流媒体技术在职教园区融合网络中的应用研究

目前,推进三网融合已纳入国家发展战略,有关三网融合的各项技术正在研究和实验中。高质量的流媒体传输是实现三网融合的基础,文章对流媒体技术进行深入研究,主要研究其在职教园区的教育教学环境中的应用,提出一个能够实际运行的流媒体实验网络的方案,为实现三网融合的全业务网络提供理论依据和实验平台。     

探讨3G网与固定网的融合业务

全业务运营商的出现是移动网与固网融合的最大驱动力,融合后运营商能使有线接入网和无线接入网共用核心基础网络,节省对下一代网络的建设投资。融合后将3G平台与固定应用业务平台结合,便于运营商灵活开展业务。移动网与固定网融合是未来通信网络发展的趋势。文章介绍了3G网与固定网业务融合的定义和技术实现方案,详细分析了业务融合的现状及需要注意的问题,最后列举了几个问题与读者共同探讨。     

三网融合现状及发展策略

 文章首先界定了三网融合的概念,指出三网融合是技术、业务、市场、法律法规和监管机构的多层次融合,其核心不是某种网络一统天下,而是发挥不同网络的物理优势,使得任何人能够通过任何一种物理网络方便的获得任何一种信息服务。在技术进步、市场需求和产业管制的驱动下,未来三网融合的发展方向是电信网、互联网、传媒网的新三网融合。文章对比了发达国家三网融合的政策法规和市场情况,通过分析中国三网融合的现状和存在的问题,从技术、市场和产业政策等方面提出中国三网融合的发展策略建议。     

“新三网融合”的特征与产业发展

以OTTTV为代表的开放互联网业务赋予了"三网融合"以新的内涵,文章阐述了"新三网融合"的特征,包括:网络、业务、终端的多元化融合是主要方向,移动互联网业务是核心业务,个性化和社交化应用成为热点,以及"内容聚合"成为竞争制胜的关键;分析了"新三网融合"时代电信业和广电业面临的挑战和机遇;指出"内容监管"将成为未来行业监管的重点。     

言论

业务融合是关注焦点,体系架构协同和业务部署能力是核心．全业务承载网络是基础．泛在化三网融合或已成为三网融合的发展趋势。     

三网融合下的广电IP城域网建设

国务院办公厅于2010年要求加快推进三网融合,并进一步公布试点城市。目前三网融合的试点工作正在紧张进行。根据国家广电总局的要求,未来的广电基础网络建设应以光纤同轴混合网为基础,而现有HFC网络的IP化是其发展的趋势。并且,从具体的项目中可知,能进行管控的IP城域网在各方面均能满足三网融合初期广电各项业务承载的需求,IP城域网的建设是必要的。     

美国有线电视网络融合业务发展情况解析

经过十多年的努力,三网融合多种业务竞争局面在世界各发达国家基本形成。三网融合的主要目的是吸引大量社会资本和政府投资建设宽带网络,普及宽带业务进入千家万户,加速社会信息化进程。本文分别从不同角度对美国有线电视网络发展情况及其融合业务发展情况进行解析,最后总结出其有线网络在三网融合进程中取得的巨大成功,以期对我国有线电视网络的未来发展提供良好借鉴。     

浅析三网融合之技术融合

三网融合,即电信网、广播电视网和互联网三大网络之间的融合。融合的内容涵盖技术、业务、市场、终端、标准等各个方面,三网融为一网已经成为网络未来发展的必然趋势。介绍了三网融合国内外的现状、三大网络的结构模式以及优缺点,主要分析了三网融合的技术选择以及相关新技术新业务的相互融合。     

抓住战略机遇 发展宽带、高清互动业务

在“三网融合”的政策环境下．传统电信、广电网络运营商相互竞争的业务和技术核心点,主要在于宽带和视频。宽带接入将是一切网络基础设施不断追求的目标．也是未来承载视频业务的核心基础,同时也是基础网络运营商今后生存和发展的必要条件。     

