Method and system for precoding data

Abstract

The present disclosure relates to channel state feedback in a communication system. The method includes obtaining a reference signal from an access point; deriving a rank indication, a codebook subset selection indication and a precoding matrix index based on the obtained reference signal; sending a first feedback message conveying the rank indication and the codebook subset selection indication, and sending a second feedback message conveying the precoding matrix index, to the access point; and receiving, from the access point, data precoded by a matrix derived based on the rank indication, the codebook subset selection indication and the precoding matrix index.

What is claimed is: 
     
       1. A non-transitory tangible computer-readable medium having stored thereon, a computer program comprising at least one code section for distributing data, the at least one code section being executable by a machine for causing the machine to perform the following:
 receiving at least one reference signal from a transmitting device; 
 deriving a rank indication, a codebook index n 1  in a first codebook C 1 , and codebook indices k 1  and k 2  in a second codebook C 2  based on the at least one reference signal; 
 sending the rank indication, the codebook index n 1  in the first codebook C 1 , and the codebook indices k 1  and k 2  in the second codebook C 2  to the transmitting device; and 
 receiving data precoded by a first precoder from the transmitting device; 
 wherein the first precoder comprises a second precoder and a third precoder, 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 . 
 
     
     
       2. The non-transitory tangible computer-readable medium according to  claim 1 , wherein the second precoder is a wideband precoder and the third precoder is a subband precoder. 
     
     
       3. The non-transitory tangible computer-readable 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 machine. 
     
     
       4. The non-transitory tangible computer-readable medium according to  claim 1 , wherein sending the rank indication, the codebook index n 1  in the first codebook C 1 , and the codebook indices k 1  and k 2  in the second codebook C 2  to the transmitting device, further comprises:
 sending a first message that contains the rank indication; 
 sending a second message that contains the indices n 1  and k 1 ; and 
 sending a third message that contains the index k 2 . 
 
     
     
       5. The non-transitory tangible computer-readable medium according to  claim 1 , wherein the machine is one of the following: a mobile device, a cellular telephone, a wireless enabled personal digital assistant and a wireless enabled laptop computer. 
     
     
       6. A non-transitory tangible computer-readable medium having stored thereon, a computer program comprising at least one code section for distributing data, the at least one code section being executable by a machine for causing the machine to perform the following:
 receiving a rank indication, a codebook index n 1  in a first codebook C 1 , and codebook indices k 1  and k 2  in a second codebook C 2  from a receiving device; 
 determining a first precoder based on the rank indication, the indices n 1 , k 1  and k 2 ; 
 precoding data to be sent to the receiving device by the first precoder; and 
 sending the precoded data to the receiving device; 
 wherein the first precoder comprises a second precoder and a third precoder, 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 . 
 
     
     
       7. The non-transitory tangible computer-readable medium according to  claim 6 , wherein the second precoder is a wideband precoder and the third precoder is a subband precoder. 
     
     
       8. The non-transitory tangible computer-readable medium according to  claim 6 , 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 
 determining the second precoder W 1  based on W 1 =W n     1     (1) W k     1     (2) ; and 
 wherein determining the third precoder, further 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 n     1     (1) W k     2     (2) . 
 
     
     
       9. The non-transitory tangible computer-readable medium according to  claim 6 , wherein determining the second precoder, further 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 
 determining the second precoder W 1  based on W 1 =W k     1     (2) W n     1     (1) ; and 
 wherein determining the third precoder, further 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) . 
 
     
     
       10. The non-transitory tangible computer-readable medium according to  claim 6 , wherein the first codebook C 1  and the second codebook C 2  are configured in both the machine and the receiving device. 
     
     
       11. The non-transitory tangible computer-readable medium according to  claim 6 , wherein the machine is a base station or an access point.