Method for transmitting feedback information in wireless communication system and device therefor
A method by which a terminal transmits feedback information in a wireless communication system can comprise the steps of: selecting a filter index for maximizing a signal to interference-plus-noise (SINR) or a signal to leakage-and-noise ratio (SLNR) in a filter book defined in advance for each resource block (RB) or subband; and transmitting, to a base station, feedback information including the selected filter index for each RB or subband.
1. A method for transmitting feedback information by a user equipment in a wireless communication system, the method comprising:
obtaining information on a predefined filter book;
receiving, from a base station, information on a plurality of subbands, wherein the plurality of subbands are configured to be applied respectively with a plurality of filter indexes;
estimating a channel for each of the plurality of subbands;
obtaining the plurality of filter indexes corresponding respectively to the plurality of subbands, wherein each of the plurality of filter indexes is selected from the predefined filter book for maximizing a signal to leakage-and-noise ratio (SLNR) of a corresponding subband among the plurality of subbands, wherein each of the plurality of subbands includes at least one resource block (RB), and each of the at least one RB includes a plurality of subcarriers; and
transmitting, to the base station, the feedback information including the plurality of filter indexes and a plurality of filter quality information (FQI) values corresponding respectively to the plurality of filter indexes,
wherein the SLNR is calculated based on following equation,
SLNR
i
,
k
=
[
C
i
]
k
,
k
[
H
i
]
k
[
F
i
,
k
]
k
2
P
i
,
k
[
H
i
]
k
[
F
i
,
k
]
k
2
P
i
,
k
∑
j
=
1
K
∑
m
=
1
K
i
[
C
i
]
j
,
m
-
[
C
i
]
k
,
k
[
H
i
]
k
[
F
i
,
k
]
k
2
P
i
,
k
+
σ
i
,
k
,
and
wherein a residual carrier frequency offset, CFO, [C i ] m,n is calculated based on following equation,
[
C
i
]
m
,
n
=
sin
(
π
N
fft
(
ϵ
i
-
(
m
-
n
)
)
(
N
fft
)
)
sin
(
π
N
fft
(
ϵ
i
-
(
m
-
n
)
)
)
e
j
2
π
(
ϵ
i
-
(
m
-
n
)
)
(
N
fft
-
1
)
,
where [C i ] is a M×N matrix,
[C i ] m,n is an element of an n-th column in an m-th row in [Ci],
SLNR i,k is an SLNR of the k-th subcarrier of the i-th user equipment,
P i,k is a power of the k-th subcarrier of the i-th user equipment,
F i,k is a filter of the K-th subcarrier of the i-th user equipment, and
[H i ] k is a channel of the k-th subcarrier of the i-th user equipment.
2. The method of claim 1 , wherein the wireless communication system comprises a Filtered Cyclic Prefix-Orthogonal Frequency Division Multiplexing (FCP-OFDM) system.
3. The method of claim 1 , wherein each of the plurality of filter indexes corresponds to a filter enabling the SLNR to become a maximum for a downlink signal to which a Filtered Cyclic Prefix-Orthogonal Frequency Division Multiplexing (FCP-OFDM) scheme is applied.
4. The method of claim 1 , wherein the plurality of subbands includes all RBs allocated to the user equipment.
5. The method of claim 1 , wherein the plurality of subbands among subbands allocated to the user equipment are instructed by the base station in order for the UE to report, to the base station, feedback.
6. A user equipment for transmitting feedback information in a wireless communication system, comprising:
a transceiver coupled to a processor; and
the processor configured to:
obtain the plurality of filter indexes corresponding respectively to the plurality of subbands, wherein each of the plurality of filter indexes is selected from the predefined codebook for maximizing a signal to leakage-and-noise ratio (SLNR) of a corresponding subband among the plurality of subbands, wherein each of the plurality of subbands includes at least one resource block (RB), and each of the at least one RB includes a plurality of subcarriers; and
transmit, to a base station, the feedback information including the plurality of filter indexes and a plurality of filter quality information (FQI) values corresponding respectively to the plurality of filter indexes,
wherein the SLNR is calculated based on following equation,
SLNR
i
,
k
=
[
C
i
]
k
,
k
[
H
i
]
k
[
F
i
,
k
]
k
2
P
i
,
k
[
H
i
]
k
[
F
i
,
k
]
k
2
P
i
,
k
∑
j
=
1
K
∑
m
=
1
K
i
[
C
i
]
j
,
m
-
[
C
i
]
k
,
k
[
H
i
]
k
[
F
i
,
k
]
k
2
P
i
,
k
+
σ
i
,
k
,
and
wherein a residual carrier frequency offset, CFO, [C i ] m,n is calculated based on following equation,
[
C
i
]
m
,
n
=
sin
(
π
N
fft
(
ϵ
i
-
(
m
-
n
)
)
(
N
fft
)
)
sin
(
π
N
fft
(
ϵ
i
-
(
m
-
n
)
)
)
e
j
2
π
(
ϵ
i
-
(
m
-
n
)
)
(
N
fft
-
1
)
,
where [C i ] is a M×N matrix,
[C i ] m,n is an element of an n-th column in an m-th row in [C i ],
SLNR i,k is an SLNR of the k-th subcarrier of the i-th user equipment,
P i,k is a power of the k-th subcarrier of the i-th user equipment,
F i,k the k-th subcarrier of the i-th user equipment, and
[H i ] k a channel of the k-th subcarrier of the i-th user equipment.
7. The user equipment of claim 6 , wherein the wireless communication system comprises a Filtered Cyclic Prefix-Orthogonal Frequency Division Multiplexing (FCP-OFDM) system.
8. The user equipment of claim 6 , wherein each of the plurality of filter indexes corresponds to a filter enabling the SLNR to become a maximum for a downlink signal to which a Filtered Cyclic Prefix-Orthogonal Frequency Division Multiplexing (FCP-OFDM) scheme is applied.
9. The user equipment of claim 6 , wherein the plurality of subbands includes all RBs allocated to the user equipment.
10. The user equipment of claim 6 , wherein the plurality of subbands among subbands allocated to the user equipment are instructed by the base station, in order for the UE to report, to the base station, feedback.