Positioning in Wireless Communications Systems

Chapter 2Positioning Principles

Positioning in general requires an observation of physical quantities. These measurement values characterize a certain position in the environment. Thus, it is evident that observations for positioning purposes have to show local dependency. In this chapter we focus on positioning principles, which are typically applied when observing electromagnetic waveforms for localization purposes. Geometric parameters significantly influence the propagation of electromagnetic signals:

1. Propagation delay: Electromagnetic waves travel with the speed of light. This yields a linear relation between the signal propagation delay and the distance of transmitter and receiver.
2. Propagation attenuation: The electromagnetic signal power decreases as the distance between transmitter and receiver increases. In free space the received power is reciprocally proportional to the square of that distance.
3. Reflection, refraction, diffraction, scattering: Discontinuities in the propagation medium cause changes in the propagation direction of electromagnetic waves. Such discontinuities are omnipresent in typical radio communications environments and cause NLOS and multipath propagation.

We may state that there is a functional relationship

which maps a waveform transmitted at the ...