快衰落信道条件下无线中继系统波束形成方案

随着设备小型化的发展趋势,天线间距较小,信道具有相关性;且假设发射端处于高速移动状态,无法获得完全信道状态信息,只能根据部分信道状态信息设计发射端波束形成方案。针对发射端和接收端配置多天线的固定增益放大转发无线中继系统,以最大化接收端信噪比为准则,设计了基于部分信道状态信息的波束形成方案,推导了系统中断概率和平均误符号率的闭合表达式,通过仿真验证了性能分析的有效性和所设计方案的优越性。在平均误符号率为10-2、相关系数为0.8时,所提方案比反馈信道状态信息的方案节约1.6 dB的信噪比。     

双选信道下一种基于混沌交织的FBMC系统

高速移动环境下，无线信道具有时频双选性衰落的特性，使得滤波器组多载波(Filter Bank Multi-carrier，FBMC)系统产生长突发差错。将一种基于Baker映射的混沌交织算法应用在滤波器组多载波系统中，根据混沌密钥对发送数据进行分块和重新排列，按照Baker映射规则完成数据交织。此方法可以将长突发差错变为单突发差错，结合卷积编码能有效地纠正双选信道产生的长突发差错。仿真结果表明，在双选择信道中，基于混沌交织的滤波器组多载波系统误比特率性能优于传统基于块交织的滤波器组多载波系统。     

一种有效解决VHF频率资源短缺问题的方法

针对我国航空通信中VHF(Very High Frequency)频率资源紧张的现状，提出将信道间隔从25kHz减小到8．33kHz的解决方法。根据对选择连续信道概率的理论分析，提出了减小信道间隔后将同波道类型频点分散到不同频谱，同时设置预留区的规划方案。在规划过程中，考虑抑制干扰和灵活指配等因素，结合现有通信系统台站频率使用情况，对频率资源进行整合，说明将信道间隔减小到8．33kHz是行之有效的方法。     

智能交通系统的无线信道建模

由于高速移动,车车、车路通信信道存在较大多普勒频移,同时接收信号到达角不符合均匀分布。针对该特点,采用了两种方法进行信道建模,一种是采用R.von Mises提出的概率密度谱函数对多径散射信号到达移动接收机的角度进行建模,另一种是通过研究接收机和发送机之间相对运动进行建模。 采用自回归模型法,根据不同的到达角平均方向、发射机和接收机速度比率和到达角宽, 建立了不同的车车信道。仿真结果表明所建立的信道理论值与仿真值基本一致,同时揭示了3个参数对车车、车路信道模型二阶特性的影响。为了进一步验证不同信道模型对车车、车路通信的影响,搭建了下一代智能交通通信协议IEEE 802.11p系统测试平台,结果表明在最大多普勒频移为790 Hz、信噪比为5 dB时,简单二维各向异性散射信道比AKKI信道的系统误比特率低17.17 dB,三种信道的误比特率随着移动速度、调制阶数的提高而提高。仿真结果为研究智能交通系统稳定通信建立了基础。     

基于数字信道化接收机对雷达信号的时频分析

本文主要研究应用多相滤波技术的信追化接收机建摸，推导了基于多相滤波器的信道化接收机数学模型，并由此模型设计了一个16信道模拟系统。通过仿真实验验证了信道化接收机对雷达信号的检测与分析能力。     

一种新的MIMO信道模型

实际无线通信环境中发送天线之间以及接收天线之间存在相关性。针对以上特点,从 多径MIMO信道的特性出发,首先建立发射天线相关系数矩阵和接收天线相关系数矩阵,并将 它们引入无线信道的莱斯MIMO信道模型中。最后通过分析LOS MIMO信道相关模型和瑞利衰落 MIMO信道相关模型,给出了具体的建模步骤。仿真结果表明采用本文方法产生的信道模型的 MIMO系统误码率更低,从而验证了该信道模型能够较好地模拟MIMO系统的空间信道。     

CDMA2000系统反向信道的性能研究

基于扩频码分多址移动通信系统(SS-CDMA)条件下,分析了CDMA2000反向接入信道的性能参数,利用SystemView5.0对反向信道进行建模、仿真分析,结果显示了设计的CDMA2000系统反向信道模型的良好性能,表明了设计的信道模型合理。     

