4G集团客户专线网关设计研究

随着4G高速无线网络的发展,集团客户专线业务发展出现了新的契机和模式,即摄即传、P2P专线、空中容灾链路等高带宽的终端间点对点互访模式出现较大发展。针对此类业务安全管控和运行维护难度大的问题,本文详述了4G集团客户专线网关的规划设计方案,不仅解决了4G网络下新业务拓展、专网设备容灾和集团客户快速开通问题,而且为集团客户专线业务发展提出了全新的思路。     

现有通信系统向4G通信系统的演化及展望

随着第三代移动通信系统逐步实施,移动通信未来的发展及演问题成了研究热点。本文综合分析了从现有通信系统向4G通信系统演化过程中所面临的难题,以及为了解决这些难题所提出的技术,并且预见了4G通信系统的发展趋势。     

基于4G通信技术的无线网络安全通信分析

21世纪是一个网络时代,网络技术、通信技术、信息技术、计算机技术得到空前发展,人们对通信业务需求越来越大,要求越来越高,传统有线网络通信已不能满足人们通信要求,无线网络通信成为未来通信核心技术。现如今4G通信技术越发成熟,无线网络得到空前发展,无线组网方式灵活,能节约线材,降低组网成本,且不受环境限制。但无线网络没有物理访问限制,易破解、通信安全性和可靠性差等问题不容忽视。因此,应积极采取相应网络安全技术,对无线网络系统进行安全防护,应对网络威胁,确保无线网络通信安全。文章将针对基于4G通信技术的无线网络安全通信展开研究。     

Reliable and infrastructure-independent routing for the internet of vehicles

The Internet of Vehicles (IoV) is a new framework for intelligent transportation systems. One of its goals is to improve safety and increase the quality of service for passengers. Topology changes in IoV present significant challenges to the function of safety applications. Most routing algorithms offer their solution, independent of infrastructure or based exclusively on infrastructure. Although the lack of access to roadside units disrupts infrastructure-based algorithms, methods that do not use infrastructure will also not enjoy the benefits of high-speed data transmission. This research proposes the reliable and infrastructure-independent routing (RIIR) routing algorithm to increase the reliability of real-time routing in the IoV. The RIIR, in addition to simultaneous covering capability to use intelligent infrastructure for accelerating data transmission and flexibility in conditions of lack of access to infrastructure, by introducing three new criteria entitled “history of vehicle movement,” “conformity of vehicle speed with the harmonic speed average of nearby vehicles,” and “number of reliable neighbors,” scores vehicles and then selects the most suitable vehicles as route members. The RIIR measures the conformity of the previous presence of vehicles on the current route and the stability of their link with adjacent vehicles. Furthermore, it prevents congestion by halting the spread of route request messages at intersections not leading to the destination. The efficiency of the RIIR has been theoretically proven, and extensive simulations with multiple scenarios in SUMO and NS3 show the superiority of the RIIR in increasing the packet delivery rate and reducing route failure, average delay, and control overhead.     

A novel IP to 3G multimedia gateway and its applications

In this paper, we use simple 3G modem cards to design and deploy a novel gateway bridging IP network and Wideband Code Division Multiple Access (WCDMA) 3G mobile network in Hong Kong. A simplified Session Initial Protocol (SIP) is devised to implement the gateway together with the 3G-324M protocol. Compared with the existent similar gateways, our gateway is much more implementable and less cost. Using the proposed gateway, we devise and develop a Video Instant Message System (VIMS) which achieves direct audio and video communications from terminals of the Internet like desktop to 3G mobile phones. Moreover, we produce and accomplish a Mobile Robotic Car Remote Control System (MRCRCS) based on the gateway and VIMS. In the MRCRCS, individuals can distantly control the moving direction of a robotic car by using a VIMS client or a 3G cell phone. By a series of practical experiments, we testify the efficiency and robustness of the gateway and its application scheme.     

