Technique for transmitting and receiving downlink reference signals

A method of receiving downlink signals from a base station (BS) at a user equipment (UE) in a multiple input multiple output (MIMO) wireless communication system, the method comprising:

• receiving a downlink control channel from the BS;
• and
• receiving a downlink data channel and a downlink reference signal for demodulation of the downlink data channel from the BS,
• wherein:
• when the downlink data channel comprises only one transmission layer, the downlink control channel includes information indicating which antenna port is used for receiving the downlink reference signal among a plurality of antenna ports, and
• when the downlink data channel comprises two or more transmission layers, the downlink reference signal is received on two or more fixed antenna ports among the plurality of antenna ports.

A base station (BS) in a multiple input multiple output (MIMO) wireless communication system, the BS comprising:

• a processor for generating downlink signals comprising a downlink control channel, a downlink data channel and a downlink reference signal for the demodulation of a downlink data channel;
• and
• a transmitter for transmitting the downlink control channel, the downlink data channel and the downlink reference signal to a user equipment (UE),
• wherein:
• when the downlink data channel comprises only one transmission layer, the downlink control channel includes information indicating which antenna port is used for transmitting the downlink reference signal among a plurality of antenna ports, and
• when the downlink data channel comprises two or more transmission layers, the downlink reference signal is transmitted on two or more fixed antenna ports among the plurality of antenna ports.

A user equipment (UE) in a multiple input multiple output (MIMO) wireless communication system, the UE comprising:

• a receiver for receiving, from a base station (BS), downlink signals comprising a downlink control channel, a downlink data channel and a downlink reference signal for a demodulation of the downlink data channel;
• and
• a processor for processing the downlink signals,
• wherein:
• when the downlink data channel comprises only one transmission layer, the downlink control channel includes information indicating which antenna port is used for receiving the downlink reference signal among a plurality of antenna ports, and
• when the downlink data channel comprises two or more transmission layers, the downlink reference signal is received on two or more fixed antenna ports among the plurality of antenna ports.