- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Hybrid TDOA/RSS based localization for visible light systems
摘要： In a visible light positioning (VLP) system, a receiver can estimate its location based on signals transmitted by light emitting diodes (LEDs). In this manuscript, we investigate a quasi-synchronous VLP system, in which the LED transmitters are synchronous among themselves but are not synchronized with the receiver. In quasi-synchronous VLP systems, position estimation can be performed by utilizing time difference of arrival (TDOA) information together with channel attenuation information, leading to a hybrid localization system. To specify accuracy limits for quasi-synchronous VLP systems, the Cramér–Rao lower bound (CRLB) on position estimation is derived in a generic three-dimensional scenario. Then, a direct positioning approach is adopted to obtain the maximum likelihood (ML) position estimator based directly on received signals from LED transmitters. In addition, a two-step position estimator is proposed, where TDOA and received signal strength (RSS) estimates are obtained in the first step and the position estimation is performed, based on the TDOA and RSS estimates, in the second step. The performance of the two-step positioning technique is shown to converge to that of direct positioning at high signal-to-noise ratios based on asymptotic properties of ML estimation. Finally, CRLBs and performance of the proposed positioning techniques are investigated through simulations.
关键词： Received signal strength (RSS),Estimation,Visible light,Localization,Time difference of arrival (TDOA)
更新于2025-09-23 15:22:29
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Experimental Evaluation of Multipath Mitigation in TDOA-Based Indoor Passive Localization System Using A Beam Steering Broadband Circular Polarization Antenna
摘要： An experimental evaluation of multipath mitigation using a beam steering broadband circular polarization antenna (BSBCPA) in indoor passive localization system based on time differences of arrival (TDOA) is presented in this paper. The BSBCPA consists of a beam switch network, four identical hexagon patch elements and their respective feeding networks. By controlling the states of a radio frequency (RF) switch in the beam switch network, four steering circular polarization beams can be excited separately for azimuth omnidirectional coverage. Combining the spatial selectivity of steering beams and circular polarization in the BSBCPA, the positioning inaccuracy from indoor multipath propagation can be mitigated. In two different indoor environments with line of sight (LOS), complex multipath, when transmitting a 20 MHz bandwidth signal in WLAN, the 2D positioning mean error obtained is 0.7 m and 0.82 m, respectively. Compared with conventional omnidirectional linear polarization antenna (OLPA), the BSBCPA can at least improve positioning accuracy by 51%. The experimental results show that the proposed BSBCPA can significantly mitigate multipath propagation for TDOA-based indoor passive localization.
关键词： multipath mitigation,beam steering antenna,indoor passive localization,circular polarization,TDOA
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Localization of an UWB Mobile Station with Sparse Antenna Array and Reference Station
摘要： The traditional positioning accuracy of TDOA positioning algorithm can only reach 5 to 10 centimeters. This paper proposes a center estimation method based on UWB equilateral triangular antenna array. The arrival time information is received by receiving antenna. The method of reference station compensates for the delay error and estimates the position of the virtual center of the receiving antenna array by solving the hyperbolic curve equation. This method can not only improve signal-to-noise ratio, but also provide the possibility of solving the poseestimate of the receiver. The positioning accuracy is within 5 cm by experiments.
关键词： TDOA,UWB,Positioning algorithm
更新于2025-09-10 09:29:36
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[IEEE 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Nantes, France (2018.9.24-2018.9.27)] 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - A Real-Time UWB Multi-Channel Indoor Positioning System for Industrial Scenarios
摘要： Tracking products, machines and important objects in factories is a key task for future efficient manufacturing processes. Providing workers and robots with accurate and reliable location information is the foundation for this innovation. In industrial facilities, the environment is more complex compared to consumer indoor positioning scenarios. Heavy machinery often blocks the line of sight path. Metal walls and surfaces increase reflections and multi-path effects. An ultra-wideband based time-difference-of-arrival positioning system is investigated. All base stations use four transceivers instead of one to increase the system robustness. Multi-path and non-line of sight situations are evaluated with respect to the channel effects and the influence on the position accuracy.
关键词： NLOS,indoor positioning,wireless synchronization,TDOA,multi-path,UWB
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Nantes (2018.9.24-2018.9.27)] 2018 International Conference on Indoor Positioning and Indoor Navigation (IPIN) - Indoor Positioning Using OFDM-Based Visible Light Communication System
摘要： Precise indoor positioning is essential to support emerging applications of location aware mobile computing. Current positioning techniques that use signals transmitted in the Gigahertz region of radio-frequency spectrum do not provide highly accurate position estimates due to multipath propagation of signals. This paper proposes a novel positioning system which uses the entities of visible light communication (VLC) system as anchors and tags. Our technique scales with the number of tags and the VLC network provides both positioning and communication capabilities. The anchor points transmit the OFDM-based VLC signals synchronously, and we estimate the time differences of arrival between anchor points and tags using positioning reference signals embedded into the air-interface of the VLC system. Simulation results show that positioning accuracy of 10 cm or better is possible for over 95% of users if the sampling clock offset is better that 10 ppm, clock jitter is below 1 ps, and a bit resolution of at least 16 bits is available.
关键词： multipath propagation,OFDM,TDOA,visible light communication,indoor positioning
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Waveform Matching Based Real-time Ablation Monitoring for Microwave Breast Cancer Ablation
摘要： As a minimal invasive tool for cancer treatment, microwave ablation (MWA) is promising. For safety and effective ablation for cancerous tissue, the real-time monitoring for the dimensions of the ablation zone should be implemented. This study focuses on microwave based MWA monitoring. The time difference of arrival (TDOA) based imaging algorithm is one of most promising methods, which achieves real-time, and highly noise-robust imaging using a prior knowledge of only dielectric constants of tissues surrounding probe, pre and during ablation states. However, it often suffers from an inaccuracy for imaging, especially in the lower impact of the ablation. To enhance the accuracy, this paper proposes the waveform matching based algorithm, where the impact of conductivity drop is also considered in boundary estimation. The statistical test with 100 different ablation cases, using the finite difference time domain (FDTD) simulation, using realistic breast phantoms derived from MRI, demonstrate that the proposed method offers more accurate ablation zone imaging, compared with that obtained by the TDOA based method, maintaining a real-time property.
关键词： Microwave based (TDOA),Time difference of arrival,Waveform matching,Microwave ablation(MWA)
更新于2025-09-04 15:30:14