Reporting of channel state information
A mobile station is connected to a multi-carrier cellular communication system having a plurality of sub-carriers. The sub-carriers are classified into K frequency sub-bands, channel state information (CSI) of the frequency sub-bands is represented by matrices W i (i=0 . . . K−1), where K is an integer grater than 1. The mobile station determines a first sub-index k 1 for the K matrices W i (i=0 . . . K−1), and a second sub-index k 2 for each one of the K matrices W i (i=0 . . . K−1). The first sub-index k 1 is common for all frequency sub-bands, and the second sub-index k 2 is specific for the indexed matrix that corresponds to one frequency sub-band. The mobile station reports to a base station of the multi-carrier cellular communication system the first sub-index k 1 and at least one second sub-index k 2 .
1. A mobile station, comprising:
a transceiver configured to communicate in a multi-carrier cellular communication system having a plurality of sub-carriers divided into K frequency sub-bands, wherein K precoding matrix indicators (PMIs) of the K frequency sub-bands represent K matrices W i , where K is an integer greater than 1 and i is an integer between 0 and K−1; and
a processor, coupled to the transceiver, configured to determine the K matrices W i for the K frequency sub-bands, determine a first sub-index k 1 for the K matrices W i , determine a second sub-indices k 2 for each of the K matrices W i , and instruct the transceiver to report, to a base station, the first sub-index k 1 and at least one second sub-index k 2 of the K second sub-indices k 2 , wherein the first sub-index k 1 is common for all of the K frequency sub-bands, and each of the K second sub-indices k 2 is specific for a matrix that corresponds to one frequency sub-band of the K frequency sub-bands, each of the K matrices is indexed by the first sub-index k 1 and one of the K second sub-indices k 2 , and each of K PMIs consisting of the first sub-index k 1 and one of the K second sub-indices k 2 .
2. The mobile station according to claim 1 , wherein each one of the K matrices W i comprises a first sub-matrix and a second sub-matrix,
the first sub-index k 1 indicates the first sub-matrix from a first sub-codebook; and
the second sub-index k 2 indicates the second sub-matrix from a second sub-codebook.
3. The mobile station according to claim 2 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
1
M
k
2
i
]
,
where M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
4. The mobile station according to claim 2 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
2
i
M
k
1
]
,
where M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
5. The mobile station according to claim 2 , wherein each one of the K matrices W i is given by:
W i =M k 2 i M k 1 or W i =M k 1 M k 2 i ,
where M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
6. The mobile station according to claim 1 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
1
e
j
d
k
2
]
,
where M k 1 is a matrix, and d k 2 is a scalar.
7. The mobile station according to claim 1 , wherein the multi-carrier cellular communication system is a long term evolution (LTE) system or a long term evolution advanced (LTE-A) system.
8. The mobile station according to claim 1 , wherein the K matrices W i are used as precoding matrices in the multi-carrier cellular communication system.
9. An apparatus in a mobile station, comprising:
a storage medium including executable instructions; and
a processor;
wherein the mobile station communicates with a base station in a multi-carrier cellular communication system having a plurality of sub-carriers divided into K frequency sub-bands, wherein K precoding matrix indicators (PMIs) of the K frequency sub-bands represent K matrices W i , where K is an integer greater than 1, and i is an integer between 0 and K−1;
wherein the executable instructions, when executed by the processor, cause the apparatus to determine the K matrices W i for the K frequency sub-bands, determine a first sub-index k 1 for the K matrices W i , determine a second sub-indices k 2 for each of the K matrices W i , and instruct a transceiver to report, to the base station, the first sub-index k 1 and at least one second sub-index k 2 of the K second sub-indices k 2 , wherein the first sub-index k 1 is common for all of the K frequency sub-bands, and each of the K second sub-indices k 2 is specific for a matrix that corresponds to one frequency sub-band of the K frequency sub-bands, each of the K matrices is indexed by the first sub-index k 1 and one of the K second sub-indices k 2 , and each of K PMIs consisting of the first sub-index k 1 and one of the K second sub-indices k 2 .
10. The apparatus according to claim 9 , wherein each one of the K matrices W i comprises a first sub-matrix and a second sub-matrix,
the first sub-index k 1 indicates the first sub-matrix from a first sub-codebook; and
the second sub-index k 2 indicates the second sub-matrix from a second sub-codebook.
11. The apparatus according to claim 10 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
1
M
k
2
i
]
,
where M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
12. The apparatus according to claim 10 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
2
i
M
k
1
]
,
where M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
13. The apparatus according to claim 10 , wherein each one of the K matrices W i is given by:
W i =M k 2 i M k 1 or W i =M k 1 M k 2 i ,
where M k i is the first sub-matrix, and M k 2 i is the second sub-matrix.
14. The apparatus according to claim 10 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
1
e
j
d
k
2
]
,
where M k 1 is a matrix, and d k 2 is a scalar.
15. The apparatus according to claim 9 , wherein the K matrices W i are used as precoding matrices in the multi-carrier cellular communication system.
16. A method performed by a mobile station, comprising:
determining, by a processor of the mobile station, K matrices W i for K frequency sub-bands, wherein the mobile station communicates with a multi-carrier cellular communication system having a plurality of sub-carriers divided into the K frequency sub-bands, wherein K precoding matrix indicators PMIs of the K frequency sub-bands represent matrices W i , where K is an integer greater than 1, and i is an integer between 0 and K−1;
determining, by the processor of the mobile station, a first sub-index k 1 for the K matrices W i and K second sub-indices k 2 , wherein each of the K second sub-indices k 2 is for one of the K matrices W i ; and
reporting, by a transceiver of the mobile station to a base station, the first sub-index k 1 and at least one of the K second sub-indices k 2 , wherein the first sub-index k 1 is common for all of the K frequency sub-bands, and each of the K second sub-indices k 2 is specific for a matrix that corresponds to one frequency sub-band of the K frequency sub-bands, each of the K matrices is indexed by the first sub-index k 1 and one of the K second sub-indices k 2 , and each of K PMIs consisting of the first sub-index k 1 and one of the K second sub-indices k 2 .
17. The method according to claim 16 , wherein each one of the K matrices W i comprises a first sub-matrix and a second sub-matrix,
the first sub-index k 1 indicates the first sub-matrix from a first sub-codebook; and
the second sub-index k 2 indicates the second sub-matrix from a second sub-codebook.
18. The method according to claim 17 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
1
M
k
2
i
]
,
where M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
19. The method according to claim 17 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
2
i
M
k
1
]
,
where W i is the i th matrix, M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
20. The method according to claim 17 , wherein each one of the K matrices W i is given by:
W i =M k 2 i M k 1 or W i =M k 1 M k 2 i ,
where M k 1 is the first sub-matrix, and M k 2 i is the second sub-matrix.
21. The method according to claim 17 , wherein each one of the K matrices W i is given by:
W
i
=
[
M
k
1
M
k
1
e
j
d
k
2
]
,
where M k 1 is a matrix, and d k 2 is a scalar.
22. The method according to claim 16 , wherein the multi-carrier cellular communication system is a long term evolution (LTE) system or a long term evolution advanced (LTE-A) system.
23. The method according to claim 16 , wherein the K matrices W i are used as precoding matrices in the multi-carrier cellular communication system.