Mobile backhaul [From the Guest Editor's Desk]

This focused issue, which is a sequel to the August 2008 focused issue "Convergence and Competition on the Way Toward 4G" [1]-[7], addresses the mobile backhaul prospects from the various viewpoints of the contributing authors, whose interests are complementary. The term mobile backhaul is commonly used for the fixed wireline and/or wireless interconnections of mobile service base stations, and their connections to the core telecommunications network. The subject is of increasing interest in consideration of the following major trends: · cellular mobile services are rapidly growing worldwide · backhaul capacity requirements are substantially increasing as cellular mobile systems transition from 2G to 3G and to 4G · the transitioning of broadband wireline and wireless transport from legacy time-division multiplexing (TDM) and asynchronous transmission mode (ATM) to IP-based transport is accelerating · the backhaul parts of mobile networks account for ever increasing percentages of the total capital and operating expenses. These trends motivated the current focused issue to address mobile backhaul issues of particular interest to the readers of IEEE Microwave Magazine.     

The next challenge for cellular networks: backhaul

Growth in the number of mobile users, coupled with the strong uptake of wireless broadband services, is driving high transport capacity requirements among cellular networks. However, revenues are not scaling linearly with increases in traffic. Demand for optimizing the cost efficiency of backhaul is becoming as critical as investment in the radio infrastructure. As a result, new transmission technologies, topologies, and network architectures are emerging in an attempt to ease the backhaul cost and capacity crunch. To explore this fundamental industry shift, we need to examine some of the existing and emerging network technologies and protocols that may be unfamiliar to some of the readers. We endeavor to define terms as we progress, but to enable a better comprehension, please also see "Summary of Selected Terms." We provide an overview of the technical challenges faced by wireless operators in providing cellular backhaul and examine the availability of new technology solutions that may meet these challenges.     

智能配电网通信业务需求分析及技术方案

配电通信网是发展智能配电网的基础条件,随着智能配电网、分布式新能源和智能用户的接入,配电通信网的业务需求发生了很大变化。文章分析了智能配电网各部分(高级配电运行、高级量测体系、高级输电运行、高级资产管理)通信业务的需求,初步给出了采用配网光纤、宽带无线接入方式实现智能配电网的通信技术方案,为制定智能配电网通信规划提供参考。     

Is microwave backhaul up to the 4G task?

Recent developments in the microwave industry support both the lowest cost per Mb/s transport and maximum Mb/s/MHz. With the evolution toward the fourth generation of mobile networks, the backhaul network--that portion of the network infrastructure that provides interconnectivity between the base stations and the core network--is expected to come under intense pressure as capacity requirements increase to support new mobile broadband services. There are many who fear that the backhaul network may well inhibit or delay the introduction of these new services, negatively impacting the end-user's quality of experience. As a key technology used in backhaul networks around the world, point-to-point microwave is rapidly evolving to support this increasing capacity demand, improve network efficiency, and allow operators to reduce network operational costs. This article details how recent developments in the microwave industry support both the lowest cost per Mb/s transport and also the maximum Mb/s/MHz. These developments embrace the dramatic shift to support Internet protocol (IP) network convergence, including the key features to enable link capacities not previously seen in the industry, and the new methods developed to enable every last drop to be squeezed out of the finite resource that is the available frequency spectrum.     

3G无线宽带专网在配电网自动化中的应用

目前,电力系统配电自动化接入网主要有光纤网络、电力载波通信、230MHz数传设备电台、公网2G/3G等方式,光通道则为一种占有主导地位的通信方式。但针对地形复杂、高楼林立的繁华城区,光纤难以联接到户,采用3G无线宽带专网作为接入网解决最后一公里的问题成为一种既经济又便捷的手段。无线宽带专网具有接入灵活、安全性高、业务支撑能力强、投资成本相对节省等特点,它在配网自动化(DA)或用电信息采集(AMI)中作为通信通道已经成为国际电力界公认的技术趋势。文中介绍了3G无线宽带专网作为配电自动化接入网的使用实例;探讨了3G无线宽带专网与配电自动化的融合、网络建设特点及网络运行管理模式等问题。     

宽带无线技术在电力光通信网拓展中的应用

电力光通信网为电网安全、稳定、经济运行提供了重要的通信保障。如何在光缆未到位的情况下实现新建变电站通信系统的临时接入,在应急情况下使电力光通信网络能拓展延伸至紧急救援地点,以满足电网安全生产的需求,一直是电力通信部门亟待解决的难题。文章介绍了目前比较成熟的几种宽带无线传输技术,提出了建设以无线技术为基础的移动通信站作为既有光纤通信网的扩展延伸的方案,详细讨论了系统构架及关键技术。     

