Compact size,high brightness,and wide field of view(FOV)are key requirements for long-wave infrared imagers used in military surveillance or night navigation.However,to meet the imaging requirements of high resolution...Compact size,high brightness,and wide field of view(FOV)are key requirements for long-wave infrared imagers used in military surveillance or night navigation.However,to meet the imaging requirements of high resolution and wide FOV,infrared optical systems often adopt complex optical lens groups,which will increase the size and weight of the optical system.In this paper,a strategy based on wavefront coding(WFC)is proposed to design a compact wide-FOV infrared imager.A cubic phase mask is inserted into the pupil plane of the infrared imager to correct the aberration.The simulated results show that,the WFC infrared imager has good imaging quality in a wide FOV of±16°.In addition,the WFC infrared imager achieves compactness with its 40 mm×40 mm×40 mm size.A fast focal ratio of 1 combined with an entrance pupil diameter of 25 mm ensures brightness.This work is of significance for designing a compact wide-FOV infrared imager.展开更多
This article investigates the distributed recursive filtering problem for discrete-time stochastic cyber–physical systems.A particular feature of our work is that we consider systems in which the state is constrained...This article investigates the distributed recursive filtering problem for discrete-time stochastic cyber–physical systems.A particular feature of our work is that we consider systems in which the state is constrained by saturation.Measurements are transmitted to nodes of a sensor network over unreliable wireless channels.We propose a linear coding mechanism,together with a distributed method for obtaining a state estimate at each node.These designs aim to minimize the state estimation error covariance.In addition,we derive a bound on this covariance,and accommodate the design parameters to minimize this bound.The resulting design depends on the packet loss probabilities of the wireless channels.This permits applying the proposed scheme to systems in which communications suffer from denial-of-service attacks,as such attacks typically affect those probabilities.Finally,we present a numerical example illustrating this application.展开更多
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
Quantum secure direct communication(QSDC) is a communication method based on quantum mechanics and it is used to transmit secret messages. Unlike quantum key distribution, secret messages can be transmitted directly o...Quantum secure direct communication(QSDC) is a communication method based on quantum mechanics and it is used to transmit secret messages. Unlike quantum key distribution, secret messages can be transmitted directly on a quantum channel with QSDC. Higher channel capacity and noise suppression capabilities are key to achieving longdistance quantum communication. Here, we report a continuous-variable QSDC scheme based on mask-coding and orbital angular momentum, in which the mask-coding is employed to protect the security of the transmitting messages and to suppress the influence of excess noise. The combination of orbital angular momentum and information block transmission effectively improves the secrecy capacity. In the 800 information blocks ×1310 bits length 10-km experiment, the results show a statistical average bit error rate of 0.38%, a system excess noise value of 0.0184 SNU, and a final secrecy capacity of 6.319×10~6 bps. Therefore, this scheme reduces error bits while increasing secrecy capacity, providing a solution for long-distance large-scale quantum communication, which is capable of transmitting text, images and other information of reasonable size.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
针对高效视频编码(High Efficiency Video Coding,HEVC)在4K超高清电视信号压缩中的技术挑战,深入分析HEVC的适用性,提出基于编码树单元(Coding Tree Unit,CTU)优化、预测单元自适应划分以及变换单元动态选择的压缩效率提升策略。实际...针对高效视频编码(High Efficiency Video Coding,HEVC)在4K超高清电视信号压缩中的技术挑战,深入分析HEVC的适用性,提出基于编码树单元(Coding Tree Unit,CTU)优化、预测单元自适应划分以及变换单元动态选择的压缩效率提升策略。实际应用效果测试表明,与传统高级视频编码(Advanced Video Coding,AVC)(又称H.264)方法相比,所提策略在保持相同视觉质量的前提下,平均压缩比提高32.7%,平均比特率节省28.5%,为4K超高清电视信号的高效传输和存储提供了有力技术支持。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
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
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
Shortening is a standard rate-matching method for polar codes in wireless communications.Since polarization-adjusted convolu⁃tional(PAC)codes also have a block length limited to the integer powers of two,they also req...Shortening is a standard rate-matching method for polar codes in wireless communications.Since polarization-adjusted convolu⁃tional(PAC)codes also have a block length limited to the integer powers of two,they also require rate-matching.To this end,we first analyze the limitations of existing shortening patterns for PAC codes and explore their feasibility.Subsequently,we propose a novel shortening scheme for PAC codes based on list decoding,where the receiver is allowed to treat the values of the deleted bits as undetermined.This ap⁃proach uses a specialized PAC codeword and activates multiple decoding paths during the initialization of list decoding,enabling it to achieve the desired reliability.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
文摘Compact size,high brightness,and wide field of view(FOV)are key requirements for long-wave infrared imagers used in military surveillance or night navigation.However,to meet the imaging requirements of high resolution and wide FOV,infrared optical systems often adopt complex optical lens groups,which will increase the size and weight of the optical system.In this paper,a strategy based on wavefront coding(WFC)is proposed to design a compact wide-FOV infrared imager.A cubic phase mask is inserted into the pupil plane of the infrared imager to correct the aberration.The simulated results show that,the WFC infrared imager has good imaging quality in a wide FOV of±16°.In addition,the WFC infrared imager achieves compactness with its 40 mm×40 mm×40 mm size.A fast focal ratio of 1 combined with an entrance pupil diameter of 25 mm ensures brightness.This work is of significance for designing a compact wide-FOV infrared imager.
