Method and apparatus for obtaining channel information in polarization division duplex systems

A receiving apparatus of acquiring channel information in a polarization division duplex system, the apparatus comprising:

• a signal receiving processor configured to receive an uplink signal from a transmitting apparatus, the uplink signal indicating that a null subcarrier is disposed in a first subcarrier overlapped with a second subcarrier including a downlink pilot signal;
• a self-interference channel estimation unit configured to estimate a self-interference channel by using a signal received from the null subcarrier;
• a null subcarrier remover configured to remove a signal corresponding to the null subcarrier from the uplink signal;
• and
• a channel estimation and equalizer configured to acquire channel information by estimating the uplink channel based on estimation results of the self-interference channel and a pilot signal included in the uplink signal from which the null subcarrier is removed.

A transmitting apparatus of transmitting an uplink signal to acquire channel information in a polarization division duplex system, the apparatus comprising:

• a DFT (discrete Fourier transform) unit configured to convert data to be transmitted into a data signal of a frequency domain by performing DFT for the data, and to map a frequency-converted signal of the data to a subcarrier;
• a null subcarrier insertion unit configured to process a first carrier that overlaps a second subcarrier in which a downlink pilot signal exists as a null subcarrier;
• an IDFT unit configured to convert a signal to be transmitted into a time domain signal by performing IDFT (inverse DFT) when signals are allocated to all subcarriers;
• and
• a signal transmitting processor configured to transmit the time domain signal through an antenna.