK/NACK in a TDD-based wireless communication system. The method includes: receiving M downlink subframes associated with an uplink subframe n in each of two serving cells; determining four candidate resources based on the M downlink subframes received in each of the two serving cells; and transmitting an ACK/NACK response for the M downlink subframes by using one resource selected from the four candidate resources in the uplink subframe n, wherein the two serving cells includes a first serving cell and a second serving cell, and wherein among the four candidate resources, a first resource and a second resource are associated with a PDSCH or a SPS release PDCCH for releasing semi-persistent scheduling received in the first serving cell, and a third resource and a fourth resources are associated with a PDSCH received in the second serving cell.

The invention claimed is: 
     
       1. A method of transmitting positive-acknowledgement (ACK)/negative-acknowledgement (NACK) by a user equipment (UE) in a time division duplex (TDD)-based wireless communication system, the method comprising:
 receiving, by the UE from a base station (BS), M downlink subframes in each of a primary serving cell and a secondary serving cell, where M is an integer greater than two, and the M downlink subframes are associated with an uplink subframe n; and 
 transmitting, by the UE to the BS in the uplink subframe n, an ACK/NACK response for the received M downlink subframes by using one resource selected from four candidate resources based on the received M downlink subframes, 
 wherein, among the four candidate resources,
 a first resource and a second resource are associated with a physical downlink shared channel (PDSCH) received in the primary serving cell or a semi-persistent scheduling release physical downlink control channel (SPS release PDCCH) for releasing semi-persistent scheduling received in the primary serving cell, and 
 a third resource and a fourth resource are associated with a PDSCH received in the secondary serving cell. 
 
 
     
     
       2. The method of  claim 1 , wherein at least one downlink subframe among the M downlink subframes received in the primary serving cell comprises:
 a physical downlink control channel (PDCCH) in which a downlink grant is transmitted by the BS, and 
 the PDSCH received in the primary serving cell corresponding to the PDCCH. 
 
     
     
       3. The method of  claim 2 , wherein the downlink grant includes a downlink assignment index (DAI) indicating a cumulative number of PDCCHs with an assigned PDSCH transmission. 
     
     
       4. The method of  claim 3 , wherein, in the M downlink subframes received in the primary serving cell:
 if a PDSCH indicated by a first PDCCH with a DAI value equal to 1 is received, then the first resource is determined based on a first control channel element (CCE) used in transmission of the first PDCCH, or 
 if a first SPS release PDCCH with a DAI value equal to 1 is received, then the first resource is determined based on a first CCE used in transmission of the first SPS release PDCCH, or 
 if a PDSCH indicated by a second PDCCH with a DAI value equal to 2 is received, then the second resource is determined based on a first CCE used in transmission of the second PDCCH, or 
 if a second SPS release PDCCH with a DAI value equal to 2 is received, then the second resource is determined based on a first CCE used in transmission of the second SPS release PDCCH. 
 
     
     
       5. The method of  claim 3 , wherein, in the M downlink subframes received in the primary serving cell:
 if an SPS PDSCH, which is a PDSCH having no corresponding PDCCH, is received, 
 then the first resource among the four candidate resources has one value determined from four values that are configured by using a higher layer signal, and the determined one value is indicated by an uplink transmit power control field in a PDCCH indicating activation of semi-persistent scheduling. 
 
     
     
       6. The method of  claim 5 , wherein, in the M downlink subframes received in the primary serving cell:
 if a PDSCH indicated by detecting a first PDCCH with a DAI value equal to 1 is received, then the second resource is determined based on a first CCE used in transmission of the first PDCCH or 
 if a first SPS release PDCCH with a DAI value equal to 1 is received, then the second resource is determined based on a first CCE used in transmission of the first SPS release PDCCH. 
 
     
     
       7. The method of  claim 3 , wherein
 if a PDSCH, indicated by a third PDCCH with a DAI value equal to 1 received in the M downlink subframes in the primary serving cell, is received in the M downlink subframes in the secondary serving cell, then the third resource is determined based on a first CCE used in transmission of the third PDCCH, or 
 if a PDSCH, indicated by a fourth PDCCH with a DAI value equal to 2 received in the M downlink subframes in the primary serving cell, is received in the M downlink subframes in the secondary serving cell, then the fourth resource is determined based on a first CCE used in transmission of the fourth PDCCH. 
 
