基于双门限的变换域通信系统基函数设计

针对单门限变换域通信系统往往无法兼顾抗干扰和隐蔽通信的问题,提出了一种基于双门限变换域通信系统基函数幅度谱的设计方法。该方法首先在干扰存在情况下进行单门限系统最优误码率门限与最差误码率门限的判断,然后通过参数灵活调整两个门限的值,将大于高门限和低于低门限的值分别设为0和1,位于双门限之间的频谱进行倒置,得到的基函数通过对数据进行调制实现通信。仿真结果表明：相比于单门限变换域通信系统,通过参数调节后的双门限变换域通信系统可以同时具有良好的抗干扰及隐蔽通信性能。     

基于快速OPAST算法的直扩信号PN码序列估计

在直接序列扩频（DSSS）通信对抗系统中，伪码（PN）序列估计是一个重要的研究课题。针对在某些情况下权值向量不收敛的问题，提出了一种基于快速正交投影逼近子空间跟踪（OPAST）算法和滑动窗技术的直扩信号PN码序列估计算法，对非同步接收DSSS信号按照宽窗口分段，利用快速OPAST算法提取主特征向量，滑动窗技术实现码同步。该算法迭代权值向量具有正交性以及良好的收敛性，同时解决了常见相位模糊问题。算法具有较低复杂度，数据存储量少，易于硬件实现与实时处理。仿真结果表明，在-10 dB的较低信噪比背景环境中，该快速OPAST算法可以正确有效地估计出PN码序列。     

一种基于局部序列匹配的跳频自同步方案

为了提高通信系统的同步信息隐蔽性和系统抗侦察能力,提出了基于局部序列匹配 的跳频自同步方案,该方案工作在跳频工作状态。本方案中,并行接收机使用很少的支路接 收具有某种特征的发送 序列L,将序列L与本地序列匹配,确定本地与发射端的跳频序列相位差,调整相位完成 同步 捕获。通过理论分析,确定了序列L唯一的条件,得到了系统复杂度和捕获时间之间的 函数 表达式,并给出了系统最优支路数。分析结果表明,该方案不需要同步引导码和勤务频率 就可以完成系统的同步保持和迟入网同步,并且捕获速度和系统复杂度均介于滑动相关法和 匹配滤波法之间。本方案结合了传统方案的优点,具有良好的隐蔽性,不易被敌方发现和干 扰 。     

MQAM-WPM-FH多载波跳频通信系统误码率性能分析

为了分析多进制正交幅度调制(MQAM)映射方式、小波滤波器长度和小波包树结构对小波包跳频通信系统（WPM-FH）的影响,首先利用多进制幅移键控(MASK)和MQAM之间的关系,推导了MQAM-WPM-FH系统在加性高斯白噪声(AWGN)信道中的误码率理论公式,分析了不同小波滤波器长度和小波包树结构对WPM-FH系统的影响。理论分析和仿真结果表明,与正交频分复用跳频（OFDM-FH）系统相比,MQAM-WPM-FH系统具有较高频带利用率和较好的性能;在给定带宽下,通过增大MQAM数据映射中的星座点数M和小波滤波器长度L,可以有效降低多址干扰(MAI)对系统的干扰;AWGN信道下,不同的小波包树结构对跳频系统的性能影响较小,但小波包调制结构的多样性可以提高系统的安全性。     

多重直序扩频信号的相关接收

本文说明了利用伪随机(PN)码的相关特性,进行多重直序扩频信号相关接收的基本原理。指出了这项技术在卫星多址通信中的重要意义,并对实验结果进行了分析,得出了一些重要的结论。     

基于虚拟多用户模型的长码直扩信号伪码估计

针对长码直接序列扩频(DSSS)信号的伪随机码(PN)盲估计问题,提出了一种新的周期 长码直接序列扩频信号(PLC DSSS)模型。该模型等同于虚拟多用户短码扩频DS-CDMA系统, 采用DS-CDMA的谱范数来估计同步偏移,该算法不需要更多假定限制,利用相关函数二阶矩 、特征值分解和模糊酉矩阵方法就可以完成伪码序列的估计。实验结果表明,在较低信噪比 下就可以完成对PN码序列的精确估计,表现出良好的性能。     

