Enhanced GNSS Signal Detection Performance Utilizing Polarization Diversity

The detection of GNSS signals in indoor environments is a challenging problem since the signals suffer from attenuation due to propagation through building materials, which induce attenuation of up to 30 dB or more. In addition, the interference between multiple reflected signals causes fluctuations in the received signal's amplitude and phase which result in spatial and temporal multipath fading. In order to overcome the difficulties of positioning under weak GPS signal conditions, such as urban and indoor environments, various approaches including High-Sensitivity GPS (HSGPS), assisted GPS (AGPS), the use of the modernised GPS signals, and combining a diverse array of antenna elements have being developed and investigated.;To examine the proposed method practically, a large number of data sets in various indoor locations are collected using a commercial dual polarization antenna mounted on a linear motion table to produce motion. The complex correlation coefficient is obtained for various space vehicles. In addition, the empirical ROC curves are derived to analyze the performance of the proposed approach. Considerable enhancement in performance based on the new designed detector can be observed. Besides, in order to compare the performance of the polarization diversity with spatial diversity using these structures, GPS signals were collected in various indoor areas and the results are analyzed and inter-compared.;GPS signal polarization changes upon reflection from right hand circular polarization (RHCP) to elliptical polarization, formed from both right and left hand polarization. In this work, the polarization diversity of received signals is investigated and utilized to improve GPS signal detection performance in indoor environments. The design of the detection algorithm is based on target values of the probability of detection and probability of false alarm metrics associated with each search hypothesis. This leads to either the Estimator Correlator (EC) or Equal Gain Combiner (EG) structure. The performance of these structures is thoroughly analyzed theoretically under different signal conditions in indoor areas.