Mimo demodulating apparatus and method, and line-of-sight wireless communications system

A MIMO demodulating method which, in a line-of-sight multiple input multiple output wireless communications system that uses multiple transmitting antennas and multiple receiving antennas to implement multiplexing of channels utilizing difference in transmission delay adjusted based on inter-antenna spacing, estimates transmitted data from received signals respectively received at the multiple receiving antennas, the method comprising:

• determining phase difference between the received signals received by the multiple receiving antennas, based on a signal that is known to a receiving side and inserted in a sequence of a transmitted signal;
• outputting a phase corrected signal by compensating for phase shift of each received signal by utilizing the phase difference;
• performing, for a plurality of the phase corrected signals, elimination of interference in the received signals inclusive of intersymbol interference, and separation and extraction of a desired signal from multiplexed signals transmitted through the transmission channels, by means of adaptive control;
• compensating for phase error remaining in the desired signal;
• determining and outputting transmitted data based on the desired signal of which the phase error has been compensated for;
• and
• regarding difference between the desired signal of which the phase error has been compensated for and the transmitted data as an error signal and subjecting the error signal to a phase rotating process in accordance with a phase error compensation amount,
• wherein the error signal having been subjected to the phase rotating process is used for the adaptive control.

A line-of-sight multiple input and multiple output wireless communications system that performs multiplexing of transmission channels based on the difference between transmission delays adjusted by spacing distance between antennas, comprising:

• a transmitter including a plurality of transmitting antennas each sending out a transmitted signal;
• and
• a receiver including a plurality of receiving antennas, and a MIMO demodulating apparatus for estimating transmitted data from the received signal received at each of the receiving antennas,
• wherein the MIMO demodulating apparatus comprises:
• a phase difference corrector that compensates for phase shift of each received signal by utilizing phase difference between received signals received at the multiple receiving antennas to output a phase corrected signal of each of the received signals;
• an interference compensator that receives the multiple phase corrected signals as input and, by means of adaptive control, performs elimination of interference in the received signals inclusive of intersymbol interference, and separation and extraction of a desired signal from multiplexed signals transmitted through the transmission channels to output the desired signal;
• a phase noise compensator connected to the interference compensator to compensate for phase error remaining in the desired signal;
• a signal determiner that determines transmitted data from the output signal of the phase noise compensator to output the transmitted data, and outputs difference between the output signal from the phase noise compensator and the transmitted data as an error signal;
• and
• an error signal phase rotator that subjects the error signal to a phase rotating process in accordance with a phase error compensation amount at the phase noise compensator,
• wherein the error signal subjected to the phase rotating process at the error signal phase rotator is used for adaptive control in the interference compensator, and
• the phase difference is determined in the phase difference corrector, based on a signal that is inserted in a sequence of the transmitted signal and known to the receiver.