Linear combination codebook for CSI reporting in advanced wireless communication systems
A method of a user equipment (UE) for a channel state information (CSI) feedback in an advanced communication system. The method comprises receiving, from a base station (BS), CSI feedback configuration information for a pre-coding matrix indicator (PMI) feedback based on a linear combination (LC) codebook, wherein the PMI comprises a first PMI (i 1 ) and a second PMI (i 2 ), determining the first PMI (i 1 ) and the second PMI (i 2 ) indicating an LC pre-coder that corresponds to a weighted linear combination of a first beam and a second beam, wherein the first PMI (i 1 ) includes a first beam indicator (i 1,1 , i 1,2 ) and a second beam indicator (i 1,3 ) that indicate the first beam and a distance (d 1 , d 2 ) of the second beam in accordance with the first beam, respectively; and the second PMI (i 2 ) indicates weights assigned to the first beam and the second beam. The method further comprises transmitting, to the BS, the CSI feedback over an uplink channel including the determined first PMI (i 1 ) and the second PMI (i 2 ).
1. A user equipment (UE) for a channel state information (CSI) feedback in an advanced communication system, the UE comprises:
a transceiver configured to receive, from a base station (BS), CSI feedback configuration information for a pre-coding matrix indicator (PMI) feedback based on a linear combination (LC) codebook, wherein the PMI comprises a first PMI value (i 1 ) and a second PMI value (i 2 ); and
at least one processor configured to determine the first PMI value (i 1 ) and the second PMI value (i 2 ) indicating an LC pre-coder that corresponds to a weighted linear combination of a first beam and a second beam, wherein:
the first PMI value (i 1 ) includes a first beam indicator (i 1,1 , i 1,2 ) that indicates the first beam in a first dimension and a second dimension, respectively, and a second beam indicator (i 1,3 ) that indicates a distance (d 1 , d 2 ) of the second beam relative to the first beam in the first and second dimensions, respectively; and
the second PMI value (i 2 ) indicates weights assigned to the first beam and the second beam; and wherein
the transceiver is further configured to transmit, to the BS, the CSI feedback over an uplink channel including the first PMI value (i 1 ) and the second PMI value (i 2 ).
2. The UE of claim 1 , wherein the first PMI value (i 1 ) includes a relative power indicator (RPI) (I p ) indicating a power of a weight assigned to the second beam relative to a power of a weight assigned to the first beam, wherein the power of the weight assigned to the first beam is set to 1 and the power of the weight assigned to the second beam is set to a value among {0, √{square root over (1/4)}, √{square root over (1/2)}, 1} {0, √{square root over (1/4)}, √{square root over (1/2)}, 1}, and wherein a first index value (i 1,1 ) and a second index value (i 1,2 ) indicate an index of the first beam in a first dimension and a second dimension, respectively, and a first distance value (d 1 ) and a second distance value (d 2 ) indicate a distance of the second beam from the first beam in the first dimension and the second dimension, respectively.
3. The UE of claim 1 , wherein the first beam and the second beam correspond to two discrete Fourier transform (DFT) beams selected from an oversampled DFT codebook comprising DFT beams:
v
l
1
,
l
2
=
[
u
l
2
e
j
2
π
l
O
1
N
1
u
l
2
…
e
j
2
π
l
1
(
N
1
-
1
)
O
1
N
1
u
l
2
]
T
,
u
l
2
=
1
if
N
2
=
1
;
u
l
2
=
[
1
e
j
2
π
l
2
O
2
N
2
…
e
j
2
π
l
2
(
N
2
-
1
)
O
2
N
2
]
otherwise
,
0
≤
l
1
≤
O
1
N
1
-
1
,
and
0
≤
l
2
≤
O
2
N
2
-
1
,
where N 1 and N 2 indicate a first and a second number of antenna ports in the first and the second dimensions, respectively, and O 1 and O 2 indicate a first and a second oversampling factors in the first and second dimensions, respectively,
wherein the distance (d 1 , d 2 ) of the second beam relative to a first beam index indicated by the first beam indicator (i 1,1 , i 1,2 ) is such that a first distance value (d 1 ) belongs to a set of integers {0, 1, . . . , L−1} and a second distance value (d 2 ) belongs to a set of integers {0, 1, . . . , L 2 −1}, respectively; and
wherein a beam group size (L 1 , L 2 ) is determined by:
N 1 ≥N 2 >1: L 1 =min( N 1 ,4), L 2 =2;
N 2 >N 1 >1: L 2 =min( N 2 ,4), L 1 =2; and
N 2 =1: L 1 =min( N 1 ,8), L 2 =1.
