Method and system for precoding data
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.
1. A non-transitory machine readable storage 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 acts of:
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 , 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 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 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 non-transitory machine readable storage medium 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 non-transitory machine readable storage medium according to claim 2 , wherein
the second precoder is a wideband precoder and the third precoder is a subband precoder.
4. The non-transitory machine readable storage medium 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.
5. The non-transitory machine readable storage medium according to claim 1 , wherein the at least one code section being executable by the machine for causing the machine to perform the act of 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:
the at least one code section being executable by the machine for causing the machine to perform the acts of:
sending a first message that contains the rank indication;
sending a second message that contains the indices n 1 and k 1 and the wideband channel quality indicator CQI 1 ; and
sending a third message that contains the index k 2 and the subband channel quality indicator CQI 2 .
6. The non-transitory machine readable storage 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.
7. A non-transitory machine readable storage 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 acts of:
receiving 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 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.
8. The non-transitory machine readable storage medium according to claim 7 , 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 .
9. The non-transitory machine readable storage medium according to claim 8 , wherein
the second precoder is a wideband precoder and the third precoder is a subband precoder.
10. The non-transitory machine readable storage medium according to claim 8 , wherein the at least one code section being executable by the machine for causing the machine to perform the act of determining the second precoder, comprises:
the at least one code section being executable by the machine for causing the machine to perform the act of:
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 the at least one code section being executable by the machine for causing the machine to perform the act of determining the third precoder, comprises:
the at least one code section being executable by the machine for causing the machine to perform the act of:
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) .
11. The non-transitory machine readable storage medium according to claim 8 , wherein the at least one code section being executable by the machine for causing the machine to perform the act of determining the second precoder, comprises:
the at least one code section being executable by the machine for causing the machine to perform the act of:
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 the at least one code section being executable by the machine for causing the machine to perform the act of determining the third precoder, comprises:
the at least one code section being executable by the machine for causing the machine to perform the act of:
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) .
12. The non-transitory machine readable storage medium according to claim 7 , wherein the first codebook C 1 and the second codebook C 2 are configured in both the machine and the receiving device.
13. The non-transitory machine readable storage medium according to claim 7 , wherein the machine is a base station or an access point.