Method and system for precoding data

1. A method for precoding data in a wireless communication system, comprising:

receiving, by a receiving device, at least one reference signal from a transmitting device;

deriving, by the receiving device, a rank indication, a codebook index n 1 in a first codebook C 1 , codebook indices k 1 and k 2 in a second codebook C 2 , a wideband channel quality indicator CQI 1 and a subband channel quality indicator CQI 2 , based on the at least one reference signal;

sending, by the receiving device, the rank indication, the codebook index n 1 in the first codebook C 1 , the codebook indices k 1 and k 2 in the second codebook C 2 , the wideband channel quality indicator CQI 1 and the subband channel quality indicator CQI 2 , to the transmitting device; and

receiving, by the receiving device, data precoded by a first precoder from the transmitting device,

wherein the first precoder is determined by the transmitting device based on the rank indication and the indices n 1 , k 1 and k 2 .

2. The method according to claim 1 , wherein the first precoder comprises a second precoder and a third precoder, wherein the second precoder is determined based on the indices n 1 and k 1 , and the third precoder is determined based on the indices n 1 and k 2 .

3. The method according to claim 2 , wherein the second precoder is a wideband precoder and the third precoder is a subband precoder.

4. The method according to claim 1 , wherein the first codebook C 1 and the second codebook C 2 are configured in both the transmitting device and the receiving device.

5. The method according to claim 1 , wherein the receiving device sending the rank indication, the codebook index n 1 in the first codebook C 1 , the codebook indices k 1 and k 2 in the second codebook C 2 , the wideband channel quality indicator CQI 1 and the subband channel quality indicator CQI 2 , to the transmitting device comprises:

sending, by the receiving device, a first message that contains the rank indication;

sending, by the receiving device, a second message that contains the indices n 1 and k 1 and the wideband channel quality indicator CQI 1 ; and

sending, by the receiving device, a third message that contains the index k 2 and the subband channel quality indicator CQI 2 .

6. A receiving device, comprising:

a receiver, configured to receive at least one reference signal from a transmitting device;

a processor, configured to derive a rank indication, a codebook index n 1 in a first codebook C 1 , codebook indices k 1 and k 2 in a second codebook C 2 , a wideband channel quality indicator CQI 1 and a subband channel quality indicator CQI 2 , based on the at least one reference signal; and

a transmitter, configured to send the rank indication, the codebook index n 1 in the first codebook C 1 , the codebook indices k 1 and k 2 in the second codebook C 2 , the wideband channel quality indicator CQI 1 and the subband channel quality indicator CQI 2 to the transmitting device;

wherein the receiver is further configured to receive, from the transmitting device, data precoded by a first precoder, and

wherein the first precoder is determined by the transmitting device based on the rank indication and the indices n 1 , k 1 and k 2 .

7. The receiving device according to claim 6 , wherein the receiving device is a user equipment in communication with a network entity in a wireless communication system.

8. The receiving device according to claim 7 , wherein the user equipment is a mobile device, a cellular telephone, a wireless enabled personal digital assistant or a wireless enabled laptop computer, and the network entity is a base station, an evolved NodeB or an access point.

9. The receiving device according to claim 6 , wherein the first precoder comprises a second precoder and a third precoder, wherein the second precoder is determined based on the indices n 1 and k 1 , and the third precoder is determined based on the indices n 1 and k 2 .

10. A method for precoding data in a wireless communication system, comprising:

receiving, by a transmitting device, a rank indication, a codebook index n 1 in a first codebook C 1 , codebook indices k 1 and k 2 in a second codebook C 2 , a wideband channel quality indicator CQI 1 and a subband channel quality indicator CQI 2 from a receiving device;

determining, by the transmitting device, a first precoder based on the rank indication, the indices n 1 , k 1 and k 2 ;

precoding, by the transmitting device, data to be sent to the receiving device by the first precoder; and

sending, by the transmitting device, the precoded data to the receiving device.

11. The method according to claim 10 , wherein the first precoder comprises a second precoder and a third precoder, wherein the second precoder is determined based on the indices n 1 and k 1 , and the third precoder is determined based on the indices n 1 and k 2 .

12. The method according to claim 11 , wherein the second precoder is a wideband precoder and the third precoder is a subband precoder.

13. The method according to claim 11 , wherein determining the second precoder comprises:

determining a matrix W n 1 (1) based on the index n 1 in the first codebook C 1 ;

determining a matrix W k 1 (2) based on the index k 1 in the second codebook C 2 ; and

determine the second precoder W 1 based on W 1 =W n 1 (1) W k 1 (2) ;

and wherein determining the third precoder comprises:

determining a matrix W n 1 (1) based on the index n 1 in the first codebook C 1 ;

determining a matrix W n 1 (2) based on the index k 2 in the second codebook C 2 ; and

determining the third precoder W 2 based on W 2 =W n 1 (1) W k 2 (2) .

14. The method according to claim 11 , wherein determining the second precoder comprises:

determining a matrix W n 1 (1) based on the index n 1 in the first codebook C 1 ;

determining a matrix W k 1 (2) based on the index k 1 in the second codebook C 2 ; and

determine the second precoder W 1 based on W 1 =W k 1 (2) W n 1 (1) ;

and wherein determining the third precoder comprises:

determining a matrix W n 1 (1) based on the index n 1 in the first codebook C 1 ;

determining a matrix W k 2 (2) based on the index k 2 in the second codebook C 2 ; and

determining the third precoder W 2 based on W 2 =W k 2 (2) W n 1 (1) .

15. The method according to claim 10 , wherein the first codebook C 1 and the second codebook C 2 are configured in both the transmitting device and the receiving device.

16. A transmitting device, comprising:

a receiver, configured to receive a rank indication, a codebook index n 1 in a first codebook C 1 , codebook indices k 1 and k 2 in a second codebook C 2 , a wideband channel quality indicator CQI 1 and a subband channel quality indicator CQI 2 from a receiving device;

a processor, configured to determine a first precoder based on the rank indication and the indices n 1 , k 1 and k 2 , and precode data to be sent to the receiving device by the first precoder; and

a transmitter, configured to send the precoded data to the receiving device.

17. The transmitting device according to claim 16 , wherein the first precoder comprises a second precoder and a third precoder, wherein the second precoder is determined based on the indices n 1 and k 1 , and the third precoder is determined based on the indices n 1 and k 2 .

18. The method according to claim 16 , wherein the second precoder is a wideband precoder and the third precoder is a subband precoder.

19. The transmitting device according to claim 16 , wherein the transmitting device is a network entity in communication with a user equipment in a wireless communication system.

20. The transmitting device according to claim 19 , wherein the user equipment is a mobile device, a cellular telephone, a wireless enabled personal digital assistant or a wireless enabled laptop computer, and the network entity is a base station, an evolved NodeB or an access point.