基于NGB的智慧城市应用建设思路

本文介绍了三网融合下运营商网络和应用的发展趋势,提出未来融合创新业务的发展方向,简单介绍了NGB网络的技术架构和特点,结合上海智慧城市建设三年行动计划,分析了上海广电网的网络、技术、大众和政企客户基础,提出了在三网融合和智慧城市建设中,基于广电NGB网络的智慧城市应用建设思路和建议。     

一个基于IEEE802．11P标准能WAVE模型样机

基于IEEE802．11p标准的车辆通信环境下的无线接入（WAVE）系统为未来的智能交通系统建造了功能性架构,旨在安全性、有效性和方便性方面极大地改善交通环境。文章阐述了WAVE系统的背景、关键技术及其对社会的深刻影响,报告了密歇根大学迪尔拜分校车载通信和网络中心进行的相关研究和进展,包括一个基于现场可编程门阵列（FPGA）的WAVE模型样机和车载网络仿真软件。     

Analysis of V2V Broadcast Performance Limit for WAVE Communication Systems Using Two‐Ray Path Loss Model

The advent of wireless access in vehicular environments (WAVE) technology has improved the intelligence of transportation systems and enabled generic traffic problems to be solved automatically. Based on the IEEE 802.11p standard for vehicle‐to‐anything (V2X) communications, WAVE provides wireless links with latencies less than 100 ms to vehicles operating at speeds up to 200 km/h. To date, most research has been based on field test results. In contrast, this paper presents a numerical analysis of the V2X broadcast throughput limit using a path loss model. First, the maximum throughput and minimum delay limit were obtained from the MAC frame format of IEEE 802.11p. Second, the packet error probability was derived for additive white Gaussian noise and fading channel conditions. Finally, the maximum throughput limit of the system was derived from the packet error rate using a two‐ray path loss model for a typical highway topology. The throughput was analyzed for each data rate, which allowed the performance at the different data rates to be compared. The analysis method can be easily applied to different topologies by substituting an appropriate target path loss model.     

Design and implementation of electromagnetic band‐gap embedded antenna for vehicle‐to‐everything communications in vehicular systems

We proposed a novel electromagnetic band‐gap (EBG) cell‐embedded antenna structure for reducing the interference that radiates at the antenna edge in wireless access in vehicular environment (WAVE) communication systems for vehicle‐to‐everything communications. To suppress the radiation of surface waves from the ground plane and vehicle, EBG cells were inserted between micropatch arrays. A simulation was also performed to determine the optimum EBG cell structure located above the ground plane in a conformal linear microstrip patch array antenna. The characteristics such as return loss, peak gain, and radiation patterns obtained using the fabricated EBG cell‐embedded antenna were superior to those obtained without the EBG cells. A return loss of 35.14 dB, peak gain of 10.15 dBi at 80°, and improvement of 2.037 dB max at the field of view in the radiation beam patterns were obtained using the proposed WAVE antenna.     

无线车联网WAVE的车地通信初步研究

通过对802.11p及无线车联网WAVE网络协议族的分析和理解,研究探索真实设备中WAVE网络的性能及其应用程序的开发方法。以构建于linux 2.6.32嵌入式操作系统之上并集成标准IEEE WAVE协议族的真实IWCU设备为平台,编程实现WAVE标准协议下车载单元与路边单元之间进行wsmp格式的数据传输,对记录下的实验结果进行分析,分析表明在短距离范围内,WAVE通信的丢包率和延时会随着距离的增加而缓慢增加。     

