2026· IEEE Open Journal of the Communications Society· Vol 7, pp. 7365-7383· 0 citations· 32 references
Computer Science
Abstract
For challenging environments where conventional line-of-sight (LOS) systems are not available, we propose a novel non-line-of-sight (NLOS) ultraviolet (UV) positioning system based on time difference of arrival (TDOA). The system operates through two complementary procedures: constructing a geometric model by optimizing the reception angle according to signal intensity and transmitter beam characteristics, and estimating the time difference of arrival via UV synchronization to resolve the positioning equations. To further improve positioning accuracy, a symbol broadening matching synchronization scheme is developed, which employs the pulsed response function of the UV single-scattering channel obtained from initial positioning results. An upper bound on the mean square error (MSE) applicable to this synchronization process is also derived. Simulation results confirm that the proposed approach significantly enhances the synchronization estimation accuracy and effectively constrains the final positioning error within the theoretical bounds. We also verify the robustness of the algorithm under different environmental conditions. An average decrease of 34.03% for the synchronization standard deviation is achieved, and an average decrease of 32.67% for the positioning error is achieved. Additionally, the proposed positioning algorithm effectively compensates for the systematic bias present in the initial estimates, bringing the corrected center closer to the ground truth. To optimize system deployment, we propose efficient impulse response approximation instead of time-consuming Monte Carlo simulations, achieving a 28.64% reduction in positioning error.
Pinching-antenna systems (PASS) enhance wireless propagation by activating or placing pinching antennas (PAs) near users. Therefore, accurate uplink positioning is essential for efficient communication. In this paper, an uplink multi-carrier positioning framework is established for PASS in multipath environments. Matrix pencil (MP)-based and low-complexity Rank-1 ranging algorithms are proposed to estimate the distances between the PAs and the user. For the MP-based ranging algorithm, the line-of-sight (LoS) component is separated from non-line-of-sight components by exploiting the shift-invariance property of the Hankel matrix, thereby enabling accurate distance estimation. For the Rank-1 ranging algorithm, the dominant LoS delay is directly isolated through truncated singular value decomposition, thereby avoiding matrix inversions. Subsequently, a two-stage weighted nonlinear least-squares (WNLS) positioning algorithm is designed to estimate the three-dimensional user position. To gain further insights, a comprehensive theoretical performance analysis of the proposed ranging and positioning algorithms is conducted. The closed-form ranging variances and position error bound (PEB) are derived to reveal the error propagation mechanism. Numerical results demonstrate that: i) The MP-based algorithm achieves higher accuracy and robustness than the Rank-1-based algorithm, while the Rank-1-based algorithm has lower computational complexity. ii) The positioning error of the MP-based algorithm follows the same trend as the derived PEB, whereas the Rank-1 algorithm exhibits an error floor due to multipath bias. iii) The positioning accuracy of the MP algorithm improves as the number of subcarriers increases.
Yaoyu Zhang, Xin Sun, Tianwei Hou et al.· 0 citations
In order to enable a wide range of applications anywhere and anytime, future communication systems are expected to employ low Earth orbit satellites to perform user verification. Single-satellite systems offer a cost-effective verification alternative, reducing implementation complexity and dependence on satellite constellations. This article develops a single-pass, single-satellite localization algorithm independent from global navigation satellite systems, supporting user verification and requiring only coarse coverage-region side information. The algorithm is based on the tracking of phase changes from received pilot signals originated from Doppler shifts, inherently related to the user's position. Our work addresses realistic channel and receiver conditions—encompassing carrier frequency offset, phase noise, and atmospheric propagation effects—while evaluating robustness against orbital perturbations, a combination that has not been jointly addressed in prior studies on Doppler-based localization. The proposed two-stage approach employs an extended Kalman filter for estimation of the referred phase shifts, followed by a weighted least squares solution. Algorithm performance is evaluated through simulations in terms of mean and $90{\text{th}}$ percentile distance error, together with the time to reach a 10-km error level, an accuracy benchmark discussed in verification studies by 3rd Generation Partnership Project (3GPP). Results demonstrate improved accuracy with respect to compatible Doppler-based baselines, with $90{\text{th}}$ percentile errors falling below the 10-km mark under the considered narrowband and line-of-sight conditions, suggesting that the method may support user verification. The time required to achieve such accuracy, particularly, may require a significant portion of the satellite's visibility window in strong phase noise conditions.
