Abstract
Multipath fading in the form of signal power fluctuation poses a formidable challenge to GNSS signal detection in harsh multipath environments such as indoors. Antenna diversity techniques such as polarization and spatial diversities can be used to combat multipath fading in wireless propagation channels. This paper studies and compares GPS signal detection performance enhancements arising from the spatial and polarization diversity techniques. Performance enhancements are quantified from a theoretical perspective and later verified based on several test measurements in various indoor environments. Enhancement is quantified based on measuring the correlation coefficient values between diversity branches, SNR levels, and computing the level crossing rate and average fade duration. In addition, the processing gain is quantified and the performance of each individual diversity system is evaluated. Experimental results show that, for a given target detection performance in terms of the probability of false alarm and the probability of detection, the required input SNR level to meet the target detection performance can be significantly reduced utilizing the diversity system.
Highlights
GNSS signal detection in indoor environments is a challenging problem since the signal suffers from insertion loss and fading
Antenna diversity systems are establish based on the fact that multiple antennas with different patterns, polarizations, and locations provide multiple diversity branches such that the moment when the multipath fading affects the output of a diversity branch, another branch may have a reasonable signal power
The experimental measurements described validate the assumptions in the context of the GNSS signal detection in indoor environments
Summary
GNSS signal detection in indoor environments is a challenging problem since the signal suffers from insertion loss and fading. They analysed the effect of the correlation coefficient between two diversity branches on diversity gain thoroughly They evaluated the performance of the polarization diversity using different antenna configurations in both Rayleigh and Rician fading environments. Lemieux et al [17] have experimentally compared the space, frequency, and polarization diversities in the indoor environment for frequency of 900 MHz. Recently, au [18] proposed a new technique based on the motion of a single antenna to form a spatially distributed synthetic array for enhancing the detection performance of the GPS signals in the indoor environments. A detection scheme based on a Rayleigh fading channel is demonstrated and the processing gain realizable through utilizing spatial and polarization diversity techniques is quantified theoretically and experimentally.
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