Method and device for transmitting signal by switching phase in mobile communication system
Disclosed are a method and a device for differently applying phase rotations for each antenna by dividing a frequency band in order to solve a problem in which reception performance deteriorates in a specific subcarrier when the correlation between antennas is high. According to the present invention, a method by which a transmitter transmits a signal comprises the steps of: estimating the transmission correlation between respective transmission paths; calculating a phase rotation value to be applied to a transmission signal on the basis of the estimated transmission correlation; applying a phase rotation in accordance with the phase rotation value to the transmission signal; and transmitting the transmission signal.
1. A signal transmission method performed by a transmitter, the method comprising:
estimating a transmit correlation between transmission paths;
determining phase rotation values to be applied to a transmission signal from a plurality of predetermined phase rotation values stored in the transmitter based on the estimated transmit correlation;
applying phase rotation to the transmission signal based on the phase rotation values, wherein the phase rotation values are determined by an equation:
(
,
)
=
arg
max
(
φ
l
,
0
,
φ
l
,
1
)
∑
k
∈
{
subcarrier
index
}
(
1
+
α
cos
(
φ
l
,
0
+
φ
l
,
1
2
k
-
φ
α
)
cos
(
φ
l
,
0
+
φ
l
,
1
2
k
)
)
,
where {tilde over (φ)} l,0 and {tilde over (φ)} l,1 denote the phase rotation values, a denotes the transmit correlation, φ α denotes a phase angle of α, and l denotes an index of a small unit constituting a frequency band; and
transmitting the transmission signal.
2. The method of claim 1 , wherein the phase rotation values are determined by the small unit constituting the frequency band based on channel state.
3. The method of claim 1 , further comprising receiving, in case that a time division duplex (TDD) system is applied, a sounding reference signal (SRS), wherein the phase rotation values are determined based on channel state information estimated based on the SRS.
4. The method of claim 1 , further comprising receiving, in case that a frequency division duplex (FDD) system is applied, channel state information transmitted by a receiver, wherein the phase rotation values are determined based on the channel state information.
5. The method of claim 4 , further comprising transmitting a reference signal (RS) to which one of predetermined phase rotation values pair sets is applied to the receiver,
wherein the channel state information is estimated based on the RS.
6. The method of claim 1 , wherein the phase rotation values are determined according to a phase rotation values set predetermined based on the estimated transmit correlation.
7. The method of claim 1 , further comprising determining phase rotation values based on a table,
wherein the table stores a first pair of predetermined phase rotation values of a plurality of predetermined phase rotation values associated with a first transmit correlation, and
wherein the table stores a second pair of predetermined phase rotation values of the plurality of predetermined phase rotation values associated with a second transmit correlation.
8. A transmitter for transmitting a signal, the transmitter comprising:
a transceiver configured to transmit and receive signals to and from a receiver; and
a controller configured to control to:
estimate a transmit correlation between transmission paths,
determine phase rotation values to be applied to a transmission signal from a plurality of predetermined phase rotation values stored in the transmitter based on the estimated transmit correlation,
apply phase rotation to the transmission signal based on the phase rotation values, wherein the phase rotation values are determined by an equation:
(
,
)
=
arg
max
(
φ
l
,
0
,
φ
l
,
1
)
∑
k
∈
{
subcarrier
index
}
(
1
+
α
cos
(
φ
l
,
0
+
φ
l
,
1
2
k
-
φ
α
)
cos
(
φ
l
,
0
+
φ
l
,
1
2
k
)
)
,
where {tilde over (φ)} l,0 and {tilde over (φ)} l,1 denote the phase rotation values, α denotes the transmit correlation, φ α denotes a phase angle of α, and l denotes an index of a small unit constituting a frequency band, and
transmit the transmission signal.
9. The transmitter of claim 8 , wherein the phase rotation values are determined by the small unit constituting the frequency band based on channel state.
10. The transmitter of claim 9 ,
wherein the controller is further configured to control to transmit a reference signal (RS) to which one of predetermined phase rotation values pair sets is applied to the receiver, and
wherein channel state information is estimated based on the RS.
11. The transmitter of claim 8 ,
wherein the controller is further configured to control to receive, in case that a time division duplex (TDD) system is applied, a sounding reference signal (SRS), and
wherein the phase rotation values are determined based on channel state information estimated based on the SRS.
12. The transmitter of claim 8 ,
wherein the controller is further configured to control to receive, in case that a frequency division duplex (FDD) system is applied, channel state information transmitted by a receiver, and
wherein the phase rotation values are determined based on the channel state information.
13. The transmitter of claim 8 , wherein the phase rotation values are determined according to a phase rotation values set predetermined based on the estimated transmit correlation.
14. The transmitter of claim 8 ,
wherein the controller is further configured to determine phase rotation value based on a table,
wherein the table stores a first pair of predetermined phase rotation values of a plurality of predetermined phase rotation values associated with a first transmit correlation, and
wherein the table stores a second pair of predetermined phase rotation values of the plurality of predetermined phase rotation values associated with a second transmit correlation.