A technique was developed that uses a combination of WiFi signals and accelerometer technology to track devices in near-real-time. The WiFi-assisted Inertial Odometry (WIO) technique uses WiFi as a velocity sensor to accurately track how far something has moved — similar to sonar but using radio waves instead of sound waves.
Many devices, such as smartphones, incorporate inertial measurement units (IMUs) to calculate how far a device has moved; however, IMUs suffer from large drift errors, meaning that even minor inaccuracies can quickly become exaggerated. In outdoor environments, many devices use GPS to correct their IMUs. But this doesn't work in indoor areas where GPS signals are unreliable or nonexistent.
WIO works in conjunction with a device's IMU, correcting any errors and improving the accuracy of speed and distance calculations. This improvement in accuracy should also improve the calculations regarding a device's precise location in any indoor environment where there is a WiFi signal.
The researchers created a prototype device that could be used in conjunction with other devices. It was found that using WIO improved a device's speed and distance calculations dramatically; for example, devices using WIO calculated distance with a margin of error ranging from 5.9 to 10.5%. Without WIO, the devices calculated distance with a margin of error from 40 to 49%.