高效视频编码(high efficiency video coding,HEVC)相较于上一代编码标准H.264降低了约50%的比特率,但为了提高帧内预测的准确性,HEVC提出的35种预测模式导致计算量大幅增加,对软件和硬件实现均构成了挑战.针对该问题,在HEVC的基础上提...高效视频编码(high efficiency video coding,HEVC)相较于上一代编码标准H.264降低了约50%的比特率,但为了提高帧内预测的准确性,HEVC提出的35种预测模式导致计算量大幅增加,对软件和硬件实现均构成了挑战.针对该问题,在HEVC的基础上提出了一种依据图片纹理方向,结合预测模式之间的关联性来确定帧内预测模式的快速算法.实验结果表明,本算法与HEVC参考软件HM16.20相比,在BD-Rate损失仅为5.79%的情况下,节省46%以上的编码时间,显著降低了帧内预测模式决策的复杂度,便于在嵌入式系统等硬件资源有限的端侧实现算法落地.展开更多
Fractional motion estimation(FME) improves the video encoding efficiency significantly. However, its high computational complexity limits the real-time processing capability. Therefore, it is a key problem to reduce t...Fractional motion estimation(FME) improves the video encoding efficiency significantly. However, its high computational complexity limits the real-time processing capability. Therefore, it is a key problem to reduce the implementation complexity of FME, especially in hardware design. This paper presents a novel deeply pipelined interpolation architecture of FME for the real-time realization of H.265/HEVC full Ultra-HD video encoder. First, a pipelined interpolation architecture together with an elegant processing order is proposed to deal with different search positions in parallel without pipeline stall and data conflict. Second, interpolation results sharing strategies are exploited among search positions to reduce the memory cost. Finally, the structure of the interpolation filter is further optimized for an area efficient implementation. As a result, the proposed design costs 41 917 slice LUTs on the Xilinx Kintex-7 FPGA platform with a 308 MHz working frequency. The measured throughput reaches a record of 1.238 Gpixels/s, which is sufficient for the real-time encoding of 8192×4320@ 30 fps video.展开更多
1 IntroductionThe screen content coding （SCC） standard [1] for high efficiency video coding （HEVC） is an international standard specially developed for screen content.
Multi?layer extension is based on single?layer design of High Efficiency Video Coding (HEVC) standard and employed as the com?mon structure for scalability and multi?view video coding extensions of HEVC. In this paper...Multi?layer extension is based on single?layer design of High Efficiency Video Coding (HEVC) standard and employed as the com?mon structure for scalability and multi?view video coding extensions of HEVC. In this paper, an overview of multi?layer extension is presented. The concepts and advantages of multi?layer extension are briefly described. High level syntax (HLS) for multi?layer extension and several new designs are also detailed.展开更多
高效视频编码标准(High Efficiency Video Coding,HEVC)作为H.264/AVC的继任者,提高了约2倍的编码效率。但其编码数据的计算复杂度和依赖性的增加,使视频编码器在硬件实现上更加困难。尤其是对编码器视频数据的处理和存取以及编码器内...高效视频编码标准(High Efficiency Video Coding,HEVC)作为H.264/AVC的继任者,提高了约2倍的编码效率。但其编码数据的计算复杂度和依赖性的增加,使视频编码器在硬件实现上更加困难。尤其是对编码器视频数据的处理和存取以及编码器内部状态控制的实现带来挑战。本文基于HEVC的宏块编码流程,提出了一种满足整体编码器实时高效运行的视频数据的存取结构和协调编码器各模块的顶层控制的方案。整个设计基于VCS和VIVADO的联合仿真环境验证功能的正确性。并在Xilinx公司的VCU118型号的FPGA上完成上板验证。测试结果表明,综合后的编码器的主频为100 MHz,可以满足编码器实现1080P30@fps的编码需求。展开更多
Along with the proliferating research interest in semantic communication(Sem Com),joint source channel coding(JSCC)has dominated the attention due to the widely assumed existence in efficiently delivering information ...Along with the proliferating research interest in semantic communication(Sem Com),joint source channel coding(JSCC)has dominated the attention due to the widely assumed existence in efficiently delivering information semantics.Nevertheless,this paper challenges the conventional JSCC paradigm and advocates for adopting separate source channel coding(SSCC)to enjoy a more underlying degree of freedom for optimization.We demonstrate that SSCC,after leveraging the strengths of the Large