基于劳伦多项式的LAS码构造及性能分析

对基于Hadamard矩阵的LA码和基于劳伦多项式（Laurent Polynomial）的LS码的生成 及相关特性进行研究,从占空比、相关特性、零干扰窗长度、码字总数等方面仿真分析了LA S码的性能,并结合实际应用,理论分析了LAS-CDMA系统与传统CDMA系统的归一化容量,仿 真比较了LAS码和Gold序列在准同步CDMA系统中的误码性能。仿真和理论分析表明：LAS码具 有均匀的零干扰窗（Interference Free Window,IFW）特性;不同主码的互相关函数IFW附 近存在较小的副峰,多址干扰较小;在准同步移动通信系统中,LAS-CDMA抗多址干扰性能 明显优于传统CDMA系统,使用 LAS码比使用Gold序列有更好的误码性能。     

基于PN序列自相关的双门限自适应DTMB频谱感知

对于地面电视的模数转换产生宝贵的广播电视“白频谱”资源,频谱感知与检测技术是高效有序地利用频谱资源的基础。在数字电视地面多媒体广播（DTMB）传输系统中,针对传统的基于信号特征的感知算法在检测性能、计算复杂度与灵活性上的不足,提出了一种自适应的DTMB频谱感知算法。该算法以双门限感知检测为基础,在双门限之外采用基于伪随机（PN）序列自相关的算法,在双门限之内采用不等间隔PN序列累积自相关的算法,同时自适应地调整双门限的取值,平衡算法复杂度、感知性能与信道环境的需求。仿真结果表明,该算法在不同的信道条件下能自适应且快速地调整参数,有效提高频谱检测性能,降低算法复杂度。     

跳时序列对UWB系统多址性能的影响

通过变换超宽带(UWB)无线电通信系统的信号模型,分析了该通信系统的多址性能,给出了跳时序列与其所产生的多址干扰之间的关系,从而明确了跳时序列的相关性能对该通信系统误码率的影响。     

截短混沌扩频序列的优选与性能分析

为了获得应用于测控通信系统具有优良相关特性的混沌扩频序列 集合,提出了截短混沌扩频序列的优选算法。基于中值比较进行平衡序列构造,相对传统方 法能够得到更大的 筛选序列集合。给出了截短扩频混沌序列的具体优选步骤,并对截短混沌序列和Gold序列在 多址系统中的性能展开了比较和分析。     

Corporate communication management: A framework based on decision-making with reference to communication resources

This paper proposes a conceptual framework for corporate communication management, based on the creation and utilisation of communication resources. The aim is to address a gap in the literature in that to date, communication tools have been identified as communication resources in very few studies, nor have communication decisions been linked to the creation and use of such resources. The paper draws on some basic resource-based view assumptions to identify firm-specific communication resources. The study also draws on Parsons' sociological approach with reference to the classification of organisational decisions (policy, allocation and coordination) and contextualises this approach to the decision-making within corporate communication function/department. The framework also takes into account some elements of the postmodernism. According to this tendency in contemporary culture, internal and external stakeholders play a proactive role in the creation and utilisation of communication resources. The study contributes to the development of corporate communication as an autonomous area of management.     

一种高可靠性的保密野战通信系统方案

针对野战环境,特别是野战车辆对通信的需求,在总结以往通信系统设计经验的 基础上,根据现在通用的各种通信手段及未来可能大量运用的通信手段,提出了一套野战通 信系统方案。该系统方案在融合有线、无线、卫星、光纤等各种常规通信手段的基础上,增 加了具有组网灵活、保密性强等优点的激光通信手段,比以往常用的野战通信系统更具灵活 性、可靠性和保密性。分析表明,该通信系统可以适应许多野战通信的场合,有相当广泛的 实用价值。     

混沌在数字通信中的应用

我国高校的国际商务英语专业在经历了20多年的办学历程之后,今天面临着从理论的高度进行整顿、提高的任务。本文发出了“加强理论建设,把我国高校的国际商务英语专业发展成为在理论与实践的结合上更为成熟的独立学科”的呼吁,并阐述了作者对有关国际商务英语学科建设的几个重大问题的看法。     

