Modeling multifrequency GPS multipath fading in land vehicle environments
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ORIGINAL ARTICLE
Modeling multifrequency GPS multipath fading in land vehicle environments Vicente Carvalho Lima Filho1 · Alison Moraes2 Received: 18 October 2019 / Accepted: 28 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The reliability and performance of GPS receivers depend on the quality of the signal received, which can be largely affected by the interference caused by buildings, trees, and other obstacles. Since obstacles are always present in practical applications, several statistical representations have been developed along the years to measure, predict, and compensate errors induced by interferences. Two of the most used models to characterize GPS signal fading are the Nakagami-m and Rice, but in this work, we present evidence that supports the κ–μ distribution as the best fit to deal with multifrequency GPS multipath channels inside urban, rural, and forest areas. A synthetic signal simulator was developed to create propagation cases involving scattering clusters and specular reflections. Additionally, experimental measurements are presented to confirm the κ–μ distribution as the best distribution to characterize different situations on the available three GPS frequencies. We then present typical values of fading coefficients in L1, L2C, and L5 signals, for cases involving urban canyons, regular urban, rural, and dense vegetation areas. These coefficients can also be used to evaluate the receiver performance under similar cases or may be applied in weights measurement methods for positioning computation improvement. Keywords Fading distribution · Multipath · Urban environments
Introduction In the near future, systems such as smart cities, autonomous cars, vehicle ad-hoc networks, and drones will hugely increase the demand for radio communication services. For mobile applications in land vehicles such as vehicular ad-hoc network (VANET) and autonomous cars, real-time positioning is needed with high availability and accuracy Li and Wang (2007), indicating the relevance of global navigation satellite system (GNSS) channel modeling inside urban areas. Mobile multipath modeling in the urban environment is a relevant subject such as Lehner and Steingass (2005), where a model that takes into account changes in elevation, azimuth, speed, and number of reflectors was developed. In crowded cities, scattering and specular reflections of the direct signal pollutes the received signal by the receptor. * Alison Moraes [email protected] 1
Instituto Tecnológico de Aeronáutica (ITA), São José dos Campos, SP, Brazil
Instituto de Aeronáutica e Espaço (IAE), São José dos Campos, SP, Brazil
2
In Strode and Groves (2016), for example, signal-to-noise measurements on three different GNSS frequencies are compared to detect multipath signals. In Håkansson (2019), GNSS observations made using a tablet showed that multipath impacts the expected accuracy of calculated positions because of induced measurement errors and also because of loss of lock of GNSS signals. Zhang et al. (20
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