4. The UE of claim 3 , wherein a second beam index (k 1 (1) ,k 2 (1) ) is determined by:
k 1 (1) =k 1 (0) +O 1 d 1 ,k 2 (1) =k 2 (0) +O 2 d 2 ,
where the (d 1 , d 2 ) is such that the (d 1 ) belongs to a set of integers {0, 1, . . . , min(N 1 ,L 1 )−1}, the (d 2 ) belongs to a set of integers {0, 1, . . . , min(N 2 , L 2 )−1}, and (d 1 , d 2 )≠(0,0).
5. The UE of claim 1 , wherein the at least one processor is further configured to map between the second beam indicator (i 1,3 ) and the distance (d 1 , d 2 ) of the second beam based on a table given by:
N 1 ≥ N 2 ,
N 2 > N 1 ,
N 1 ≥ 4,
N 1 = 3,
N 1 = 2,
N 2 ≥ 4,
N 2 = 3,
N 1 ≥ 8
N 1 = 2,
N 1 = 4,
N 2 ≠ 1
N 2 = 2
N 2 = 2
N 1 ≠ 1
N 1 = 2
N 2 = 1
N 2 = 1
N 2 = 1
Value of i 1,3
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
0
1
0
1
0
1
0
0
1
0
1
1
0
1
0
1
0
1
2
0
2
0
0
1
0
2
0
2
2
0
2
0
2
3
0
0
1
1
1
0
3
1
0
3
0
3
0
3
0
1
1
1
1
0
1
1
4
0
4
1
1
2
1
1
1
1
2
5
0
5
2
1
1
2
6
0
6
3
1
1
3
7
0.
6. The UE of claim 1 , wherein the at least one processor is further configured to at least one of:
report a single wideband (WB) bit stream that indicates three components jointly, the (i 1,1 , i 1,2 ) indicating the first beam, the (i 1,3 ) indicating the distance (d 1 , d 2 ) of the second beam from the first beam, and the (I p ) indicating a power of the weight assigned to the second beam; or
report multiple WB bit streams that indicate three components separately, a first bit stream for the (i 1,1 , i 1,2 ) indicating the first beam, and either a second bit stream jointly indicating the (i 1,3 ) and the (I p ) for the second beam or a second bit stream and a third bit stream separately indicating the (i 1,3 ) and the (I p ) for the second beam, respectively.
7. The UE of claim 1 , wherein the at least one processor is further configured to separate the distance (d 1 , d 2 ) of the second beam in accordance with a PMI (i 1,1-2 , i 1,2-2 ), wherein the (d 1 ) of the distance (d 1 , d 2 ) corresponds to a (i 1,1-2 ) of the PMI (i 1,1-2 , i 1,2-2 ) and the (d 2 ) of the distance (d 1 , d 2 ) corresponds to a (i 1,2-2 ) of the PMI (i 1,1-2 , i 1,2-2 ), and wherein if one PMI (i 3 ) or (i 1,1-2 , i 1,2-2 ) is reported to the BS, a bit width for the PMI is determined by ┌log 2 (L 1 L 2 )┐ and if two PMIs, (i 1,1-2 ) and (i 1,2-2 ), are reported to the BS, bit widths for the two PMIs are determined by ┌log 2 (L 1 )┐ and ┌log 2 (L 2 )┐, respectively.
