Apparatus and method for allocating channel state information-reference signal in wireless communication system

A method, comprising:

• receiving and extracting, by a User Equipment (UE), Channel State Information Reference Signals (CSI-RSs) for four pairs of antenna ports being allocated to a portion of Resource Elements (REs) in a time-frequency resource area determined by one subframe and 12 subcarriers;
• and
• acquiring Channel State Information (CSI) based on the extracted CSI-RSs,
• wherein two CSI-RSs in one of the four pairs of antenna ports are associated with different orthogonal codes, respectively,
• wherein the CSI-RSs of a first pair (1st, 2nd) of antenna ports are allocated to a first two consecutive REs, the CSI-RSs of a second pair (3rd, 4th) of antenna ports are allocated to a second two consecutive REs, the CSI-RSs of a third pair (5th, 6th) of antenna ports are allocated to a third two consecutive REs, and the CSI-RSs of a fourth pair (7th, 8th) of antenna ports are allocated to a fourth two consecutive REs,
• wherein each of the first two consecutive REs, the second two consecutive REs, the third two consecutive REs, and the fourth two consecutive REs corresponds to one subcarrier in a frequency axis and 8th and 9th symbols in a time axis, and
• wherein the first two consecutive REs has subcarrier index 9, the second two consecutive REs has subcarrier index 6, the third two consecutive REs has subcarrier index 3, and the fourth two consecutive REs has subcarrier index 0.

An apparatus, comprising:

• a processor configured to allocate Channel State Information-Reference Signals (CSI-RSs) for four pairs of antenna ports in a wireless communication system,
• wherein the CSI-RSs of the four pairs of antenna ports are allocated to a portion of Resource Elements (REs) in a time-frequency resource area determined by one subframe and 12 subcarriers,
• wherein two CSI-RSs in one of the four pairs of antenna ports are associated with different orthogonal codes, respectively,
• wherein the CSI-RSs of a first pair (1st, 2nd) of antenna ports are allocated to a first two consecutive REs, the CSI-RSs of a second pair (3rd, 4th) of antenna ports are allocated to a second two consecutive REs, the CSI-RSs of a third pair (5th, 6th) of antenna ports are allocated to a third two consecutive REs, and the CSI-RSs of a fourth pair (7th, 8th) of antenna ports are allocated to a fourth two consecutive REs,
• wherein each of the first two consecutive REs, the second two consecutive REs, the third two consecutive REs, and the fourth two consecutive REs corresponds to one subcarrier in a frequency axis and 8th and 9th symbols in a time axis, and
• wherein the first two consecutive REs has subcarrier index 9, the second two consecutive REs has subcarrier index 6, the third two consecutive REs has subcarrier index 3, and the fourth two consecutive REs has subcarrier index 0.