Position calculation method and position calculation apparatus

A position calculation apparatus comprising a receiver that receives signals from a plurality of antennas located at known and different positions and from a base antenna, a delay profile analysis apparatus that performs delay profile analysis for the signals received by said receiver, and a calculation apparatus that uses wireless signal delay times included in the delay profile analysis produced by said delay profile analysis apparatus, to calculate a position of said position calculation apparatus, wherein

• said calculation apparatus comprises:
• first range difference calculation means for calculating, for each of said plurality of antennas, a first range difference between a first range from said terminal to each of said plurality of antennas and a second range from said terminal to the base antenna, each of said first and second ranges being calculated based on a respective wireless signal delay time;
• second range difference calculation means for calculating, for each of said plurality of antennas, a second range difference between a third range from one of a plurality of terminal position candidates to each of said plurality of antennas and a fourth range from the candidate to said base antenna;
• error calculation means for calculating, for each of said plurality of antennas, an error that is a difference between the first range difference and the second range difference;
• likelihood calculation means for calculating based upon the errors calculated by said error calculation means having an asymmetric distribution for positive and negative values, a likelihood of the candidate using the distribution and the errors;
• and
• terminal position search means for obtaining a most likely candidate with the maximum likelihood as the position of said terminal.

A position calculation system comprising:

• a terminal comprising:
• a receiver that receives signals from a plurality of antennas located at known and different positions and from a base antenna;
• a delay profile analysis apparatus that performs delay profile analysis for the signals received by said receiver;
• and
• transmission apparatus that transmits delay profile analysis results produced by said delay profile analysis apparatus;
• a wireless apparatus that receives the delay profile analysis results from said terminal;
• and
• a calculation apparatus that uses wireless signal delay times included in the received delay profile analysis results to calculate a position of said terminal, wherein
• said calculation apparatus comprises:
• first range difference calculation means for calculating, for each of said plurality of antennas, a first range difference between a first range from said terminal to each of said plurality of antennas and a second range from said terminal to the base antenna, each of said first and second ranges being calculated based on a respective wireless signal delay time;
• second range difference calculation means for calculating, for each of said plurality of antennas, a second range difference between a third range from one of a plurality of terminal position candidates to each of said plurality of antennas and a fourth range from the candidate to said base antenna;
• error calculation means for calculating, for each of said plurality of antennas, an error that is a difference between the first range difference and the second range difference;
• likelihood calculation means for calculating based upon the errors calculated by said error calculation means having an asymmetric distribution for positive and negative values, a likelihood of the candidate using the distribution and the errors;
• and
• terminal position search means for obtaining a most likely candidate with the maximum likelihood as the position of said terminal.

A position calculation system comprising a plurality of antennas located at known and different positions and a base antenna that receive signals from a terminal, a delay profile analysis apparatus that performs delay profile analysis for the signals received by the base antenna, and a calculation apparatus that uses wireless signal delay times included in the delay profile analysis produced by said delay profile analysis apparatus, to calculate a position of said terminal, wherein

• said calculation apparatus comprises:
• first range difference calculation means for calculating, for each of said plurality of antennas, a first range difference between a first range from said terminal to each of said plurality of antennas and a second range from said terminal to the base antenna, each of said first and second ranges being calculated based on a respective wireless signal delay time;
• second range difference calculation means for calculating, for each of said plurality of antennas, a second range difference between a third range from one of a plurality of terminal position candidates to each of said plurality of antennas and a fourth range from the candidate to said base antenna;
• error calculation means for calculating, for each of said plurality of antennas, an error that is a difference between the first range difference and the second range difference;
• likelihood calculation means for calculating based upon the errors calculated by said error calculation means having an asymmetric distribution for positive and negative values, a likelihood of the candidate using the distribution and the errors each calculated for each of said plurality of antennas;
• and
• terminal position search means for obtaining a most likely candidate with the maximum likelihood as the position of said terminal.