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19th International Conference on Advanced Intelligent Computing Technology and Applications (ICIC)

作者： Zhao, Hongguo Liu, Yunxia Wang, Yonghao Liu, Hui Zhao, Zhenghang Zhengzhou Normal Univ Coll Informat Sci & Technol Zhengzhou Peoples R China Birmingham City Univ Comp & Digital Technol Birmingham W Midlands England Henan Univ Tradit Chinese Med Coll Marxism Zhengzhou Peoples R China Zhengzhou Univ Sch Cyber Sci & Engn Zhengzhou Peoples R China

ISBN: (纸本)9789819947546;9789819947553

In H.265/HEVC, DST transformation is first utilized for the 4x4 residual coefficient block to deal with complex texture features region, which improves the compression efficiency compared with the earlier H.264/AVC, and also provides a potential embedding position for video steganography. This paper presents a novel video steganography method based on constructing an N-dimensional space coding of 4 x 4 DCT/DST residual coefficients. First, 4 x 4 DCT/DST residual coefficient blocks are selected for embedding according to embedding strength, random number and coefficient values of TB. Second, high frequency coefficients are normalized into an N-dimensional array and mapped to a point in the constructed N-dimensional space, and the mapping value of this point is calculated based on pre-defined mapping rules. Third, according to the value of the metadata (embedded data) and mapping value, traversing all neighbor points in the N-dimensional space, video steganography can be achieved by modifying N-dimensional array coefficients to neighbor point that satisfies whose mapping value is equal to the value of metadata. The proposed method can embed multiple metadata bits while only modify at most one DCT/DST coefficient, so the embedding error is limited. The experimental results have been proven the superiority of the proposed video steganography method.

关键词： Video steganography space coding Residual coefficients 4x 4 DCT/DST blocks

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Multi-Channel Wireless Communication Based on Amplitude-Phase Reconfigurable space-coding Beamforming Metasurface

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ADVANCED ELECTRONIC MATERIALS 2024年第8期10卷

作者： Xiong, Qi Zhang, Zuojun Ma, Xiaoliang Huang, Cheng Pu, Mingbo Luo, Jun Guo, Yinghui Wang, Yanxun Bai, Wenlin Ye, Jia Yan, Lianshan Luo, Xiangang Chinese Acad Sci Natl Key Lab Opt Field Manipulat Sci & Technol POB 350 Chengdu 610209 Peoples R China Chinese Acad Sci Inst Opt & Elect State Key Lab Opt Technol Nanofabricat & Microengn POB 350 Chengdu 610209 Peoples R China Southwest Jiaotong Univ Sch Informat Sci & Technol Chengdu 611756 Peoples R China Chinese Acad Sci Res Ctr Vector Opt Fields Inst Opt & Elect Chengdu 610209 Peoples R China Tianfu Xinglong Lake Lab Chengdu 610209 Peoples R China Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Wuhan 430074 Peoples R China

Reconfigurable metasurfaces have exhibited significant potential in wireless communication owing to their capacity to transmit information without relying on traditional complex radio frequency (RF) chain transmitters. Nonetheless, the majority of metasurface-based wireless communication systems modulate signals only in the time domain. Here, an amplitude-phase reconfigurable metasurface is proposed to establish a wireless communication system that can simultaneously transmit different messages to users by encoding digital signals within the spatial domain. By changing the bias voltages of varactors integrated in the meta-atom, the reconfigurable metasurface can achieve independent 3-bit phase and 1-bit amplitude coding. Through a beamforming methodology, the proposed metasurface generates diverse scattering beams with suppressed sidelobe levels, which not only enables multiple channels through space coding but also reduces signal leakage in undesired directions. Numerical simulations and experiments are carried out to verify the beamforming scheme, and a dual-channel wireless communication system is established. The results show that two distinct images can be simultaneously retrieved by two separate users, which demonstrates the dual-channel transmission capability of the wireless communication system. The proposed strategy opens up an avenue for implementing multi-channel wireless communication systems, which indicates its great potential in multiple-user collaborative wireless communication and radar systems. This work presents an innovative amplitude-phase reconfigurable metasurface designed to construct a robust multi-channel wireless communication framework. Notably, the signal is modulated in the spatial domain without involving time modulation. First, it generates desired scattering beams through beamforming to establish multiple channels. Second, the metasurface significantly curbs sidelobe level, thus mitigating signal leakage in unfavorable directions. i

