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Angular modulation of terahertz wavefront scattering based on all-silicon dielectric coded metasurface grating

JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS 2022年第3-4期24卷 91-100页

作者： Shi, Siqi Yang, Kai Jing, Xufeng China Jiliang Univ Inst Optoelect Technol Hangzhou 310018 Peoples R China

In order to simplify the design and fabrication difficulties, and to improve the efficiency of the transmission device, we designed an all-silicon monolayer coded metasurface grating. The single layer coded metasurface is composed of circular hole elements with different sizes. Based on the generalized Snell's law, we can know that the far-field scattering angle of the coded metasurface depends on the coding period. If we want to get different scattering angles, we need to design different coding periods. In general, the traditional coded metasurface sequence cannot realize the continuous control of the scattering angle. Here, by addition and subtraction of the coded sequence, a new coded metasurface sequence is obtained, and a new scattering angle is obtained. Through the addition and subtraction operations of coded metasurface sequences, we can obtain the flexible control of scattering angle without redesigning the coding unit.

关键词： Metasurface encoding sequence Grating

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Diffuse reflection metasurface optimization design based on Genetic algorithm

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Procedia Computer Science 2024年 243卷 1273-1279页

作者： Yuan Zhang Hui Zhang Shan Wu Ziyi Wan Key Laboratory of Functional Materials and Devices for Informatics of Anhui Higher Education Institutes Fuyang Normal University Fuyang Anhui China

Conventional metasurfaces rely heavily on manual design and optimization, which is tedious and inefficient and cannot be adapted to the engineering applications of modern wireless communication networks. The use of intelligent algorithms to design smart metasurfaces with high accuracy and efficiency is becoming a growing trend. In this paper, a uniform scattering smart metasurface based on a 2-bit cell structure is implemented by optimizing the coding sequence of the metasurface using genetic algorithm. By increasing the number of scattering beams, the incident wave is reflected to as many directions as possible with uniform energy. It has an important application prospect in the fields of future 6G mobile communication and radar stealth technology.

关键词： Smart metasurface Genetic algorithm encoding sequence Diffuse reflection

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Genetic Algorithm Based Optimization of encoding sequence for a Reduced Complexity OFDM Time Synchronization Technique

Genetic Algorithm Based Optimization of Encoding Sequence fo...

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IEEE 78th Vehicular Technology Conference (VTC Fall)

作者： Nasraoui, Leila Atallah, Leila Najjar Siala, Mohamed Univ Carthage Higher Sch Commun COSIM Lab Carthage Tunisia Univ Carthage Higher Sch Commun MEDIATRON Lab Tunis Tunisia

ISBN: (纸本)9781467361873

A new Genetic Algorithm (GA) based sequence optimization is here proposed. The studied sequence, which we refer to as encoding sequence (ES), is used in a recently proposed OFDM preamble-based synchronization technique. The optimal ES is generated offline by differentially correlating the preamble samples to each other respecting a shift. To determine the frame start at the receiver, the ES is correlated to a version of the received signal generated using differential correlation respecting the same shift as in the ES generation. This treatment, carried online, is of high complexity due to the differential correlation operations. To reduce the computational load at the receiver, the idea here is to replace the differential correlation operations, carried during the synchronization process, by simple sign changes. To this aim, we need to derive the best sub-optimal ES, in terms of providing near optimal performance, from a finite QPSK alphabet +/- 1 +/- j. Even if this search procedure is carried off-line, considering an exhaustive search over the whole ES candidates within QPSK alphabet results in a prohibitive complexity. As an alternative, we here suggest to use a GA-based approach. Performance comparison of the proposed ES, generated through GA-based search, to the optimal ES, generated from the preamble, and a previously proposed QPSK ES optimized through an iterative algorithm has been conducted. It is demonstrated that compared to the iteratively generated ES, the herein proposed one improves the detection accuracy. The GA-based provides slightly lower detection accuracy with respect to the optimal ES, yet with important reduction in the receiver complexity.

关键词： OFDM Time synchronization encoding sequence Off-line design Genetic Algorithms

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encoding sequence Design for a Reduced Complexity Time Synchronization Approach for OFDM Systems

Encoding Sequence Design for a Reduced Complexity Time Synch...

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19th IEEE International Conference on Electronics, Circuits, and Systems (ICECS 2012)

作者： Nasraoui, Leila Atallah, Leila Najjar Siala, Mohamed Univ Carthage Higher Sch Commun COSIM Lab Carthage Tunisia Univ Carthage Higher Sch Commun MEDIATRON Lab Carthage Tunisia

ISBN: (纸本)9781467312608

We here deal with a recently proposed data-aided reduced-complexity approach for OFDM time synchronization. In the considered approach, an encoding sequence generated from the preamble is differentially correlated with the received signal to estimate the frame start. In this paper, we study the off-line design of the encoding sequence. We present two efficient algorithms for deriving QPSK encoding sequence that allows replacing the differential correlation process, characterized by its high complexity, by a simple sign change. The resulting quantified encoding sequence performs well in both AWGN and multipath channels, compared to the optimal, previously used, encoding sequence. Furthermore, the complexity involved for the metric calculation, using the herein proposed encoding sequence, is reduced considerably by applying the sign change operations. The simulation results show that the use of sub-optimal sequence gives near best detection performances which are provided by the optimal sequence with lower complexity.

关键词： OFDM Differential modulation encoding sequence Off-line design Quantification

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encoding sequence Design for a Reduced Complexity Time Synchronization Approach for OFDM Systems

Encoding Sequence Design for a Reduced Complexity Time Synch...

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IEEE International Conference on Electronics, Circuits and Systems

作者： Leila Nasraoui Leila Najjar Atallah Mohamed Siala Higher School of Communications University of Carthage

ISBN: (纸本)9781467312615

关键词： OFDM Differential modulation encoding sequence Off-line design Quantification Orthogonal frequency division multiplexing differential modulation clock recovery Multipath channels AWGN received signal

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