共查询到18条相似文献,搜索用时 140 毫秒
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视频信息必须经过压缩以便在低带宽信道上传输,而压缩数字媒体对无线信道误码十分敏感,容易发生传输错误,误差隐藏技术是弥补此类问题的方法之一。本文在对现有的误差隐藏处理方法分析的基础上,提出了一种基于模式选择的时空域误差隐藏技术。此方法不仅从时、空两方面考虑,分别应用时域取代法和加权内插空域法。还通过边界检测,区分了平坦型和边界穿越型两类宏块,减少算法复杂性。仿真实验表明,该方法可有效地抑制视频差错的扩散,取得较好的差错掩盖效果。 相似文献
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可逆变长编码的解码器设计及VLSI实现 总被引:1,自引:0,他引:1
变长编码(VLCs,Variable Length Codes)因其高效的数据压缩能力被广泛地应用在多媒体压缩领域,但VLCs的自身性质使它对信道错误的恢复能力很弱。随着在不可靠信道,如无线信道和网络上进行视频传送需求的增加,视频通讯的错误控制和错误恢复技术变得越来越重要。可逆变长编码(RVLCs,Reversible Variable Length Codes),当遇到传输错误时,充分利用了可用的数据,错误恢复能力强于VLCs。许多视频标准,如ITU H.263 ,ISO MPEG-4已经采用了RVLCs。本文详细描述了RVLCs解码器的解码算法和解码器的体系结构设计,给出了一个基于MPEG-4 ASP@L5的解码器VLSI实现。结果表明,该实现完全适用于MPEG-4实时编解码系统。 相似文献
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为了提高在高误码率窄带无线信道下的合成语音质量,提出了一种信源信道联合编解码保护的语音编码抗误码算法。该算法在编码端利用编码后的冗余度进行BCH编码和奇偶校验以保护对语音合成质量影响较大的参数;在解码端对清浊音参数采用分支判决和改进的最大后验概率算法进行恢复,在浊音帧对线谱对(LSP)参数进行基于信源信道联合特性的线谱对参数差错后处理,在清音帧采用BCH解码和前向替代。该算法在不消耗任何额外带宽且无算法延时的条件下可以显著提高语音编码抗信道误码能力和恶劣信道条件下的合成语音质量。仿真实验显示,在较高信道误码率下平均谱失真降低了25%~36.1%,平均意见得分(MOS)提高了12.33%。 相似文献
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随着无线网络的快速发展和Internet中流媒体视频的巨大成功,无线网络中的视频服务有望在不久的将来得到大规模部署,无线网络上的实时流媒体传输技术已成为研究热点,而其中组包算法的选取是其中的一个关键问题,但是,由于无线网络中有限的带宽和错误易发环境,数据丢包和误码在无线流媒体业务中是不可避免的,为提高无线流媒体业务的服务质量,研究人员设计众多的差错控制算法,一个精心设计的组包算法不仅可以明显地促进流媒体视频抵抗误码能力,还能够减小压缩编码的负载,如何设计一个高效的抗错误的组包算法,是当前流媒体应用的一个备受关注的问题,针对无线视频应用,针对一个基于无线网络多层非对等保护和动态优化的组包算法进行研究,并进行算法评价。 相似文献
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用量子特性函数方法得到了纠缠辅助单模压缩信道在限定输入功率下的经典信息容量的表达式,并进行了数值分析.计算结果表明,信道压缩参数越大,其容量也越大.与没有纠缠辅助下的单模压缩信道的信道容量不同,在纠缠辅助下信道容量一般在信源为压缩态时达到,且此时信源与信道的压缩复参数的相角关系相差π. 相似文献
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从最新的H.263 Annex V选项出发,提出了一个基于数据分类封装和编码信息RS误码保护的抗误码算法,在不过多增加码率的前提下,提供更强的误码抵抗力,实验结果表明,本编码算法在高衰码的无线信道条件下具有比以前一般算法更好的适应性和更强的健壮性。 相似文献
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Wen Li David Zhang Zhiyong Liu Xiangzhen Qiao 《International journal of imaging systems and technology》2003,13(4):189-200
Best Neighborhood Matching (BNM) algorithm is a good approach of error concealment in terms of restored image quality. However, this kind of error concealment algorithm is commonly computation‐intensive, which restricts their real applications on large‐scale image or video sequence restoration. In this article, we propose a fast method, named Jump and look around Best Neighborhood Matching (JBNM), which reduces computing time to one sixth of that by BNM, while the quality of the restored images remains almost the same. To further reduce processing time and meet large‐scale image restorations, a parallel JBNM working on a cluster of workstations is proposed. Several critical techniques, including reading policy, overlap stripe data distribution, and communication strategies, have been developed to obtain high performance. Both theoretical analysis and experiment results indicate that our parallel JBNM provides an efficient technique for image restoration applications. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 13, 189–200, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10057 相似文献
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目的研究当前市场上电助力自行车电池盒的隐蔽程度,并对其进行量化评价,对电助力自行车电池盒的隐蔽性进行设计研究,在一定程度上提高设计评价的客观性,并为电助力自行车的生产企业和设计从业人员提供一定的参考依据。方法采用眼动追踪实验,分析实验中的AOI(AreaOfInterest,AOI)首次注视时间和AOI区域的总注视时间数据,采用李克特量表法对电助力自行车电池盒的隐蔽程度进行主观评价,将眼动追踪实验分析结果与主观评价结果相结合进行分析,对市场上具有代表性的九款电助力自行车电池盒的隐蔽程度进行量化分析。结论得出电池盒安装在自行车的下管位置时隐蔽性最好,其次是后座和立管的位置。此方法可以为电助力自行车设计的整体化及一体化提供一定的设计参考和分析方法。 相似文献
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In this study, it is proposed that the diffusion least mean square (LMS) algorithm can be improved by applying the fractional order signal processing methodologies. Application of Caputo’s fractional derivatives are considered in the optimization of cost function. It is suggested to derive a fractional order variant of the diffusion LMS algorithm. The applicability is tested for the estimation of channel parameters in a distributed environment consisting of randomly distributed sensors communicating through wireless medium. The topology of the network is selected such that a smaller number of nodes are informed. In the network, a random