多信道应答机信道增益的附加余量

本文指出了多信道应答机信道实际增益的影响因素，提出了多信道应签机信道增益的附加余量，为今后改进应答机信道设计方法提供了某些参考。     

适用于Rayleigh衰落信道的一种新型MMSE接收机

智能天线中一般的MMSE接收机缺乏有效跟踪Rayleigh衰落信道变化的机制。在分析了MMSE接收机在Rayleigh信道中的特点之后，提出了一种新型的MMSE接收机。计算机仿真结果表明，此接收机性能较好，适用于Rayleigh衰落信道。     

离散信道信道容量的计算

信道容量的计算是信道研究的核心,据此对信道容量定义和特性进行了探讨,并研究了三种特殊离散信道的信道容量计算方法,有对称离散信道、强对称离散信道和准对称离散信道,并对三种信道容量计算方法进行了区分与比较。最后介绍了一般离散信道的信道容量计算方法。     

智能天线中空时信道模型的分析与比较

当前,有管理的自由贸易政策已经成为对外贸易政策的国际趋势。在这种国际背景下,本文从中国对外贸易政策的现状出发,结合相关的贸易理论,阐述了中国加入WTO以后,对外贸易政策应走的创新路线。并就此路线,给出了从对外贸易政策目标到具体措施的初步建议。     

基于雨衰雪衰影响的空间信道统计模型

针对某些特殊的移动通信环境中信号的到达角度（TOA）、到达时间（AOA）等信道参数估计的复杂性，提出一种基于散射体均匀分布室外统计信道模型。该模型将树木中的树冠层作为散射体呈均匀分布在移动台与基站周围的椭圆形区域内，通过树冠层在雨雪环境中的相对介电常数来分析降雨降雪量对信号传输带来的影响，可以方便地估计出此室外微小区的空时信道参数，如AOA概率密度分布函数、TOA概率密度分布函数以及到达角度/到达时间（AOA/TOA）联合概率密度分布函数。仿真结果表明，信号的到达时间TOA以及到达角度AOA随着降雨降雪量的增大而增大，尤其当降雪量增大使得树冠层相对介电常数达到4.5时，信号的传输将被阻塞。该模型的信道参数估计结果符合理论与经验，扩展了移动无线通信信道模型的研究与应用。     

Under the sway of a mobile device during an in‐store shopping experience

Mobile device technology is transforming the retail shopping experience. Today's consumers are mobile dependent, preferring to consult with their phone, instead of using the salesperson, while shopping at the retail store. In the absence of literature investigating how the salesperson might sell to this omni‐channel, mobile‐connected consumer, this paper proposes a conceptual model and tests its proposed linkages. The empirically tested model presents a dyadic view of the omni‐channel consumer and the salesperson. Uniquely contributing to the omni‐channel and marketing literature, samples from an emerging economy (India) and developed (United States) economy represent the contexts. Specifically, the research examines the salesperson's role in selling to a mobile‐dependent consumer who uses mobile technology to search for information during the sales meeting. Findings show that adaptive selling can affect purchase intention and customer predisposition to comply with salesperson input. Results also reveal how perceived control, mobile dependence, and customer predisposition to comply with mobile device input affect purchase intention. Managerial and research implications specifically appropriate for the omni‐consumer retail setting are offered.     

Channels for search and purchase: Does mobile Internet matter?

Recent industry reports indicate that consumers own four digital devices on an average, and switching devices during shopping is the “new normal.” The addition of mobile Internet as a new channel of search and purchase has spurred the adoption of the digital medium, and easy accessibility of the Internet on multiple devices is influencing shopping patterns. A consumer may prefer some channels for search and others for purchase or use a combination of channels to search and purchase simultaneously. As a new channel, it is unclear 1) whether mobile Internet offers greater search or purchase benefits and 2) what type of products are more suitable for mobile Internet search and purchase. In this study, we develop a framework that describes the factors that drive the use of mobile Internet in a multi-channel environment. We test the framework using survey data from a sample of U.S consumers. The main findings from our study indicate that 1) the choice of channel combinations that include mobile relative to other channel combinations increases with an increase in perceived search convenience of mobile channel. 2) in the digital channel, mobile and desktop differ in their utility along search dimensions. The probability of choosing channel combinations that include mobile increases due to search convenience whereas desktop is attractive due to perceived gains of price comparison search; and 3) mobile Internet search increases for consumers searching for utilitarian products. The insights from this study deepen our understanding of how digital media is used in the search-purchase process and have important managerial implications.     

