Patent ID: 8730850

Claim:
A method of transmitting a reference signal in a time division duplex (TDD) system, the method comprising: generating a plurality of demodulation reference signals (DMRSs) for respective layers; mapping the plurality of DMRSs to a downlink pilot time slot (DwPTS) region for downlink transmission within a special subframe; and transmitting the plurality of DMRSs through a plurality of antennas, wherein the special subframe is a subframe for separating uplink and downlink between an uplink (UL) subframe and a downlink (DL) subframe within a frame, wherein the DwPTS region occupies only 10 to 12 orthogonal frequency division multiplexing (OFDM) symbols for the special subframe having a normal cyclic prefix (CP) structure according to the configuration of the special subframe and only 9 or 10 OFDM symbols for the special subframe having an extended CP structure according to the configuration of the special subframe in order to use both a code division multiplexing-time (CDM-T) method and a code division multiplexing-frequency (CDM-F) method based on the plurality of DMRSs, and wherein the DwPTS region occupies only 9 orthogonal frequency division multiplexing (OFDM) symbols for the special subframe having a normal cyclic prefix (CP) structure according to the configuration of the special subframe and only 8 OFDM symbols for the special subframe having an extended CP structure according to the configuration of the special subframe in order to use only the CDM-T method based on the plurality of DMRSs.