Method and apparatus for transmitting downlink reference signal and method and apparatus for transmitting control information in cooperative multi-point communication system
A method for a base station to configure a channel state information (CSI)-reference signal (RS) is provided. The base station configures a CSI-RS antenna port for a terminal. The base station selects one of at least one port number mapping rule for mapping a port number on the CSI-RS antenna port for the terminal. The base station notifies the terminal of the selected port number mapping rule.
1. A method for receiving channel state information (CSI)-reference signal (RS) by a terminal, the method comprising:
receiving first information on a number of CSI-RS antenna ports of each port group and second information on a number of port from a base station;
when the number of port groups is 2 and the number of CSI-RS antenna ports of each port group is 8, deriving port numbers of 8 first CSI-RS antenna ports belonging to a first port group and 8 second CSI-RS antenna ports belonging to a second port group based on the first information and the second information;
when the number of port groups is 3 and the number of CSI-RS antenna ports of each port group is 4, deriving port numbers of 4 third CSI-RS antenna ports belonging to a third port group, 4 fourth CSI-RS antenna ports belonging to a fourth port group, and 4 fifth CSI-RS antenna ports belonging to a fifth port group, based on the first information and the second information; and
receiving the CSI-RS based on the derived port numbers.
2. The method of claim 1 , wherein,
the deriving of port numbers of 8 first CSI-RS antenna ports and 8 second CSI-RS antenna ports comprises:
deriving new port numbers of 15 to 30 for the 8 first CSI-RS antenna ports and the 8 second CSI-RS antenna ports, using 8 first existing port numbers of 15 to 22 of the 8 first CSI-RS antenna ports and 8 second existing port numbers of 15 to 22 of the 8 second CSI-RS antenna ports.
3. The method of claim 2 , wherein, receiving the CSI-RS comprises:
receiving the CSI-RS using first resource elements and second resource elements,
wherein the 8 first CSI-RS antenna ports are mapped to the first resource elements using a first mapping rule based on the existing port numbers,
and the 8 second CSI-RS antenna ports are mapped to the second resource elements using the first mapping rule based on the existing port numbers N ports group N group .
4. The method of claim 1 , wherein,
the deriving of port numbers of 8 first CSI-RS antenna ports and 8 second CSI-RS antenna ports comprises:
deriving new port numbers of 15 to 30 for the 8 first CSI-RS antenna ports and the 8 second CSI-RS antenna ports using the following equation:
p
=
{
p
′
+
N
ports
group
2
i
,
for
p
′
∈
{
15
,
…
,
15
+
N
ports
group
2
-
1
}
p
′
+
N
ports
group
2
(
i
+
N
group
-
1
)
,
for
p
′
∈
{
15
+
N
ports
group
2
,
…
,
15
+
N
ports
group
-
1
}
[
Equation
]
(p: a new port number derived for a CSI-RS antenna port whose existing port number is p′ and belonging to a port group whose index is i, p′: an existing port number for each CSI-RS antenna port belonging to a port group whose index is i, N ports group : the number of CSI-RS antenna ports of each port group, N group : the number of port groups, i: an index of a port group where CSI-RS antenna ports belong to, wherein i=0 for the first port group, i=1 for the second port group).
5. The method of claim 1 , wherein,
the deriving of port numbers of 4 third CSI-RS antenna ports, 4 fourth CSI-RS antenna ports, and 4 fifth CSI-RS antenna ports comprises:
deriving new port numbers of 15 to 26 for the 4 third CSI-RS antenna ports, the 4 fourth CSI-RS antenna ports, and the 4 fifth CSI-RS antenna ports, using 4 third existing port numbers of 15 to 18 of the 4 third CSI-RS antenna ports, 4 fourth existing port numbers of 15 to 18 of the 4 fourth CSI-RS antenna ports and 4 fifth existing port numbers of 15 to 18 of the 4 fifth CSI-RS antenna ports N ports group N group .
6. The method of claim 5 , wherein,
the receiving the CSI-RS comprises:
receiving the CSI-RS using third resource elements, fourth resource elements, and fifth resource elements,
wherein the 4 third CSI-RS antenna ports are mapped to the third resource elements using a second mapping rule based on the existing port numbers,
the 4 fourth CSI-RS antenna ports are mapped to the fourth resource elements using the second mapping rule based on the existing port numbers,
and the 4 fifth CSI-RS antenna ports are mapped to the fifth resource elements using the second mapping rule based on the existing port numbers.
7. The method of claim 1 , wherein the deriving of port numbers of 4 third CSI-RS antenna ports, 4 fourth CSI-RS antenna ports, and 4 fifth CSI-RS antenna ports comprises:
deriving new port numbers of 15 to 26 for the 4 third CSI-RS antenna ports, the 4 fourth CSI-RS antenna ports, and the 4 fifth CSI-RS antenna ports using the following equation:
p
=
{
p
′
+
N
ports
group
2
i
,
for
p
′
∈
{
15
,
…
,
15
+
N
ports
group
2
-
1
}
p
′
+
N
ports
group
2
(
i
+
N
group
-
1
)
,
for
p
′
∈
{
15
+
N
ports
group
2
,
…
,
15
+
N
ports
group
-
1
}
[
Equation
]
(p: a new port number derived for a CSI-RS antenna port whose existing port number is p′ and belonging to a port group whose index is i, p′: an existing port number for each CSI-RS antenna port belonging to the port group whose index is i, N ports group : the number of CSI-RS antenna ports of each port group, N group : the number of port groups, i: an index of a port group where CSI-RS antenna ports belong to, wherein i=0 for the third port group, i=1 for the fourth port group, i=2 for the fifth port group).
