Beamforming method and apparatus therefor
The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data transmission rate than a 4G communication system such as LTE. An embodiment of the present specification relates to an apparatus and a method for MIMO transmission and reception in a closed-loop beamforming system. A communication method of a base station, according to one embodiment of the present invention, may comprise the steps of: transmitting information for channel measurement to a terminal; receiving channel-related information from the terminal; transmitting a first symbol via at least two antennas; and transmitting a second symbol via the at least two antennas by applying different channel mapping rules to the second symbol in the at least two antennas. One embodiment of the present invention can improve overall performance without downward leveling by a symbol transmitted via an antenna having low average channel power.
1. A method of a base station, the method comprising:
transmitting channel measurement configuration information to a terminal;
receiving channel information from the terminal;
generating a first symbol and a second symbol for the terminal;
transmitting, to the terminal, a first signal through a first antenna, the first signal comprising the first symbol and the second symbol, wherein a first mapping parameter is applied to the second symbol; and
transmitting, to the terminal, a second signal through a second antenna, the second signal comprising the first symbol and the second symbol, wherein a second mapping parameter different from the first mapping parameter is applied to the second symbol,
wherein the first symbol and the second symbol are transmitted through the first antenna and the second antenna based on one of following Equation 1, Equation 2 or Equation 3:
wherein the Equation 1 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
-
s
2
]
,
wherein the Equation 2 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
+
e
j
θ
2
s
2
]
,
and
wherein the Equation 3 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
a
1
s
2
s
1
-
a
2
s
2
]
,
where the x 1 denotes the first signal transmitted through the first antenna, the x 2 denotes the second signal transmitted through the second antenna, the s 1 and s 2 denote the first symbol and the second symbol, the θ 1 denotes a phase rotation to be applied to the second symbol for transmission through the first antenna, the θ 2 denotes a phase rotation to be applied to the second symbol for transmission through the second antenna, the a 1 denotes the first mapping parameter to be applied to the second symbol transmitted through the first antenna, and the a 2 denotes the second mapping parameter to be applied to the second symbol transmitted through the second antenna.
2. The method of claim 1 , wherein receiving the channel information further comprises receiving information on at least one of the first mapping parameter or the second mapping parameter.
3. The method of claim 1 , further comprising:
determining the first mapping parameter and the second mapping parameter based on the channel information; and
transmitting information on the first mapping parameter and the second mapping parameter to the terminal.
4. A method of a terminal, the method comprising:
receiving channel measurement configuration information from a base station;
measuring channels;
transmitting channel information to the base station;
receiving, from the base station, a first signal through a first antenna, the first signal comprising a first symbol and a second symbol, wherein a first mapping parameter is applied to the second symbol; and
receiving, from the base station, a second signal through a second antenna, the second signal comprising the first symbol and the second symbol, wherein a second mapping parameter different from the first mapping parameter is applied to the second symbol,
wherein the first symbol and the second symbol are transmitted through the first antenna and the second antenna based on one of following Equation 1, Equation 2 or Equation 3:
wherein the Equation 1 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
-
s
2
]
,
wherein the Equation 2 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
+
e
j
θ
2
s
2
]
,
and
wherein the Equation 3 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
a
1
s
2
s
1
-
a
2
s
2
]
,
where the x 1 denotes the first signal transmitted through the first antenna, x 2 denotes the second signal transmitted through the second antenna, the s 1 and s 2 denote the first symbol and the second symbol, θ 1 denotes a phase rotation to be applied to the second symbol for transmission through the first antenna, θ 2 denotes a phase rotation to be applied to the second symbol for transmission through the second antenna, a 1 denotes the first mapping parameter to be applied to the second symbol transmitted through the first antenna, and a 2 denotes the second mapping parameter to be applied to the second symbol transmitted through the second antenna.
5. The method of claim 4 , further comprising:
determining at least one of the first mapping parameter and the second mapping parameter, and
wherein at least one of the first mapping parameter and the second mapping parameter is included in the channel information.
