Linear combination PMI codebook based CSI reporting in advanced wireless communication systems
A method 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 . The method further comprises determining, by a user equipment (UE), 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, where a power of a weight assigned to the first beam is 1 and a power of a weight assigned to the second beam is between 0 and 1 and transmitting, to the BS, the CSI feedback over an uplink channel including the determined first PMI i 1 and second PMI i 2 .
1. A user equipment (UE) for a channel state information (CSI) feedback in an advanced communication system, the UE comprising:
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 i 1 and a second PMI i 2; and
at least one processor configured to determine 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 a power of a weight assigned to the first beam is 1 and a power of a weight assigned to the second beam is between 0 and 1,
wherein the transceiver is further configure to transmit, to the BS, the CSI feedback over an uplink channel including the determined first PMI i 1 and second PMI i 2.
2. The UE of claim 1 , wherein:
the CSI feedback configuration information includes a number of dual-polarized CSI reference signal (CSI-RS) antenna ports P, wherein a first half of the CSI-RS antenna ports corresponds to a first antenna polarization and a second half of the CSI-RS antenna ports corresponds to a second antenna polarization,
the LC pre-coder corresponding to a weighted linear combination of the first beam, v l,m , and the second beam, v l+l′,m+m′ , is determined as:
W
l
,
m
,
l
′
,
m
′
,
p
,
n
1
,
n
2
,
n
3
(
l
)
=
1
P
(
1
+
p
2
)
[
v
l
,
m
+
p
φ
n
1
v
l
+
l
′
,
m
+
m
′
φ
n
2
(
v
l
,
m
+
p
φ
n
3
v
l
+
l
′
,
m
+
m
′
)
]
,
p denotes the power of the weight assigned to the second beam, φ n 1 denotes a phase of the weight assigned to the second beam for the first half of the CSI-RS ports with the first polarization, and φ n 2 and φ n 3 denote a phase of the weights assigned to the first and second beams, respectively, for the second half of the CSI-RS ports with the second polarization.
3. The UE of claim 1 , wherein the LC codebook is a single codebook and used to report the CSI feedback for a plurality of layers.
4. The UE of claim 2 , wherein:
the transceiver is further configured to receive, from the BS, dual polarized CSI-RS port layout values comprising (N 1 , N 2 ) using a higher layer signaling that determines a number of CSI-RS ports P=2N 1 N 2 ;
the at least one processor is further configured to:
determine an oversampling factor (O 1 , O 2 ) based on a layer value for the CSI feedback, wherein:
for a 1-layer and 2-layer CSI feedback, O 1 =4 and O 2 =1 if N 1 =1, and O 1 =4 otherwise:
for more than the 2-layer CSI feedback, (O 1 , O 2 )=(16,1) if (N 1 , N 2 )=(2,1), (O 1 , O 2 )=(8,1) if (N 1 , N 2 )=(4,1), and (O 1 , O 2 ) are configured using a higher layer signaling for other values of (N 1 , N 2 ), and
φ
n
=
e
j
π
n
/
2
u
m
=
[
1
e
j
2
π
m
O
2
N
2
…
e
j
2
π
m
(
N
2
-
1
)
O
2
N
2
]
v
l
,
m
=
[
u
m
e
j
2
π
l
O
1
N
1
u
m
…
e
j
2
π
l
(
N
1
-
1
)
O
1
N
1
u
m
]
T
.
5. The UE of claim 4 , wherein a combination of the (N 1 , N 2 ) is determined as:
Number of CSI-RS antenna ports, P
(N 1 , N 2 )
4
(2, 1)
8
(2, 2)
(4, 1)
12
(2, 3)
(3, 2)
16
(2, 4)
(4, 2)
(8, 1)
20
(2, 5)
(5, 2)
(10, 1)
24
(2, 6)
(3, 4)
(4, 3)
(6, 2)
(12, 1)
28
(2, 7)
(7, 2)
(14, 1)
32
(2, 8)
(4, 4)
(8, 2)
(16, 1).
6. The UE of claim 2 , wherein the processor is further configured to at least one of:
derive the first PMI i 1 and the second PMI i 2 based on the LC codebook when a rank indicator (RI) is less than or equal to two; or
derive the first PMI i 1 and the second PMI i 2 based on a non-LC codebook when the RI is greater than two, wherein the non-LC codebook is determined in accordance with a long-term-evolution (LTE) specification, and
wherein, for the LC codebook, the first PMI i 1 comprises indices (i 1,1 , i 1,2 ), i 1,b , and i 1,p indicating (l,m), (l′, m′), and p, respectively, in a first five subscripts of a LC pre-coder equation, and the second PMI i 2 =i 2,0 for a 1-layer CSI feedback and i 2 =64·i 2,1 +i 2,0 , where i 2,0 =i 2,l mod 64 and i 2,1 =└i 2,l /64┘, for a 2-layer CSI feedback, where i 2,l for l=0,1 indicates a last three subscripts of the LC pre-coder equation as └i 2,l /4┘ mod 4, i 2,l mod 4, and x=└i 2,l /16┘, respectively.
