Position estimation method, position estimation system, position estimation server, and position estimation program

A position estimation method comprising:

• transmitting a measurement signal and receiving a response signal between multiple n wireless stations respectively provided with known antennas i (i=1, 2, . . . , n) installed at known positions different from each other and a wireless terminal station provided with a terminal antenna installed at an unknown position;
• measuring RTT, which is a round-trip delay time of the transmission and the reception;
• measuring RSSI, which is a strength of received radio waves of the signals;
• obtaining coordinate information of an estimated position of the wireless terminal station with the terminal antenna in response to the measured RTT and the measured RSSI by the known antennas i;
• applying the coordinate information to an RTT evaluation function fti and an RSSI evaluation function fri to evaluate the estimated position of the wireless terminal station with the terminal antenna, each of the RTT evaluation function fti and the RSSI evaluation function fri having terms relating to the coordinate information, a value of each of the terms being variable;
• determine, by using a range evaluation function k, whether the value of each of the terms of the RTT evaluation function fti and the RSSI evaluation function fri is within an acceptable range in which the wireless terminal station with the terminal antenna is to be present, the range evaluation function fL having the terms;
• setting a value of each of the terms of the range evaluation function fL to zero when the value of each of the terms of the RTT evaluation function fti and the RSSI evaluation function fri is within the acceptable range;
• setting the value of each of the terms of the range evaluation function fL to a proportional value when the value of each of the terms of the RTT evaluation function fti and the RSSI evaluation function fri deviates from the acceptable range by a deviation amount, the proportional value being larger as the deviation amount becomes larger;
• and
• estimating a position of the wireless terminal station with the terminal antenna based on either:
• a solution of simultaneous equations of the RTT evaluation function fti, the RSSI evaluation function fri, and the range evaluation function fL;
• or
• a value obtained by searching for an estimate value in a case in which an error evaluation function ferror obtained by combining the RTT evaluation function fti, the RSSI evaluation function fri, and the range evaluation function fL is minimum.

A position estimation method comprising:

• transmitting a measurement signal and receiving a response signal between multiple n wireless stations respectively provided with known antennas i (i=1, 2, . . . , n) installed at known positions different from each other and a wireless terminal station provided with a terminal antenna installed at an unknown position;
• measuring RSSI, which is a strength of received radio waves of the signals;
• obtaining coordinate information of an estimated position of the wireless terminal station with the terminal antenna in response to the measured RSSI by the known antennas i;
• applying the coordinate information to an RSSI evaluation function fri to evaluate the estimated position of the wireless terminal station with the terminal antenna, the RSSI evaluation function fri having terms relating to the coordinate information, a value of each of the terms being variable;
• determine, by using a range evaluation function fL, whether the value of each of the terms of the RSSI evaluation function fri is within an acceptable range in which the wireless terminal station with the terminal antenna is to be present, the range evaluation function fL having the terms;
• setting a value of each of the terms of the range evaluation function fL to zero when the value of each of the terms of the RSSI evaluation function fri is within the acceptable range;
• setting the value of each of the terms of the range evaluation function fL to a proportional value when the value of each of the terms of the RSSI evaluation function fri deviates from the acceptable range by a deviation amount, the proportional value being larger as the deviation amount becomes larger;
• and
• estimating a position of the wireless terminal station with the terminal antenna based on either:
• a solution of simultaneous equations of the RSSI evaluation function fri and the range evaluation function fL;
• or
• a value obtained by searching for an estimate value in a case in which an error evaluation function ferror obtained by combining the RSSI evaluation function fri and the range evaluation function fL is minimum.