椭圆球面波脉冲信号快速设计方法

在基于椭圆球面波的非正弦短波通信系统中,椭圆球面波脉冲信号原设计方法存在 计算量大、计算时间长的问题。为了解决此问题,提出了椭圆球面波脉冲信号快速设计方法 。该方法利用基于带通采样的椭圆球面波函数数值解法,求得椭圆球面波函数近似数值解, 椭圆球面波函数在时间轴上向右平移,可得椭圆球面波脉冲信号。理论分析和仿真结果表明 ,快速设计方法能使计算量和计算时间降低2～4个数量级,同时椭圆球面波脉冲信号的时域 、频域和正交性能还能保持与原设计方法相当。     

MFSK和GMSK调制方式在短波跳频通信系统中的应用及性能仿真

本文主要讨论MFSK和GMSK(高斯滤波最小频移键控)调制方式在短波跳频通信系统中的应用,并对其性能进行了数值仿真.对于MFSK调制方式,本文重点讨论了将带反馈链路的选择式频率分集和编码技术应用于短波FH/MFSK系统对性能的改善,并分析当在具有加性高斯噪声的瑞利衰落信道中存在部分频带阻塞时的性能.GMSK具有优良的频谱特性,本文仿真了结合Viterbi算法非相干解调方案时跳频系统的性能.最后对两种调制方式进行了初步比较.     

基于频-时域的非正弦波通信系统设计方法

为了突破正弦载波通信体制的约束,有效提高系统的频带利用率,提出了基于频-时域的非正弦波通信系统设计方法。采用从频域出发再到时域波形设计的通信系统设计思想,通过构建频域特性函数,反向设计时域脉冲波形;经时域正交脉冲组构建、非正弦时域正交调制,实现了信息的无载波传输。理论分析及仿真结果表明：该方法可使已调信号具有较好的能量聚集性,无需滤波而直接送往信道传输,可有效减少对其它频段用户产生电磁干扰,且系统的频带利用率可快速接近2 bit/s·Hz-1。     

基于脉冲调制的GSM语音信道数据传输方法

针对全球移动通信系统 (GSM) 的安全机制不能实现端到端安全通信问题,提出了一种低复杂度基于脉冲调制的数据传输方案及优化方法。分别设计了基于脉冲位置调制及脉位结合极性调制的类语音信号,给出了基于跳时脉冲的帧同步方法。搭建了基于脉冲调制的GSM语音信道数据传输仿真平台,分析比较了不同调制阶数和不同自适应多速率编码 (AMR) 码率下系统的性能。为了提高系统可靠性,引入卷积码进一步降低了系统误码率。仿真结果表明,4阶脉冲调制最适用于语音信道,所提脉冲调制方法与传统低复杂度频移键控 (FSK) 调制方式误码率近似,但传输速率高,且提出的脉位结合极性调制进一步提高了传输速率,总提高比例达到36%。     

基于System View的256QAM信号调制与解调的仿真实现

在介绍正交振幅调制(QAM)信号的调制、解调原理的基础上,以相对比较复杂的256QAM为例,对QAM信号的频带利用率和误码率性能进行了分析,给出了用动态系统仿真和分析软件SystemView进行系统仿真的具体设置,并分析了仿真结果。     

一种高效的混合M元扩频通信方案

为进一步提高扩频通信系统的频带利用率和抗截获性能,将正交扩频技术与码相位循环移位调制技术相结合,提出了一种新的高效多进制扩频通信方案。在正交信道的每条支路上,首先采用M元双正交扩频调制,再以每一个扩频码为原型码进行码相位循环移位调制,选用专用的伪噪声码进行同步,在接收端用基于变换域处理的循环相关器进行解扩。计算机仿真表明,该方案易于实现同步,同时有较高的频带利用率和更强的抗截获性能。该方案在卫星隐蔽通信、数据链通信等领域有较大的应用价值。     

短波信道下的信号调制方式识别

针对短波信道条件下的通信信号调制识别问题,提取了以信号功率谱的各种特征为主要特征参数,使用判决树分类器,对基于Watterson信道模型下的九类常用短波信号进行调制识别.仿真结果表明,所选取的特征参数具有很好的稳健性,在中等短波信道且在低信噪比条件下有较高的正确识别率,且方法简单便于工程实现.     

优化参数对CPM-PSWF信号性能的影响

基于椭圆球面波信号的连续相位调制（Continuous Phase Modulation Based on Prolate Spheroidal Wave Function,CPM-PSWF）方法是一种新颖的数字调制方式,调制参数的优化与其调制信号性能有着直接联系。分析不同调制参数对CPM-PSWF信号性能的影响,优化选择调制参数,对获得能量聚集性和功率效率都较高的CPM信号具有重要意义。首先,对基于椭圆球面波信号的CPM信号进行描述;其次,采用韦尔奇(Welch)谱密度估计法,对时间带宽积、调制指数、关联长度等不同参数对CPM-PSWF调制信号的功率谱密度和带宽特性的影响进行了仿真分析。实验结果表明,选用0阶椭圆球面波信号,小时间带宽积、调制指数和符号进制数越小,关联长度越大时,CPM-PSWF信号具有频谱带外高频滚降快、占用带宽小的特点。     

基于对消解调的时相调制误码率分析

以二进制为例,从对消解调的角度,导出了时相调制(TPM)信号在加性白高斯噪声信道下的 误码率解析表达式。可以发现：TPM信号误码率与码元突变后的波形持续时间成反比,即相 同信噪比条件下持续时间越长则误码率越小。通过对比判决统计量,可以发现对消解调是相 关解调的简洁实现方式。仿真结果验证了上述理论推导。其结论可为进一步分析时相调制的 其他解调方法性能提供参照和依据。     

一种基于非正交信道的分布式中继选择及功率分配方法

针对非正交两跳多中继协作通信系统中的分布式中继选择问题,提出了一种基于非正 交信道的中继选择准则,简化了系统的设计。分析了其误码率性能,给出了其解析表达式 和以总功率为约束条件下的最优功率分配方案。仿真结果表明,最佳中继选择准则明显优于 传统的中继选择准则,且在最优功率分配方案下,可以获得明显的分集增益,系统的误码率 显著下降。     

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。