Professor Toshiaki Yokoi of Tokyo City University has developed a program that can estimate a location using only an existing wireless LAN base station and a smartphone, even indoors where GPS signal strength is weak, such as inside buildings, underground malls, and elevators.
Indoor position estimation in a building can be used to grasp evacuees and respond quickly and ensure safety of rescuers in the event of a disaster, and to develop various services linked to locations during normal times.However, satellite positioning services such as GPS are not available indoors, and many indoor localization techniques require additional equipment.In public facilities such as schools, investment in equipment has become an issue for introduction and maintenance.
In our research, we have developed a method of estimating location using wireless LAN base stations, which have been developed along with the rapid spread of smartphones. We obtained the possibility of estimating the position by
This time, the wireless LAN reception signal (RSSI) was measured in a reinforced concrete building on the 7th floor and 2nd basement floor (101 wireless LAN base stations, operating frequency bands of 2.4GHz and 5.0GHz).We have developed a program that records and analyzes the identification name, frequency band, RSSI, etc. of wireless LAN reception signals at locations where wireless LAN base stations are installed, inside elevators (doors closed), and in front of elevators.At that time, we proposed a calculation formula for the similarity evaluation value (similarity index) of features called the "fingerprint of the radio wave environment" for each location indoors.This evaluation value clarifies the difference in the characteristics of each radio wave situation, and the current floor can be identified from the measured value inside the elevator.
The program developed this time uses the existing wireless LAN, so there is almost no additional cost.It is expected to be used in various situations such as rescue operations in the event of a disaster, autonomous driving of robots in smart cities, and watching over the elderly.
