Research highlights
(For a full list of publications, please see below or go to Google Scholar, ORCID, ResearcherID)
In this work, we analyzed the NLOS effects on both STLs and VTLs mathematically, based on which an NLOS detection and correction algorithm using the VTL was proposed. We used the metric of equivalent noise bandwidth of VTL to find potential NLOS reception and then confirmed it using the time delay of multicorrelator peaks and code discriminator output. The NLOS-induced measurement error was furtherly corrected before being fed forward into the Kalman filter.
B. Xu, Q. Jia, L.-T. Hsu
IEEE Transactions on Instrumentation and Measurement 69(7):4604-4619 (2020)
We developed open-source MATLAB code for GPS VT SDR to enable researchers and scientists to investigate its pros and cons in various applications and under various environments. To achieve this goal, we developed an “equivalent conventional tracking (CT)” SDR as a baseline to compare with VT. The GPS positioning estimator of this equivalent CT is based on an extended Kalman filter (EKF), which has exactly the same state, system, and carrier measurement models and noise tuning method as VT. This baseline provides users with a tool to compare the performance of VT and CT on common ground.
B. Xu, L.‑T. Hsu
In this paper, a fair comparison among NMEA-, RINEX-, and correlator-level GNSS signal type (LOS/MP/NLOS) classifiers is carried out on a common ground by a software defined receiver. Results show that the correlator-level classifier improves the metric of F1 score by about 25% over the conventional NMEA- and RINEX-level classifiers for testing data collected at different places to that of training data. In addition to this finding, correlator-level classifier is found to be more feasible in practical applications due to its less dependency on surrounding scenarios compared with the NMEA/RINEX-level classifiers.
B. Xu, Q. Jia, Y. Luo, L.‑T. Hsu
Remote Sens. 11(16):1851 (2019)
In this work, we improve the acquisition precision and sensitivity of the CZT-based acquisition by extending coherent integration time. To reduce computation load, we introduce a down-sampling operation to the extended data without degrading acquisition performance. Results show that the CZT-based acquisition with a coherent integration time of 10 ms obtains a frequency error of 5.9 Hz for the carrier-to-noise ratio (CNR) of 25 dB-Hz and can acquire signals with a CNR down to 22 dB-Hz.
B. Xu, L. Dou
Electronics Letters 54(16):995-997 (2018)
Research grants
In the capacity of PI:
- Research on direct position estimation based GNSS and 5G positioning and GNSS/5G deep integration mechanism, 2022~2024, NSFC for Young Scholar
- Security reinforcement for high-precision fusion positioning, 2021~2024, Industrial research collaborative project
- Research on GNSS Vector Tracking based Anti-multipath Mechanism in Urban Environment, 2022~2024, Guangdong Natural Science Foundation
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Development and verification of SLAM+RTK navigation technology for smartphones, 2023~2025, State Key Laboratory of Satellite Navigation System and Equipment Technology Open Fund Project
- A-GNSS Based Direct Position Estimation: Modelling, Implementation and Performance Assessment, 2021~2023, PolyU Start-up Fund for RAPs under the Strategic Hiring Scheme
In the capacity of Co-PI:
- Reliable Multiagent Collaborative Global Navigation Satellite System Positioning for Intelligent Transportation Systems, 2022~2025, RGC Research Impact Fund Scheme (RIF)
In the capacity of Co-I:
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Unlocking the potential of AI edge intelligence and cloud-edge computing for flexible robotic and facility control system, 2021~2023, Innovation and Technology Fund - Partnership Research Programme (ITF-PRP)
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Ultra-Tightly Coupled GNSS/INS Integration for Smartphone, 2018~2020, Industrial research collaborative project
Journal Papers
(*: Corresponding authorr)
2023
Robust GNSS Positioning using Unbiased Finite Impulse Response Filter
J. Dou, B. Xu, and L. Dou
Remote Sensing, 15(18):4528, 2023.
Performance Evaluation of Vectorized NavIC Receiver Using Improved Dual-Frequency NavIC Measurements
A. Dey, K. Iyer, B. Xu, N. Sharma and L.-T Hsu
IEEE Transactions on Instrumentation and Measurement, 72, 8505213, 2023.