Language Model(LLM)for source coding and Error Correction Code Transformer(ECCT)complemented for channel coding,offers superior performance over JSCC.Our proposed framework also effectively highlights the compatibility challenges between Sem Com approaches and digital communication systems,particularly concerning the resource costs associated with the transmission of high-precision floating point numbers.Through comprehensive evaluations,we establish that assisted by LLM-based compression and ECCT-enhanced error correction,SSCC remains a viable and effective solution for modern communication systems.In other words,separate source channel coding is still what we need.展开更多
目前市面上HEVC(High Efficiency Video Coding)实时编码器要求能够实现在500 MHz时钟的情况下,完成4k 30 fps(Frames Per Second)及以下图像的实时编码。由于HEVC帧内预测模式有35种,并且预测单元PU(Prediction Unit)分为4×4、8&#...目前市面上HEVC(High Efficiency Video Coding)实时编码器要求能够实现在500 MHz时钟的情况下,完成4k 30 fps(Frames Per Second)及以下图像的实时编码。由于HEVC帧内预测模式有35种,并且预测单元PU(Prediction Unit)分为4×4、8×8、16×16、32×32、64×64这么多层,对于实时编码是一个很大的挑战,因此需要进行帧内预测模式的初步选择,减少RDO(Rate distortion optimization)中帧内模式的数量,降低硬件开销和满足实时性。本文提供一种HEVC帧内预测模式提前判决装置PRE_INTRA(Previous Intra Prediction),使用原始数据替代重构数据,从帧内35种预测模式中,使用SAD(Sum of Absolute Differences)算法的方式选择出亮度6种模式,色度一种模式,供RDO判决模块进行选择。实验结果表明:提出的算法与HM已有快速算法相比,PSNR(Peak signal-to-noise ratio)平均下降0.02 dB,输出码率平均增加0.22%,但是可以满足HEVC实施编码器性能要求。展开更多
Multiple functional metasurfaces with high information capacity have attracted considerable attention from researchers.This study proposes a 2-bit tunable spin-decoupled coded metasurface designed for the terahertz ba...Multiple functional metasurfaces with high information capacity have attracted considerable attention from researchers.This study proposes a 2-bit tunable spin-decoupled coded metasurface designed for the terahertz band,which utilizes the tunable properties of Dirac semimetals(DSM)to create a novel multilayer structure.By incorporating both geometric and propagating phases into the metasurface design,we can effectively control the electromagnetic wave.When the Fermi level(EF)of the DSM is set at 6 meV,the electromagnetic wave is manipulated by the gold patch embedded in the DSM film,operating at a frequency of 1.3 THz.When the EF of the DSM is set at 80 meV,the electromagnetic wave is manipulated by the DSM patch,operating at a frequency of 1.4 THz.Both modes enable independent control of beam splitting under left-rotating circularly polarized(LCP)and rightrotating circularly polarized(RCP)wave excitation,resulting in the generation of vortex beams with distinct orbital angular momentum(OAM)modes.The findings of this study hold significant potential for enhancing information capacity and polarization multiplexing techniques in wireless communications.展开更多
隐写术是信息安全领域的一个热门研究方向。由于视频媒体的广泛使用,视频隐写术受到了研究领域的广泛关注。在视频隐写术中,HEVC编码视频中的基于预测单元划分模式(Prediction Unit Partition Mode,简称PUPM)的视频隐写术以其更高的视...隐写术是信息安全领域的一个热门研究方向。由于视频媒体的广泛使用,视频隐写术受到了研究领域的广泛关注。在视频隐写术中,HEVC编码视频中的基于预测单元划分模式(Prediction Unit Partition Mode,简称PUPM)的视频隐写术以其更高的视觉质量成为研究人员关注的热点之一。本文主要研究了基于PUPM的视频隐写术。首先,讨论了基于PUPM的隐写术的基本原理和评价标准。其次,根据不同的技术特点,将基于PUPM域的隐写分为三类:传统的PUPM隐写、基于编码的PUPM隐写和基于最小化嵌入失真框架的自适应PUPM隐写。说明了上述代表性方法的优缺点。最后,提出了基于多因素的失真函数设计、基于深度学习的PUPM隐写以及将基于PUPM的隐写从实验室应用到现实世界等三个未来的研究方向。展开更多
随着高清和超高清直播需求的增长,传统编码技术在压缩效率和传输质量方面逐渐显现出局限性。针对这一问题,提出基于高效视频编码(High Efficiency Video Coding,HEVC)技术的优化策略,以期改善直播电视信号的压缩效率、传输延迟及画质清...随着高清和超高清直播需求的增长,传统编码技术在压缩效率和传输质量方面逐渐显现出局限性。针对这一问题,提出基于高效视频编码(High Efficiency Video Coding,HEVC)技术的优化策略,以期改善直播电视信号的压缩效率、传输延迟及画质清晰度。实验结果表明,HEVC技术结合快速用户数据报协议互联网连接(Quick User Datagram Protocol Internet Connections,QUIC)协议和硬件加速技术,可显著提高高分辨率场景下的信号稳定性和实时性。展开更多
