Apparatus and method for transmitting ACK/NACK in TDD system

• US 20110267995A1
• Filed: 04/29/2011
• Published: 11/03/2011
• Est. Priority Date: 04/30/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Ju-Ho, Li, Yingyang
• Granted Patent: US 8,705,413 B2
• Time in Patent Office: Days
• US Class Current: 370/280
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex

Abstract

The present invention provides a method and apparatus for transmitting an ACK/NACK in a TDD system. A component carrier (CC) configuration for a user equipment (UE) and a transmission mode of each CC are received. An ACK/NACK feedback mode is selected based on an overhead status for feedback in an uplink. An ACK/NACK is processed according to the selected feedback mode. And the ACK/NACK is transmitted in the uplink. The method provided by the present invention can avoid excessive overhead for feedback in uplink in various extreme circumstances while ensuring satisfying performances of downlinks under many configurations.

Claims

1. A method for transmitting an acknowledgement indicator (ACK/NACK) in a TDD system, the method comprising:

receiving a component carrier (CC) configuration for a user equipment (UE) and a transmission mode of each CC;

selecting an ACK/NACK feedback mode based on overhead information for feedback in an uplink;

processing an ACK/NACK according to the selected feedback mode; and

transmitting the ACK/NACK in the uplink.

2. The method of claim 1, wherein the selected ACK/NACK feedback mode comprises one of a first ACK/NACK feedback mode and a second ACK/NACK feedback mode,

wherein processing the ACK/NACK according to the first ACK/NACK feedback mode comprises:

performing no bundling procedure for the ACK/NACK, and

directly transmitting one ACK/NACK of each transmission block in the uplink, and

wherein processing the ACK/NACK according to the second ACK/NACK feedback mode comprises;

compressing an ACK/NACK, and

transmitting the compressed ACK/NACK in the uplink.

3. The method of claim 2, wherein compressing an ACK/NACK comprises:

performing bundling on each code word (CW) of an ACK/NACK for data transmitted in up to M sub-frames of a CC, wherein M is a number of sub-frames.

4. The method of claim 2, wherein compressing an ACK/NACK comprises:

obtaining an ACK/NACK by spatially bundling each sub-frame and bundling ACK/NACKs of up to M sub-frames after the spatial bundling, wherein M is a number of sub-frames.

5. The method of claim 1, wherein selecting an ACK/NACK feedback mode comprises:

selecting an ACK/NACK transmission mode based on an M number of sub-frames.

6. The method of claim 1, wherein selecting an ACK/NACK feedback mode comprises:

selecting an ACK/NACK transmission mode based on a number of CCs configured by a base station for the UE to receive.

7. The method of claim 1, wherein selecting an ACK/NACK feedback mode comprises:

selecting an ACK/NACK transmission mode based on a number of transmission blocks (TBs) configured by a base station for the UE to receive.

8. The method of claim 1, wherein selecting an ACK/NACK feedback mode comprises:

determining a maximum number of bits for feeding back an ACK/NACK; and

selecting an ACK/NACK transmission mode based on the maximum number.

9. The method of claim 8, wherein determining the maximum number of bits for feeding back an ACK/NACK comprises determining the number of bits needed for feeding back an ACK/NACK without any bundling.

10. The method of claim 1, wherein selecting an ACK/NACK feedback mode comprises:

selecting an ACK/NACK transmission mode based on a total number of CWs in all CCs received by the UE.

11. An apparatus for transmitting an acknowledgement indicator (ACK/NACK) in a TDD system, the apparatus comprising:

a receiver configured to receive a component carrier (CC) configuration for a user equipment (UE) and a transmission mode of each CC;

a hybrid automatic repeat request (HARQ) controller configured to select an ACK/NACK feedback mode based on overhead information for feedback in an uplink; and

a transmitter configured to process an ACK/NACK according to the selected feedback mode and transmit the ACK/NACK in the uplink.

12. The apparatus of claim 11, wherein the HARQ controller is further configured to:

perform no bundling procedure for the ACK/NACK, and directly feed back an ACK/NACK of each transmission block when a first ACK/NACK feedback mode is selected; and

compress an ACK/NACK such that a number of bits of the ACK/NACK is reduced when a second ACK/NACK feedback mode is selected.

13. The apparatus of claim 12, wherein the transmitter is further configured to, when compressing an ACK/NACK, perform bundling on each code word (CW) of an ACK/NACK for data transmitted in up to M sub-frames of a CC, wherein M is a number of sub-frames.

14. The apparatus of claim 12, wherein the transmitter is further configured to, when compressing an ACK/NACK, obtain an ACK/NACK by spatially bundling each sub-frame and bundling ACK/NACKs of up to M sub-frames after the spatial bundling, wherein M is a number of sub-frames.

15. The apparatus of claim 11, wherein the HARQ controller is further configured to select an ACK/NACK transmission mode based on an M number of sub-frames.

16. The apparatus of claim 11, wherein the HARQ controller is further configured to select an ACK/NACK transmission mode based on a number of CCs configured by a base station for the UE to receive.

17. The apparatus of claim 11, wherein the HARQ controller is further configured to select an ACK/NACK transmission mode based on a number of transmission blocks (TBs) configured by a base station for the UE to receive.

18. The apparatus of claim 11, wherein the HARQ controller is further configured to determine a maximum number of bits for feeding back an ACK/NACK.

19. The apparatus of claim 18, wherein the HARQ controller is further configured to determine the maximum number of bits for feeding back an ACK/NACK without any bundling.

20. The apparatus of claim 11, wherein the HARQ controller is further configured to select an ACK/NACK transmission mode based on a total number of CWs in all CCs received by the UE.