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Weighted symbol-flipping decoding algorithm for nonbinary LDPC codes with flipping patterns 被引量:2
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作者 Bing Liu Jun Gao +1 位作者 Wei Tao Gaoqi Dou 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第5期848-855,共8页
A novel low-complexity weighted symbol-flipping algorithm with flipping patterns to decode nonbinary low-density parity-check codes is proposed. The proposed decoding procedure updates the hard-decision received symbo... A novel low-complexity weighted symbol-flipping algorithm with flipping patterns to decode nonbinary low-density parity-check codes is proposed. The proposed decoding procedure updates the hard-decision received symbol vector iteratively in search of a valid codeword in the symbol vector space. Only one symbol is flipped in each iteration, and symbol flipping function, which is employed as the symbol flipping metric, combines the number of failed checks and the reliabilities of the received bits and calculated symbols. A scheme to avoid infinite loops and select one symbol to flip in high order Galois field search is also proposed. The design of flipping pattern's order and depth, which is dependent of the computational requirement and error performance, is also proposed and exemplified. Simulation results show that the algorithm achieves an appealing tradeoff between performance and computational requirement over relatively low Galois field for short to medium code length. 展开更多
关键词 nonbinary low-density parity-check (LDPC) codes quasi-cyclic symbol-flipping (sf decoding.
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基于多特征决策级融合的表情识别方法 被引量:3
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作者 黄忠 胡敏 刘娟 《计算机工程》 CAS CSCD 北大核心 2015年第10期171-176,共6页
为实现多源特征的优势互补并融合多分类器的决策结果,提出一种改进的多特征表情识别方法。利用链码编码刻画表情形状特征并构建形变特征描述面部几何变化,构造Gabor特征融合图以表征表情局部纹理细节。采用支持向量机分类器分别获取3类... 为实现多源特征的优势互补并融合多分类器的决策结果,提出一种改进的多特征表情识别方法。利用链码编码刻画表情形状特征并构建形变特征描述面部几何变化,构造Gabor特征融合图以表征表情局部纹理细节。采用支持向量机分类器分别获取3类特征的类别后验概率并在决策级实现多分类器的融合。在有监督学习下提出一种基于粒子群算法的权重寻优策略求解最优融合权重。Cohn-Kanade表情库上的实验结果表明,该方法在平均识别率和鲁棒性方面均优于单分类器识别方法,与现有的多分类器融合方法相比,权重寻优策略在识别率和可靠性方面更优。 展开更多
关键词 决策级融合 主动形状模型 链码 形状特征 形变特征 GABOR纹理特征 粒子群寻优
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空频码异步协作通信中的多CFO补偿
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作者 朱冰莲 张松 +1 位作者 刘海丰 杨晓芳 《计算机工程与应用》 CSCD 北大核心 2011年第18期149-152,共4页
在协作通信中为了对抗同步误差,可基于OFDM技术在中继节点采用空频码实现协作分集和多径分集。OFDM可以抗定时误差,但对载波频率偏移非常敏感,对于协作通信,多个载波频率偏移的存在使得频率补偿很难实现。利用空频码结构和载波间干扰能... 在协作通信中为了对抗同步误差,可基于OFDM技术在中继节点采用空频码实现协作分集和多径分集。OFDM可以抗定时误差,但对载波频率偏移非常敏感,对于协作通信,多个载波频率偏移的存在使得频率补偿很难实现。利用空频码结构和载波间干扰能量分布特点,提出在发射端调整空频码相对位置,在接收端进行多次频率搬移和相应的FFT变换,能有效对抗多个载波频率偏移。在此基础上采用Q抽头滤波算法,以较低的算法复杂度实现了接近于最小均方误差的性能。 展开更多
关键词 协作通信 空频码 载波频率偏移 正交频分复用技术
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一种基于随机线性网络编码的机会网络路由协议 被引量:2
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作者 肖亮 马春光 +1 位作者 王九如 高训兵 《信息网络安全》 2013年第3期16-20,共5页
为了提高机会网络的路由性能,将网络编码技术引入到机会网络路由协议中,文章提出了基于随机线性网络编码的机会网络SF-RLNC路由协议,详细描述了该协议以及其编码和解码过程,最后通过仿真实验表明,相比传统的SF路由协议,SF-RLNC路由协议... 为了提高机会网络的路由性能,将网络编码技术引入到机会网络路由协议中,文章提出了基于随机线性网络编码的机会网络SF-RLNC路由协议,详细描述了该协议以及其编码和解码过程,最后通过仿真实验表明,相比传统的SF路由协议,SF-RLNC路由协议能极大的提高机会网络的传输效率和的整体性能。 展开更多
关键词 机会网络 随机线性网络编码 sf路由协议
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Symbols detection for frequency-selective V-BLAST OFDM systems
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作者 WuXiaojun LiXing WangJilong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第2期418-425,共8页
As the combining form of the orthogonal frequency-division multiplexing (OFDM) technique and the vertical Bell Labs layered space-time (V-BLAST) architecture, the V-BLAST OFDM system can better meet the demand of next... As the combining form of the orthogonal frequency-division multiplexing (OFDM) technique and the vertical Bell Labs layered space-time (V-BLAST) architecture, the V-BLAST OFDM system can better meet the demand of next-generation (NextG) broadband mobile wireless multimedia communications. The symbols detection problem of the V-BLAST OFDM system is investigated under the frequency-selective fading environment. The joint space-frequency demultiplexing operation is proposed in the V-BLAST OFDM system. Successively, one novel half-rate rotational invariance joint space-frequency coding scheme for the V-BLAST OFDM system is proposed. By elegantly exploiting the above rotational invariance property, we derive one direct symbols detection scheme without knowing channels state information (CSI) for the frequency-selective V-BLAST OFDM system. Extensive simulation results demonstrate the validity of the novel half-rate rotational invariance joint space-frequency coding scheme and the performance of the direct symbols detection scheme. 展开更多
关键词 orthogonal frequency-division multiplexing vertical Bell Labs layered space-time architecture symbols detection frequency-selective fading joint space-frequency demultiplexing rotational invariance joint space-frequency coding.
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