Aiming at the problem that the bit error rate(BER)of asymmetrically clipped optical orthogonal frequency division multiplexing(ACO-OFDM)space optical communication system is significantly affected by different turbule...Aiming at the problem that the bit error rate(BER)of asymmetrically clipped optical orthogonal frequency division multiplexing(ACO-OFDM)space optical communication system is significantly affected by different turbulence intensities,the deep learning technique is proposed to the polarization code decoding in ACO-OFDM space optical communication system.Moreover,this system realizes the polarization code decoding and signal demodulation without frequency conduction with superior performance and robustness compared with the performance of traditional decoder.Simulations under different turbulence intensities as well as different mapping orders show that the convolutional neural network(CNN)decoder trained under weak-medium-strong turbulence atmospheric channels achieves a performance improvement of about 10^(2)compared to the conventional decoder at 4-quadrature amplitude modulation(4QAM),and the BERs for both 16QAM and 64QAM are in between those of the conventional decoder.展开更多
Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propos...Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propose a quasi-orthogonal spacetime block code(QOSTBC)that can achieve a full transmission code rate for backscatter communication systems with a four-antenna tag and then extend the scheme to support tags with 2i antennas.Specifically,we first present the system model for the backscatter system.Next,we propose the QOSTBC scheme to encode the tag signals.Then,we provide the corresponding maximum likelihood detection algorithms to recover the tag signals.Finally,simulation results are provided to demonstrate that our proposed QOSTBC scheme and the detection algorithm can achieve a better transmission code rate or symbol error rate performance for backscatter communication systems compared with benchmark schemes.展开更多
Semantic secure communication is an emerging field that combines the principles of source-channel coding with the need for secure data transmission.It is of great significance in modern communications to protect the c...Semantic secure communication is an emerging field that combines the principles of source-channel coding with the need for secure data transmission.It is of great significance in modern communications to protect the confidentiality and privacy of sensitive information and prevent information leaks and malicious attacks.This paper presents a novel approach to semantic secure communication through the utilization of joint source-channel coding,which is based on the design of an automated joint source-channel coding algorithm and an encryption and decryption algorithm based on semantic security.The traditional and state-of-the-art joint source-channel coding algorithms are selected as two baselines for different comparison purposes.Experimental results demonstrate that our proposed algorithm outperforms the first baseline algorithm,the traditional source-channel coding,by 61.21%in efficiency under identical channel conditions(SNR=15 dB).In security,our proposed method can resist 2 more types of attacks compared to the two baselines,exhibiting nearly no increases in time consumption and error rate compared to the state-of-the-art joint source-channel coding algorithm while the secure semantic communication is supported.展开更多
