Apparatus and method for transmitting pilot signal in wireless communication system

A method for detecting a signal at a receiver of a multi-antenna system, the method comprising:

• estimating a channel based on first pilot signals received through at least two streams and a second pilot signal shared by the streams;
• generating a vector orthogonal to the channel estimated based on the first pilot signal, if the first pilot signal is not the pilot signal allocated to the stream of the receiver;
• generating a postcode based on the orthogonal vector;
• estimating a channel gain based on the postcode and the channel estimated based on the second pilot signal;
• and
• detecting a signal based on the postcode and the channel gain.

A transmitting apparatus of a multi-antenna system, the apparatus comprising:

• at least two antennas;
• a channel detector for detecting downlink channel information of at least two receivers located in a service area;
• a weight generator for generating, based on the downlink channel information, postcodes and pre-codes for streams used to transmit signals to the receivers;
• a pilot controller for allocating a pilot signal to at least one of the streams and for allocating an additional pilot signal shared by at least one of the streams;
• and
• a pre-coder for preceding the pilot signal allocated to at least one of the streams, the additional pilot signal, and data to be transmitted to each of the receivers, based on the pre-code for each of the streams.

A receiving apparatus of a multi-antenna system, the apparatus comprising:

• a channel estimator for estimating a channel based on first pilot signals and a second pilot signal received through at least two streams;
• a postcode generator for generating a postcode based on a vector orthogonal to a channel estimated based on the first pilot signal, if the first pilot signal is not the pilot signal allocated to the stream of the receiving apparatus, and for generating a postcode based on a channel estimated based on the first pilot signal, if the first pilot signal is the pilot signal allocated to the stream of the receiving apparatus;
• a channel gain estimator for estimating a channel gain based on the pre-code and the channel estimated based on the first pilot signal or the second pilot signal;
• a postcoder for postcoding a received signal based on the generated postcode;
• and
• an equalizer for equalizing the postcoded signal based on the estimated channel gain.