7. The UE of claim 1 , wherein the LC codebook is used for the PMI comprising the first beam and the second beam that are common for a plurality of layers, a weight being assigned to the first beam and the second beam is independent for each layer.
8. The UE of claim 2 , wherein the LC pre-coder for 1-layer and 2-layer are given by:
W l,m,l′,m′,p,n 1 ,n 2 ,n 3 (1) =W l,m,l′,m′,p,n 1 ,n 2 ,n 3 (l=0) , and
W l,m,l′,m′,p,n 1,0 ,n 2,0 ,n 3,0 ,n 1,1 ,n 2,1 ,n 3,1 (2) =1/√{square root over (2)}[W l,m,l′,m′,p,n 1,0 ,n 2,0 ,n 3,0 (l=0) W l,m,l′,m′,p,n 1,1 ,n 2,1 ,n 3,1 (l=1)] ,
respectively, where l=0 and l=1 denote a layer value 0 and a layer value 1, respectively.
9. The UE of claim 6 , wherein the LC codebook for both 1-layer and 2-layer CSI feedback is given by:
If N 1 > 1,N 2 > 1, 0 ≤ i 1,1 ≤ 4N 1 − 1, 0 ≤ i 1,2 ≤ 4N 2 − 1
If N 2 = 1, 0 ≤ i 1,1 ≤ 4N 1 − 1, i 1,2 = 0
0 ≤ i 2,1 ≤ 63
0 + 16x
1 + 16x
2 + 16x
3 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,3,x
4 + 16x
5 + 16x
6 + 16x
7 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,3,x
8 + 16x
9 + 16x
10 + 16x
11 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,2,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,2,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,2,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,2,3,x
12 + 16x
13 + 16x
14 + 16x
15 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,3,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,3,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,3,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,3,3,x
wherein
x
=
⌊
i
2
,
l
/
16
⌋
,
W
l
,
m
,
l
′
,
m
′
,
p
,
n
1
,
n
2
,
n
3
(
l
)
=
1
P
(
1
+
p
2
)
[
v
l
,
m
+
p
φ
n
1
v
l
+
l
′
,
m
+
m
′
φ
n
2
(
v
l
,
m
+
p
φ
n
3
v
l
+
l
′
,
m
+
m
′
)
]
,
and (i 1,1 , i 1,2 ) indicates the first beam, v l,m , (d 1 , d 2 ), indicates the second beam, v l+1′,m+m′ , p
indicates the power assigned to the second beam, and the last three subscripts indicate φ n 1 , φ n 2
and φ n 3 .
10. A base station (BS) for a channel state information (CSI) feedback in an advanced communication system, the BS comprising:
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 i 1 and a second PMI i 2; and
receive, from the UE, the CSI feedback over an uplink channel including the first PMI i 1 and 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 a power of a weight assigned to the first beam is 1 and a power of a weight assigned to the second beam is between 0 and 1.
11. The BS of claim 10 , wherein:
the CSI feedback configuration information includes a number of dual-polarized CSI reference signal (CSI-RS) antenna ports P, wherein a first half of the CSI-RS antenna ports corresponds to a first antenna polarization and a second half of the CSI-RS antenna ports corresponds to a second antenna polarization,
the LC pre-coder corresponding to the weighted linear combination of the first beam, V l,m , and the second beam, v l+l′,m+m′ , is determined as:
W
l
,
m
,
l
′
,
m
′
,
p
,
n
1
,
n
2
,
n
3
(
l
)
=
1
P
(
1
+
p
2
)
[
v
l
,
m
+
p
φ
n
1
v
l
+
l
′
,
m
+
m
′
φ
n
2
(
v
l
,
m
+
p
φ
n
3
v
l
+
l
′
,
m
+
m
′
)
]
,
p denotes the power of the weight assigned to the second beam, φ n 1 denotes a phase of the weight assigned to the second beam for the first half of the CSI-RS ports with the first polarization, and φ n 2 , and φ n 3 , denote a phase of the weights assigned to the first and second beams, respectively, for the second half of the CSI-RS ports with the second polarization.
