Frequency-Polarization Signal Processing to Combat Multipath in Local Positioning Systems.

Abstract

The properties of a local positioning system operating in the 2.4 GHz ISM band, which is capable of supplementing the constellation with local system signals to achieve high positioning accuracy in a complex interference environment, are investigated. In this case, global navigation satellite systems (GNSS) signal receivers often also implement other methods for estimating the position or parameters associated with it: inertial systems, ultra-wideband systems, radars, etc. In this paper, the study of the properties of a local positioning system operating in the 2.4 GHz ISM band , capable of supplementing the constellation with local system signals to achieve high positioning accuracy in difficult conditions. The emphasis here is on indoor operation of the system when GNSS signals are unavailable. In addition, there are a large number of reflected signals in the room. The paper presents a method for describing reflected signals using the Jones vector, as well as the synthesis of optimal algorithms for estimating signal parameters under complex conditions for simplified scenarios. With the help of modeling, it is shown that the optimal methods are poorly applicable to real situations, however, they allow a better understanding of the physics of processes. Based on this understanding, a signal shaping technique is proposed to create a large redundancy of measurements in the receiver, as well as an empirical method for rejecting false measurements. With the help of this method, it has been experimentally shown that indoors in difficult conditions and in the presence of multipath, it is possible to achieve the RMS positioning error of less than 10 centimeters.