关键词： amplitude-phase reconfigurable metasurface beamforming multi-channel wireless communication space coding

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The Role of Architectural and Learning Constraints in Neural Network Models: A Case Study on Visual space coding

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FRONTIERS IN COMPUTATIONAL NEUROSCIENCE 2017年 11卷 13-13页

作者： Testolin, Alberto De Grazia, Michele De Filippo Zorzi, Marco Univ Padua Dept Gen Psychol Padua Italy San Camillo Hosp IRCCS Venice Italy

The recent "deep learning revolution" in artificial neural networks had strong impact and widespread deployment for engineering applications, but the use of deep learning for neurocomputational modeling has been so far limited. In this article we argue that unsupervised deep learning represents an important step forward for improving neurocomputational models of perception and cognition, because it emphasizes the role of generative learning as opposed to discriminative (supervised) learning. As a case study, we present a series of simulations investigating the emergence of neural coding of visual space for sensorimotor transformations. We compare different network architectures commonly used as building blocks for unsupervised deep learning by systematically testing the type of receptive fields and gain modulation developed by the hidden neurons. In particular, we compare Restricted Boltzmann Machines (RBMs), which are stochastic, generative networks with bidirectional connections trained using contrastive divergence, with autoencoders, which are deterministic networks trained using error backpropagation. For both learning architectures we also explore the role of sparse coding, which has been identified as a fundamental principle of neural computation. The unsupervised models are then compared with supervised, feed-forward networks that learn an explicit mapping between different spatial reference frames. Our simulations show that both architectural and learning constraints strongly influenced the emergent coding of visual space in terms of distribution of tuning functions at the level of single neurons. Unsupervised models, and particularly RBMs, were found to more closely adhere to neurophysiological data from single-cell recordings in the primate parietal cortex. These results provide new insights into how basic properties of artificial neural networks might be relevant for modeling neural information processing in biological systems.

关键词： connectionist modeling unsupervised deep learning restricted Boltzmann machines autoencoders sparseness space coding gain modulation sensorimotor transformations

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A Hybrid DCT/DST Based Embedding Framework for Video Steganography in H.265/HEVC 20th

A Hybrid DCT/DST Based Embedding Framework for Video Stegano...

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20th International Conference on Intelligent Computing (ICIC)

作者： Zhao, Hongguo Liu, Yunxia Liu, Hui Zheng, Yuqing Liu, Si Fang, Haipeng Zhengzhou Normal Univ Sch Informat Sci & Technol Zhengzhou Peoples R China Zhengzhou Normal Univ Sch Math & Stat Zhengzhou Peoples R China Henan Univ Tradit Chinese Med Sch Marxism Zhengzhou Peoples R China Zhengzhou Univ Sch Cyber Sci & Engn Zhengzhou Peoples R China

ISBN: (纸本)9789819756087;9789819756094

In H.265/HEVC, high occupancy rates in bitstreams indicate DCT/DST residual coefficients are ideal embedding positions for video steganography. This paper presents a novel hybrid video steganography embedding framework based on DCT/DST residual coefficients. For intra-prediction, 4 x 4 DST residual coefficients are selected as embedding carrier for high imperceptibility, intra-prediction modes and coefficient pairs are used for averting intra distortion drift and improving visual quality of stego video. For inter-prediction, 4 x 4 DCT residual coefficients and N-dimensional space coding are used for limiting inter-embedding error, where the superiority is that we can embed multiple bits of secret message while only one 4 x 4 DCT residual coefficient needs to be modified at most, where the high visual quality and low bit-rate increase can be achieved. The proposed embedding framework combines the advantages of the technique of intra-averting distortion drift and inter-N-dimensional space coding of DCT residual coefficients to an integrated solution, where increasing the embedding capacity significantly. The experimental results have been proven the superiority of the proposed video steganography embedding framework in terms of high visual quality, high embedding capacity and low bit rate increase.

