Positioning system, access control system, and positioning method

A positioning method for use in a positioning system including:

• a transmitting and receiving part having a plurality of antennas and positioned overhead in a positioning target area where there is a side entrance;
• a distance calculation part configured to calculate a distance between a communication device that can move in the positioning target area, and the transmitting and receiving part, based on results gained from signals of a plurality of frequencies transmitted bidirectionally between the communication device and the transmitting and receiving part;
• and
• an angle calculation part configured to calculate an angle that indicates a position of the communication device with respect to the transmitting and receiving part, based on a phase difference between the signals received by the plurality of antennas of the transmitting and receiving part,
• the positioning method comprising determining whether or not the communication device is approaching the side entrance based on the distance calculated by the distance calculation part and the angle calculated by the angle calculation part.