A post-correlation graphical way for continuous GNSS spoofing detection
C.-L Tsang, Y. Luo, B. Xu and L.-T. Hsu
Journal of Aeronautics, Astronautics and Aviation, 55(2), 169-184, 2023.
2022
Analytic Models of a Loosely-coupled GNSS/INS/LiDAR Kalman Filter considering Update Frequency under a Spoofing Attack
J. Chang, L. Zhang, L.-T. Hsu, B. Xu, F. Huang and D. Xu
IEEE Sensors Journal, 22(23), 23341-23355, DOI 10.1109/TIM.2022.3184357, 1 December 2022.
Hyperparameter Optimization of Neural Networks Based on Q-learning
X. Qi and B. Xu*
Signal, Image and Video Processing, published online, DOI 10.1007/s11760-022-02377-y, 8 Oct 2022
A Robust Nonlinear Filter Strategy Based on Maximum Correntropy Criterion for Multi-GNSS and Dual-Frequency RTK
J. Liu, T. Liu, Y. Ji, M. Sun, M. Lyu, B. Xu, Z. Lu, and G. Xu
Remote Sensing, 14(18), 4578, DOI 10.3390/rs14184578, 13 Sep 2022
FPS-Fast Path Planner Algorithm Based on Sparse Visibility Graph and Bidirectional Breadth-First Search
Q. Li, F. Xie, J. Zhao, B. Xu, J. Yang, X. Liu, and H. Suo
Remote Sensing, 14(15), 3720, DOI 10.3390/rs14153720, 3 August 2022
Data Denoising Based on Hadamard Matrix Transformation and Rayleigh Quotient Maximization, Application to GNSS Signal Classification
J. Yue, B. Xu*, and L.-T. Hsu
IEEE Transactions on Instrumentation and Measurement, DOI 10.1109/TIM.2022.3184357, 20 June 2022
GNSS Code Multipath Time-frequency Analysis Using Wavelet-based Synchrosqueezing Transform in Urban Environments
A. Dey, B. Xu*, X. Lu, and N. Sharma
IEEE Geoscience and Remote Sensing Letters, published online, DOI 10.1109/LGRS.2022.3167738, 18 April 2022
Vector Tracking Based on Factor Graph Optimization for GNSS NLOS Bias Estimation and Correction
C. Jiang, Y. Chen, B. Xu, J. Jia, H. Sun, T. Wang, Z. Duan, and J. Hyyppä
IEEE Internet of Things Journal, published online, DOI 10.1109/JIOT.2022.3150764, 11 February 2022
Carrier-Aided Dual Frequency Vectorized Tracking Architecture for NavIC Signals
A. Dey, K. Iyer, B. Xu*, N. Sharma, and L.-T. Hsu
IEEE Transactions on Instrumentation and Measurement, 71:1-13 (2022)
2021
Probabilistic Approach to Detect and Correct GNSS NLOS Signals Using an Augmented State Vector in the Extended Kalman Filter
C. Jiang, B. Xu*, and L.-T. Hsu
GPS Solutions 25, 72 (2021)
Impact assessment of the asynchronous clocks between reference and user receivers in differential pseudolite navigation system
J. Dou, B. Xu, L. Dou
IEEE Sensors Journal 21(1):403-411 (2021)
A cost-effective beam forming structure for global navigation satellite system multipath mitigation and its assessment
Q. Jia, L.-T. Hsu, B. Xu, and R. Wu
The Journal of Navigation 74:2 (2021)
GNSS RUMS: GNSS Realistic Urban Multiagent Simulator for Collaborative Positioning Research
G. Zhang, B. Xu, H.-F. Ng, L.-T. Hsu
Remote Sensing 13(4):544 (2021)
2020
Vector Tracking Loop-Based GNSS NLOS Detection and Correction: Algorithm Design and Performance Analysis
B. Xu, Q. Jia, L.-T. Hsu
IEEE Transactions on Instrumentation and Measurement 69(7):4604-4619 (2020)
Extending Shadow Matching to Tightly-Coupled GNSS/INS Integration Systems
G. Zhang, W. Wen, B. Xu, L.-T. Hsu
IEEE Transactions on Vehicular Technology 69(5):4979-4991 (2020)
Integrity monitoring using multi-GNSS pseudorange observations in the urban environment combining ARAIM and 3D city models
