GPS Multipath Detection Based on Carrier-to-Noise-Density Ratio Measurements from a Dual-Polarized Antenna

Kim, Sang-Hyun; Lee, Halim; Park, Kwansik

doi:10.23919/iccas52745.2021.9648845

Cited by 13 publications

(5 citation statements)

References 28 publications

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“…M UAVs are equipped with receivers capable of measuring RSS of a signal transmitted from the target. It is assumed that UAVs can estimate their own positions through their navigation systems (e.g., GNSS (Misra and Enge, 1994;Sun et al, 2021;Park et al, 2022;Seo and Walter, 2014;Lee et al, 2022b;Park and Seo, 2021;Kwak and Sung, 2018;Kim et al, 2021) or alternative navigation systems (Zhang et al, 2011;Kim et al, 2014;Lee et al, 2019;Huang et al, 2019;Jia et al, 2021;Strandjord et al, 2021;Rhee et al, 2021;Jeong et al, 2020;Kim et al, 2022;Lee et al, 2022d)). When the maximum allowable search time is limited to N seconds, the position of the m-th…”

Section: Problem Descriptionmentioning

confidence: 99%

“…To meet those requirements and provide various location-based services (LBS), most modern mobile devices contain global navigation satellite system (GNSS) chipsets. However, the accuracy and availability of GNSS may be largely degraded in harsh environments, such as urban or indoors, owing to signal blockage and attenuation by buildings (Soloviev, 2010;Strandjord et al, 2020;Lee et al, 2022c;Kim et al, 2021;Lee and Park, 2022). Further, in countries where emergency positioning services are non-mandatory for manufacturers or carriers, the position information of a user in an emergency may not be accessible on some devices.…”

Section: Introductionmentioning

confidence: 99%

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Performance Evaluation and Hybrid Application of the Greedy and Predictive UAV Trajectory Optimization Methods for Localizing a Target Mobile Device

Lee,

Seo

2023

Preprint

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Section: Problem Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance Evaluation and Hybrid Application of the Greedy and Predictive UAV Trajectory Optimization Methods for Localizing a Target Mobile Device

Lee,

Seo

2023

Preprint

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“…This is based on the principle that the difference in C/N 0 between the frequencies changes in a multipath environment. Similarly, the C/N 0 difference between the right-handcircularly-polarized (RHCP) and left-hand-circularly-polarized (LHCP) signals of the dual-polarized antenna have been used [31], [32]. When a GNSS signal is reflected, its polarization changes from RHCP to LHCP.…”

Section: Introductionmentioning

confidence: 99%

The Academic Traditions of Yonsei University Law School – Emphasis on Education, Respect for Humans, and Practice of Reforms –

Kim¹

2023

YLA

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In urban areas, dense buildings frequently block and reflect global positioning system (GPS) signals, resulting in the reception of a few visible satellites with many multipath signals. This is a significant problem that results in unreliable positioning in urban areas. If a signal reception condition from a certain satellite can be detected, the positioning performance can be improved by excluding or de-weighting the multipath contaminated satellite signal. Thus, we developed a machinelearning-based method of classifying GPS signal reception conditions using a dual-polarized antenna. We employed a decision tree algorithm for classification using three features, one of which can be obtained only from a dual-polarized antenna. A machinelearning model was trained using GPS signals collected from various locations. When the features extracted from the GPS raw signal are input, the generated machine-learning model outputs one of the three signal reception conditions: non-line-of-sight (NLOS) only, line-of-sight (LOS) only, or LOS+NLOS. Multiple testing datasets were used to analyze the classification accuracy, which was then compared with an existing method using dual single-polarized antennas. Consequently, when the testing dataset was collected at different locations from the training dataset, a classification accuracy of 64.47% was obtained, which was slightly higher than the accuracy of the existing method using dual single-polarized antennas. Therefore, the dual-polarized antenna solution is more beneficial than the dual single-polarized antenna solution because it has a more compact form factor and its performance is similar to that of the other solution.

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“…However, as GNSS navigation signals are transmitted from satellites, the received signal strength on the ground is very weak. Consequently, GNSS is vulnerable to signal blockage and radio frequency interference (RFI) [7], [8], [9], [10], [11], [12], [13]. Especially, receiving GNSS signals in indoor environments such as buildings, underground areas, and tunnels, is challenging [14], [15], [16].…”

Section: Introductionmentioning

confidence: 99%

Low-Cost GNSS Simulators With Wireless Clock Synchronization for Indoor Positioning

Kim

Seo

2023

IEEE Access

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In regions where global navigation satellite systems (GNSS) signals are unavailable, such as underground areas and tunnels, GNSS simulators can be deployed for transmitting simulated GNSS signals. Then, a GNSS receiver in the simulator coverage outputs the position based on the received GNSS signals (e.g., Global Positioning System (GPS) L1 signals in this study) transmitted by the corresponding simulator. This approach provides periodic position updates to GNSS users while deploying a small number of simulators without modifying the hardware and software of user receivers. However, the simulator clock should be synchronized to the GNSS satellite clock to generate almost identical signals to the live-sky GNSS signals, which is necessary for seamless indoor and outdoor positioning handover. The conventional clock synchronization method based on the wired connection between each simulator and an outdoor GNSS antenna causes practical difficulty and increases the cost of deploying the simulators. This study proposes a wireless clock synchronization method based on a private time server and time delay calibration. Additionally, we derived the constraints for determining the optimal simulator coverage and separation between adjacent simulators. The positioning performance of the proposed GPS simulator-based indoor positioning system was demonstrated in the underground testbed for a driving vehicle with a GPS receiver and a pedestrian with a smartphone. The average position errors were 3.7 m for the vehicle and 9.6 m for the pedestrian during the field tests with successful indoor and outdoor positioning handovers. Since those errors are within the coverage of each deployed simulator, it is confirmed that the proposed system with wireless clock synchronization can effectively provide periodic position updates to users where live-sky GNSS signals are unavailable.INDEX TERMS Indoor navigation, GNSS simulators, clock synchronization, network time protocol (NTP).

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GPS Multipath Detection Based on Carrier-to-Noise-Density Ratio Measurements from a Dual-Polarized Antenna

Cited by 13 publications

References 28 publications

Performance Evaluation and Hybrid Application of the Greedy and Predictive UAV Trajectory Optimization Methods for Localizing a Target Mobile Device

Performance Evaluation and Hybrid Application of the Greedy and Predictive UAV Trajectory Optimization Methods for Localizing a Target Mobile Device

The Academic Traditions of Yonsei University Law School – Emphasis on Education, Respect for Humans, and Practice of Reforms –

Low-Cost GNSS Simulators With Wireless Clock Synchronization for Indoor Positioning

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