基于TD-LTE系统的新型SNR和CQI映射方案

为了在链路自适应、混合自动重传、快速调度过程中最大程度地满足长期演进(LTE) 系统的性能和吞吐量,提出了一种新型的信噪比(SNR)和信道质量指示(CQI)映射方案。这种 新的方案通过系统链路级仿真得到信噪比和误块率之间的仿真曲线,然后通过区域拟合的方 式得到SNR和CQI之间的关系。和传统的映射方案相比,它不仅易于实现和存储而且具有很好 的自适应能力。结合仿真曲线可以看出这种新型的方案能够满足协议规定误块率和吞吐量的 要求。该方案已应用于TD-LTE无线综合测试仪表的开发中。     

基于OPNET的混合关键性网络建模与仿真分析

混合关键性网络是一种新型的通信架构,可以满足非实时性和实时性业务的需求。为分析其网络性能,提出在OPNET网络仿真环境中建模的方法。以开放式系统互联模型为基础,采用层次化建模,构建网络的节点模型和进程模型。该模型考虑了事件触发和时间触发消息的特点,通过设计调度算法和容错方式,实现了仿真实验的灵活配置和端到端延迟抖动等性能指标的验证。对仿真结果的性能分析表明,混合关键性网络能够保证实时业务的确定性以及兼容标准以太网的非实时业务。     

一种改善TCP性能的cdma2000链路层RLP重传方案

在无线数据传输网络中,物理层帧差错率(FER)是影响网络性能的一个主要因素。无线链路层重传技术是改善网络性能因无线信道误码率较高而下降的一项重要措施。本文主要研究cdma2000无线网络中链路层重传技术对无线TCP数据传输的影响,提出一种cdma2000链路层重传方案,并通过OPNET仿真技术对该重传方案进行仿真,验证了该方案能改善TCP数据在cdma2000无线网络中的传输性能。     

An efficient scheme for single-cell point-to-multipoint e-MBMS transmission

多媒体广播多播业务（MBMS）是3GPP-R6版本中定义的一种典型的广播、多播业务。随着技 术的演进,在LTE系统中 提出了增强的MBMS,即e-MBMS业务。针对e-MBMS业务,提出了一种有效的技术解决 方案。该方案可看作下行发射分集、基于DoA的波束赋形与HARQ技术的结合。同时,仿真结 果也表明,该方案相对于单独的发射分集来说能带来显著的性能增益。     

采用介质偏移技术的LTE基站双工器

为了在小尺寸且较低加工难度的情况下实现模式可控的多模双工器，一种新型双工器设计法——介质偏移技术被提出。根据对介质偏移多模谐振器谐振特性的分析，建立耦合矩阵，通过耦合系数与物理参数的关系算出理论物理参数值，最后通过仿真软件优化各个物理参数值。利用该技术设计了两个具有尺寸小、插损低和功率容量高等优点的长期演进(LTE)基站的双工器，丰富和发展了基站双工器的设计方法。     

广电网络EPON＋EOC双向网组网方案的探讨

本文通过对广电现有的ttFC网络进行分析，并详细介绍了广电当前双向网络改造的几种可行方案，最后提出一种最适合广电双向网络改造的方案。该方案采用EPON＋EOC技术，采用该方案改造广电现有网络具有建设成本低，维护管理简单，和能够充分利用现有HFC网络资源的优点。为广电网络迅速开拓宽带接入业务提供了新的解决方案。     

一种新型正交相关延迟混沌开关键控系统

在相关延迟键控(CDSK)和混沌开关键控(COOK)这两种传统方案的基础上提出了一种新型的混沌键控方案——正交相关延迟混沌开关键控(OCD-COOK)。该方案结合了CDSK系统和COOK系统各自的特点，同时引入了一对简单的Walsh码序列，克服了CDSK系统误码性能差的缺点，具有比特误码率低、传输速率高、安全性好等优势。理论分析及仿真结果均表明，该系统的比特误码率低于CDSK和差分混沌键控(DCSK)，传输速率是DCSK的2倍，具有很好的实际应用价值。     