基金supported by the KGJ Basic Research Fund(JCKY2023110C080)the National Natural Science Foundation of China(62322306,62173057,62033006)+2 种基金Aviation Science Foundation Project(2022Z018063001)the Argentinean Agency for Scientific and Technological Promotion(PICT-2021-I-A-00730)the National Foreign Expert Individual Project(H20240983).
文摘This article investigates the distributed recursive filtering problem for discrete-time stochastic cyber–physical systems.A particular feature of our work is that we consider systems in which the state is constrained by saturation.Measurements are transmitted to nodes of a sensor network over unreliable wireless channels.We propose a linear coding mechanism,together with a distributed method for obtaining a state estimate at each node.These designs aim to minimize the state estimation error covariance.In addition,we derive a bound on this covariance,and accommodate the design parameters to minimize this bound.The resulting design depends on the packet loss probabilities of the wireless channels.This permits applying the proposed scheme to systems in which communications suffer from denial-of-service attacks,as such attacks typically affect those probabilities.Finally,we present a numerical example illustrating this application.
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.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62071381 and 62301430)Shaanxi Fundamental Science Research Project for Mathematics and Physics (Grant No. 23JSY014)+1 种基金Scientific Research Plan Project of Shaanxi Education Department (Natural Science Special Project (Grant No. 23JK0680)Young Talent Fund of Xi’an Association for Science and Technology (Grant No. 959202313011)。
文摘Quantum secure direct communication(QSDC) is a communication method based on quantum mechanics and it is used to transmit secret messages. Unlike quantum key distribution, secret messages can be transmitted directly on a quantum channel with QSDC. Higher channel capacity and noise suppression capabilities are key to achieving longdistance quantum communication. Here, we report a continuous-variable QSDC scheme based on mask-coding and orbital angular momentum, in which the mask-coding is employed to protect the security of the transmitting messages and to suppress the influence of excess noise. The combination of orbital angular momentum and information block transmission effectively improves the secrecy capacity. In the 800 information blocks ×1310 bits length 10-km experiment, the results show a statistical average bit error rate of 0.38%, a system excess noise value of 0.0184 SNU, and a final secrecy capacity of 6.319×10~6 bps. Therefore, this scheme reduces error bits while increasing secrecy capacity, providing a solution for long-distance large-scale quantum communication, which is capable of transmitting text, images and other information of reasonable size.
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。
文摘针对高效视频编码(High Efficiency Video Coding,HEVC)在4K超高清电视信号压缩中的技术挑战,深入分析HEVC的适用性,提出基于编码树单元(Coding Tree Unit,CTU)优化、预测单元自适应划分以及变换单元动态选择的压缩效率提升策略。实际应用效果测试表明,与传统高级视频编码(Advanced Video Coding,AVC)(又称H.264)方法相比,所提策略在保持相同视觉质量的前提下,平均压缩比提高32.7%,平均比特率节省28.5%,为4K超高清电视信号的高效传输和存储提供了有力技术支持。
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 in part by the National Natural Sciences Foun⁃dation of China(NSFC)under Grant Nos.62301185 and 62027802in part by ZTE Industry⁃University-Institute Cooperation Fundsin part by The Major Key Project of PCL under Grant No.PCL2024A01.
文摘Shortening is a standard rate-matching method for polar codes in wireless communications.Since polarization-adjusted convolu⁃tional(PAC)codes also have a block length limited to the integer powers of two,they also require rate-matching.To this end,we first analyze the limitations of existing shortening patterns for PAC codes and explore their feasibility.Subsequently,we propose a novel shortening scheme for PAC codes based on list decoding,where the receiver is allowed to treat the values of the deleted bits as undetermined.This ap⁃proach uses a specialized PAC codeword and activates multiple decoding paths during the initialization of list decoding,enabling it to achieve the desired reliability.
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.
