Radio communication system, base station, terminal apparatus and pilot signal controlling method

A radio communication system in which a base station using a multicarrier transmission scheme as a transmission scheme and a terminal apparatus each having a plurality of transmission antennas are wirelessly connected,

• wherein the base station comprises:
• a data generator configured to generate first pilot signals for the terminal apparatus to measure channel quality, second pilot signals for the terminal apparatus to estimate a channel and data signals to be transmitted to the terminal apparatus and divide the data signals into portions corresponding in number to the plurality of transmission antennas;
• a transmission power controller configured to control transmission power of the second pilot signals and each divided data signals by adjusting the amplitude of the second pilot signals and each divided data signals respectively;
• and
• a plurality of transmitters provided in correspondence with the respective transmission antennas configured to map the first or second pilot signals and the divided data signals to a plurality of subcarriers to generate subcarrier data in such a way that the first and second pilot signals are each transmitted from at least one of the transmission antennas and transmit generated subcarrier data from the respective transmission antennas.

A base station which is wirelessly connected to a terminal apparatus and uses a multicarrier transmission scheme as a transmission scheme, comprising:

• a data generator configured to generate first pilot signals for the terminal apparatus to measure channel quality, second pilot signals for the terminal apparatus to estimate a channel and data signals to be transmitted to the terminal apparatus;
• a transmission power controller configured to control transmission power of the second pilot signals and the data signals by adjusting amplitude of the second pilot signals and the data signals respectively;
• and
• a transmitter configured to generate subcarrier data by mapping the first pilot signals, the second pilot signals power-controlled by the transmission power controller and the data signals power-controlled by the transmission power controller to a plurality of subcarriers and transmit the subcarrier data generated.

A terminal apparatus wirelessly connected to a base station using a multicarrier transmission scheme as a transmission scheme, comprising:

• a receiver configured to perform a Fourier transform on received signals obtained by an antenna and thereby acquire first pilot signals for measuring channel quality and second pilot signals for estimating a channel and data signals;
• an amplitude measuring unit configured to measure amplitude of the second pilot signals;
• an amplitude adjuster configured to adjust the amplitude of the first pilot signals to same amplitude as that of the second pilot signals;
• a channel estimator configured to estimate a channel using the first pilot signals whose amplitude is adjusted and the second pilot signals and thereby acquire a channel estimated value indicating a state of the channel;
• and
• a demodulator configured to demodulate the data signals using the channel estimated value.

A base station having a plurality of transmission antennas which is wirelessly connected to a terminal apparatus and uses a multicarrier transmission scheme as a transmission scheme, comprising:

• a data generator configured to generate first pilot signals for the terminal apparatus to measure channel quality, second pilot signals for the terminal apparatus to estimate a channel and data signals to be transmitted to the terminal apparatus and divide the data signals into portions corresponding in number to the plurality of transmission antennas;
• a transmission power controller configured to control transmission power of the second pilot signals and each divided data signals by adjusting the amplitude of the second pilot signals and each divided data signals respectively;
• and
• a plurality of transmitters provided in correspondence with the respective transmission antennas configured to map the first or second pilot signals and the divided data signals to a plurality of subcarriers to generate subcarrier data in such a way that the first and second pilot signals are each transmitted from at least one of the transmission antennas and transmit generated subcarrier data from the respective transmission antennas.

A pilot signal controlling method of a radio communication system in which a base station using a multicarrier transmission scheme as a transmission scheme and a terminal apparatus are wirelessly connected, comprising:

• generating by the base station first pilot signals for the terminal apparatus to measure channel quality, second pilot signals for the terminal apparatus to estimate a channel and data signals to be transmitted to the terminal apparatus;
• controlling by the base station transmission power of the second pilot signals and the data signals by adjusting amplitude of the second pilot signals and the data signals respectively;
• and
• generating by the base station subcarrier data by mapping the first pilot signals, the second pilot signals power-controlled and the data signals power-controlled to a plurality of subcarriers and transmitting by the base station the subcarrier data generated.