Precoding matrix codebook design and periodic channel state information feedback for advanced wireless communication systems
Channel quality indicator (CQI) and precoding feedback from a user equipment includes reporting of at least a first and a second precoding matrix indicator (PMI). First, second and third indices are determined based upon the first and the second PMI and third and fourth PMI and are employed to select the precoding matrix. The selected precoding matrix includes a first column comprising a first row partition and a second row partition, where the first row partition is a Kronecker product of at least first and second precoding vectors and the second row partition is a Kronecker product of a first term and a second term. The first term is a product of a co-phasing factor and the first precoding vector and the second term is the second precoding vector. The first precoding vector is selected from a first codebook and the second precoding vector is selected from a second codebook.
1. A user equipment, comprising:
a transceiver configured to communicate with at least one base station; and
processing circuitry configured to control the transceiver to:
receive a set of channel state information reference signals (CSI-RS);
estimate channels based on the received CSI-RS;
derive a channel quality indicator (CQI) based on the channel estimates and a precoding matrix; and
report the CQI and at least a first and a second precoding matrix indicator (PMI) i 2V and i 2H ,
wherein at least a first index m, a second index m′, and a third index n are determined based upon the first and the second PMI i 2V and i 2H and a third and a fourth PMI i 1V and i 1H ,
wherein the indices m, m′ and n are employed to select the precoding matrix,
wherein the selected precoding matrix includes a first column comprising a first row partition and a second row partition,
wherein the first row partition is a Kronecker product of at least first and second precoding vectors ν m and ν m′ and the second row partition is a Kronecker product of a first term and a second term, wherein the first term is a product of a co-phasing factor φ n and the first precoding vector ν m and the second term is the second precoding vector ν m′ , and
wherein the first precoding vector ν m is selected from a first codebook and the second precoding vector ν m′ is selected from a second codebook.
2. The user equipment according to claim 1 , wherein the report of the CQI and the PMI is made on a PUCCH and wherein a report prior to the report on the PUCCH includes the third and the fourth PMI i 1V and i 1H .
3. The user equipment according to claim 2 , wherein subsampling of the second PMI i 2H selects even-numbered entries.
4. The user equipment according to claim 2 , wherein subsampling of the second PMI i 2H selects the first half of entries within a set of entries for the second PMI i 2H .
5. The user equipment according to claim 1 , wherein the report of the CQI and the PMI is made on a PUSCH, wherein the report of the CQI and the PMI on the PUSCH is for subband and a report of the third and the fourth PMI i 1V and i 1H on the PUSCH is for wideband.
6. The user equipment according to claim 1 , wherein the precoding matrix indicators relate to a rank-1 precoding matrix w m,m′,n constructed by
w
m
,
m
′
,
n
=
q
[
v
m
⊗
v
m
′
φ
n
v
m
⊗
v
m
′
]
,
where q is a normalizing factor.
7. The user equipment according to claim 1 , wherein the first codebook, from which the precoding vector ν m is selected, is a Discrete Fourier Transform (DFT) codebook having size N 1 that is oversampled with an oversampling factor o 1 and wherein the second codebook, from which the precoding vector ν m′ is selected, is a DFT codebook having size N 2 that is oversampled with an oversampling factor o 2 .
8. The user equipment according to claim 1 , wherein the precoding matrix indicators relate to a rank-2 precoding matrix W m,m′,m″,n (2) constructed by
W
m
,
m
′
,
m
″
,
n
(
2
)
=
q
[
v
m
⊗
v
m
′
v
m
⊗
v
m
″
φ
n
v
m
⊗
v
m
′
-
φ
n
v
m
⊗
v
m
″
]
,
where m″ is a fourth index employed with the indices m, m′ and n to select the rank-2 precoding matrix, ν m″ is a third precoding vector selected from the second codebook, and q is a normalizing factor.
9. The user equipment according to claim 1 , wherein the first index m is a function of the first PMI i 2V the third PMI i 1V , the second index m′ is a function of the second PMI i 2H and the fourth PMI i 1H , and the third index n is a function of the second PMI i 2H .
