一种新的超准正交空时网格码及性能分析

提出了一种新的超准正交空时网格码(SQOSTTC),这种新的超准正交空时网格码是在一种基于旋转因子的准正交空时分组码的基础上提出的,它可以取得全速率和完全分集,并且不增加编码和解码的复杂度.本文通过分析编码增益距离(CGD)和成对差错概率,对新的超准正交空时网格码的性能进行了分析.理论分析和仿真实验结果表明,在相同的频谱利用率下,本文提出的超准正交空时网格码比Jafarkhni等人提出的超准正交空时网格码的性能有明显的提高.     

Public-Key Cryptosystems and Bounded Distance Decoding of Linear Codes

Error-correcting codes form an important topic in information theory. They are used to correct errors that occur during transmission on a noisy channel. An important method for correcting errors is bounded distance decoding. The public-key cryptosystem is a cryptographic protocol that has two different keys. One of them is a public-key that can be known by everyone, and the other is the private-key only known to the user of the system. The data encrypted with the public-key of a given user can only be decrypted by this user with his or her private-key. In this paper, we propose a public-key cryptosystem based on the error-correcting codes. The decryption is performed by using the bounded distance decoding of the code. For a given code length, dimension, and error-correcting capacity, the new system allows dealing with larger plaintext than other code based public-key cryptosystems.     

Higher-Order Belief Propagation Correction Decoder for Polar Codes

Belief propagation (BP) decoding for polar codes has been extensively studied because of its inherent parallelism. However, its performance remains inferior to that of successive cancellation list decoding (SCL) due to the structure of the decoding graph. To improve the block error rate (BLER) performance, the BP correction (BPC) decoding, a post-processing scheme that corrects prior knowledge of the identified code bit, improves convergence by executing additional iterations on the failed BP decoder. Moreover, the BPC decoder demonstrates a better decoding performance than the BP-based bit-flipping decoder. Nevertheless, the additional decoding attempts lead to increased latency. In this article, a modified BPC decoder is proposed to reduce the number of decoding attempts by redefining the correction rules. A new metric is designed to effectively identify the corrected location. Numerical results show that the proposed modified BPC decoder achieves a slight improvement in BLER compared with the original BPC, with a dramatic reduction in average complexity. Furthermore, a higher-order version, named MBPC-Ω, is extended to further improve the performance, where the Ω is the maximum correction order. Numerical results show that the higher-order modified BPC achieves a similar BLER performance to existing multiple bit-flipping BP decoders but has around half the latency overhead. In addition, the proposed MBPC-2 decoder performs better than the cyclic redundancy check-aided SCL (CA-SCL) decoder with list size 4 and is slightly worse than the CA-SCL with list size 8 in high signal-to-noise ratio (SNR) regions but with significant decoding latency reduction.     

Permutation decoding for binary codes from lattice graphs

By finding explicit PD sets, we show that permutation decoding can be used for the binary code obtained from the row span over the field F₂ of an adjacency matrix of the lattice graph L₂(n) for any n?5.     

On universally decodable matrices for space–time coding

The notion of universally decodable matrices (UDMs) was recently introduced by Tavildar and Viswanath while studying slow-fading channels. It turns out that the problem of constructing UDMs is tightly connected to the problem of constructing maximum-distance separable codes. In this paper, we first study the properties of UDMs in general and then we discuss an explicit construction of a class of UDMs, a construction which can be seen as an extension of Reed–Solomon codes. In fact, we show that this extension is, in a sense to be made more precise later on, unique. Moreover, the structure of this class of UDMs allows us to answer some open conjectures by Tavildar, Viswanath, and Doshi in the positive, and it also allows us to formulate an efficient decoding algorithm for this class of UDMs. It turns out that our construction yields a coding scheme that is essentially equivalent to a class of codes that was proposed by Rosenbloom and Tsfasman. Moreover, we point out connections to so-called repeated-root cyclic codes.     

激光混沌同步和解码以及优化

进行了激光混沌模拟信号(0.1—10GHz)和数字信号(0.2和0.3Gbit/s)以及频率键控调制解调等研究，优化分析了调制信号的频率和幅度等对同步误差和解调的影响以及激光器混沌键控速率极限；分析了彻底同步和伪同步，并优化分析了系统参数失配、反馈系数对同步误差以及同步时间的影响. 关键词： 激光 混沌 同步 解码 优化     

A novel three-dimensional imaging method by means of coded cameras array recording and computational reconstruction

In this paper, we propose a novel three-dimensional imaging method by which the object is captured by a coded cameras array (CCA) and computationally reconstructed as a series of longitudinal layered surface images of the object. The distribution of cameras in array, named code pattern, is crucial for reconstructed images fidelity when the correlation decoding is used. We use DIRECT global optimization algorithm to design the code patterns that possess proper imaging property. We have conducted primary experiments to verify and test the performance of the proposed method with a simple discontinuous object and a small-scale CCA including nine cameras. After certain procedures such as capturing, photograph integrating, computational reconstructing and filtering, etc., we obtain reconstructed longitudinal layered surface images of the object with higher signal-to-noise ratio. The results of experiments show that the proposed method is feasible. It is a promising method to be used in fields such as remote sensing, machine vision, etc.     

Design of Header Recognition Filter for Binary Phase Shift Keying in Header Recognition Unit using Time-Space Conversion

Optical header recognition is one key function that enables ultrafast optical routing in photonic packet-switched networks. Especially, optical header recognition based on optical correlation processing has attracted much attention. Header signals using optical codes are decoded using optical correlation processing. We improve the decoding method for Binary Phase Shift Keying (BPSK) header signals in order to suppress crosstalk caused by matched filtering in the header recognition unit. We design a header recognition filter using the technique of a multiple-object discriminant filter (MODF). Results of preliminary experiments show that the designed header recognition filter can suppress crosstalk. The intensity ratio of correlation signals of a target header signal to non-target ones is higher than 1.95 : 1 in case of 4-bits BPSK header signals.     

电话智能遥控系统的设计与实现

电话智能遥控系统以单片机AT89C51和解码芯片MT8870集成电路为核心，通过电话实现对远程设备智能化控制．文章介绍了该系统的组成、工作原理及程序设计方法．同时对“振铃检测、模拟摘机、双音频解码及电器控制”等电路作了详细的说明．本装置适用于家庭、商店等场所，应用电话来控制电器设备．     

数据采集卡译码电路的设计方法

介绍了捷联航姿系统中数据采集卡译码电路的详细设计思路,并给出了部分具体设计,该设计方法也可用于其他接口卡译码电路的设计。