A broadband polarization-independent terahertz multifunctional coding metasurface based on topological optimization using liquid crystal(LC)is proposed.The metasurface can achieve reconfigurability for beam steering a...A broadband polarization-independent terahertz multifunctional coding metasurface based on topological optimization using liquid crystal(LC)is proposed.The metasurface can achieve reconfigurability for beam steering and vortex beam generation within a frequency range of 0.68 THz–0.72 THz.Firstly,the metasurface unit is topologically optimized using the non-dominant sequencing genetic algorithms(NSGA-II)multi-objective optimization algorithm.By applying the LC’s electrically tunable refractive index properties,the metasurface unit enables polarization-independent 2-bit coding within a frequency range of 0.68 THz–0.72 THz.Then,based on the designed metasurface unit,the array arrangement of the metasurface is reverse-designed to achieve beam steering and vortex beam generation.The results show that,for beam steering,not only can polarization-independent steering of both single-and multi-beam be achieved within the 35°elevation angle range,but also independent control of the target angle of each beam in the multi-beam steering.For vortex beam generation,the metasurfaces can achieve the generation of single-and multi-vortex beams with topological charges l=±1,±2 within the 35elevation angle range,and the generation angles of each vortex beam in the multi-vortex beam can be independently controlled.This provides flexibility and diversity in the generation of vortex beams.Therefore,the proposed terahertz LC metasurface can realize flexible control of reconfigurable functions and has certain application prospects in terahertz communication,phased array radar,and vortex radar.展开更多
Digital watermarking must balance imperceptibility,robustness,complexity,and security.To address the challenge of computational efficiency in trellis-based informed embedding,we propose a modified watermarking framewo...Digital watermarking must balance imperceptibility,robustness,complexity,and security.To address the challenge of computational efficiency in trellis-based informed embedding,we propose a modified watermarking framework that integrates fuzzy c-means(FCM)clustering into the generation off block codewords for labeling trellis arcs.The system incorporates a parallel trellis structure,controllable embedding parameters,and a novel informed embedding algorithm with reduced complexity.Two types of embedding schemes—memoryless and memory-based—are designed to flexibly trade-off between imperceptibility and robustness.Experimental results demonstrate that the proposed method outperforms existing approaches in bit error rate(BER)and computational complexity under various attacks,including additive noise,filtering,JPEG compression,cropping,and rotation.The integration of FCM enhances robustness by increasing the codeword distance,while preserving perceptual quality.Overall,the proposed framework is suitable for real-time and secure watermarking applications.展开更多
Structural colors based on metasurfaces have very promising applications in areas such as optical image encryption and color printing.Herein,we propose a deep learning-enabled reverse design of polarization-selective ...Structural colors based on metasurfaces have very promising applications in areas such as optical image encryption and color printing.Herein,we propose a deep learning-enabled reverse design of polarization-selective structural color based on coding metasurface.In this study,the long short-term memory(LSTM)neural network is presented to enable the forward and inverse mapping between coding metasurface structure and corresponding color.The results show that the method can achieve 98%accuracy for the forward prediction of color and 93%accuracy for the inverse design of the structure.Moreover,a cascaded architecture is adopted to train the inverse neural network model,which can solve the nonuniqueness problem of the polarization-selective color reverse design.This study provides a new path for the application and development of structural colors.展开更多