     
     
       8. The method of  claim 3 , wherein
 if
 at least one PDCCH is received in the M downlink subframes received in the secondary serving cell, and 
 a PDSCH indicated by the at least one PDCCH is received in the secondary serving cell: 
 
 then
 the third resource and the fourth resource are have values determined by a higher layer signal, and 
 the third and fourth resources are indicated by an uplink transmission power control (TPC) field included in the at least one PDCCH. 
 
 
     
     
       9. A user equipment (UE) configured to transmit positive-acknowledgement (ACK)/negative-acknowledgement (NACK) in a time division duplex (TDD)-based wireless communication system, the UE comprising:
 a radio frequency (RF) unit; and 
 a processor operatively connected to the RF unit and configured to:
 receive, from a base station (BS), M downlink subframes in each of a primary serving cell and a secondary serving cell, where M is an integer greater than two, and the M downlink subframes are associated with an uplink subframe n; and 
 transmit, to the BS in the uplink subframe n, an ACK/NACK response for the received M downlink subframes by using one resource selected from four candidate resources based on the received M downlink subframes, 
 wherein, among the four candidate resources,
 a first resource and a second resource are associated with a physical downlink shared channel (PDSCH) received in the primary serving cell or a semi-persistent scheduling release physical downlink control channel (SPS release PDCCH) for releasing semi-persistent scheduling received in the primary serving cell, and 
 a third resource and a fourth resource are associated with a PDSCH received in the secondary serving cell. 
 
 
 
     
     
       10. The UE of  claim 9 , wherein at least one downlink subframe among the M downlink subframes received in the primary serving cell comprises:
 a physical downlink control channel (PDCCH) in which a downlink grant is transmitted by the BS, and 
 the PDSCH received in the primary serving cell corresponding to the PDCCH. 
 
     
     
       11. The UE of  claim 10 , wherein the downlink grant includes a downlink assignment index (DAI) indicating a cumulative number of PDCCHs with an assigned PDSCH transmission. 
     
     
       12. The UE of  claim 11 , wherein, in the M downlink subframes received in the primary serving cell:
 if a PDSCH indicated by a first PDCCH with a DAI value equal to 1 is received, then the first resource is determined based on a first control channel element (CCE) used in transmission of the first PDCCH, or 
 if a first SPS release PDCCH with a DAI value equal to 1 is received, then the first resource is determined based on a first CCE used in transmission of the first SPS release PDCCH, or 
 if a PDSCH indicated by a second PDCCH with a DAI value equal to 2 is received, then the second resource is determined based on a first CCE used in transmission of the second PDCCH, or 
 if a second SPS release PDCCH with a DAI value equal to 2 is received, then the second resource is determined based on a first CCE used in transmission of the second SPS release PDCCH. 
 
     
     
       13. The UE of  claim 11 , wherein, in the M downlink subframes received in the primary serving cell:
 if an SPS PDSCH, which is a PDSCH having no corresponding PDCCH, is received, 
 then the first resource among the four candidate resources has one value determined from four values that are configured by using a higher layer signal, and the determined one value is indicated by an uplink transmit power control field in a PDCCH indicating activation of semi-persistent scheduling. 
 
     
     
       14. The UE of  claim 13 , wherein, in the M downlink subframes received in the primary serving cell:
 if a PDSCH indicated by detecting a first PDCCH with a DAI value equal to 1 is received, then the second resource is determined based on a first CCE used in transmission of the first PDCCH or 
 if a first SPS release PDCCH with a DAI value equal to 1 is received, then the second resource is determined based on a first CCE used in transmission of the first SPS release PDCCH. 
 
     
     
       15. The UE of  claim 11 , wherein
 if a PDSCH, indicated by a third PDCCH with a DAI value equal to 1 received in the M downlink subframes in the primary serving cell, is received in the M downlink subframes in the secondary serving cell, then the third resource is determined based on a first CCE used in transmission of the third PDCCH, or 
 if a PDSCH, indicated by a fourth PDCCH with a DAI value equal to 2 received in the M downlink subframes in the primary serving cell, is received in the M downlink subframes in the secondary serving cell, then the fourth resource is determined based on a first CCE used in transmission of the fourth PDCCH. 
 
     
     
       16. The UE of  claim 11 , wherein
 if
 at least one PDCCH is received in the M downlink subframes received in the secondary serving cell, and 
 a PDSCH indicated by the at least one PDCCH is received in the secondary serving cell: 
 
 then
 the third resource and the fourth resource are have values determined by a higher layer signal, and 
 the third and fourth resources are indicated by an uplink transmission power control (TPC) field included in the at least one PDCCH.