A. El-Mowafy, B. Xu, L.-T. Hsu
Journal of Spatial Science, DOI 10.1080/14498596.2020.1734109
2019
An intelligent joint filter for vector tracking loop considering noise interference
J. Dou, B. Xu, L. Dou
Optik 22:164984 (2020)
Open-source MATLAB code for GPS vector tracking on a software defined receiver
B. Xu, L.‑T. Hsu
GPS Solutions 23, 46 (2019)
Intelligent GPS L1 LOS/Multipath/NLOS Classifiers Based on Correlator-, RINEX- and NMEA-Level Measurements
B. Xu, Q. Jia, Y. Luo, L.‑T. Hsu
Remote Sens. 11(16):1851 (2019)
Research on Time-Correlated Errors Using Allan Variance in a Kalman Filter Applicable to Vector-Tracking-Based GNSS Software-Defined Receiver for Autonomous Ground Vehicle Navigation
Y. Luo, J. Li, C. Yu, B. Xu, L. You, L.-T. Hsu
Remote Sens. 11(9):1026 (2019)
A GPS Spoofing Generator Using an Open Sourced Vector Tracking-Based Receiver
Q. Meng, L.-T. Hsu, B. Xu, X. Luo
Sensors 19(18):3993 (2019)
Performance assessment of GNSS scalar and vector frequency tracking loops
J. Dou, B. Xu, L. Dou
Optik 202:163552 (2019)
2018
GNSS IF Signal Simulation Considering Oscillator Phase Noise
B. Xu, L. Dou
The Journal of Navigation 71(4):805-820 (2018)
Benefits of long coherent integration for CZT-based GPS signal acquisition
B. Xu, L. Dou
Electronics Letters 54(16):995-997 (2018)
2017
Novel acquisition of global positioning system signals based on parameter prediction and the chirp z-transform
B. Xu, L. Dou
Proceedings of the Institution of Mechanical Engineers, Part G, Journal of Aerospace Engineering 231(8):1391-1401 (2017)
Conference Papers
3DMA Sky Visibility Matching: An Example using a Simulated LEO Constellation
H. Xu, B. Xu and L.-T. Hsu
Proceedings of the 2022 International Technical Meeting of The Institute of Navigation, Long Beach, California, January 2022, pp. 686-700
Adaptive GNSS Positioning Strategy Switching: Metric Modelling, Algorithm Design and Performance Analysis
J. Fang, S. Vicenzo, J. Marcelino and B. Xu
The International Conference on Smart Living, Hong Kong, March 31-April 1, 2022
Ultra-tight GNSS/UWB integration for seamless indoor/outdoor pedestrian navigation
S. Vicenzo, J. Marcelino and B. Xu
The International Conference on Smart Living, Hong Kong, March 31-April 1, 2022
Vector Tracking Loop Based Mixed-Level Satellite Signal Type Classification in Urban Areas
Z. Li, J. Fang and B. Xu
The International Conference on Smart Living, Hong Kong, March 31-April 1, 2022
Intermediate Frequency Level GPS Multipath Simulator based on Vector Tracking and Ray-tracing
B. Xu, L.-T. Hsu, and T. Suzuki
ION ITM 2020, San Diego, California, January 21-24, 2020
NLOS Detection and Compensation using a Vector Tracking-based GPS Software Receiver
B. Xu, L.-T. Hsu
ION PNT 2019, Honolulu, Hawaii, April 8-11, 2019
Assessment of Ultra-Tightly Coupled GNSS/INS Integration System towards Autonomous Ground Vehicle Navigation Using Mobile-Phone IMU
Y. Luo, C. Yu, B. Xu, G.-J. Tsai, J. Li, Y. Li, N. El-Sheimy
IEEE International Conference on Signal, Information and Data Processing 2019, Chongqing, China, December 11-13, 2019
Performance of the Vector Tracking Loop Assisted by Desired Trajectory during Short Signal Outages
B. Xu, L. Dou
Proceedings of 2016 IEEE Chinese Guidance, Navigation and Control Conference August 12-14, 2016 Nanjing, China