Efficient elastic wave focusing is crucial in materials and physical engineering.Elastic coding metasurfaces,which are innovative planar artificial structures,show great potential for use in the field of wave focusing...Efficient elastic wave focusing is crucial in materials and physical engineering.Elastic coding metasurfaces,which are innovative planar artificial structures,show great potential for use in the field of wave focusing.However,elastic coding lenses(ECLs)still suffer from low focusing performance,thickness comparable to wavelength,and frequency sensitivity.Here,we consider both the structural and material properties of the coding unit,thus realizing further compression of the thickness of the ECL.We chose the simplest ECL,which consists of only two encoding units.The coding unit 0 is a straight structure constructed using a carbon fiber reinforced composite material,and the coding unit 1 is a zigzag structure constructed using an aluminum material,and the thickness of the ECL constructed using them is only 1/8 of the wavelength.Based on the theoretical design,the arrangement of coding units is further optimized using genetic algorithms,which significantly improves the focusing performance of the lens at different focus and frequencies.This study provides a more effective way to control vibration and noise in advanced structures.展开更多
文摘高效视频编码(high efficiency video coding,HEVC)相较于上一代编码标准H.264降低了约50%的比特率,但为了提高帧内预测的准确性,HEVC提出的35种预测模式导致计算量大幅增加,对软件和硬件实现均构成了挑战.针对该问题,在HEVC的基础上提出了一种依据图片纹理方向,结合预测模式之间的关联性来确定帧内预测模式的快速算法.实验结果表明,本算法与HEVC参考软件HM16.20相比,在BD-Rate损失仅为5.79%的情况下,节省46%以上的编码时间,显著降低了帧内预测模式决策的复杂度,便于在嵌入式系统等硬件资源有限的端侧实现算法落地.
基金Supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ15F010001,LY16F020029)the General Research Project of Zhejiang Provincial Education Department(No.Y201430479)
文摘Fractional motion estimation(FME) improves the video encoding efficiency significantly. However, its high computational complexity limits the real-time processing capability. Therefore, it is a key problem to reduce the implementation complexity of FME, especially in hardware design. This paper presents a novel deeply pipelined interpolation architecture of FME for the real-time realization of H.265/HEVC full Ultra-HD video encoder. First, a pipelined interpolation architecture together with an elegant processing order is proposed to deal with different search positions in parallel without pipeline stall and data conflict. Second, interpolation results sharing strategies are exploited among search positions to reduce the memory cost. Finally, the structure of the interpolation filter is further optimized for an area efficient implementation. As a result, the proposed design costs 41 917 slice LUTs on the Xilinx Kintex-7 FPGA platform with a 308 MHz working frequency. The measured throughput reaches a record of 1.238 Gpixels/s, which is sufficient for the real-time encoding of 8192×4320@ 30 fps video.
基金supported in part by National Natural Science Foundation of China under Grant No.61201226 and 61271096Specialized Research Fund for the Doctoral Program under Grant No.20130072110054
文摘1 IntroductionThe screen content coding （SCC） standard [1] for high efficiency video coding （HEVC） is an international standard specially developed for screen content.
文摘Multi?layer extension is based on single?layer design of High Efficiency Video Coding (HEVC) standard and employed as the com?mon structure for scalability and multi?view video coding extensions of HEVC. In this paper, an overview of multi?layer extension is presented. The concepts and advantages of multi?layer extension are briefly described. High level syntax (HLS) for multi?layer extension and several new designs are also detailed.
