Position estimation device, position estimation method, program and integrated circuit

A position estimation device which estimates a current position of a wireless terminal, the device comprising:

• a distance estimation unit configured to estimate, using a receiving strength of a signal received by the wireless terminal from each of a plurality of base stations communicating with the wireless terminal, distance information indicating a distance from the base station to the wireless terminal;
• a position estimation unit configured to estimate a first position to be a current position of the wireless terminal using base station information indicating a position of the base station and the estimated distance information;
• and
• a correction unit configured to correct the distance information by:
• obtaining, using terminal posture information that is obtained by an acceleration sensor and a direction sensor of the wireless terminal and indicates an orientation of a surface of the wireless terminal at the estimated first position, surface orientation information on an orientation of the surface of the wireless terminal at the estimated first position as seen from the position of the base station;
• and correcting the distance from the base station to the wireless terminal based on the obtained surface orientation information,
• wherein the position estimation unit is further configured to estimate a second position to be a current position of the wireless terminal using the base station information and the corrected distance information.

A position estimation device which estimates a current position of a wireless terminal, the device comprising:

• a storage unit configured to preliminarily store an electric field strength map in which a receiving strength of a signal received by the wireless terminal from each of a plurality of base stations communicating with the wireless terminal is recorded at predetermined space intervals;
• a measurement unit configured to measure a receiving strength of a signal received by the wireless terminal from the base station;
• a position estimation unit configured to estimate a first position to be a current position of the wireless terminal and at which the receiving strength is measured, using the receiving strength measured by the measurement unit and the electric field strength map stored in the storage unit;
• a placement state determination unit configured to determine a placement state indicating where the wireless terminal at the estimated first position is placed on a user using an acceleration of the wireless terminal;
• a movement direction determination unit configured to determine a movement direction of the wireless terminal at the estimated first position using the acceleration and a direction of the wireless terminal;
• and
• a correction unit configured to:
• obtain, using terminal posture information that is obtained by an acceleration sensor and a direction sensor of the wireless terminal and indicates an orientation of a surface of the wireless terminal at the estimated first position, surface orientation information on an orientation of the surface of the wireless terminal at the estimated first position as seen from the position of the base station;
• specify a positional relationship among the base station, the user, and the wireless terminal, using the obtained surface orientation information, the determined placement state, the determined movement direction, and the estimated first position;
• and correct the receiving strength according to the orientation of the surface of the wireless terminal at the estimated first position and the specified positional relationship,
• wherein the position estimation unit is configured to estimate a second position to be a current position of the wireless terminal, using the corrected receiving strength and the stored electric field strength map.

A position estimation method for estimating a current position of a wireless terminal, the method comprising:

• estimating, using a receiving strength of a signal received by the wireless terminal from each of a plurality of base stations communicating with the wireless terminal, distance information indicating a distance from the base station to the wireless terminal;
• estimating a first position to be a current position of the wireless terminal using base station information indicating a position of the base station and the estimated distance information;
• and
• correcting the distance information by:
• obtaining, using terminal posture information that is obtained by an acceleration sensor and a direction sensor of the wireless terminal and indicates an orientation of a surface of the wireless terminal at the estimated first position, surface orientation information on an orientation of the surface of the wireless terminal at the estimated first position as seen from the position of the base station;
• and correcting the distance from the base station to the wireless terminal based on the obtained surface orientation information,
• wherein the estimating of a first position further includes estimating a second position to be a current position of the wireless terminal using the base station information and the corrected distance information.

A non-transitory computer-readable recording medium on which a program for causing a computer to execute position estimation processing for estimating a current position of a wireless terminal is recorded, the position estimation processing comprising:

• estimating, using a receiving strength of a signal received by the wireless terminal from each of a plurality of base stations communicating with the wireless terminal, distance information indicating a distance from the base station to the wireless terminal;
• estimating a first position to be a current position of the wireless terminal using base station information indicating a position of the base station and the estimated distance information;
• and
• correcting the distance information by:
• obtaining, using terminal posture information that is obtained by an acceleration sensor and a direction sensor of the wireless terminal and indicates an orientation of a surface of the wireless terminal at the estimated first position, surface orientation information on an orientation of the surface of the wireless terminal at the estimated first position as seen from the position of the base station;
• and correcting the distance from the base station to the wireless terminal based on the obtained surface orientation information,
• wherein the estimating of a first position further includes estimating a second position to be a current position of the wireless terminal using the base station information and the corrected distance information.

An integrated circuit which estimates a current position of a wireless terminal, the integrated circuit comprising:

• a distance estimation unit configured to estimate, using a receiving strength of a signal received by the wireless terminal from each of a plurality of base stations communicating with the wireless terminal, distance information indicating a distance from the base station to the wireless terminal;
• a position estimation unit configured to estimate a first position to be a current position of the wireless terminal using base station information indicating a position of the base station and the estimated distance information;
• and
• a correction unit configured to correct the distance information by:
• obtaining, using terminal posture information that is obtained by an acceleration sensor and a direction sensor of the wireless terminal and indicates an orientation of a surface of the wireless terminal at the estimated first position, surface orientation information on an orientation of the surface of the wireless terminal at the estimated first position as seen from the position of the base station;
• and
• correcting the distance from the base station to the wireless terminal based on the obtained surface orientation information,
• wherein the position estimation unit is further configured to estimate a second position to be a current position of the wireless terminal using the base station information and the corrected distance information.