How information processing and mobile channel choice influence product returns: An empirical analysis

The mobile internet is starting to overtake the desktop device‐based internet as a purchase channel. Its impact on consumer behavior is therefore increasingly important to understand. This study seeks to understand and measure, if usage of mobile devices for online purchases leads to a lower decision quality and, in effect, to more product returns. In doing so, the impact of information environments on the end‐to‐end consumer purchase decision‐making process is better understood and it is investigated, if the information environment of mobile devices leads consumers to take more error‐prone purchase decisions. An exclusive data set spanning more than 140 million transactions of a European online retailer is used to empirically analyze changes in product return behavior after mobile channel adoption. The results show that mobile channel usage is positively related to product returns, overall and for both, purchases made with mobile devices and purchases made with desktop devices, although prior literature predicts that returns from desktop purchases should not increase. These findings suggest that through new channels, consumers’ information environment is altered sufficiently to affect their decision accuracy. Moreover, the results indicate that previous research may be overestimating the positive effect of mobile channel adoption on sales by disregarding changes in product return behavior.     

EPP模式下的并口与DSP高速数据传输的实现

DSP与PC机间进行高速数据传输是DSP的一个重要应用。本文分析了并口处于EPP模式时和ADSP21060间的高速数据交换的原理，同时详细讨论了其硬件设计结构及其相应的并口程序设计方法，经调试证明此方案可行。     

小仰角下移动卫星通信性能的改善及仿真

移动卫星通信系统为功率受限系统,相对地面移动通信而言,其链路余量较小,而且由于多径及遮蔽效应,当系统工作在小仰角时,其信号衰落可达到30dB,这对系统的设计提出了严峻的挑战。本文研究了信道编码和交织技术在移动卫星通信系统中的应用。通过仿真,得到了应用该技术对不同仰角特别是小仰角条件下系统性能的改善程度。同时,在研究信道相关的基础上,给出了交织相关参数的设计准则。     

Mobile Marketing in the Retailing Environment: Current Insights and Future Research Avenues

Mobile marketing, which involves two- or multi-way communication and promotion of an offer between a firm and its customers using the mobile, a term that refers to the mobile medium, device, channel, or technology, is growing in importance in the retailing environment. It has the potential to change the paradigm of retailing from one based on consumers entering the retailing environment to retailers entering the consumer's environment through anytime, anywhere mobile devices. We propose a conceptual framework that comprises three key entities: the consumer, the mobile, and the retailer. The framework addresses key related issues such as mobile consumer activities, mobile consumer segments, mobile adoption enablers and inhibitors, key mobile properties, key retailer mobile marketing activities and competition. We also address successful retailer mobile marketing strategies, identify the customer-related and organizational challenges on this topic, and outline future research scenarios and avenues related to these issues.     

Evaluating strategies for promoting retail mobile channel using a hidden Markov model

With the proliferation of mobile communication technology, many firms, including retailers and consumer banks, are making efforts to develop mobile platforms to better engage with their customers and reduce operational costs. However, the cost advantage of these mobile technologies will not yield fruition unless the mobile channel accounts for a significant share of total transactions. In this article, we explore potential options for firms to promote usage of the mobile channel. To achieve this, we propose a hidden Markov model to both model customers’ decisions and assess different managerial strategies through simulations. While we apply our proposed model to data from a leading financial institution, our approach is equally applicable to other retail settings. The results show that customers’ choices of services and channels are sensitive to process time by type of channel. A 10% increase in process time through non-mobile channels leads to a nearly 14% increase in utilization of mobile banking channel. Therefore, retailing firms could potentially influence customers’ choice of different channels by changing channel-specific process times. Motivated by these findings, we present and compare performances across five different policies, in promoting the usage of mobile channel. Drawing on our simulation results, we also make personalized policy recommendations to firms facing different levels of financial constraints. For those with financial constraints, we recommend a policy of increasing process time for a selected subset of service requests through non-mobile channels. Firms not constrained by the resources might be better off improving process time with the mobile channel by targeting customers identified as having a better relationship with the firm.     

User Perceptions of Mobile and Online Channels for Purchasing Financial Products

ABSTRACT

This study investigates users' perceptions of costs and benefits of mobile versus online, PC-based, channels for accessing financial information and completing financial transactions. Results indicate that, in the financial services context, the mobile channel has no perceived advantages over the online channel. The older online channel does have several perceived advantages related to transaction cost, risk, ease of use, meeting financial goals, and information accessibility. The channels are similar on four dimensions, but most of the similarities arise because the online and mobile channels enable purchase of the same financial products. Finally, users are more willing to use the mobile channel for less risky tasks (accessing information) than they are for more risky tasks (buying financial products).