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409 results on '"Yu Shihui"'

1. Ultraviolet Positioning via TDOA: Error Analysis and System Prototype

Author

Yu, Shihui, Lv, Chubing, Yang, Yueke, Pan, Yuchen, Sun, Lei, Cao, Juliang, Yu, Ruihang, Gong, Chen, Wu, Wenqi, and Xu, Zhengyuan

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

This work performs the design, real-time hardware realization, and experimental evaluation of a positioning system by ultra-violet (UV) communication under photon-level signal detection. The positioning is based on time-difference of arrival (TDOA) principle. Time division-based transmission of synchronization sequence from three transmitters with known positions is applied. We investigate the positioning error via decomposing it into two parts, the transmitter-side timing error and the receiver-side synchronization error. The theoretical average error matches well with the simulation results, which indicates that theoretical fitting can provide reliable guidance and prediction for hardware experiments. We also conduct real-time hardware realization of the TDOA-based positioning system using Field Programmable Gate Array (FPGA), which is experimentally evaluated via outdoor experiments. Experimental results match well with the theoretical and simulation results.

Published
2024

9. The design and optimization of synchronization sequence for Ultraviolet communication

Author

Yu, Shihui, Gong, Chen, and Xu, Zhengyuan

Subjects
Electrical Engineering and Systems Science - Signal Processing
Abstract

In the ultraviolet (UV) scattering communication, the received signals exhibit the characteristics of discrete photoelectrons due to path loss. The synchronization is based on maximum Pulse Number-Sequence correlation problem. First of all, the accuracy of synchronization is vital to channel estimation and decoding. This article focuses on improving synchronization accuracy by designing and optimizing synchronization sequences. As for the maximum Pulse Number-Sequence correlation problem, it is assumed that the correlation values satisfy the Gaussian distribution and their mathematical expectation, variance and covariance are derived to express the upper bound of synchronization offset. The synchronization sequence we designed has two equilong RANDOM parts (Symbols meet Bernoulli distribution with equal probability.) and a $\{1,0,1,0,1,0,...,1,0,1,0\}$ part between them with $ \alpha $ as its proportion of entire sequence. On the premise of ensuring the synchronization reliability, the synchronization deviation can be reduced by optimizing $ \alpha $. There are simulation experiments to verify correctness of the derivation, reasonableness of the hypothesis and reliability of optimization. Compared with equilong random sequence, the synchronization accuracy of the optimized synchronization sequence is significantly improved.

Published
2022

26. The excellent tunable performance of BaSnxTi1−xO3 ceramics at low electric field.

Author

Zheng, Haoran, Guo, Hailong, Yang, Pan, Xiao, Xinyuan, Zhang, Yongdong, Sun, Xiaopeng, and Yu, Shihui

Abstract

BaSnxTi1−xO3 ceramics with excellent tunable properties are prepared via solid-state reaction method. The content of Sn4+ has an important influence on the micromorphology, dielectric and tunable performance. It is shown that the Sn4+ has a negative effect on the grain growth, leading to the gradual decrease of grain size as x increases. Meanwhile, when the B-site is partially occupied by Sn4+, it is effortless to form polar nano-regions (PNRs) due to the weaker orbital hybridization between Sn4+ and O2− atoms. Influenced by the PNRs, the diffusion phase transition (DPT) behavior at the low- and high-temperature region are distinctly discrepant. The DPT behavior of high-temperature region is stronger than that of low-temperature region. Owing to the influence of grain size and formed PNRs, BaSn0.12Ti0.88O3 and BaSn0.15Ti0.85O3 ceramics possess the large dielectric constant at room temperature. However, the high loss tangent results in the small figure of merit though possessing higher tunability (> 75%) at an electric field of ~ 8 kV/cm. When Sn4+ content is 0.18, an ultralow tan δ (< 0.01%) with a moderate tunability (~ 46%) is obtained at ~ 8 kV/cm, resulting in the ultrahigh FOM value of ~ 5790. The ultrahigh FOM at low electric field makes it more attractive to be used in microwave tunable devices. [ABSTRACT FROM AUTHOR]

Published
2025
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