垂直水声通信中的伪随机序列精确定时算法*

针对垂直水声通信中时变多普勒引起的定时偏差问题,研究一种基于伪随机序列的迭代定时估计及补偿算法。该方法利用伪随机序列作为同步信号,分三步估计时变多普勒：采用低复杂度的模糊函数法粗补偿接收信号内的平均多普勒;通过迭代插值法实现残留时变多普勒的精确估计及补偿;利用基于信道相关函数的相位信息,纠正均衡后信号的偏转相位。为实现高阶海试数据的有效解调,采用基于伪随机序列均方误差的多通道加权合并方式,获得空间分集增益。仿真及海试数据处理结果证明所提方法具有良好的时变多普勒估计及补偿性能,同时对30个通道内的1024QAM数据进行合并处理,在500 m的通信距离下,误码率为0.04,信道容量达到7.6 bits/symbol。与传统数据帧结构相比,无需使用线性调频信号,可以提高有效数据传输率。     

Low-Complexity Alternatives to the Optimal Linear Coding Scheme for Transmitting ARMA Sources

In the era of the Internet of Things, there are many applications where numerous devices are deployed to acquire information and send it to analyse the data and make informed decisions. In these applications, the power consumption and price of the devices are often an issue. In this work, analog coding schemes are considered, so that an ADC is not needed, allowing the size and power consumption of the devices to be reduced. In addition, linear and DFT-based transmission schemes are proposed, so that the complexity of the operations involved is lowered, thus reducing the requirements in terms of processing capacity and the price of the hardware. The proposed schemes are proved to be asymptotically optimal among the linear ones for WSS, MA, AR and ARMA sources.     

Quantum Stream Cipher Based on Holevo–Yuen Theory

In this review paper, we first introduce the basic concept of quantum computer-resistant cryptography, which is the cornerstone of security technology for the network of a new era. Then, we will describe the positioning of mathematical cryptography and quantum cryptography, that are currently being researched and developed. Quantum cryptography includes QKD and quantum stream cipher, but we point out that the latter is expected as the core technology of next-generation communication systems. Various ideas have been proposed for QKD quantum cryptography, but most of them use a single-photon or similar signal. Then, although such technologies are applicable to special situations, these methods still have several difficulties to provide functions that surpass conventional technologies for social systems in the real environment. Thus, the quantum stream cipher has come to be expected as one promising countermeasure, which artificially creates quantum properties using special modulation techniques based on the macroscopic coherent state. In addition, it has the possibility to provide superior security performance than one-time pad cipher. Finally, we introduce detailed research activity aimed at putting the quantum stream cipher into practical use in social network technology.     

Error Performance of Amplitude Shift Keying-Type Asymmetric Quantum Communication Systems

We propose an amplitude shift keying-type asymmetric quantum communication (AQC) system that uses an entangled state. As a first step toward development of this system, we evaluated and considered the communication performance of the proposed receiver when applied to the AQC system using a two-mode squeezed vacuum state (TSVS), the maximum quasi-Bell state, and the non-maximum quasi-Bell state, along with an asymmetric classical communication (ACC) system using the coherent state. Specifically, we derived an analytical expression for the error probability of the AQC system using the quasi-Bell state. Comparison of the error probabilities of the ACC system and the AQC systems when using the TSVS and the quasi-Bell state shows that the AQC system using the quasi-Bell state offers a clear performance advantage under specific conditions. Additionally, it was clarified that there are cases where the universal lower bound on the error probability for the AQC system was almost achieved when using the quasi-Bell state, unlike the case in which the TSVS was used.     

天线旋转器虚拟控制面板的串行实现

针对在采用微处理器控制天线旋转、PC机实现虚拟控制面板的串行通信方案中,因数据传输速度过低,难以用常规方法完成控制定时以及PC机和微处理器之间运行同步的问题,利用虚拟仪器技术,采取问歇工作、主从同步、定时微调和控制步长优化选择等措施,设计并实现了具有串行通信虚拟控制面板的数字式天线旋转器;给出了虚拟控制面板实现的原理、关键技术措施和运行结果.结果表明,该旋转器在实时控制天线旋转的同时,控制面板上的模拟指针能实时反映天线的实际方位;具有操作方便、面板布置灵活、功能强、成本低的特点;实际旋转控制的分辩率为3.,误差小于3.;旋转1周所需时间的分辩率为1 s,误差小于1 s.     

Secure Direct Communication Using Ensembles with the Same Compressed Density Matrix

In this paper, a quantum secure direct communication protocol using ensembles with the same density matrix is proposed. The two communication parties can realize the message transmission using this method through a quantum channel, each bit of information can be transmitted using an ensemble and read out through global measurement.The eavesdropping behavior can be detected through the channel diagnoses.     

一种新型的多址接入中继协作方案

现有多址中继协作方案的编码增益有限且用户之间不能相互辅助,为此,文中提出了一种结合网络与信道编码的多址中继协作方案:在中继端利用网络编码将不同用户的编码冗余同时转发,目的端通过对某个用户信息的正确译码恢复出其他用户的编码冗余.通过对译码错误事件概率的分析,推导了该方案的中断率与误码率近似值表达式.仿真结果表明,随着信噪比的提升,文中方案可获得比编码协作更好的中断率和误码率性能,同时信噪比较高的用户还可辅助提升信噪比较低的用户的性能.     

软硬件协同教学方法在微机原理中的研究与应用

针对软硬件协同的教学思想和方法,以调动学生学习的积极性为目的,根据课程的实际情况及问题,从本校师生现状出发,实现了以硬件教学法和软件教学法为基础的协同教学方法,并举例加以分析和说明.     

大学英语网络自主学习成效归因研究

随着高等教育和信息技术的发展,大学英语网络自主学习及其学习者比例的扩大,网络自主学习的优势充分体现.但是,研究数据也表明,学习者个体学习成效却有相当大的差异.对网络环境下大学英语自主学习成效进行归因研究日显重要.基于社会心理学中常见归因分析方式,就网络自主学习中学习策略指导、合作学习模式组织及合作学习活动设计等方面进行归因探究并提出可行性建议.     

基于SCMA的无人机中继辅助上行通信方案

为提高蜂窝通信系统的上行总吞吐量,在满足用户服务质量需求的前提下,提出了一种基于稀疏码多址接入(sparse code multiple access,SCMA)的无人机中继辅助上行通信方案,通过部署无人机增强网络覆盖,并利用SCMA提高系统传输性能。根据用户的分布和概率视距传输模型,通过交替优化码本、功率和无人机坐标,确定无人机的3维部署位置;进行资源优化后,根据信道状态信息,对子载波进行配对并迭代码本、功率,以获得优化的码本和功率分配方案。仿真结果表明,提出的方案能够有效提高上行吞吐量,并满足用户的服务质量需求。