一种适用于超密集网络下行链路的干扰抑制方案

在超密集网络（UDN）下行链路场景中,为了有效克服因节点间距减小、邻近节点传输损耗相差不大而产生多个强度相近的干扰源对用户性能的影响,提出了一种基于优先级以用户为中心的小区间干扰抑制方案。为了便于量化基站协作取得的带宽性能增益,采用了一种计算带宽盈亏率的定量分析指标。通过该指标,易于确定在特定UDN场景下干扰协调方案是否处于盈利状态,进而通过系统能够接受的最大损耗比优化参数配置。仿真结果表明,该干扰抑制方案能显著提升用户的信号干扰噪声比（SINR）性能,且能更好地保障用户公平性,有效地克服了用户SINR性能在基站数较多时受天线数限制的缺陷,为提升UDN网络用户性能和系统性能提供了一种解决方案。     

PSTN网络演进分析

随着网络的演进和业务的发展,传统的PSTN网络由于设备老化,用户量减少等原因迫切需要进行设备的更新替换和业务的发展创新.分析了PSTN网络的现状和演进策略,给出PSTN向IMS网络演进的必要性,并详细分析了PSTN网络的演进方案,包括端局改造方案,终端接入方案,传统固网业务和智能业务的继承方案.     

语义分割网络下的混合信号频谱分离

单通道接收机下，多个时频混合信号的分离属于非稀疏欠定信号分离问题，难以求解。针对这类非稀疏欠定信号分离问题，提出了一种基于语义分割网络、从频域实现多个指定类别信号分离的新方法。利用语义分割网络提取信号的频域分布特征，克服了单通道接收机下信号先验信息过少的问题。仿真表明，该方法具有较高的分离精度，且响应时间短，可用于单通道接收机中时频混叠信号的分离。     

Evaluating the Appropriateness of Market Segmentation Solutions Using Artificial Neural Networks and the Membership Clustering Criterion

The appropriateness of a given segmentation solution is a key consideration in all marketing segmentation studies. By appropriate, it is meant that not only has the optimal segmentation solution been identified, but also that the proper number of segments to market to has been correctly specified. This research focuses on the second, and more fundamental, issue of determining the appropriate number of segments in a marketplace. If the appropriate number of segments is over-specified, marketers may over-segment the market and treat audience segments separately that could effectively be treated inclusively. Conversely, if the appropriate number of segments is under-specified, marketers may under-segment the market and fail to identify distinct, viable segments that should be marketed to separately.The issue of market under- and over-segmentation may be addressed with the membership clustering criterion (MCC), an analytical technique based on fuzzy sets derived from artificial neural networks (mathematical models of animal nervous systems). Using artificial and real world data sets, we empirically test the MCC, compare it to existing methods for determining the number of segments in a market, and demonstrate its advantages in evaluating the appropriateness of marketing to different numbers of market segments.     

利用VPN技术拓展检验检疫专网

本文针对新形势下检验检疫工作中产生的移动办公需求,引入VPN概念,通过隧道等安全技术的分析和探讨,主要是IPSec技术的应用研究,并以温州出入境检验检疫局为实例,提出了检验检疫专网拓展解决方案。     

基于以太网传输的E1到IP适配设计

利用包网络传输成本的优势,在现有的以太网 /IP网络上仿真电路业务,可以实现传统时分复用(TDM)设备间的无缝连接,从而保护投资。本文提出了在基于以太网的IP网络上传输E1业务的一种整体解决方案,介绍了适配电路的设计和实现。     

基于软交换的下一代网络组网结构

下一代网络将是基于软交换系统的通信网络。在研究各种软交换系统互联机制的基础之上,结合软交换基于IP网络构建、信令与媒体分离等特点提出了基于软交换系统的下一代网络中可以采用的各种组网结构,比较了各种方式的优缺点,指明了其适用范围。最后给出了现有通信网向下一代通信网络演进过程中网络体系结构的演进方案。     

基于Packet over SDH的以太网业务接入的设计实现

POS（Packet over SDH)是一项新兴的技术，它能够在传统的SDH传输平台上提供灵活和高效的数据业务支持，从而实现网络功能的增值。目前，POS作为IP宽带传送技术得到了广泛应用，特别是在城域网建设中受到人们的青睐。在现有的SDH设备中开发POS接口能极大地提高产品的竞争力，推动网络建设的发展。本文提出了一种在SDH设备中实现以太接入的整体解决方案，并介绍了基于FPGA设计的POS方案的设计思想和结构。该方案实现效率高，充分考虑了传输的可靠性，并且易于扩展。     

