Method and apparatus for allocating channel state information-reference signal in wireless communication system
Disclosed are an apparatus for Channel State Information-Reference Signal (CSI-RS) allocation and a method for CSI-RS transmission using the same in a wireless communication system. A CSI-RS for each antenna port is allocated to REs or subcarriers on a basis of a symbol or symbol axis in a subframe or Resource Block (RB), and is allocated in such a manner that a distance between neighboring CSI-RS allocation REs or subcarriers may be 3 REs or subcarriers. Accordingly, in the range of following CSI-RS transmission overhead, CSI-RSs are allocated to a time-frequency resource domain in such a manner so as to have perfect orthogonality or quasi-orthogonality according to cells or cell groups. Then, the CSI-RSs, which have been allocated to the time-frequency resource domain, are transmitted.
1. A method for receiving a signal, comprising:
receiving a signal comprising Channel State Information Reference Signals (CSI-RSs) for antenna ports in an antenna port set; and
acquiring channel state information of a first antenna port in the antenna port set and channel state information of a second antenna port in the antenna port set based on the CSI-RSs,
wherein the CSI-RSs for the antenna ports in the antenna port set are mapped to 2 consecutive Resource Elements (REs) in a time-frequency resource area, the time-frequency resource area being defined by one sub-frame and 12 sub-carriers, and the 2 consecutive REs corresponding to 1 sub-carrier in a frequency axis and two symbols in a time axis, and
wherein the CSI-RSs for the first antenna port and the second antenna port in the antenna port set are discriminated from each other by orthogonal codes.
2. The method of claim 1 , wherein the CSI-RSs correspond to first CSI-RSs and the antenna port set corresponds to a first antenna port set,
wherein the signal further comprises second CSI-RSs for antenna ports in a second antenna port set,
wherein the second CSI-RSs are mapped to 2 consecutive REs in the time-frequency resource area different from the 2 consecutive REs in which the first CSI-RSs are mapped, and
wherein the 2 consecutive REs in which the first CSI-RSs are mapped and the 2 consecutive REs in which the second CSI-RSs are mapped are spaced apart from each other along the frequency axis.
3. The method of claim 1 , wherein the first antenna port and the second antenna port in the antenna port set have consecutive antenna port numbers.
4. The method of claim 1 , wherein, if 4 antenna port sets including the antenna port set are determined for transmitting CSI-RSs, CSI-RSs for antenna ports in the 4 antenna port sets are mapped to 8 REs, the 8 REs corresponding to 4 evenly-spaced sub-carriers in a frequency axis and two symbols in a time axis, and
wherein CSI-RSs for antenna ports in each antenna port set are mapped to 2 consecutive REs corresponding to one of the 4 evenly-spaced sub-carriers and the two symbols.
5. The method of claim 4 , wherein the 4 antenna port sets are determined such that a first antenna port set has antenna port numbers M and M+1, a second antenna port set has antenna port numbers M+2 and M+3, a third antenna port set has antenna port numbers M+4 and M+5, and a fourth antenna port set has antenna port numbers M+6 and M+7, where M is an integer.
6. A method for transmitting a signal, comprising:
mapping Channel State Information Reference Signals (CSI-RSs) for antenna ports in an antenna port set to 2 consecutive Resource Elements (REs) in a time-frequency resource area, the time-frequency resource area being defined by one sub-frame and 12 sub-carriers, and the 2 consecutive REs corresponding to 1 sub-carrier in a frequency axis and two symbols in a time axis;
generating a signal comprising the mapped CSI-RSs; and
transmitting the signal to a User Equipment,
wherein the CSI-RSs for a first antenna port and a second antenna port in the antenna port set are discriminated from each other by orthogonal codes.
7. The method of claim 6 , wherein the CSI-RSs correspond to first CSI-RSs and the antenna port set corresponds to a first antenna port set,
wherein the signal further comprises second CSI-RSs for antenna ports in a second antenna port set,
wherein the second CSI-RSs are mapped to 2 consecutive REs in the time-frequency resource area different from the 2 consecutive REs in which the first CSI-RSs are mapped, and
wherein the 2 consecutive REs in which the first CSI-RSs are mapped and the 2 consecutive REs in which the second CSI-RSs are mapped are spaced apart from each other along the frequency axis.
8. The method of claim 6 , wherein the first antenna port and the second antenna port in the antenna port set have consecutive antenna port numbers.
9. The method of claim 6 , wherein, if 4 antenna port sets including the antenna port set are determined for transmitting CSI-RSs, CSI-RSs for antenna ports in the 4 antenna port sets are mapped to 8 REs, the 8 REs corresponding to 4 evenly-spaced sub-carriers in a frequency axis and two symbols in a time axis, and
wherein CSI-RSs for antenna ports in each antenna port set are mapped to 2 consecutive REs corresponding to one of the 4 evenly-spaced sub-carriers and the two symbols.
