车载通信中增强型多跳广播算法研究

提出了一种高速公路场景下基于邻居信息的增强型多跳广播协议(enhanced neighbor information-based muti-hop broadcast protocol,ENIMBP),提出的协议利用车辆的邻居信息同时结合车辆的位置、行驶速度和方向来确定转发等待时间,以选择最优的转发车辆。根据车辆的位置,ENIMBP可以初步确定与广播车辆距离不同的车辆的转发等待时间。而在与广播车辆距离相同的情况下,ENIMBP则利用车辆速度和方向来区分转发等待时间。ENIMBP很好地解决了高速公路场景下的网络分割问题以及隐藏/暴露节点问题。仿真结果表明,在不同的车辆密度场景下,ENIMBP能显著地降低端到端时延,同时保持较好的分组到达率。     

Enhanced GPSR Routing in Multi-Hop Vehicular Communications through Movement Awareness

Providing reliable and efficient routing in presence of relative movement motivates the introduction of movement awareness to improve performance of existing position-based routing schemes in vehicular ad-hoc networks. The proposed algorithm represents a modification of well-known GPSR which exploits information about movement in order to improve the next forwarding node decision. Performance evaluation of the proposed protocol underlines a promising and robust basis for designing a routing strategy suitable for the automotive scenario.     

无人机网络中人工噪声增强的短包隐蔽通信

考虑无人机（Unmanned Aerial Vehicle, UAV）网络中人工噪声（Artificial Noise, AN）增强的隐蔽无线通信,其中UAV工作在全双工状态,不仅接收Alice发送的隐蔽信息,而且产生AN恶化Willie的探测性能。构建了UAV的三维位置部署和AN发射功率以及Alice发射功率设计的联合优化问题。所构建的优化问题是非凸的且其优化变量相互耦合,这导致该优化问题很难直接求解。为了求解该优化问题,首先根据优化问题隐含的特性,将其等价地转换为更易处理的形式。随后,推导了Alice发射功率和AN发射功率的最优解析表达式。随后证明了UAV的最优水平位置一定位于Alice和Willie的连线上。在此基础上,推导了UAV的最优三维放置位置。仿真结果表明,与无AN方案相比,所提方案可以显著的提高系统的隐蔽传输性能。      

一种低信噪比环境下的符号同步改进算法

针对OFDM符号同步基本算法在低信噪比条件下定时度量值低和干扰峰严重的缺点,提出了一种改进算法。该算法在基于训练序列符号同步的典型算法基础上,对训练序列的帧结构进行了改进,将共轭序列带入到帧结构中,同时改变了度量函数的计算方法。改进后的算法在低信噪比条件下有5 d B的性能提升,且具有计算量小、受信噪比影响小和实现简单等优点。仿真验证了改进算法在低信噪比环境下的有效性。     

改进的FM-DCSK:一种新型的混沌通信调制方式

本文提出一种改进的复合混沌调制方式，给出了系统的组成框图和实现方法，计算机仿真结果表明，在不降低传输速率的前提下，系统性能得到改善，在误比特率BER＝10^-3时，较FM-DCSK调制方式信噪比提高了1dB：在双路径条件下，提高1．6dB。     

Architecture, Design, and Development of the System 75 Office Communications System

AT&T-IS System 75 is a new customer-premises digital communications system. It is designed to complement the larger AT&TIS System 85 in the intermediate size range of 20-400 stations and makes use of the same terminals and adjuncts. System 75 utilizes a distributed switching and control architecture and employs VLSI for a compact cost-effective realization. Integrated voice and data communications are supported with full voice conferencing capabilities and high-speed data switching. A process and message-based software architecture supports a large number of features and services, including a flexible user-oriented maintenance and administration capability, accessible from a local or remote system management terminal. This paper describes the system, the switch, common control, software architecture, system management capabilities, and product testing methods.     