Non-IP Multi-protocol Stack for Vehicular Communications

Wireless vehicular communications are gaining momentum, mainly to improve road safety through the use of cooperative systems. Such visionary cooperative applications are based on recently established families of standards, notably the IEEE Wireless Access for Vehicular Environment (WAVE) and the ETSI ITS G5. Despite some relevant differences, both family of standards share the same physical and MAC layers, described in the IEEE 802.11:2012 - amendment 6, also know as IEEE 802.11p. Due to the characteristics of the wireless communications in vehicular environment, e.g., high-speed mobility causing unpredictable time-varying changes in connectivity, IP protocols are not suitable for safety communications as they require channel scanning, authentication and association under strict time limits. Safety vehicular communications rely, instead on non-IP protocols, either the WAVE Short Message Protocol (WSMP) or the FAST Network and Transport Protocol (FNTP). In this paper, we explore some of the challenges of implementing such protocols, and designed an architecture for a stack capable of handling both standards. The proposed architecture, including the communication and transport layers of the stack, was implemented in a custom ETSI ITS G5 compliant platform (IT2S), and its performance was assessed using a prototype.     

Wave: a tutorial - [Topics in automotive networking]

Intelligent transportation systems have been under development since at least the early 1990s. The rationale behind the concept is to automate the interactions among vehicles and infrastructure to achieve high levels of security, comfort, and efficiency. Communications, in general, and networking, in particular, have been essential elements in the evolution of these systems. The IEEE has developed a system architecture known as WAVE to provide wireless access in vehicular environments. This article gives an overview of the associated standards. The presentation loosely follows the order of the layers of the open systems interconnection model.     

Enhancing IEEE 802.11p/WAVE to provide infotainment applications in VANETs

IEEE 802.11p/WAVE (Wireless Access for Vehicular Environment) is the emerging standard to enable wireless access in the vehicular environment. Most of the research contributions in this area has focused on safety-related applications, while comfort and information/entertainment applications (such as on board Internet access, point-of-interest notification, e-map download) have been considered only recently. Notwithstanding, the user interest in this kind of applications is expected to become a big market driver in a near future. In this paper, an extension to IEEE 802.11p is proposed that is compliant with the multi-channel operation of the WAVE architecture and targets at the support of non-safety applications, while preserving the delivery of safety services. The proposed W-HCF (WAVE-based Hybrid Coordination Function) protocol leverages controlled access capabilities on top of the basic contention-based access of the IEEE 802.11p; it exploits vehicles’ position information and coordination among WAVE providers in order to improve performances of delay-constrained and loss-sensitive non-safety applications.     

WAVE协议栈下基于高斯混合模型的无线定位研究

无线定位是车联网中各应用的基础,对实时性和精度要求更高。基于此,本文提出了一个在WAVE系统下基于混合高斯模型的位置指纹定位算法。该算法由离线训练和在线定位两部分组成,采用GMM对离线训练阶段的指纹数据库进行聚类建模处理,并在定位阶段对结果采用多点均值方法,不仅降到了系统定位误差,也减少了定位阶段的运算量,提高了定位的实时性。实验结果表明,该算法有较好的定位精度和实时性,为WAVE环境下的快速定位进一步研究提供有效参考价值。     

线性预测编码(LPC)技术及其在音频文件上的应用

介绍了线性预测编码 ( L PC)技术原理和音频文件 ,尤其是波形音频文件格式 ,并且讨论了 L PC技术在音频文件上的应用 ,同时给出了 L PC处理 WAVE文件流程图和 WAVE文件恢复流程图。     

Heterogeneous Vehicular Communication Architecture and Key Technologies

Vehicular networks have traditionally been used in specific scenarios, such as Electronic Toll Collection (ETC). New vehicular networks, however, support communication of safety information between vehicles using self-organized ad-hoc technology. Because of limitations in network architecture, current vehicular networks only provide communication for mobile terminals in a vehicle cluster. Vehicles cannot exchange information with an Intelligent Traffic System (ITS) control center nor can they access broadband wireless networks. This paper proposes a novel heterogeneous vehicular wireless architecture based on Wireless Access in Vehicular Environment (WAVE, IEEE 802.11 p) and Worldwide Interoperability for Microwave Access (WiMAX,IEEE 802.16e). A new network infrastructure and system model is introduced, and key technologies are discussed. For WAVE, these technologies include adaptive multichannel coordination mechanism and scheduling algorithm; and for WiMAX, these technologies include group handover scheme and two-level resource allocation algorithm.