Modulation apparatus and demodulation apparatus

A modulation apparatus used in a line of sight multiple input multiple output (LOS-MIMO:

• Line Of Sight-Multiple Input Multiple Output) radio communication system, comprising:
• means for generating a spread code of a sequence length of a time-domain pilot signal sequence and generating a second number of cyclic shift sequences by cyclically shifting the generated spread code;
• means for transforming the second number of pilot signals into a third number of frequency-domain signals corresponding to the sequence length;
• means for mapping the third number of frequency-domain signals onto a fifth number of frequency components at a fourth number of subcarrier intervals by shifting mapping positions of heads of the frequency-domain signals one after another by an amount equivalent to one subcarrier so that the frequency-domain signals do not overlap each other, the fourth number being a number based on the number of transmitting antennas of the modulation apparatus and the second number, and the fifth number being a number based on the sequence length and the fourth number;
• means for transforming the mapped frequency-domain signals into time-domain signals;
• and
• means for setting the time-domain signals in a pilot block.

A demodulation apparatus used in a line of sight multiple input multiple output (LOS-MIMO:

• Line Of Sight-Multiple Input Multiple Output) radio communication system, comprising:
• means for estimating, by using a pilot signal contained in a reception signal, a first channel response of a transmission signal transmitted from each of a plurality of transmitting antennas provided in another radio communication apparatus;
• means for estimating, based on the estimated first channel response, a phase variation at a pilot block position at which the pilot signal is set;
• means for, based on the phase variation at the pilot block position, interpolating and compensating for the phase variation at a block position at which an information symbol included between adjacent pilot block positions is set;
• means for transforming the reception signal which has been compensated for the phase variation into a frequency-domain signal;
• means for estimating, by using the pilot signal contained in the frequency-domain signal, a second channel response indicating a channel response, at each of a plurality of subcarrier positions, to a transmission signal transmitted from each of the plurality of transmission antennas;
• means for generating an equalization weight based on the estimated second channel response, and equalizing the frequency-domain signal by multiplying an information symbol at each of the plurality of subcarrier positions by the equalization weight;
• and
• means for transforming the equalized frequency-domain signal into a time-domain signal.

A demodulation apparatus used in a line of sight multiple input multiple output (LOS-MIMO:

• Line Of Sight-Multiple Input Multiple Output) radio communication system, comprising:
• means for transforming a time-domain reception signal into a frequency-domain signal;
• means for estimating, by using a pilot signal contained in the transformed frequency-domain signal, a channel response, at each of a plurality of subcarrier positions, to a transmission signal transmitted from each of a plurality of transmission antennas provided in another radio communication apparatus;
• means for estimating, based on the estimated channel response, a common phase variation common to all the subcarrier positions, and compensating for the estimated common phase variation from the transformed frequency-domain signal;
• means for generating an equalization weight based on the estimated channel response, and equalizing the frequency-domain signal by multiplying an information symbol at each of the plurality of subcarrier positions at which the common phase variation has been compensated for by the equalization weight;
• and
• means for transforming the equalized frequency-domain signal into a time-domain signal.