文摘高效视频编码标准(High Efficiency Video Coding,HEVC)作为H.264/AVC的继任者,提高了约2倍的编码效率。但其编码数据的计算复杂度和依赖性的增加,使视频编码器在硬件实现上更加困难。尤其是对编码器视频数据的处理和存取以及编码器内部状态控制的实现带来挑战。本文基于HEVC的宏块编码流程,提出了一种满足整体编码器实时高效运行的视频数据的存取结构和协调编码器各模块的顶层控制的方案。整个设计基于VCS和VIVADO的联合仿真环境验证功能的正确性。并在Xilinx公司的VCU118型号的FPGA上完成上板验证。测试结果表明,综合后的编码器的主频为100 MHz,可以满足编码器实现1080P30@fps的编码需求。
基金supported in part by the National Key Research and Development Program of China under Grant No.2024YFE0200600the Zhejiang Provincial Natural Science Foundation of China under Grant No.LR23F010005the Huawei Cooperation Project under Grant No.TC20240829036。
文摘Along with the proliferating research interest in semantic communication(Sem Com),joint source channel coding(JSCC)has dominated the attention due to the widely assumed existence in efficiently delivering information semantics.Nevertheless,this paper challenges the conventional JSCC paradigm and advocates for adopting separate source channel coding(SSCC)to enjoy a more underlying degree of freedom for optimization.We demonstrate that SSCC,after leveraging the strengths of the Large Language Model(LLM)for source coding and Error Correction Code Transformer(ECCT)complemented for channel coding,offers superior performance over JSCC.Our proposed framework also effectively highlights the compatibility challenges between Sem Com approaches and digital communication systems,particularly concerning the resource costs associated with the transmission of high-precision floating point numbers.Through comprehensive evaluations,we establish that assisted by LLM-based compression and ECCT-enhanced error correction,SSCC remains a viable and effective solution for modern communication systems.In other words,separate source channel coding is still what we need.
文摘目前市面上HEVC(High Efficiency Video Coding)实时编码器要求能够实现在500 MHz时钟的情况下,完成4k 30 fps(Frames Per Second)及以下图像的实时编码。由于HEVC帧内预测模式有35种,并且预测单元PU(Prediction Unit)分为4×4、8×8、16×16、32×32、64×64这么多层,对于实时编码是一个很大的挑战,因此需要进行帧内预测模式的初步选择,减少RDO(Rate distortion optimization)中帧内模式的数量,降低硬件开销和满足实时性。本文提供一种HEVC帧内预测模式提前判决装置PRE_INTRA(Previous Intra Prediction),使用原始数据替代重构数据,从帧内35种预测模式中,使用SAD(Sum of Absolute Differences)算法的方式选择出亮度6种模式,色度一种模式,供RDO判决模块进行选择。实验结果表明:提出的算法与HM已有快速算法相比,PSNR(Peak signal-to-noise ratio)平均下降0.02 dB,输出码率平均增加0.22%,但是可以满足HEVC实施编码器性能要求。
文摘Multiple functional metasurfaces with high information capacity have attracted considerable attention from researchers.This study proposes a 2-bit tunable spin-decoupled coded metasurface designed for the terahertz band,which utilizes the tunable properties of Dirac semimetals(DSM)to create a novel multilayer structure.By incorporating both geometric and propagating phases into the metasurface design,we can effectively control the electromagnetic wave.When the Fermi level(EF)of the DSM is set at 6 meV,the electromagnetic wave is manipulated by the gold patch embedded in the DSM film,operating at a frequency of 1.3 THz.When the EF of the DSM is set at 80 meV,the electromagnetic wave is manipulated by the DSM patch,operating at a frequency of 1.4 THz.Both modes enable independent control of beam splitting under left-rotating circularly polarized(LCP)and rightrotating circularly polarized(RCP)wave excitation,resulting in the generation of vortex beams with distinct orbital angular momentum(OAM)modes.The findings of this study hold significant potential for enhancing information capacity and polarization multiplexing techniques in wireless communications.