6. The method of claim 4 , further comprising receiving at least one of the first mapping parameter and the second mapping parameter from the base station.
7. A base station comprising:
a transceiver configured to transmit and receive signals; and
at least one processor configured to:
transmit channel measurement configuration information to a terminal,
receive channel information from the terminal,
generate a first symbol and a second symbol for the terminal,
transmit, to the terminal, a first signal through a first antenna, the first signal comprising the first symbol and the second symbol, wherein a first mapping parameter is applied to the second symbol, and
transmit, to the terminal, a second signal through a second antenna, the second signal comprising the first symbol and the second symbol, wherein a second mapping parameter different from the first mapping parameter is applied to the second symbol,
wherein the first symbol and the second symbol are transmitted through the first antenna and the second antenna based on one of following Equation 1, Equation 2 or Equation 3:
wherein the Equation 1 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
-
s
2
]
,
wherein the Equation 2 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
+
e
j
θ
2
s
2
]
,
and
wherein the Equation 3 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
a
1
s
2
s
1
-
a
2
s
2
]
,
where the x 1 denotes the first signal transmitted through the first antenna, the x 2 denotes the second signal transmitted through the second antenna, the s 1 and s 2 denote the first symbol and the second symbol, the θ 1 denotes a phase rotation to be applied to the second symbol for transmission through the first antenna, the θ 2 denotes a phase rotation to be applied to the second symbol for transmission through the second antenna, the a 1 denotes the first mapping parameter to be applied to the second symbol transmitted through the first antenna, and the a 2 denotes the second mapping parameter to be applied to the second symbol transmitted through the second antenna.
8. The base station of claim 7 , wherein the at least one processor is further configured to receive information on at least one of the first mapping parameter and the second mapping parameter.
9. The base station of claim 7 , wherein the at least one processor is further configured to:
determine the first mapping parameter and the second mapping parameter based on the channel information, and
transmit information on the first mapping parameter and the second mapping parameter.
10. A terminal comprising:
a transceiver configured to transmit and receive signals; and
at least one processor configured to:
receive channel measurement configuration information from a base station,
measure channels,
transmit channel information to the base station,
receive, from the base station, a first signal through a first antenna, the first signal comprising a first symbol and a second symbol, wherein a first mapping parameter is applied to the second symbol, and
receive, from the base station, a second signal through a second antenna, the second signal comprising the first symbol and the second symbol, wherein a second mapping parameter different from the first mapping parameter is applied to the second symbol,
wherein the first symbol and the second symbol are transmitted through the first antenna and the second antenna based on one of following Equation 1, Equation 2 or Equation 3:
wherein the Equation 1 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
-
s
2
]
,
wherein the Equation 2 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
e
j
θ
1
s
2
s
1
+
e
j
θ
2
s
2
]
,
and
wherein the Equation 3 recites
[
x
1
x
2
]
=
1
2
[
s
1
+
a
1
s
2
s
1
-
a
2
s
2
]
,
where the x 1 denotes the first signal transmitted through the first antenna, the x 2 denotes the second signal transmitted through the second antenna, the s 1 and s 2 denote the first symbol and the second symbol, the θ 1 denotes a phase rotation to be applied to the second symbol for transmission through the first antenna, the θ 2 denotes a phase rotation to be applied to the second symbol for transmission through the second antenna, the a 1 denotes the first mapping parameter to be applied to the second symbol transmitted through the first antenna, and the a 2 denotes the second mapping parameter to be applied to the second symbol transmitted through the second antenna.
11. The terminal of claim 10 , wherein the at least one processor is further configured to determine at least one of the first mapping parameter and the second mapping parameter,
wherein at least one of the first mapping parameter and the second mapping parameter is included in the channel information.
12. The terminal of claim 10 , wherein the at least one processor is further configured to receive at least one of the first mapping parameter and the second mapping parameter from the base station.
13. The method of claim 1 , wherein the first mapping parameter is different from the second mapping parameter.
14. The method of claim 4 , wherein the first mapping parameter is different from the second mapping parameter.