适用于2．5／3G移动通信、网关设备的高性能DSP产品

随着通信技术的发展,多业务支持、宽带、高速已经成为一种趋势,SoC(片上系统)设计思路的引入使设备小型化、低成本、高可靠性有了更广的发展空间。在高端设备中采用高性能的芯片来提高集成度、降低单位功耗越来越多地被广泛采用。DSP技术的发展为这些需求提供了保证。本文主要介绍了Agere Systems公司推出的几款高性能DSP产品及其应用实例。     

Signaling and multiple access techniques for ultra wideband 4G wireless communication systems

Due to the demanding performance requirements for fourth-generation wireless systems, several technologies have been considered for replacing third-generation wireless systems. Potential technologies for fourth-generation wireless systems are ultra wideband, orthogonal frequency-division multiplexing, and multi-input multi-output antenna systems. Ultra wideband is of particular interest for fourth-generation wireless applications that emphasize short range, high data rate, and/or low power. We focus on ultra wideband radio due to its unique advantages: high data rate, low power, and resilience to multipath fading effects. We discuss the signal characteristics, channel propagation, modulation schemes, and hardware implementation. Two major approaches to ultra wideband signaling, impulse-based and multicarrier ultra wideband, are elaborated. Furthermore, two categories of multiple access are also considered: distributed and centralized.     

高铁4G专网质量提升探索

高铁专网覆盖是4G信号网覆盖的一个难点;目前高铁专网受限于传统覆盖手段单一,受限于铁路站址建设难度,覆盖质量较公网更差,更不稳定,缺乏行之有效的覆盖手段,本文主要介绍了如何立足现网的基础上提升专网质量,如何通过功能特性研究以及对于不同场景的优化,多维度探索网络性能提升方法,创新的开创有效、实用的专网覆盖手段,解决目前高铁专网覆盖手段瓶颈,突破业界的覆盖难点.     

基于革新视角下的4G移动通信技术研究

通信技术的发展是衡量一个国家科技实力的重要指标之一,随着4G移动通信技术的推出,便以其抗干扰、通信速度快、智能性与灵活性更高等优势被广泛运用与发展.本文基于革新视角下的4G移动通信技术的特点和关键技术进行全面分析,以期对我国未来移动通信技术的发展提供重要的指导意义.     

浅析4G通信技术的发展现状和应用趋势

4G移动通信技术已经逐渐走进人们的生活,成为新一代移动通信技术的领头羊。不难判断,未来的移动通信将成为4G的天下,而研讨相关话题则具有前瞻性的现实意义。文章对4G移动通信技术的发展现状和未来应用趋势进行了简要论述,提出了一些个人的思考和见解。     

4G移动通信技术发展概述

文章说明在不同频带的网络中,或者在不固定的无线平台中,4G都可以提供无线网络,并且除了通信,还有其他的功能,例如:采集数据、远程控制、定位等等。     

5G卫星通信系统频偏估计算法

卫星通信系统中存在的大的多普勒频偏严重影响着系统的性能.为了提高频偏估计的性能,基于5G NR帧结构和同步信号,提出新的利用级联积分梳状(Cascaded Integrator Comb,CIC)滤波器插值的小数倍频偏估计算法.该算法分两步实现小数倍频偏估计:首先,利用结构简单、运算快速的CIC滤波器对接收主同步序列(...     