文摘隐写术是信息安全领域的一个热门研究方向。由于视频媒体的广泛使用,视频隐写术受到了研究领域的广泛关注。在视频隐写术中,HEVC编码视频中的基于预测单元划分模式(Prediction Unit Partition Mode,简称PUPM)的视频隐写术以其更高的视觉质量成为研究人员关注的热点之一。本文主要研究了基于PUPM的视频隐写术。首先,讨论了基于PUPM的隐写术的基本原理和评价标准。其次,根据不同的技术特点,将基于PUPM域的隐写分为三类:传统的PUPM隐写、基于编码的PUPM隐写和基于最小化嵌入失真框架的自适应PUPM隐写。说明了上述代表性方法的优缺点。最后,提出了基于多因素的失真函数设计、基于深度学习的PUPM隐写以及将基于PUPM的隐写从实验室应用到现实世界等三个未来的研究方向。
文摘随着高清和超高清直播需求的增长,传统编码技术在压缩效率和传输质量方面逐渐显现出局限性。针对这一问题,提出基于高效视频编码(High Efficiency Video Coding,HEVC)技术的优化策略,以期改善直播电视信号的压缩效率、传输延迟及画质清晰度。实验结果表明,HEVC技术结合快速用户数据报协议互联网连接(Quick User Datagram Protocol Internet Connections,QUIC)协议和硬件加速技术,可显著提高高分辨率场景下的信号稳定性和实时性。
基金supported by the National Natural Science Foundation of China(No.12104141).
文摘Aiming at the problem that the bit error rate(BER)of asymmetrically clipped optical orthogonal frequency division multiplexing(ACO-OFDM)space optical communication system is significantly affected by different turbulence intensities,the deep learning technique is proposed to the polarization code decoding in ACO-OFDM space optical communication system.Moreover,this system realizes the polarization code decoding and signal demodulation without frequency conduction with superior performance and robustness compared with the performance of traditional decoder.Simulations under different turbulence intensities as well as different mapping orders show that the convolutional neural network(CNN)decoder trained under weak-medium-strong turbulence atmospheric channels achieves a performance improvement of about 10^(2)compared to the conventional decoder at 4-quadrature amplitude modulation(4QAM),and the BERs for both 16QAM and 64QAM are in between those of the conventional decoder.
基金supported by Beijing Municipal Natural Science Foundation(L222002)the Natural Science Foundation of China(U22B2004).
文摘Existing orthogonal space-time block coding(OSTBC)schemes for backscatter communication systems cannot achieve a full transmission code rate when the tag is equipped with more than two antennas.In this paper,we propose a quasi-orthogonal spacetime block code(QOSTBC)that can achieve a full transmission code rate for backscatter communication systems with a four-antenna tag and then extend the scheme to support tags with 2i antennas.Specifically,we first present the system model for the backscatter system.Next,we propose the QOSTBC scheme to encode the tag signals.Then,we provide the corresponding maximum likelihood detection algorithms to recover the tag signals.Finally,simulation results are provided to demonstrate that our proposed QOSTBC scheme and the detection algorithm can achieve a better transmission code rate or symbol error rate performance for backscatter communication systems compared with benchmark schemes.
基金supported in part by the National Key R&D Program of China under Grant 2022YFB3103500in part by the National Natural Science Foundation of China under Grant 62302195.
文摘Semantic secure communication is an emerging field that combines the principles of source-channel coding with the need for secure data transmission.It is of great significance in modern communications to protect the confidentiality and privacy of sensitive information and prevent information leaks and malicious attacks.This paper presents a novel approach to semantic secure communication through the utilization of joint source-channel coding,which is based on the design of an automated joint source-channel coding algorithm and an encryption and decryption algorithm based on semantic security.The traditional and state-of-the-art joint source-channel coding algorithms are selected as two baselines for different comparison purposes.Experimental results demonstrate that our proposed algorithm outperforms the first baseline algorithm,the traditional source-channel coding,by 61.21%in efficiency under identical channel conditions(SNR=15 dB).In security,our proposed method can resist 2 more types of attacks compared to the two baselines,exhibiting nearly no increases in time consumption and error rate compared to the state-of-the-art joint source-channel coding algorithm while the secure semantic communication is supported.
基金Project supported by the Open Fund of Wuhan National Research Center for Optoelectronics(Grant No.2022WNLOKF012)the National College Students Innovation Innovation and Entrepreneurship Training Program(Grant No.2023102930147).
