共查询到20条相似文献，搜索用时 343 毫秒
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刘俊 《安徽教育学院学报》2010,28(6)
本文利用MATLAB软件仿真平台,比较研究了TD-SCDMA系统中基于传统的Schur算法和block-Schur两种联合检测算法。对两种算法在三种瑞利衰落信道模型中最差的CASE3情况下进行了性能比较,并对两种算法在不同用户数下的运算量做了仿真分析,仿真结果表明两种算法都能达到比较好的误码性能,在3GPP协议规定处,两种算法都能被系统所接受,并且block-Schur算法比传统的Schur算法具有更好的误码性能,运算效率高。 相似文献
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刘俊 《深圳信息职业技术学院学报》2014,(3):8-11
针对无线环境下FTCP性能恶化的问题,在研究分析一种自适应拥塞避免算法的基础上,提出一种基于该算法的无线TCP改进机制。该机制引入拥塞丢包与误码丢包的判决因子,能针对无线误码的判断采取更为准确的发送速率调整机制,很大程度上实现了拥塞控制与差错控制的分离,从而提升了无线TCP6的性能改善。仿真结果表明,基于自适应拥塞避免算法的TCP改进机制性能得到显著优化。 相似文献
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针对数字通信系统,介绍了一种新的滤波算法.该算法基于最小误比特率(MBER)准则,并利用梯度下降法实现.通过采用内核密度估计的方法来估计误码率函数,可将其推广到自适应的最小误比特率(LBER)滤波算法.仿真结果表明,LBER具有良好的收敛性能和误码性能,可以广泛应用于均衡、波束成形、检测等. 相似文献
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把网格编码调制（TCM）引入到光脉冲幅度位置调制（APPM）中,研究其对无线光通信系统误码性能的改善．通过分析及对2×4-TCMAPPM、4PPM和2×8-TCMAPPM、8PPM分别进行MATLAB仿真,得到以下结论;在保持带宽不变的前提下,2×4-TCMAPPM与4PPM信息速率相同,但前者误码性能优于后者,且最大达到14．7dB;2×8-TCMAPPM的信息速率与8PPM相同,但前者误码性能优于后者,且最大可达到11．7dB．TCM确实能有效地改善系统的差错性能． 相似文献
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粱冀 《南宁师范高等专科学校学报》2012,(3):36-38
针对OFDN技术对定时、频偏和相位噪声敏感,较小的同步偏差即会导致系统的误码性能恶化,甚至通信失效的缺点,主要研究了OFDM符号同步的一种改进算法,即在传统的SCA（最大相关）估计算法的基础上采用多符号同步的方法。仿真表明该方法减少了符号偏差的均方误差,改善了系统的性能。 相似文献
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高速漏磁检测中缺陷的信号易被噪声掩盖,采用自适应滤波消除相关噪声,并采用小波软阈值消噪方法消除残余系统噪声,可有效识别被噪声掩盖的信号． 相似文献
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刘汉顶 《中学数学教学参考》1997,(5)
浅析数学问题中的“表象”掩盖“本质”安徽省枞阳中学刘汉顶一道数学题能否解得顺利、迅速和富有创造性，常常决定于能否透过表象洞悉本质．从这个角度讲，解数学题的过程实质上就是揭示问题本质的过程．那么，中学数学问题中常有哪些“表象”，又掩盖了什么“本质”呢？... 相似文献
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Audio Video coding Standard (AVS) is the latest audio and video coding standard of China. AVS Part 7 (also known as AVS-M) targets mobility applications where error concealment is of great importance. This paper first briefly introduces the general concept of error concealment. Then two error concealment schemes are proposed and implemented on AVS-M decoder under different test conditions. Simulation results of the schemes and suggestions on how to use these tools are also provided. 相似文献
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Audio Video coding Standard (AVS) is the latest audio and video coding standard of China. AVS Part 7 (also known as A VS-M) targets mobility applications where error concealment is of great importance. This paper first briefly introduces the general concept of error concealment. Then two error concealment schemes are proposed and implemented on AVS-M decoder under different test conditions. Simulation results of the schemes and suggestions on how to use these tools are also provided. 相似文献
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把高斯混合模型(GMM)用于视频流的错误隐藏技术中,并对此进行了分析、论证、研究。GMM依据邻近的时域和空域的信息,用最小均方差来估计丢失像素的区域;如部分视频数据丢失,根据丢失视频数据邻近的时-空域信息通过GMM做一个最小均方差估计;如丢失宏块周围的时域信息也随之丢失,则采用反复迭代估计的方法来解决。和现有的基于时-空域的错误隐藏方法相比,基于GMM的错误隐藏方法提高了PSNR,且对于大范围内的丢包率都是有效的。仿真实验也证实了基于GMM的错误隐藏方法能较好地提高和改善视频的主客观质量。 相似文献
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Concerning inter4v mode employed widely in MPEG-4 video, a new temporal error concealment scheme for MPEG-4 video sequences is proposed, which can selectively interpolate one or four motion vectors (MVs) for the missing macroblock (MB) according to the estimated MB coding mode. Performance of the proposed scheme is compared with the existing schemes with multiple testing sequences at different bit error rates. Experimental results show that the proposed algorithm can mask the impairments caused by transmission errors more efficiently than 0 MV and average MV methods by consuming more time for different bit error rates. It has an acceptable image quality close to that obtained by the selective motion vector matching (SMVM) algorithm, while taking less than half of cycles of operations. The proposed concealment scheme is suitable for low complexity video real-time implementations. 相似文献
