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 comprising:
a transceiver configured to receive, from a base station (BS), CSI feedback configuration information for precoding matrix indicator (PMI) feedback based on a linear combination (LC) codebook, wherein the PMI feedback 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 precoder that corresponds to a weighted linear combination of a plurality of beams, wherein:
the plurality of beams are indicated by first beam information and second beam information, the first beam information indicating a reference beam in first and second dimensions, the second beam information indicating a distance from the reference beam in the first and second dimensions, and
the second PMI value (i 2 ) indicates a phase of weights assigned to the plurality of beams; and
wherein the transceiver is further configured to transmit, to the BS, the CSI feedback over an uplink channel including the determined first PMI value (i 1 ) and the determined second PMI value (i 2 ).
2. The UE of claim 1 , wherein CSI feedback further includes a power indicator indicating a power of a weight assigned to the plurality of beams.
3. The UE of claim 2 , wherein the power indicator is set to a value among a first set of values comprising {0, √{square root over (¼)}, √{square root over (½)}, 1}.
4. The UE of claim 1 , wherein each beam of plurality of beams corresponds to a discrete Fourier transform (DFT) beam selected from an oversampled DFT codebook comprising DFT beams:
v
l
1
,
l
2
=
[
u
l
2
e
j
2
π
l
1
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.
5. The UE of claim 1 , wherein the plurality of beams comprise a first beam and a second beam.
6. 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 precoding matrix indicator (PMI) feedback based on a linear combination (LC) codebook, wherein the PMI feedback 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 precoder that corresponds to a weighted linear combination of a plurality of beams,
the plurality of beams are indicated by first beam information and second beam information, the first beam information indicating a reference beam in first and second dimensions, the second beam information indicating a distance from the reference beam in the first and second dimensions, and
the second PMI value (i 2 ) indicates a phase of weights assigned to the plurality of beams; 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 ).
7. The BS of claim 6 , wherein CSI feedback further includes a power indicator indicating a power of a weight assigned to the plurality of beams.
8. The BS of claim 7 , wherein the power indicator is set to a value among a first set of values comprising {0, √{square root over (¼)}, √{square root over (½)}, 1}.
9. The BS of claim 6 , wherein each beam of plurality of beams corresponds to a discrete Fourier transform (DFT) beam selected from an oversampled DFT codebook comprising DFT beams:
v
l
1
,
l
2
=
[
u
l
2
e
j
2
π
l
1
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.
10. The BS of claim 6 , wherein the plurality of beams comprise a first beam and a second beam.
11. 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 precoding matrix indicator (PMI) feedback based on a linear combination (LC) codebook, wherein the PMI feedback 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 precoder that corresponds to a weighted linear combination of a plurality of beams, wherein:
the plurality of beams are indicated by first beam information and second beam information, the first beam information indicating a reference beam in first and second dimensions, the second beam information indicating a distance from the reference beam in the first and second dimensions, and
the second PMI value (i 2 ) indicates a phase of weights assigned to the plurality of beams; and
transmitting, to the BS, the CSI feedback over an uplink channel including the determined first PMI value (i 1 ) and the determined second PMI value (i 2 ).
12. The method of claim 11 , wherein CSI feedback further includes a power indicator indicating a power of a weight assigned to the plurality of beams.
13. The method of claim 12 , wherein the power indicator is set to a value among a first set comprising {0, √{square root over (¼)}, √{square root over (½)}, 1}.
14. The method of claim 11 , wherein each beam of plurality of beams corresponds to a discrete Fourier transform (DFT) beam selected from an oversampled DFT codebook comprising DFT beams:
v
l
1
,
l
2
=
[
u
l
2
e
j
2
π
l
1
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.
15. The method of claim 11 , wherein the plurality of beams comprise a first beam and a second beam.