文摘A broadband polarization-independent terahertz multifunctional coding metasurface based on topological optimization using liquid crystal(LC)is proposed.The metasurface can achieve reconfigurability for beam steering and vortex beam generation within a frequency range of 0.68 THz–0.72 THz.Firstly,the metasurface unit is topologically optimized using the non-dominant sequencing genetic algorithms(NSGA-II)multi-objective optimization algorithm.By applying the LC’s electrically tunable refractive index properties,the metasurface unit enables polarization-independent 2-bit coding within a frequency range of 0.68 THz–0.72 THz.Then,based on the designed metasurface unit,the array arrangement of the metasurface is reverse-designed to achieve beam steering and vortex beam generation.The results show that,for beam steering,not only can polarization-independent steering of both single-and multi-beam be achieved within the 35°elevation angle range,but also independent control of the target angle of each beam in the multi-beam steering.For vortex beam generation,the metasurfaces can achieve the generation of single-and multi-vortex beams with topological charges l=±1,±2 within the 35elevation angle range,and the generation angles of each vortex beam in the multi-vortex beam can be independently controlled.This provides flexibility and diversity in the generation of vortex beams.Therefore,the proposed terahertz LC metasurface can realize flexible control of reconfigurable functions and has certain application prospects in terahertz communication,phased array radar,and vortex radar.
基金funded by the National Science and Technology Council,Taiwan,under grant number NSTC 114-2221-E-167-005-MY3,and NSTC 113-2221-E-167-006-.
文摘Digital watermarking must balance imperceptibility,robustness,complexity,and security.To address the challenge of computational efficiency in trellis-based informed embedding,we propose a modified watermarking framework that integrates fuzzy c-means(FCM)clustering into the generation off block codewords for labeling trellis arcs.The system incorporates a parallel trellis structure,controllable embedding parameters,and a novel informed embedding algorithm with reduced complexity.Two types of embedding schemes—memoryless and memory-based—are designed to flexibly trade-off between imperceptibility and robustness.Experimental results demonstrate that the proposed method outperforms existing approaches in bit error rate(BER)and computational complexity under various attacks,including additive noise,filtering,JPEG compression,cropping,and rotation.The integration of FCM enhances robustness by increasing the codeword distance,while preserving perceptual quality.Overall,the proposed framework is suitable for real-time and secure watermarking applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.62375137 and 62175114).
文摘Structural colors based on metasurfaces have very promising applications in areas such as optical image encryption and color printing.Herein,we propose a deep learning-enabled reverse design of polarization-selective structural color based on coding metasurface.In this study,the long short-term memory(LSTM)neural network is presented to enable the forward and inverse mapping between coding metasurface structure and corresponding color.The results show that the method can achieve 98%accuracy for the forward prediction of color and 93%accuracy for the inverse design of the structure.Moreover,a cascaded architecture is adopted to train the inverse neural network model,which can solve the nonuniqueness problem of the polarization-selective color reverse design.This study provides a new path for the application and development of structural colors.
基金Project supported by the National Natural Science Foundation of China(Grant No.12404531)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(Grant No.23KJB140011)。
文摘Efficient elastic wave focusing is crucial in materials and physical engineering.Elastic coding metasurfaces,which are innovative planar artificial structures,show great potential for use in the field of wave focusing.However,elastic coding lenses(ECLs)still suffer from low focusing performance,thickness comparable to wavelength,and frequency sensitivity.Here,we consider both the structural and material properties of the coding unit,thus realizing further compression of the thickness of the ECL.We chose the simplest ECL,which consists of only two encoding units.The coding unit 0 is a straight structure constructed using a carbon fiber reinforced composite material,and the coding unit 1 is a zigzag structure constructed using an aluminum material,and the thickness of the ECL constructed using them is only 1/8 of the wavelength.Based on the theoretical design,the arrangement of coding units is further optimized using genetic algorithms,which significantly improves the focusing performance of the lens at different focus and frequencies.This study provides a more effective way to control vibration and noise in advanced structures.