The Effects of Multimedia Communication on Web-Based Negotiation

With the rapid growth of electronic commerce, there is growing demand forremote online negotiations. Although the Internet now enables audio and video communication, most Web-based negotiation systems are still text-based. There is, however, a lack of research on the effects of multimedia on remote negotiations. In this paper, we present a theoretical model to investigate the impacts of multimedia communication in an online negotiation setting. The constructs in our model include communication efficiency, communication effectiveness, and positive and negative social-emotional communication. Through a simulated house purchasing negotiation experiment, we study how different multimedia combinations (text only; text with audio; text with audio and video) affect our constructs and thus further influence negotiation results. Our results showed that both text with audio and text with audio and video communication were significantly preferred to text alone. However, the addition of video to text and audio communication in a negotiation environment was not found to be beneficial. It did not significantly improve communication efficiency, effectiveness or positive social-emotional communication, but distracted negotiators from focusing on the negotiation task. Our analysis also revealed that the communication efficiency construct did not correlate with the perceived success of the negotiation solution; however communication effectiveness and social-emotional communication did correlate with negotiation satisfaction.     

Avow or Avoid?

Abstract

Sixteen press releases from Enron and 16 releases from WorldCom representing the first three months of each organization's financial crises were gathered from the organization's web sites. The goal of this study was to determine whether the dominant public communication tactic of these companies was to avow or promote frankness, a traditional public relations stance, or to avoid or be evasive, a traditional legal stance. The releases were compared with 47 published accounts of the unfolding financial crises to determine whether the organizational messages remained intact. The findings show no dominant communication strategy in either company. Both professed openness but engaged in blame shifting. The combined message strategy suggests cooperation between legal and public relations counsel. The messages of both organizations were successfully transmitted via the mass media but were tempered by solid reporting. These findings suggest additional evidence that legal and public relations crisis communication strategies are starting to blur.     

美军机载射频与FSO混合通信发展述评

机载光与射频混合通信系统概念是美国防先期研究计划局（DARPA）提出的创新性概念，用以为机载平台提供定向高速宽带数据链，支持空基骨干网等宽带通信应用。目前该概念已经进行了概念验证以及多次演示和测试。概述了美军机载光与射频混合通信研究进展，分析了相关关键技术，指出了发展趋势，并给出了相关的启示和建议。     

The ‘Catch 22’ of communicating CSR: Findings from a Danish study

This research explored the apparent ‘Catch 22’ of communicating Corporate Social Responsibility (CSR). Although companies are regularly encouraged to engage in CSR, they are simultaneously discouraged to communicate about this engagement. We contribute with two models that may help to explain how companies can best communicate about their CSR initiatives. Based on a reputation survey and two case studies of Danish corporate CSR frontrunners, first we develop an ‘inside‐out approach’ to suggest how managers can manage their CSR activities to achieve favourable CSR reputation in a ‘Catch 22’ context. Employees appear as a key component in building trustworthiness as CSR communication is shown to evolve when taking an ‘inside‐out approach’. Second, we develop a CSR communication model with two CSR communication processes targeting different stakeholder groups: ‘the expert CSR communication process’ and ‘the endorsed CSR communication process’. Integrating these models and processes may help companies strategically capture reputational advantage from their CSR initiatives.     

Face-to-face communication: Is it really necessary in a digitizing world?

Many predictions regarding the extinction of face-to-face communication have themselves begun to disappear. While emerging information technologies are substantially altering the face of business communication, close-quarter discussion and debate remain important, as evidenced in the productivity of the medium and what we have recently learned about social behavior. Still, the possibility of dramatic change cannot be completely discounted. If technology ever manages to deliver what it has promised, there could be a significant shift toward digital communication. Although this will not likely occur over the next decade or two, beyond that, it should not be excluded from the realm of possibility.     

整合营销传播(IMC)：概念及实践特征探析

整合营销传播是适应信息多元化与品牌中心时代的新型沟通体系。"整合营销传播"概念框架中的"整合"有质、量两方面不同的内涵,在整合目标上有品牌战术传播和组织整体战略传播两个高低不同的层次,整合营销传播实践的运行特征包括"接触管理"、"协同效应"、"双向沟通"等三项指标。     

浅析品牌3.0时代的品牌传播特征

品牌传播理念的发展是跟品牌及形成品牌的时代的发展相辅相成的，造就品牌的环境是一个复杂、充满活力并不断变化的有机体系。在品牌3.0时代，品牌的传播出现新的特征，这既是环境使然，也是传播技术进步后的必然趋势，研究其特征，有利于品牌的成长。