8. A base station (BS) for a channel state information (CSI) feedback in an advanced communication system, the BS comprises:
a transceiver configured to:
transmit, to a user equipment (UE), CSI feedback configuration information for a pre-coding matrix indicator (PMI) feedback based on a linear combination (LC) codebook, wherein the PMI comprises a first PMI value (i 1 ) and a second PMI value (i 2 ), wherein:
the first PMI value (i 1 ) and the second PMI value (i 2 ) indicate an LC pre-coder that corresponds to a weighted linear combination of a first beam and a second beam;
the first PMI value (i 1 ) includes a first beam indicator (i 1,1 , i 1,2 ) that indicates the first beam in a first dimension and a second dimension, respectively, and a second beam indicator (i 1,3 ) that indicates a distance (d 1 , d 2 ) of the second beam relative to the first beam in the first and second dimensions, respectively; and
the second PMI value (i 2 ) indicates weights assigned to the first beam and the second beam; and
receive, from the UE, the CSI feedback over an uplink channel including the first PMI value (i 1 ) and the second PMI value (i 2 ).
9. The BS of claim 8 , wherein the first PMI (i 1 ) includes a relative power indicator (RPI) (I p ) indicating a power of a weight assigned to the second beam relative to a power of a weight assigned to the first beam, wherein the power of the weight assigned to the first beam is set to 1 and the power of the weight assigned to the second beam is set to a value among {0, √{square root over (1/4)}, √{square root over (1/2)}, 1}, and wherein a first index value (i 1,1 ) and a second index value (i 1,2 ) indicate an index of the first beam in a first dimension and a second dimension, respectively, and a first distance value (d 1 ) and a second distance value (d 2 ) indicate a distance of the second beam from the first beam in the first dimension and the second dimension, respectively.
10. The BS of claim 8 , wherein the first beam and the second beam correspond to two discrete Fourier transform (DFT) beams selected from an oversampled DFT codebook comprising DFT beams:
v
l
1
,
l
2
=
[
u
l
2
e
j
2
π
l
O
1
N
1
u
l
2
…
e
j
2
π
l
1
(
N
1
-
1
)
O
1
N
1
u
l
2
]
T
,
u
l
2
=
1
if
N
2
=
1
;
u
l
2
=
[
1
e
j
2
π
l
2
O
2
N
2
…
e
j
2
π
l
2
(
N
2
-
1
)
O
2
N
2
]
otherwise
,
0
≤
l
1
≤
O
1
N
1
-
1
,
and
0
≤
l
2
≤
O
2
N
2
-
1
,
where N 1 and N 2 indicate a first and a second number of antenna ports in the first and the second dimensions, respectively, and O 1 and O 2 indicate a first and a second oversampling factors in the first and second dimensions, respectively,
the distance (d 1 , d 2 ) of the second beam relative to a first beam index indicated by the first beam indicator (i 1,1 , i 1,2 ) is such that a first distance value (d 1 ) belongs to a set of integers {0, 1, . . . , L 1 −1} and a second distance value (d 2 ) belongs to a set of integers {0, 1, . . . , L 2 −1}, respectively, and
wherein a beam group size (L 1 , L 2 ) is determined by:
N 1 ≥N 2 >1: L 1 =min( N 1 ,4), L 2 =2;
N 2 >N 1 >1: L 2 =min( N 2 ,4), L 1 =2; and
N 2 =1: L 1 =min( N 1 ,8), L 2 =1.
11. The BS of claim 10 , wherein a second beam index (k 1 (1) ,k 2 (1) ) is determined by:
k 1 (1) =k 1 (0) +O 1 d 1 ,k 2 (1) =k 2 (0) +O 2 d 2 ,
where the (d 1 , d 2 ) is such that the (d 1 ) belongs to a set of integers {0, 1 . . . , min(N 1 ,L 1 )−1}, the (d 2 ) belongs to a set of integers {0, 1, . . . , min(N 2 , L 2 )−1}, and (d 1 , d 2 )≠(0,0).
