Satellite-to-Indoor Wave Propagation for Positioning Applications

Abstract

Indoor positioning is an emerged field of research and a challenging task. A promising approach is to use a multi-sensor fusion framework. Global satellite navigation systems may provide considerable benefits in multi-sensor navigation systems, but low signal power and multipath propagation impede both the precision and availability of indoor positioning. In order to validate, test and develop advanced signal processing algorithms, multipath channel models reflecting real propagation scenarios, are necessary. In this thesis, the wave propagation between a satellite based transmitter and an indoor located receiver is analysed and modelled. The spatial variability of the satellite-to-indoor channel is emphasised because of the targeted application of navigating a moving pedestrian indoors. To analyse the satellite-to-indoor wave propagation channel, a measurement campaign was conducted. By using an experimental mobile platform, it was possible to obtain a precise position measurement of the receive antenna and to measure adjacent channel impulse responses within sub-millimetre distances. The measurements were used in two ways. First, the wideband satellite-to-indoor propagation channel for L- and C-band carrier frequencies was compared and, second, a satellite-to-indoor channel model for L-band transmissions was developed. The comparison of the satellite-to-indoor propagation channel at L- and C-band frequencies is of high interest for upcoming satellite navigation signals. Measurement results show that signal transmissions at C-band suffer from higher penetration loss compared to L-band while the mean delay and the delay spread do not show distinct differences. In the developed wideband satellite-to-indoor channel model, deterministic and stochastic components are combined in a hybrid approach. For the development of the model novel methods were used. To extract multipath parameters from the measurement data a new super resolution algorithm was developed which allows the estimation of the changes of the parameters for individual multipath components. To simulate the satellite-to-indoor for different indoor environments, a deterministic model for calculating the received power was developed. Based on the same model, diffraction and transmission effects on the line-of-sight component are calculated. To represent the interior multipath channel accurately, deterministic and stochastic elements are combined in a physical-statistical approach.