Patent ID: 8400994

Claim:
A method for transmitting Reference Signals (RSs) via downlink communication in a multi-antenna wireless communication system, the method comprising: allocating RSs for a first antenna group to a subframe having a predetermined area with different access levels for User Equipments (UEs) having different access capabilities; pairing RSs for a second antenna group with RSs for the first antenna group; and allocating the paired RSs to the predetermined area of the subframe in Code Division Multiplexing (CDM); and transmitting the subframe via the downlink, wherein: allocating the RSs for the first antenna group comprises allocating the RSs in the predetermined area of the subframe in Pattern 1-1 or Pattern 1-2, Pattern 1-1 comprises: Slot 1 Slot 2 Subframe l = 3 or l = 4 l = 0 l = 1 l = 3 or l = 4 Antenna port 0 3, 9 0, 6 — 3, 9 Antenna port 1 0, 6 3, 9 — 0, 6 Antenna port 2 — — 3, 9 — Antenna port 3 — — 0, 6 —; [Pattern 1-2] comprises: Slot 1 Slot 2 Subframe l = 3 or l = 4 l = 0 l = 1 l = 3 or l = 4 Antenna port 0 — 0, 6 — 3, 9 Antenna port 1 — 3, 9 — 0, 6 Antenna port 2 0, 6 — 3, 9 — Antenna port 3 3, 9 — 0, 6 —; I indicates an index of an Orthogonal Frequency Division Multiplexing (OFDM) symbol, numerals indicate subcarrier indexes within a resource block and — indicates non-RS allocation; antenna port 0 to antenna port 3 may be permuted; and RSs may be shifted along a frequency axis or a time axis.