Cross-layer-based adaptive TCP algorithm for cloud computing services in 4G LTE-A relaying communication

Cloud computing provides various diverse services for users accessing big data through high data rate cellular networks, e.g., LTE-A, IEEE 802.11ac, etc. Although LTE-A supports very high data rate, multi-hop relaying, and cooperative transmission, LTE-A suffers from high interference, path loss, high mobility, etc. Additionally, the accesses of cloud computing services need the transport layer protocols (e.g., TCP, UDP, and streaming) for achieving end-to-end transmissions. Clearly, the transmission QoS is significantly degraded when the big data transmissions are done through the TCP protocol over a high interference LTE-A environment. The issue of providing high data rate and high reliability transmissions in cloud computing needs to be addressed completely. Thus, this paper proposes a cross-layer-based adaptive TCP algorithm to gather the LTE-A network states (e.g., AMC, CQI, relay link state, available bandwidth, etc.), and then feeds the state information back to the TCP sender for accurately executing the network congestion control of TCP. As a result, by using the accurate TCP congestion window (cwnd) under a high interference LTE-A, the number of timeouts and packet losses are significantly decreased. Numerical results demonstrate that the proposed approach outperforms the compared approaches in goodput and fairness, especially in high interference environment. Especially, the goodput of the proposed approach is 139.42 % higher than that of NewReno when the wireless loss increases up to 4 %. Furthermore, the throughput and the response functions are mathematically analyzed. The analysis results can justify the claims of the proposed approach.     

4G移动通信城市环境电波传播特性测量与建模

开展IMT-Advanced频谱特性研究对于促进4G移动通信技术发展意义重大.针对中国4G现场测试环境,研究提出了一种电波传播特性测量与建模方法,结合高性能测试仪器和虚拟仪器技术设计构建了3.5 GHz测量系统,在宽带无线业务集中的城市热点地区开展了测量,提取了路径损耗指数、阴影衰落标准方差等特性参数,建立了实测模型.通过与国际标准SUI模型及COST-231 Hata模型进行比较,发现SUI模型与实测结果更为吻合,说明在3.5 GHz频段国际标准模型对于中国城市热点地区适用存在差异性.这为我国无线电管理部门进一步开展4G频段频谱特性研究提供了参考依据.     

一种3G环境中基于无线网关的内网接入技术方案

随着政府信息化建设工程的快速发展和通信运营商3G网络的建设加速,手持终端设备作为信息接入点安全接入内网信息系统的需求越来越多,尤其是在电子政务、企业应用等应用方面。该文主要介绍了一种在3G无线网络环境下利用无线网络安全接入网关中转,实现移动终端和应用服务器的异构公钥证书的认证、安全数据传输的技术方案。     

Integrated alerting and system broadcast channel for a wirelessaccess system

A protocol is described which allows a wireless access system to dynamically multiplex the alerting, system information, and priority access request subchannels on its system-wide broadcast channel. These subchannels each have different requirements with respect to the message length and position within the framing structure; the described protocol meets each of their requirements. The protocol efficiently accommodates a wide range of alerting traffic levels and provides for efficient downloading of system information to subscriber units by using excess capacity when alerting traffic is low. It provides error detection capabilities above that provided by the radio channel alone and is easily extendible to accommodate other services such as paging and low bandwidth broadcast messaging. The flexibility provided by this protocol could permit a broad range of network architectures for wireless access     

兼容多种通信方式的智能网关软件设计

为解决异构测控网络的以太网接入问题,以ARM9处理器S3C2440A和多个功能模块组成硬件平台,在移植嵌入式操作系统Linux和嵌入式数据库SQLite3的基础上,设计了多线程网关服务程序,实现了兼容无线数传、通用串口、WiFi等通信方式的以太网接入。测试结果表明:该网关具有成本低,兼容性强,使用方便等特点。     

4G移动通信系统的研究进展与关键技术

本文概要介绍了第四代移动通信系统(4G)的最新研究进展.文中详细讨论了4G系统的主要技术特点、主要技术目标,重点讨论了4G系统中可能采用的有关关键技术.     

4G时代的移动通信基站环评标准

随着4G基站的大规模建设,4G基站的环境影响评价工作也越来越多,由于4G基站使用的是2GHz以上的频段,其信号衰耗远大于900MHz系统,但是现有的环境影响评价标准中没有考虑高频和低频的差别,所以本文对4G时代的移动通信基站环评标准的问题进行了探讨,并提出了一种测试的方法.