关键词： DCT/DST residual coefficients intra distortion drift space coding

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Reconfigurable Intelligent Surfaces: Simplified-Architecture Transmitters--From Theory to Implementations

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PROCEEDINGS OF THE IEEE 2022年第9期110卷 1266-1289页

作者： Cheng, Qiang Zhang, Lei Dai, Jun Yan Tang, Wankai Ke, Jun Chen Liu, Shuo Liang, Jing Cheng Jin, Shi Cui, Tie Jun Southeast Univ State Key Lab Millimeter Waves Nanjing 210096 Peoples R China Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Peoples R China

Reconfigurable intelligent surfaces (RISs) offer an entirely new route to alter the propagation properties of electromagnetic waves and thus control their reflection, refraction, and scattering features in arbitrary manners. Such physical attributes are perceived to bring about fundamental influence on the modern wireless communication system due to the possibilities to establish artificial and controllable propagation environments for radio signals, which no longer rely on the complex encoding, decoding, and other signal processing techniques. Recent studies reveal that the wave manipulation is not the only skill of the RISs. With the rapid developments of space-time digital metasurface and information metasurface, there has been increasing attention focused on the information manipulation via these artificial surfaces. In this article, we provide an overview of the theoretical models of the space-time digital metasurface and information metasurface, the mechanisms of wavefront shaping, and the signal modulations in space and time domains during the wave-matter interactions. We will also address some practical issues during implementations of the reconfigurable intelligent metasurfaces and the associated hardware architectures at microwave frequencies to realize simplified radio frequency transmitters. Several modulation schemes and the corresponding demonstration systems are introduced to illustrate the powerful abilities of the reconfigurable intelligent metasurfaces. Potential research directions of this technique are briefly discussed for their potential applications in future wireless networks.

关键词： Metasurfaces Encoding Harmonic analysis Surface waves Time-domain analysis P-i-n diodes Surface impedance Digital-coding metasurface information metasurface reconfigurable intelligent surface (RIS) space coding spectral modulation time coding transmitter wavefront shaping wireless network

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Maximum-Likelihood Integer Frequency Offset Estimator for Alamouti SFBC-OFDM Systems

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IEEE COMMUNICATIONS LETTERS 2020年第4期24卷 777-781页

作者： Marey, Mohamed Mostafa, Hala Prince Sultan Univ Coll Engn Riyadh 11586 Saudi Arabia Menoufia Univ Fac Elect Engn Menoufia 32952 Egypt Princess Nourah Bint Abdul Rahman Univ Coll Comp & Informat Sci Riyadh 84428 Saudi Arabia Menoufia Univ Fac Elect Engn Menoufia 32952 Egypt

In this letter, we address the problem of estimating the integer part of carrier frequency offset (CFO) in space frequency block codes (SFBCs) systems with orthogonal frequency division multiplexing (OFDM) modulation schemes. We derive a maximum-likelihood (ML) estimator assuming that the receiver has two receive antenna, and then we extend the analytical analysis to an arbitrary number of receive antennas. The proposed estimator is designed in a way that exploits the additional two-dimensional space-frequency redundancy provided by SFBCs. Because of its popularity, Alamouti code is chosen to be the code of interest. However, a similar analytical treatment could be applied to any other code. The computational complexity analysis and Monte Carlo experiments are carried out to verify effectiveness of the proposed estimator for practical applications.

关键词： Estimation multi-carrier space coding

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Wireless Communication through Long Term Evolution (LTE) over Satellite Channel by using MIMO-OFDM Model

Wireless Communication through Long Term Evolution (LTE) ove...

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2nd International Conference on Advances in Electrical Engineering (ICAEE)

作者： Hasan, Md. Mahmudul Sagar, Saleh Mohammad Daffodil Int Univ Dept Comp Sci & Engn Dhaka Bangladesh Univ Surrey Dept Elect Engn Guildford GU2 5XH Surrey England

ISBN: (纸本)9781479924653

This paper is intended for verifying the implementation of Long Term Evolution (LTE) over satellite in Forward Link. Recent developments in wireless communication such as MIMO technique that allow improving the received signal quality and capacity, in combination with OFDM makes the signals more robust against delay spread in frequency selective channel. A dual satellite Orthogonal Frequency Division Multiplexing and Multiple-Input and Multiple-Output (OFDM-MIMO) model is considered which provides a handy and robust resource over satellite channel for this purpose. It is OFDM in aggregation to quadrature phase shift keying (QPSK) with Turbo coding using 2x2 MIMO as specified for LTE 5 MHz BW, transmitted with satellite power delay profile has analyzed in terms of Bit Error Rate (BER). Spatial multiplexing and diversity are the two features that MIMO provides which has also been investigated. The investigation has been conducted considering downlink transmission over satellite forward link over dual-satellite 2x2 MIMO channel.