12. The BS of claim 10 , wherein the LC codebook is a single codebook and used to report the CSI feedback for a plurality of layers.
13. The BS of claim 11 , wherein the transceiver is further configured to transmit, to the UE, dual polarized CSI-RS port layout values comprising (N 1 , N 2 ) using a higher layer signaling that determines a number of CSI-RS ports P=2N 1 N 2 .
14. The BS of claim 13 , wherein a combination of the (N 1 , N 2 ) is determined as:
Number of CSI-RS antenna ports, P
(N 1 , N 2 )
4
(2, 1)
8
(2, 2)
(4, 1)
12
(2, 3)
(3, 2)
16
(2, 4)
(4, 2)
(8, 1)
20
(2, 5)
(5, 2)
(10, 1)
24
(2, 6)
(3, 4)
(4, 3)
(6, 2)
(12, 1)
28
(2, 7)
(7, 2)
(14, 1)
32
(2, 8)
(4, 4)
(8, 2)
(16, 1).
15. The BS of claim 10 , wherein the LC codebook is used for the PMI comprising the first beam and the second beam that are common for a plurality of layers, a weight being assigned to the first beam and the second beam is independent for each layer.
16. The BS of claim 11 , wherein the LC pre-coder for 1-layer and 2-layer are given by:
W l,m,l′,m′,p,n 1 ,n 2 ,n 3 (1) =W l,m,l′,m′,p,n 1 ,n 2 ,n 3 (l=0) , and
W l,m,l′,m′,p,n 1,0 ,n 2,0 ,n 3,0 ,n 1,1 ,n 2,1 ,n 3,1 (2) =1 /√{square root over (2)}[W l,m, l′,m′,p,n 1,0 ,n 2,0 ,n 3,0 (l=0) W l,m,l′,m′,p, n 1,1 ,n 2,1 ,n 3,1 (l=1)] ,
respectively, where l=0 and l=1 denote a layer value 0 and a layer value 1, respectively.
17. A method 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 i 1 and a second PMI i 2;
determining, by a user equipment (UE), 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, where a power of a weight assigned to the first beam is 1 and a power of a weight assigned to the second beam is between 0 and 1; and
transmitting, to the BS, the CSI feedback over an uplink channel including the determined first PMI i 1 and second PMI i 2 .
18. The method of claim 17 , wherein the CSI feedback configuration information includes a number of dual-polarized CSI reference signal (CSI-RS) antenna ports P, wherein a first half of the CSI-RS antenna ports corresponds to a first antenna polarization and a second half of the CSI-RS antenna ports corresponds to a second antenna polarization, and wherein the LC pre-coder corresponding to the weighted linear combination of the first beam, v l,m , and the second beam, v l+l′,m+m′ , is determined as:
W
l
,
m
,
l
′
,
m
′
,
p
,
n
1
,
n
2
,
n
3
(
l
)
=
1
P
(
1
+
p
2
)
[
v
l
,
m
+
p
φ
n
1
v
l
+
l
′
,
m
+
m
′
φ
n
2
(
v
l
,
m
+
p
φ
n
3
v
l
+
l
′
,
m
+
m
′
)
]
,
wherein p denotes the power of the weight assigned to the second beam, φ n 1 denotes a phase of the weight assigned to the second beam for the first half of the CSI-RS ports with the first polarization, and φ n 2 , and φ n 3 , denote a phase of the weights assigned to the first and second beams, respectively, for the second half of the CSI-RS ports with the second polarization.
19. The method of claim 17 , wherein the LC codebook is a single codebook and used to report the CSI feedback for a plurality of layers.
20. The method of claim 18 , further comprising:
receiving, from the BS, dual polarized CSI-RS port layout values comprising (N 1 , N 2 ) using a higher layer signaling, which determines a number of CSI-RS ports P =2N 1 N 2 ; and
determining an oversampling factor (O 1 , O 2 ) based on a layer value for the CSI feedback, wherein:
for a 1-layer and 2-layer CSI feedback, O 1 =4 and O 2 =1 if N 1 =1, and O 1 =4otherwise:
for more than the 2-layer CSI feedback, (O 1 , O 2 )=(16,1) if (N 1 , N 2 )=(2,1), (O 1 , O 2 )=(8,1) if (N 1 , N 2 )=(4,1), and (O 1 , O 2 ) are configured using a higher layer signaling for other values of (N 1 , N 2 ), and
φ
n
=
e
j
π
n
/
2
u
m
=
[
1
e
j
2
π
m
O
2
N
2
…
e
j
2
π
m
(
N
2
-
1
)
O
2
N
2
]
v
l
,
m
=
[
u
m
e
j
2
π
l
O
1
N
1
u
m
…
e
j
2
π
l
(
N
1
-
1
)
O
1
N
1
u
m
]
T
.