统一建模语言在VPN中的应用研究

互连网的无处不在和企业的需求促进了虚拟专用网（VPN）技术的快速发展，也加快了VPN的开发进程。本文分析了VPN开发的特点，指出了利用统一建模语言（UML）描述VPN的优势，并采用UML对VPN系统进行了总体分析，对边界网关协议／多协议标记交换（BGP／MPLS）VPN进行了描述。     

Balancing risk with virtual private networking during a pandemic

When the pandemic struck and teaching went online worldwide, universities had to make pressing decisions that balanced cybersecurity against other factors, including health and safety, usability, and cost. One such challenge Indiana University (IU) faced was how to accommodate the secure telecommunications needs of 130,000 faculty, staff, and students who would now be teaching, learning, doing research, and working from home. Some universities reflexively promoted virtual private network (VPN) use for all activities. Such an approach would have been unsustainable at IU, however, owing both to the licenses and resources needed for the sheer number of users and to the high-throughput applications on which they rely. Perhaps even worse, it would have increased the chances that the VPN would be unavailable during a critical incident or other situation in which secure communications must be guaranteed. Instead, IU launched an awareness campaign demonstrating exactly when VPN use is and isn’t needed. In addition, network staff employed a VPN feature called split tunneling to reduce the load. This article discusses the advantages and disadvantages of this approach and how IU made the decision to balance both sides of the risk equation to ensure the continued advancement of its mission throughout the pandemic.     

Broadening versus reinforcing investor portfolios: Social structure and the search for venture capital investors

This paper highlights the venture capital investor (VC) portfolios of startups, and explores how the portfolios evolve. We emphasize the important trade-off between broadening and reinforcing VC portfolios (i.e., expanding to new VCs versus relying on existing VCs). This is because, to startups, new and existing VCs generate very different opportunities and constraints. Focusing on the social structure of existing VCs, we argue that startups are more likely to opt for new VCs when the internal networks of existing VCs are denser, when the external networks of existing VCs are smaller, and when the status of existing VCs is lower. Additionally, we not only focus on whether new VCs are on board, but also pay attention to which new VCs are introduced, by analyzing the ex-ante embeddedness between existing and newly-introduced VCs. We stress that when new VCs are highly embedded with existing VCs, their involvement makes only a limited contribution to broadening a startup's portfolio and network. We test the hypotheses using a sample of VC financing rounds in the U.S. and find broad support.     

一种高效可靠的无人机自组网多跳TDMA协议

设计无人机自组网媒体接入控制（Medium Access Control,MAC）协议时,需要考虑其控制开销和数据传输的可靠性。鉴于此,结合现有无线自组网多跳时分多址接入（Time Division Multiple Access,TDMA）协议和无人机自组网特点,提出了一种高效可靠的无人机自组网多跳TDMA协议。首先采用高效负载均衡的时隙请求信息上传机制,选择一个负载较小的节点转发节点时隙请求信息;然后根据相互通信的父节点删除重复节点的时隙请求信息,减少相同节点的时隙请求信息转发次数;最后通过实时更新节点时隙请求信息机制,提高节点时隙请求信息传输的可靠性。仿真结果表明,该协议在数据传输成功率、平均时延、控制开销方面优于现有协议,可较好地应用在无人机自组网中。     

A life cycle model of multi-stakeholder networks

In multi-stakeholder networks, actors from civil society, business and governmental institutions come together in order to find a common solution to a problem that affects all of them. Problems approached by such networks often affect people across national boundaries, tend to be very complex and are not sufficiently understood. In multi-stakeholder networks, information concerning a problem is gathered from different sources, learning takes place, conflicts between participants are addressed and cooperation is sought. Corporations are key actors in many networks, because the problems addressed are frequently related to business activities. The aim of this article is to conceptualise multi-stakeholder networks by proposing a problem-centred stakeholder definition. From an analysis of several case studies, a life cycle model is deduced that distinguishes seven phases: initiation, acquaintance, first and second agreement, implementation, consolidation and institutionalisation.