André B. de F. Diniz, Thomas Eriksson, U. Gustavsson et al.· IEEE Transactions on Aerospa...· 0 citations
In this paper, the Doppler frequency shift (DFS) is exploited as the only sensing parameter for low-cost indoor mobile device tracking. The existing trajectory tracking methods via DFS of Wi-Fi systems often require the knowledge of the starting position or additional information, like angle-of-arrival (AoA) and time-of-flight (ToF), to recover the trajectory of a moving target. This paper proposes the DoDTrack, a novel Difference-of-Doppler (DoD)-based tracking system, to track an active mobile device using a single receiver with distributed antennas. By comparing the signals received at the distributed receive antennas, which share the oscillator, the DoDs among the antennas can be detected robustly. Then, the reconstruction of the trajectory without prior knowledge of the trajectory starting position can be formulated as a minimum mean square error (MMSE) problem, which can be solved via alternating optimization. Particularly, the starting position and the trajectory shape are updated alternately in the proposed algorithm. In performance validation, we implemented the proposed DoDTrack design on a USRP-X310 platform, and assessed its estimation accuracy with various trajectory shapes in an indoor environment. Experimental results demonstrate that DoDTrack achieves a median tracking error of 0.34 m within a 6 m $\times$ 6 m sensing area, offering a high-precision and low-cost solution for active device tracking.
Jingwen Zhang, Chunxi Chen, Yu Chao et al.· 0 citations
In two-station 3-D passive source localization, combined angle of arrival (AOA) and time difference of arrival (TDOA) methods often exhibit performance degradation at low signal-to-noise ratios (SNRs). To address this issue, this letter first derives an error propagation model and demonstrates the limitations of the conventional algorithm. Based on this basis, we develop a two-station constrained weighted total least squares (CWTLS) estimator that accurately accounts for noise in both the measurement and the coefficient matrix. Simulations and field experiments show that, compared to the traditional weighted least squares (WLS) algorithm, the proposed method reduces bias by 75% under low SNR and achieves localization accuracy that is closer to the Cramér–Rao bound (CRB) across different geometric configurations.
Free-space optical (FSO) communication has emerged as a promising technology, but its performance is highly dependent on line-of-sight (LOS) conditions. To address this limitation, we propose a multistage optical intelligent reflecting surface (OIRS)-assisted FSO communication system, which utilizes multiple OIRS nodes to dynamically reflect and redirect optical signals toward the receiver, even in the absence of direct LOS paths. In this work, we first establish a generalized geometric misalignment loss (GML) model for multistage OIRS systems under both two-dimensional (2D) and three-dimensional (3D) deployment scenarios. Building on the 3D GML model, we construct a comprehensive statistical channel model by incorporating Gamma-Gamma (GG) atmospheric turbulence and attenuation losses. Furthermore, we propose a multi-OIRS-assisted unmanned aerial vehicle (UAV)-based non-terrestrial network (NTN) system and analyze its performance. We derive semi closed-form expressions for the outage probability (OP), average bit error rate (BER), channel capacity, and moments of the signal-to-noise ratio (SNR). Additionally, we present asymptotic expressions for OP and BER in the high-SNR regime and determine the diversity order of the system.
Shunyuan Shang, Emna Zedini, A. Kammoun et al.· IEEE Transactions on Wireles...· 0 citations
Satellite-to-ground laser one-way timing and positioning technology, owing to its unique advantages including high precision and robust anti-interference performance, plays a key role in high-precision navigation. However, unlike two-way transmission, this technology cannot satisfy the condition of link symmetry and reciprocity. Consequently, the timing and positioning errors introduced by atmospheric refraction cannot be mitigated through differential techniques. To address this issue, this paper proposes a user self-compensation method. By integrating real-time measured meteorological data with precise ephemerides, this approach enables users to autonomously calculate and compensate for timing and positioning errors. The aim is to achieve timing accuracy at the picosecond level and positioning accuracy at the millimeter level.
Yunming Zhang, T. Pu, Lin Lu et al.· International Conference on...· 0 citations