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Although H.264 video coding standard provides several error resilience tools, the damage caused by error propagation may still be tremendous. This work is aimed at developing a robust and standard-compliant error resilient coding scheme for H.264 and uses techniques of mode decision, data hiding, and error concealment to reduce the damage from error propagation. This paper proposes a system with two error resilience techniques that can improve the robustness of H.264 in noisy channels. The first technique is Nearest Neighbor motion compensated Error Concealment (NNEC) that chooses the nearest neighbors in the reference frames for error concealment. The second technique is Distortion Estimated Mode Decision (DEMD) that selects an optimal mode based on stochastically distorted frames. Observed simulation results showed that the rate-distortion performances of the proposed algorithms are better than those of the compared algorithms. 相似文献
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许志良 《深圳信息职业技术学院学报》2008,6(2):48-51
为了解决视频图像在传输过程中产生运动矢量丢失问题,本文提出一种新的后处理差错掩盖算法。我们在DCT域进行边缘检测,把与丢失块相邻的图像块分为边缘块和平滑块,同时把丢失块周围的图像块运动矢量的大小和方向分成九类。结合边缘检测与运动矢量分类,我们提出一种加权运动矢量恢复算法。仿真结果表明对不同视频序列,此算法都能比传统的方法恢复出质量更高的图像。 相似文献
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Frame loss error concealment for SVC 总被引：2，自引：0，他引：2
INTRODUCTION Real-time transmission of video data in network environments, such as wireless and Internet, is a challenging task, as it requires coding efficiency, network friendliness and error robustness. Scalability is a possible solution for network adaptive applica- tions. The Scalable Extension of H.264/AVC (SVC) (JVT of ISO/IEC MPEG & ITU-T VCEG, 2005b) aims at achieving both high compression performance and adaptivity for video delivery over heterogeneous networks. SVC… 相似文献
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Error-resilient video communication over lossy packet networks is often designed and operated based on models for the effect of losses on the reconstructed video quality. This paper analyzes the channel distortion for video over lossy packet networks and proposes a new model that, compared to previous models, more accurately estimates the expected mean-squared error distortion for different packet loss patterns by accounting for inter-frame error propagation and the correlation between error frames. The accuracy of the proposed model is validated with JVT/H.264 encoded standard test sequences and previous frame concealment, where the proposed model provides an obvious accuracy gain over previous models. 相似文献
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Error-resilient video communication over lossy packet networks is often designed and operated based on models for the effect of losses on the reconstructed video quality. This paper analyzes the channel distortion for video over lossy packet networks and proposes a new model that, compared to previous models, more accurately estimates the expected mean-squared error distortion for different packet loss patterns by accounting for inter-frame error propagation and the correlation between error frames. The accuracy of the proposed model is validated with JVT/H.264 encoded standard test sequences and previous frame concealment, where the proposed model provides an obvious accuracy gain over previous models. 相似文献
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研究了在语音传输过程中由于参数丢失导致语音质量急剧下降的丢帧补偿问题.利用大规模隐式马尔可夫模型对自适应多速率宽带语音编码(AMR-WB)的ISF参数进行建模,然后对丢失的ISF参数进行基于最小均方误差(MMSE)准则的最优估计,将估计的ISF参数和前帧的ISF参数进行加权以平滑估计值,得到补偿的ISF参数.在接收端,利用ISF参数的估计值进行语音合成.将本算法的合成语音和由G.722.2标准附件Ⅰ的基准补偿的合成语音进行比较,仿真结果表明,本补偿算法可以得到更好的性能,在频率加权谱失真和信噪比这2种评价准则上都有所改善,信噪比提高约2.41 dB,频率加权谱失真下降约0.885 dB,证明了该算法的有效性. 相似文献