21. The method of claim 20 , wherein a combination of the (N 1 , N 2 ) is determined as:
Number of CSI-RS antenna ports, P
(N 1 , N 2 )
4
(2, 1)
8
(2, 2)
(4, 1)
12
(2, 3)
(3, 2)
16
(2, 4)
(4, 2)
(8, 1)
20
(2, 5)
(5, 2)
(10, 1)
24
(2, 6)
(3, 4)
(4, 3)
(6, 2)
(12, 1)
28
(2, 7)
(7, 2)
(14, 1)
32
(2, 8)
(4, 4)
(8, 2)
(16, 1).
22. The method of claim 17 , further comprising at least one of:
deriving the first PMI i 1 and the second PMI i 2 based on the LC codebook when a rank indicator (RI) is less than or equal to two; or
deriving the first PMI i 1 and the second PMI i 2 based on a non-LC codebook when the RI is greater than two, wherein the non-LC codebook is determined in accordance with a long-term-evolution (LTE) specification, and
wherein, for the LC codebook, the first PMI i 1 comprises indices (i 1,1 , i 1,2 ), i 1,b , and i 1,p indicating (l,m), (l′,m′), and p, respectively, in a first five subscripts of a LC pre-coder equation, and the second PMI i 2 =i 2,0 for a 1-layer CSI feedback and i 2 =64·i 2,1 +i 2,0 , where i 2,0 =i 2,l mod 64 and i 2,1 =└i 2,l /64┘, for a 2-layer CSI feedback, where i 2,l for l=0,1 indicates a last three subscripts of the LC pre-coder equation as └i 2,l /4┘ mod 4,i 2,l mod 4, and x=└i 2,l /16┘, respectively.
23. The method of claim 17 , wherein the LC codebook is used for the PMI comprising the first beam and the second beam that are common for a plurality of layers, a weight being assigned to the first beam and the second beam is independent for each layer.
24. The method of claim 18 , wherein the LC pre-coder for 1-layer and 2-layer are given by:
W l,m,l′,m′,p,n 1 ,n 2 ,n 3 (1) =W l,m,l′,m′,p,n 1 ,n 2 ,n 3 (l=0) , and
W l,m,l′,m′,p,n 1,0 ,n 2,0 ,n 3,0 ,n 1,1 ,n 2,1 ,n 3,1 (2) =1/√{square root over (2)}[W l,m,l′,m′,p, n 1,0 ,n 2,0 ,n 3,0 (l=0) W l,m,l′,m′,p,n 1,1 ,n 2,1 ,n 3,1 (l=1)] ,
respectively, where l=0 and l=1 denote a layer value 0 and a layer value 1, respectively.
25. The method of claim 22 , wherein the LC codebook for both 1-layer and 2-layer CSI feedback is given by:
If N 1 > 1,N 2 > 1, 0 ≤ i 1,1 ≤ 4N 1 − 1, 0 ≤ i 1,2 ≤ 4N 2 − 1
If N 2 = 1, 0 ≤ i 1,1 ≤ 4N 1 − 1, i 1,2 = 0
0 ≤ i 2,1 ≤ 63
0 + 16x
1 + 16x
2 + 16x
3 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,0,3,x
4 + 16x
5 + 16x
6 + 16x
7 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,1,3,x
8 + 16x
9 + 16x
10 + 16x
11 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,2,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 , p,2,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,2,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,2,3,x
12 + 16x
13 + 16x
14 + 16x
15 + 16x
W (l) i 1,1 ,i 1,2 ,4d 1 , 4d 2 ,p,3,0,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,3,1,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,3,2,x
W (l) i 1,1 ,i 1,2 ,4d 1 ,4d 2 ,p,3,3,x
wherein
x
=
⌊
i
2
,
l
/
16
⌋
,
W
l
,
m
,
l
′
,
m
′
,
p
,
n
1
,
n
2
,
n
3
(
l
)
=
1
P
(
1
+
p
2
)
[
v
l
,
m
+
p
φ
n
1
v
l
+
l
′
,
m
+
m
′
φ
n
2
(
v
l
,
m
+
p
φ
n
3
v
l
+
l
′
,
m
+
m
′
)
]
,
and (i 1,1 , i 1,2 ) indicates the first beam, v l,m , (d 1 , d 2 ), indicates the second beam, v l+1′,m+m′ , p
indicates the power assigned to the second beam, and the last three subscripts indicate φ n 1 , φ n 2
and φ n 3 .