12. The BS of claim 8 , wherein the second beam indicator (i 1,3 ) and the distance (d 1 , d 2 ) of the second beam are mapped based on a table given by:
N 1 ≥ N 2 ,
N 2 > N 1 ,
N 1 ≥ 4,
N 1 = 3,
N 1 = 2,
N 2 ≥ 4,
N 2 = 3,
N 1 ≥ 8
N 1 = 2,
N 1 = 4,
N 2 ≠ 1
N 2 = 2
N 2 = 2
N 1 ≠ 1
N 1 = 2
N 2 = 1
N 2 = 1
N 2 = 1
Value of i 1,3
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
0
1
0
1
0
1
0
0
1
0
1
1
0
1
0
1
0
1
2
0
2
0
0
1
0
2
0
2
2
0
2
0
2
3
0
0
1
1
1
0
3
1
0
3
0
3
0
3
0
1
1
1
1
0
1
1
4
0
4
1
1
2
1
1
1
1
2
5
0
5
2
1
1
2
6
0
6
3
1
1
3
7
0.
13. The BS of claim 8 , wherein the transceiver is further configured to at least one of:
receive a single wideband (WB) bit stream that indicates three components jointly, the (i 1,1 , i 1,2 ) indicating the first beam, the (i 1,3 ) indicating the distance (d 1 , d 2 ) of the second beam from the first beam, and the (I p ) indicating a power of the weight assigned to the second beam; or
receive multiple WB bit streams that indicate three components separately, a first bit stream for the (i 1,1 , i 1,2 ) indicating the first beam, and either a second bit stream jointly indicating the (i 1,3 ) and the (I p ) for the second beam or a second bit stream and a third bit stream separately indicating the (i 1,3 ) and the (I p ) for the second beam, respectively.
14. A method of a user equipment (UE) for a channel state information (CSI) feedback in an advanced communication system, the method comprising:
receiving, from a base station (BS), CSI feedback configuration information for a pre-coding matrix indicator (PMI) feedback based on a linear combination (LC) codebook, wherein the PMI comprises a first PMI value (i 1 ) and a second PMI value (i 2 );
determining the first PMI value (i 1 ) and the second PMI value (i 2 ) indicating an LC pre-coder that corresponds to a weighted linear combination of a first beam and a second beam, wherein:
the first PMI value (i 1 ) includes a first beam indicator (i 1,1 , i 1,2 ) that indicates the first beam in a first dimension and a second dimension, respectively, and a second beam indicator (i 1,3 ) that indicates a distance (d 1 , d 2 ) of the second beam relative to the first beam in the first and second dimensions, respectively; and
the second PMI value (i 2 ) indicates weights assigned to the first beam and the second beam; and
transmitting, to the BS, the CSI feedback over an uplink channel including the determined first PMI value (i 1 ) and the second PMI value (i 2 ).
15. The method of claim 14 , wherein the first PMI (i 1 ) includes a relative power indicator (RPI) indicating a power of a weight assigned to the second beam relative to a power of a weight assigned to the first beam, and wherein the power of the weight assigned to the first beam is set to 1 and the power of the weight assigned to the second beam is set to a value among {0, √{square root over (1/4)}, √{square root over (1/2)}, 1}, and wherein a first index value (i 1,1 ) and a second index value (i 1,2 ) indicate an index of the first beam in a first dimension and a second dimension, respectively, and a first distance value (d 1 ) and a second distance value (d 2 ) indicate a distance of the second beam from the first beam in the first dimension and the second dimension, respectively.
16. The method of claim 14 , wherein the first beam and the second beam correspond to two discrete Fourier transform (DFT) beams selected from an oversampled DFT codebook comprising DFT beams:
v
l
1
,
l
2
=
[
u
l
2
e
j
2
π
l
O
1
N
1
u
l
2
…
e
j
2
π
l
1
(
N
1
-
1
)
O
1
N
1
u
l
2
]
T
,
u
l
2
=
1
if
N
2
=
1
;
u
l
2
=
[
1
e
j
2
π
l
2
O
2
N
2
…
e
j
2
π
l
2
(
N
2
-
1
)
O
2
N
2
]
otherwise
,
0
≤
l
1
≤
O
1
N
1
-
1
,
and
0
≤
l
2
≤
O
2
N
2
-
1
,
where N 1 and N 2 indicate a first and a second number of antenna ports in the first and the second dimensions, respectively, and O 1 and O 2 indicate a first and a second oversampling factors in the first and second dimensions, respectively,
the distance (d 1 , d 2 ) of the second beam relative to a first beam index indicated by the first beam indicator (i 1,1 , i 1,2 ) is such that a first distance value (d 1 ) belongs to a set of integers {0, 1, . . . , L 1 −1} and a second distance value (d 2 ) belongs to a set of integers {0, 1, . . . , L 2 −1}, respectively, and
where a beam group size (L 1 , L 2 ) is determined by:
N 1 ≥N 2 >1: L 1 =min( N 1 ,4), L 2 =2;
N 2 >N 1 >1: L 2 =min( N 2 ,4), L 1 =2; and
N 2 =1: L 1 =min( N 1 ,8), L 2 =1.