10. The method of claim 9 , wherein the 4 antenna port sets are determined such that a first antenna port set has antenna port numbers M and M+1, a second antenna port set has antenna port numbers M+2 and M+3, a third antenna port set has antenna port numbers M+4 and M+5, and a fourth antenna port set has antenna port numbers M+6 and M+7, where M is an integer.
11. A User Equipment (UE) to receive a signal, comprising:
a receiver to receive a signal comprising Channel State Information Reference Signals (CSI-RSs) for antenna ports in an antenna port set;
a processor to acquire channel state information of a first antenna port in the antenna port set and channel state information of a second antenna port in the antenna port set based on the CSI-RSs,
wherein the CSI-RSs for the antenna ports in the antenna port set are mapped to 2 consecutive Resource Elements (REs) in a time-frequency resource area, the time-frequency resource area being defined by one sub-frame and 12 sub-carriers, and the 2 consecutive REs corresponding to 1 sub-carrier in a frequency axis and two symbols in a time axis, and
wherein the CSI-RSs for the first antenna port and the second antenna port in the antenna port set are discriminated from each other by orthogonal codes.
12. The UE of claim 11 , wherein the CSI-RSs correspond to first CSI-RSs and the antenna port set corresponds to a first antenna port set,
wherein the signal further comprises second CSI-RSs for antenna ports in a second antenna port set,
wherein the second CSI-RSs are mapped to 2 consecutive REs in the time-frequency resource area different from the 2 consecutive REs in which the first CSI-RSs are mapped, and
wherein the 2 consecutive REs in which the first CSI-RSs are mapped and the 2 consecutive REs in which the second CSI-RSs are mapped are spaced apart from each other along the frequency axis.
13. The UE of claim 11 , wherein the first antenna port and the second antenna port in the antenna port set have consecutive antenna port numbers.
14. The UE of claim 11 , wherein, if 4 antenna port sets including the antenna port set are determined for transmitting CSI-RSs, CSI-RSs for antenna ports in the 4 antenna port sets are mapped to 8 REs, the 8 REs corresponding to 4 evenly-spaced sub-carriers in a frequency axis and two symbols in a time axis, and
wherein CSI-RSs for antenna ports in each antenna port set are mapped to 2 consecutive REs corresponding to one of the 4 evenly-spaced sub-carriers and the two symbols.
15. The UE of claim 14 , wherein the 4 antenna port sets are determined such that the first antenna port set has antenna port numbers M and M+1, a second antenna port set has antenna port numbers M+2 and M+3, a third antenna port set has antenna port numbers M+4 and M+5, and a fourth antenna port set has antenna port numbers M+6 and M+7, where M is an integer.
16. An evolved node B (eNodeB) to transmit a signal, comprising:
a processor to map Channel State Information Reference Signals (CSI-RSs) for antenna ports in an antenna port set to 2 consecutive Resource Elements (REs) in a time-frequency resource area, and to generate a signal comprising the mapped CSI-RSs, the time-frequency resource area being defined by one sub-frame and 12 sub-carriers, and the 2 consecutive REs corresponding to 1 sub-carrier in a frequency axis and two symbols in a time axis; and
a transmitter to transmit the signal to a User Equipment,
wherein the CSI-RSs for a first antenna port and a second antenna port in the antenna port set are discriminated from each other by orthogonal codes.
17. The eNodeB of claim 16 , wherein the CSI-RSs correspond to first CSI-RSs and the antenna port set corresponds to a first antenna port set,
wherein the signal further comprises second CSI-RSs for antenna ports in a second antenna port set,
wherein the second CSI-RSs are mapped to 2 consecutive REs in the time-frequency resource area different from the 2 consecutive REs in which the first CSI-RSs are mapped, and
wherein the 2 consecutive REs in which the first CSI-RSs are mapped and the 2 consecutive REs in which the second CSI-RSs are mapped are spaced apart from each other along the frequency axis.
18. The eNodeB of claim 16 , wherein the first antenna port and the second antenna port in the antenna port set have consecutive antenna port numbers.
19. The eNodeB of claim 16 , wherein, if 4 antenna port sets including the antenna port set are determined for transmitting CSI-RSs, CSI-RSs for antenna ports in the 4 antenna port sets are mapped to 8 REs, the 8 REs corresponding to 4 evenly-spaced sub-carriers in a frequency axis and two symbols in a time axis, and
wherein CSI-RSs for antenna ports in each antenna port set are mapped to 2 consecutive REs corresponding to one of the 4 evenly-spaced sub-carriers and the two symbols.
20. The eNodeB of claim 19 , wherein the 4 antenna port sets are determined such that a first antenna port set has antenna port numbers M and M+1, a second antenna port set has antenna port numbers M+2 and M+3, a third antenna port set has antenna port numbers M+4 and M+5, and a fourth antenna port set has antenna port numbers M+6 and M+7, where M is an integer.