Indoor Positioning Using Ultrasound and Radio Combination

The paper introduces a method of indoor positioning using a combination of ultrasound and radio frequency. This method allows for a more effective usage of radio frequency as it is employed for both object identification and time synchronization by calculating ultrasound propagation time, as well as object positioning using radio signal strength values. Application of this method forms the basis of positioning system that can estimate the position of mobile and stationary objects when an object has been detected by at least two ultrasound listeners, while the systems that are in usage today require for the object to be detected by at least three listeners. Experiments on an object that was detected by only two ultrasonic listeners resulted in a mean error of 34.1 cm, whereas consistent positioning would not have been possible when limited only to ultrasound technology. The aforementioned mean error is also a few times lower than the one resulting from positioning when only radio frequency is used.