17. The method of claim 16 , wherein a second beam index (k 1 (1) ,k 2 (1) ) is determined by:
k 1 (1) =k 1 (0) +O 1 d 1 ,k 2 (1) =k 2 (0) +O 2 d 2 ,
where the (d 1 , d 2 ) is such that the (d 1 ) belongs to a set of integers {0, 1, . . . , min(N 1 ,L 1 )−1}, the (d 2 ) belongs to a set of integers {0, 1, . . . , min(N 2 , L 2 )−1}, and (d 1 , d 2 )≠(0,0).
18. The method of claim 14 , further comprising mapping between the second beam indicator (i 1,3 ) and the distance (d 1 , d 2 ) of the second beam based on a table given by:
N 1 ≥ N 2 ,
N 2 > N 1 ,
N 1 ≥ 4,
N 1 = 3,
N 1 = 2,
N 2 ≥ 4,
N 2 = 3,
N 1 ≥ 8
N 1 = 2,
N 1 = 4,
N 2 ≠ 1
N 2 = 2
N 2 = 2
N 1 ≠ 1
N 1 = 2
N 2 = 1
N 2 = 1
N 2 = 1
Value of i 1,3
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
d 1
d 2
0
1
0
1
0
1
0
0
1
0
1
1
0
1
0
1
0
1
2
0
2
0
0
1
0
2
0
2
2
0
2
0
2
3
0
0
1
1
1
0
3
1
0
3
0
3
0
3
0
1
1
1
1
0
1
1
4
0
4
1
1
2
1
1
1
1
2
5
0
5
2
1
1
2
6
0
6
3
1
1
3
7
0.
19. The method of claim 14 , further comprising at least one of:
reporting a single wideband (WB) bit stream that indicates three components jointly, the (i 1,1 , i 1,2 ) indicating the first beam, the (i 1,3 ) indicating the distance (d 1 , d 2 ) of the second beam from the first beam, and the (I p ) indicating a power of the weight assigned to the second beam; or
reporting multiple WB bit streams that indicate three components separately, a first bit stream for the (i 1,1 , i 1,2 ) indicating the first beam, and either a second bit stream jointly indicating the (i 1,3 ) and the (I p ) for the second beam or a second bit stream and a third bit stream separately indicating the (i 1,3 ) and the (I p ) for the second beam, respectively.
20. The method of claim 14 , further comprising separating the distance (d 1 , d 2 ) of the second beam in accordance with a PMI (i 1,1-2 , i 1,2-2 ), wherein the (d 1 ) of the distance (d 1 , d 2 ) corresponds to a (i 1,1-2 ) of the PMI (i 1,1-2 , i 1,2-2 ) and the (d 2 ) of the distance (d 1 , d 2 ) corresponds to a (i 1,2-2 ) of the PMI (i 1,1-2 , i 1,2-2 ), and wherein if one PMI (i 3 ) or (i 1,1-2 , i 1,2-2 ) is reported to the BS, a bit width for the PMI is determined by ┌log 2 (L 1 L 2 )┐ and if two PMIs, (i 1,1-2 ) and (i 1,2-2 ), are reported to the BS, bit widths for the two PMIs are determined by ┌log 2 (L 1 )┐ and ┌log 2 (L 2 )┐, respectively.