8. The method of claim 1 , further comprising:
measuring CSI based on the received CSI-RS and the derived port numbers.
9. The method of claim 8 , further comprising:
reporting the measured CSI to the base station.
10. A method for transmitting channel state information (CSI)-reference signal (RS) by a base station, the method comprising:
transmitting first information on a number of CSI-RS antenna ports of each port group and second information on a number of port groups to a terminal; and
transmitting the CSI-RS to the terminal,
wherein when the number of port groups is 2 and the number of CSI-RS antenna ports of each port group is 8, port numbers of 8 first CSI-RS antenna ports belonging to a first port group and port numbers of 8 second CSI-RS antenna ports belonging to a second port group are derived based on the first information and the second information, and,
wherein when the when the number of port groups is 3 and the number of CSI-RS antenna ports of each port group is 4, port numbers of 4 third CSI-RS antenna ports belonging to a third port group, port numbers of 4 fourth CSI-RS antenna ports belonging to a fourth port group, and port numbers of 4 fifth CSI-RS antenna ports belonging to a fifth port group are derived based on the first information and the second information.
11. The method of claim 10 , wherein when the number of port groups is 2 and the number of CSI-RS antenna ports of each port group is 8, new port numbers of 15 to 30 for the 8 first CSI-RS antenna ports and the 8 second CSI-RS antenna ports are derived by using 8 first existing port numbers of 15 to 22 of the 8 first CSI-RS antenna ports and 8 second existing port numbers of 15 to 22 of the 8 second CSI-RS antenna ports.
12. The method of claim 11 , wherein the transmitting the CSI-RS comprises:
transmitting the CSI-RS using first resource elements and second resource elements,
wherein the 8 first CSI-RS antenna ports are mapped to the first resource elements using a first mapping rule based on the existing port numbers, and the 8 second CSI-RS antenna ports are mapped to the second resource elements using the first mapping rule based on the existing port numbers.
13. The method of claim 10 , wherein new port numbers of 15 to 30 for the 8 first CSI-RS antenna ports and the 8 second CSI-RS antenna ports are derived by using the following equation:
p
=
{
p
′
+
N
ports
group
2
i
,
for
p
′
∈
{
15
,
…
,
15
+
N
ports
group
2
-
1
}
p
′
+
N
ports
group
2
(
i
+
N
group
-
1
)
,
for
p
′
∈
{
15
+
N
ports
group
2
,
…
,
15
+
N
ports
group
-
1
}
[
Equation
]
(p: a new port number derived for a CSI-RS antenna port whose existing port number is p′ and belonging to a port group whose index is i, p′: an existing port number for each CSI-RS antenna port belonging to a port group whose index is i, N ports group : the number of CSI-RS antenna ports of each port group, N group : the number of port groups, i: an index of a port group where CSI-RS antenna ports belong to, wherein i=0 for the first port group, i=1 for the second port group).
14. The method of claim 10 , wherein when the number of port groups is 3 and the number of CSI-RS antenna ports of each port group is 4, new port numbers of 15 to 26 for the 4 third CSI-RS antenna ports, the 4 fourth CSI-RS antenna ports, and the 4 fifth CSI-RS antenna ports are derived by using 4 third existing port numbers of 15 to 18 of the 4 third CSI-RS antenna ports, 4 fourth existing port numbers of 15 to 18 of the 4 fourth CSI-RS antenna ports, and 4 fifth existing port numbers of 15 to 18 of the 4 fifth CSI-RS antenna ports.
15. The method of claim 14 , wherein the transmitting the CSI-RS comprises:
transmitting the CSI-RS using third resource elements, fourth resource elements, and fifth resource elements,
wherein the 4 third CSI-RS antenna ports are mapped to the third resource elements using a second mapping rule based on the existing port numbers,
the 4 fourth CSI-RS antenna ports are mapped to the fourth resource elements using the second mapping rule based on the existing port numbers,
and the 4 fifth CSI-RS antenna ports are mapped to the fifth resource elements using the second mapping rule based on the existing port numbers.
16. The method of claim 10 , wherein,
new port numbers of 15 to 26 for the 4 third CSI-RS antenna ports, the 4 fourth CSI-RS antenna ports, and the 4 fifth CSI-RS antenna ports are derived by using the following equation:
p
=
{
p
′
+
N
ports
group
2
i
,
for
p
′
∈
{
15
,
…
,
15
+
N
ports
group
2
-
1
}
p
′
+
N
ports
group
2
(
i
+
N
group
-
1
)
,
for
p
′
∈
{
15
+
N
ports
group
2
,
…
,
15
+
N
ports
group
-
1
}
[
Equation
]
(p: a new port number derived for a CSI-RS antenna port whose existing port number is p′ and belonging to a port group whose index is i, p′: an existing port number for each CSI-RS antenna port belonging to the port group whose index is i, N ports group : the number of CSI-RS antenna ports of each port group, N group : the number of port groups, i: an index of a port group where CSI-RS antenna ports belong to, wherein i=0 for the third port group, i=1 for the fourth port group, i=2 for the fifth port group).
17. The method of claim 10 , further comprising:
receiving CSI reported from the terminal,
wherein the CSI is measured by the terminal based on the CSI-RS and the derived port numbers.