sleep strategy is followed to conserve the transmission power at the nodes. The proposed fractional order modified diffusion LMS algorithms are applied in the two configurations of combine-then-adapt and adapt-then-combine. The average squared error performance of the proposed algorithms along with its traditional counterparts are evaluated for the estimation of the Rayleigh channel parameters. A mathematical proof of convergence is provided showing that the addition of the nonlinear term resulting from fractional derivatives helps adjusts the autocorrelation matrix in such a way that the spread of its eigenvalues decreases. This increases the convergence as well as the steady state response even for the larger step sizes. Experimental results are shown for different number of nodes and fractional orders. The simulation results establish that the accuracy of the proposed scheme is far better than its classical counterparts, therefore, helps better solves the channel gains estimation problem in a distributed wireless environment. The algorithm has the potential to be applied in other applications related to learning and adaptation. 相似文献
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传统基于训练序列及块状导频结构的滤波器组多载波(Filter Bank Multicarrier,FBMC)信道估计方法花费额外的频谱资源,这在频谱资源较为紧张的水声通信环境中具有一定的局限性。针对这一问题并结合水声信道稀疏性的特点,文章提出了一种基于压缩感知的离散导频结构FBMC信道估计方法。首先基于等效导频能量最大化的思想,设计了一种新的离散导频结构来解决FBMC系统信道估计时存在的固有虚部干扰问题;然后配合该结构,提取出导频处的接收信息并利用重构效果优良的压缩感知gOMP算法对水声信道进行重构。该方法在保证水声信道估计精度的同时有效提高了FBMC系统的频谱利用率,改善了水声通信的性能。仿真结果表明,文中所提方法相较于传统方法在估计精度和频谱利用率方面具有一定的优越性。 相似文献
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提出了一种基于压缩感知理论的多中继协作通信系统稀疏信道估计方法.采用正交匹配追踪(Orthogonal Matching Pursuit,OMP)压缩感知算法,对时域信道脉冲响应进行估计.对多中继协作通信系统进行稀疏建模;结合压缩感知理论构建观测矩阵,并给出卷积信道的稀疏表示;利用压缩信道感知算法重建了系统的卷积复合信道.仿真结果表明,与传统的最小二乘法(Least Square,LS)相比,采用压缩感知理论的信道估计算法,能利用较少的导频信号获得很好的信道估计性能,提高了频谱利用率. 相似文献
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Mohammad Sh. Daoud Areej Fatima Waseem Ahmad Khan Muhammad Adnan Khan Sagheer Abbas Baha Ihnaini Munir Ahmad Muhammad Sheraz Javeid Shabib Aftab 《计算机、材料和连续体(英文)》2022,70(1):109-124
The numbers of multimedia applications and their users increase with each passing day. Different multi-carrier systems have been developed along with varying techniques of space-time coding to address the demand of the future generation of network systems. In this article, a fuzzy logic empowered adaptive backpropagation neural network (FLeABPNN) algorithm is proposed for joint channel and multi-user detection (CMD). FLeABPNN has two stages. The first stage estimates the channel parameters, and the second performs multi-user detection. The proposed approach capitalizes on a neuro-fuzzy hybrid system that combines the competencies of both fuzzy logic and neural networks. This study analyzes the results of using FLeABPNN based on a multiple-input and multiple-output (MIMO) receiver with conventional partial opposite mutant particle swarm optimization (POMPSO), total-OMPSO (TOMPSO), fuzzy logic empowered POMPSO (FL-POMPSO), and FL-TOMPSO-based MIMO receivers. The FLeABPNN-based receiver renders better results than other techniques in terms of minimum mean square error, minimum mean channel error, and bit error rate. 相似文献
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Gonzalez O. Martin-Gonzalez J.A. Poves E. Lopez-Hernandez F.J. Perez-Jimenez R. 《Optoelectronics, IET》2009,3(4):187-196
The authors have designed an adaptive optical codes-based system for communications over the indoor wireless optical channel when large numbers of users access to the channel simultaneously. This system uses a code-division multiple access (CDMA) scheme based on the named random optical codes (ROC). The authors present the characteristics of this kind of optical codes and several results about its performance over noisy indoor wireless optical channels. Finally, the authors describe a CDMA system which adapts its performance to the number of users which are accessing simultaneously to the channel. The proposed system is able to maintain a target bit error rate adapting its data throughput independently of the number of simultaneous users in the optical environment, whenever certain conditions are accomplished. 相似文献