Robust pattern decoding in shape-coded structured light

Decoding is a challenging and complex problem in a coded structured light system. In this paper, a robust pattern decoding method is proposed for the shape-coded structured light in which the pattern is designed as grid shape with embedded geometrical shapes. In our decoding method, advancements are made at three steps. First, a multi-template feature detection algorithm is introduced to detect the feature point which is the intersection of each two orthogonal grid-lines. Second, pattern element identification is modelled as a supervised classification problem and the deep neural network technique is applied for the accurate classification of pattern elements. Before that, a training dataset is established, which contains a mass of pattern elements with various blurring and distortions. Third, an error correction mechanism based on epipolar constraint, coplanarity constraint and topological constraint is presented to reduce the false matches. In the experiments, several complex objects including human hand are chosen to test the accuracy and robustness of the proposed method. The experimental results show that our decoding method not only has high decoding accuracy, but also owns strong robustness to surface color and complex textures.     

Jointly-check iterative decoding algorithm for quantum sparse graph codes

<正>For quantum sparse graph codes with stabilizer formalism,the unavoidable girth-four cycles in their Tanner graphs greatly degrade the iterative decoding performance with a standard belief-propagation(BP) algorithm.In this paper, we present a jointly-check iterative algorithm suitable for decoding quantum sparse graph codes efficiently.Numerical simulations show that this modified method outperforms the standard BP algorithm with an obvious performance improvement.     

基于LDPC/Turbo双模译码器的自适应迭代译码算法研究

针对现有WIMAX标准中LDPC/Turbo双模译码器设计在精确计算时未充分考虑迭代次数的问题,提出了一种适用于LDPC和Turbo码的自适应迭代译码算法,可灵活应用于由FPGA技术实现的双模译码器.该算法通过跟踪中间消息计算错误概率,根据多条件判定精确计算迭代次数,从而实现译码算法与错误概率变化特征的自适应性;通过改进的预判决机制减少平均迭代次数.利用Matlab搭建WIMAX系统测试链路,对TDMP多种算法的误码性能与迭代次数的关系进行测试,实现了12个SISO处理单元并行的LDPC/Turbo双模译码器.结果表明,所设计的译码器减少了算法中冗余的迭代过程,并且完全满足该标准下最大码长的要求.     

Low-Latency Short-Packet Transmission over a Large Spatial Scale

Short-packet transmission has attracted considerable attention due to its potential to achieve ultralow latency in automated driving, telesurgery, the Industrial Internet of Things (IIoT), and other applications emerging in the coming era of the Six-Generation (6G) wireless networks. In 6G systems, a paradigm-shifting infrastructure is anticipated to provide seamless coverage by integrating low-Earth orbit (LEO) satellite networks, which enable long-distance wireless relaying. However, how to efficiently transmit short packets over a sizeable spatial scale remains open. In this paper, we are interested in low-latency short-packet transmissions between two distant nodes, in which neither propagation delay, nor propagation loss can be ignored. Decode-and-forward (DF) relays can be deployed to regenerate packets reliably during their delivery over a long distance, thereby reducing the signal-to-noise ratio (SNR) loss. However, they also cause decoding delay in each hop, the sum of which may become large and cannot be ignored given the stringent latency constraints. This paper presents an optimal relay deployment to minimize the error probability while meeting both the latency and transmission power constraints. Based on an asymptotic analysis, a theoretical performance bound for distant short-packet transmission is also characterized by the optimal distance–latency–reliability tradeoff, which is expected to provide insights into designing integrated LEO satellite communications in 6G.     

Some application of difference equations in Cryptography and Coding Theory

ABSTRACT

In this paper, we present some applications of a difference equation of degree k. Using such an equation, we provide an algorithm for messages encryption and decryption. Moreover, by using the matrix associated to a difference equation of degree k, we present an application in Coding Theory.     

Codes with a Disparity Property

Kth order zero disparity codes have been considered in several recent papers. In the first part of this paper we remove the zero disparity condition and consider the larger class of codes, Kth order disparity D codes. We establish properties of disparity D codes showing that they have many of the properties of zero disparity codes. We give existence criteria for them, and discuss how new codewords may be formed from ones already known. We then discuss Kth order disparity D codes that have the same number of codewords. We discuss the minimum distance properties of these new codes and present a decoding algorithm for them. In the second part of the paper we look at how the minimum distance of disparity D codes can be improved. We consider subsets of a very specialised subclass, namely first order zero disparity codes over alphabet Aq of size q. These particular subsets have q codewords of length n and minimum Hamming distance n. We show that such a subset exists when q is even and nis a multiple of 4, and also when q is odd and n is even. These subsets have the best error correction capabilities of any subset of q first order zero disparity codewords.     

Twin-image elimination in optical scanning holography

We propose a novel multiplexing technique to solve the twin image problem in optical scanning holography without the use of a spatial carrier, as commonly used in conventional off-axis holography. The technique involves simultaneously acquiring sine and cosine Fresnel zone-lens plate coded images by optical scanning. A complex addition of the two coded images will then be performed and decoded to give a twin-image rejection reconstruction. Computer simulations will be presented to demonstrate the validity of the idea.     

基于广义线性模型的针刺足三里脊髓背根神经活动解码

神经系统以时空编码形式刻画外部刺激信息, 针刺作为对穴位的机械作用可以等效为对神经系统的一种外部刺激. 为了揭示神经系统如何表达和传递针刺作用, 本文设计了不同频率的针刺动物实验, 即在针刺大鼠足三里穴位时获取脊髓背根神经节电信号. 首先, 经过数据预处理获得单神经元动作电位序列并转化为点过程序列. 其次, 应用广义线性模型(GLM)编码针刺作用, 产生模拟的神经放电序列. 另外, 在模型基础上应用贝叶斯解码, 根据神经放电序列重构针刺随时间变化的位移波形. 最后, 基于时间重标度理论应用分位数分位数(Q-Q)图方法检验编码模型与点过程数据的一致性. 结果表明, GLM能够模拟针刺神经编码, 并正确解码针刺信息. 本文为针刺研究提供了新的视角, 对于构建神经系统与机器接口以改善针刺的临床研究具有潜在意义. 关键词： 针刺 点过程 广义线性模型 神经解码