向HSPA+演进:提供高价值有竞争力的无线宽带服务

本文从无线宽带市场发展、用户需求和技术演进角度出发,分析了HSPA+技术的引入特点和必要性,并着重阐述了HSPA+的几个关键技术和对市场需求的契合度.最终针对上海贝尔的WCDMA设备提出了软硬件系统演进的发展思路.     

数字通信中增强型六维64PSK调制设计与性能分析

为了进一步提高数字通信的可靠性,在两个三维8PSK星座图的基础上设计了一种增强型六维64PSK调制格式.相比传统的二维64PSK、64QAM调制格式,在功率归一化的条件下,增强型六维64PSK调制格式的最小欧氏距离(Minimum Euclidean Distance,MED)变得更大,而且能够分别获得21.6 dB和11.8 dB的解调增益.在最大化最小欧氏距离的过程中没有使用重复的算法,因此新方法的计算复杂度较低,这种增强型六维64PSK调制格式非常适合完成一个高可靠性的数字通信系统.     

Communications for manufacturing: an overview

Computer-integrated manufacturing (CIM) is introduced, and the communications needed to support CIM applications described. The GMT400 project, a CIM experiment which is intended to investigate the applicability of MAP (manufacturing automation protocol) technology in automotive manufacturing, is presented. Several other development projects in the CIM area are identified. Research and development issues in CIM are summarized     

智能反射面辅助及人工噪声增强的无线隐蔽通信

该文考虑一种智能反射面(IRS)辅助及人工噪声(AN)增强的无线隐蔽通信以提升隐蔽传输性能。首先,分析了Willie的探测性能并给出了总的最小探测错误概率下界表达式。 在此基础之上,构建以最大化有效吞吐量为目标函数,以隐蔽需求和最大AN发射功率为约束的优化问题。该优化问题为非凸的,通常很难直接求解。该文提出基于Dinkelbach方法的交替迭代算法联合设计IRS的反射系数和Alice的发射功率及Bob的AN发射功率。为了降低计算复杂度,进一步提出一种低复杂度算法以获取相应优化变量的解析表达式。仿真结果表明：与无IRS及无AN方案相比,所提方案可以显著提升隐蔽传输性能。     

副载波光纤通信

副载波光纤通信是目前多路光纤通信的一个热门研究课题。本文首先对副载波光纤通信作一简单介绍,然后深入讨论对副载波的调制问题及对发送激光器的调制问题;介绍几种副载波光纤通信系统,最后对副载波多路光纤通信给出评价。     

Wireless Indoor Communications Using an Optical Highway

The wireless indoor communications system employing an optical backboneprovides an economic and flexible approach for local area networks in officebuildings. In this approach the wireless communication serves small picocellsthat are interconnected by optical highways. The performance of the system isenhanced by assigning specific subcarriers for the individual picocells whichenables the transmission of the radio channels without altering theirmodulation format. The reception is simplified by a direct optical-microwavemixing method providing simultaneous optical detection and frequency shifting.This method allows for simple and cost-effective radio nodes.     

开放式办公室内部声场计算机模拟

介绍了几种常用的建筑声学模拟软件,并通过实例研究了ODEON软件在开放式办公室内部声场特性分析中的应用。     

Development and Installation of an Optical-Fiber Cable for Communications

An optical-fiber cable has been developed which has a superior performance; which has high reliability; which can be installed in lengths of 1 km or more by direct burial or in ducts without additional protection; which can be handled with the equipment and personnel regularly employed for conventional wire cables; which will withstand the rough treatment normally encountered in a field environment. The paper describes cable construction; measured results; methods of installation, splicing, testing and pressurization; specialized hardware; instruments and tools developed for field use. Several systems employing this type of cable have been installed and have been placed under observation with automatic monitoring equipment.     

利用校园网营造一个智能的办公环境

随着计算机与网络的普及，数字技术正在改变人类所赖以生存的社会环境，并因此人类的生活和工作环境具备了更多的数字化特征。校园网的蓬勃兴起，必将带来高校办公方式的巨大变化。从校园智能办公系统功能、如何营造校园智能办公环境以及校园智能办公系统的未来几方面进行了研讨。