10. A base station, comprising:
a transceiver configured to communicate with at least one user equipment; and
processing circuitry configured to control the transceiver to:
transmit a set of channel state information reference signals (CSI-RS); and
receive a report of a channel quality indicator (CQI) and at least a first and a second precoding matrix indicator (PMI) i 2V and i 2H , the CQI derived based on channel estimates and a precoding matrix and the channel estimates estimated based on the CSI-RS,
wherein at least a first index m, a second index m′, and a third index n are determined based upon the first and the second PMI i 2V and i 2H and a third and a fourth PMI i 1V and i 1H ,
wherein the indices m, m′ and n are employed to select the precoding matrix,
wherein the selected precoding matrix includes a first column comprising a first row partition and a second row partition,
wherein the first row partition is a Kronecker product of at least first and second precoding vectors ν m and ν m′ and the second row partition is a Kronecker product of a first term and a second term, wherein the first term is a product of a co-phasing factor φ n and the first precoding vector ν m and the second term is the second precoding vector ν m′ , and
wherein the first precoding vector ν m is selected from a first codebook and the second precoding vector ν m′ is selected from a second codebook.
11. The base station according to claim 10 , wherein the report of the CQI and the PMI is made on a PUCCH and wherein a report prior to the report on the PUCCH includes the third and the fourth PMI i 1V and i 1H .
12. The base station according to claim 11 , wherein subsampling of the second PMI i 2H selects even-numbered entries.
13. The base station according to claim 10 , wherein subsampling of the second PMI i 2H selects the first half of entries within a set of entries for the second PMI i 2H .
14. The base station according to claim 10 , wherein the report of the CQI and the PMI is made on a PUSCH, wherein the report of the CQI and the PMI on the PUSCH is for subband and a report of the third and the fourth PMI i 1V and i 1H on the PUSCH is for wideband.
15. The base station according to claim 10 , wherein the precoding matrix indicators relate to a rank-1 precoding matrix w m,m′,n constructed by
w
m
,
m
′
,
n
=
q
[
v
m
⊗
v
m
′
φ
n
v
m
⊗
v
m
′
]
,
where q is a normalizing factor.
16. The base station according to claim 10 , wherein the first codebook, from which the precoding vector ν m is selected, is a Discrete Fourier Transform (DFT) codebook having size N 1 that is oversampled with an oversampling factor o 1 and wherein the second codebook, from which the precoding vector ν m′ is selected, is a DFT codebook having size N 2 that is oversampled with an oversampling factor o 2 .
17. The base station according to claim 10 , wherein the precoding matrix indicators relate to a rank-2 precoding matrix W m,m′,m″,n (2) constructed by
W
m
,
m
′
,
m
″
,
n
(
2
)
=
q
[
v
m
⊗
v
m
′
v
m
⊗
v
m
″
φ
n
v
m
⊗
v
m
′
-
φ
n
v
m
⊗
v
m
″
]
,
where m″ is a fourth index employed with the indices m, m′ and n to select the rank-2 precoding matrix, ν m″ is a third precoding vector selected from the second codebook, and q is a normalizing factor.
18. The base station according to claim 10 , wherein the first index m is a function of the first PMI i 2V the third PMI i 1V , the second index m′ is a function of the second PMI i 2H and the fourth PMI i 1H , and the third index n is a function of the second PMI i 2H .
19. A method, comprising:
transmitting, from a base station, a set of channel state information reference signals (CSI-RS); and
receiving, at the base station, a report from a user equipment of a channel quality indicator (CQI) and at least a first and a second precoding matrix indicator (PMI) i 2V and i 2H , the CQI derived based on channel estimates and a precoding matrix and the channel estimates estimated based on the CSI-RS,
wherein at least a first index m, a second index m′, and a third index n are determined based upon the first and the second PMI i 2V and i 2H and a third and a fourth PMI i 1V and i 1H ,
wherein the indices m, m′ and n are employed to select the precoding matrix,
wherein the selected precoding matrix includes a first column comprising a first row partition and a second row partition,
wherein the first row partition is a Kronecker product of at least first and second precoding vectors ν m and ν m′ and the second row partition is a Kronecker product of a first term and a second term, wherein the first term is a product of a co-phasing factor φ n and the first precoding vector ν m and the second term is the second precoding vector ν m′ , and
wherein the first precoding vector ν m is selected from a first codebook and the second precoding vector ν m′ is selected from a second codebook.
20. The method according to claim 19 , wherein the report of the CQI and the PMI is made on a PUCCH and wherein a report prior to the report on the PUCCH includes the third and the fourth PMI i 1V and i 1H .