关键词： Wireless System LTE MIMO QPSK OFDM space coding Dual Satellite Channel

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Succinct Landmark Database

Succinct Landmark Database

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12th International Conference of Intelligent Autonomous Systems

作者： Tanaka, Kanji Univ Fukui Dept Human & Artificial Intelligent Syst Fukui 9108507 Japan

ISBN: (纸本)9783642339257;9783642339264

Recently developed robotic mapping techniques enable the acquisition of large scale landmark databases. This paper explores an approach for succinct landmark database, which memorizes a large collection of point landmarks while allowing to random access the location of i-th landmark. Our approach combines and extends three independent compression techniques: space coding, succinct data structure, and exemplar-based scene compression. Experiments using real datasets evaluate effectiveness of the presented techniques in terms of compactness, access speed, and accuracy of landmark database.

关键词： landmark database space coding succinct data structure exemplar-based scene compression

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The spatial encoding of body parts in patients with neglect and neurologically unimpaired participants

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NEUROPSYCHOLOGIA 2010年第1期48卷 334-340页

作者： Sposito, Ambra V. Bolognini, Nadia Vallar, Giuseppe Posteraro, Lucio Maravita, Angelo Univ Milano Bicocca Dipartimento Psicol I-20126 Milan Italy IRCCS Ist Auxol Italiano Neuropsychol Lab Milan Italy Osped Suzzara SpA MN Milan Italy

Body parts are represented in the brain in a very specific fashion, as compared to other three-dimensional objects, with reference to their prototypic shape and multisensory coding. However, evidence is lacking about the spatial representation of body parts. To address this issue, in Experiment I we first compared the metric representation of body parts and of non-bodily objects in 14 right-brain-damaged patients with left unilateral spatial neglect (USN), and in 14 neurologically unimpaired control participants. Participants bisected, by manual pointing, a three-dimensional object, or their own left forearm. Patients showed the well-known ipsilesional rightward displacement of the subjective midpoint, in both forearm and solid bisection. Both USN patients and control participants were overall more accurate in the bisection of their own forearm, relative to the extracorporeal object. in four patients this advantage of the forearm was significant in a single-case analysis, while two patients showed the opposite dissociation, being more accurate with the solid object. In Experiment 2 neurologically unimpaired participants were more accurate in the bisection of a fake forearm, as well as of their own forearm, as compared to the extrapersonal object. Overall, the results indicate that the representation of the metric of the body is more reliable than that of extrapersonal objects, and also more resistant to the disruption of spatial representations brought about by USN, possibly due to the prototypical shape of body parts. Furthermore, the double dissociation found in USN patients suggests that the metrics of body parts and of extrapersonal objects are supported by independent spatial processes. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Spatial impairments space coding Body representation Multisensory integration Unilateral spatial neglect

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Rangefinding system using hybrid pattern projections

Rangefinding system using hybrid pattern projections

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Conference on Three-Dimensional Image Capture and Applications 2008

作者： Kagiyama, Osamu Sato, Yukio Saito, Hideo Keio Univ Dept Informat & Comp Sci Kohoku Ku Yokohama Kanagawa 2238522 Japan

ISBN: (纸本)9780819469779

The practical three-dimensional measurement system with a high resolution based on a space code light pattern projection and a phase-shifted light pattern projection is presented. Three-dimensional measurement device's so-called, rangefinder, are expected to be applied in the apparel, medical and various fields. The performance of a rangefinder is evaluated by the measurements of time, depth, size, etc. The system using a space code technique can stably acquire the depth of an object although the resolution of the depth is not good because an object's space is coded in the shape of a wedge. On the other hand, in a phase shift technique, the high resolution depth of an object is able to be theoretically acquired because the object's space is divided finely by phase shifted light projection. But it is difficult to stably acquire the depth of an object because of the phase connection problem. In this paper, these problems (which are high resolution and phase connection problem) are able to be solved by both the space code technique and the phase shift technique. The effectiveness of this system is also described.

关键词： rangefinder three-dimensional measurement space coding phase shifting

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