基于Cloud-RAN的协作式无线接入网架构

Cloud-RAN架构和CoMP技术是未来蜂窝移动通信的两个重要演进方向。基于Cloud-RAN的网络架构结合了信息通信技术领域最先进的云计算、虚拟化以及软件无线电等技术,具有维护升级简单、可扩展性强,基站调度灵活、能耗低,便于实现协作式无线传输技术等特点。CoMP技术是一种重要的协作式无线接入网技术,通过小区间的协作传输,可以有效降低小区间干扰,提高系统容量。通过将这两种技术融合起来,构建基于Cloud-RAN的协作式无线接入网,可以在多基站间进行高效的数据传递与共享,结合软件无线电技术,可以针对移动通信技术特征实现分层次的软件优化,通过使用多线程设计和指令集并行技术,提高软件运行效率,实现基于通用处理器平台的协作化无线接入网。基于Cloud-RAN的协作式无线接入网系统设计方案和实现优化方案具有一定的通用性,可以为未来Cloud-RAN架构和CoMP技术的融合提供参考。     

Size matters: next generation wireless networks[industry forum]

Broadband wireless deployments, so-called fourth generation (4G) networks, are now considered the holy grail for most operators primarily to maintain their revenue growth and, of course, subscriber base. The rapid build-out of wireless fidelity (WiFi) hotspots and planned municipal WiFi networks around the world has further fueled consumer expectations. However, there are problems: broadband wireless is restricted in range and consequently requires a significant number of access points (APs) to make the coverage ubiquitous and reliable. Furthermore, the installation costs of such a large number of wired APs to build a broadband network can make it very unprofitable for Internet providers.     

WiMAX在电力行业的应用模型

W iMAX技术是一项基于IEEE 802.16标准的宽带无线接入城域网(BWAMAN)技术,具有50 km覆盖范围和高达75 M带宽,在解决城域网络数据接入上具有独特的优势。将其应用于电力行业,适当与PLC等技术配合,即可建立由电力通信部门独立运营的W iMAX网络,辅助已有的光纤网络,可以有效解决配网自动化、负荷控制、自动抄表等数据网络急需业务,并且还可以介入宽带接入市场。文章论述了W iMAX技术概要,然后以一个典型的W iMAX与PLC等技术相结合进行配网和小区数据通信的应用模型为例,介绍了网络组织架构,讨论分析了实施过程中存在的难点和问题。     

利用无线宽带技术构建智能配网通信接入方式

智能化电网通信传输平台能实现配电系统正常运行及事故情况下的监测、保护、控制和配电管理,已成为智能化配网调度生产不可或缺的重要支撑.绍兴电力局利用无线宽带技术,完美解决了配网通信“最后一千米”的接入问题.文章介绍了绍兴电力局建设的无线宽带接入网工程,成功实现了智能化配网通信的无线接入,满足了更加快速、便捷、安全的数据传输...     

用电信息采集系统远程应急通道平台设计

目前除有线方式（光纤、PLC）外,多种新型无线通信技术（LTE、WiMax等）也在用电信息采集系统中大量应用。这类通信系统采用基站对区域内大量采集终端进行信息采集和管理,一旦出现故障,会引起大范围电力用户信息无法获取,影响整个电力输配系统的正常运行。设计了一种利用无人机搭建低空无线通信平台的应急方案,并对该场景下的空中无线信道进行了分析和建模,以此为根据,设计了基于宽带正交频分复用技术（OFDM）的远距离上行信道传输方案,并分析了该方案的通信性能和系统容量。仿真结果表明该方案可以满足10 km范围内的远程应急补站。     

基于TDMA的宽带无线应急通信系统实现

文章介绍一种基于TDMA的专网宽带无线应急通信系统的实现方法.首先对专网和公网无线应急通信系统特点进行比较,指出了基于TDMA的宽带无线应急通信系统的优点;然后从组网结构和无线接口方面描述了基于TDMA组网的宽带无线应急系统的框架;最后从网络接入方式、帧同步技术、调制编码技术、QoS保障技术、抗干扰技术方面提出了基于T...     

基于环境中移动运输代理的传感器网络建模

针对大型稀疏传感器网络中的数据获取,本文提出了一种利用环境中普遍存在的移动代理来连接稀疏传感器的网络体系结构和一种2-维网格随机游走分析模型;提出的传感器网络模型由3个抽象层构成,即由无线传感器构成的底层、由各种运输代理构成的中间层和由接入点/中央存储库构成的顶层。具体实现原理是位于中间层的移动运输代理从底层分布的无线传感器收集数据并缓冲数据,然后经过游走运输,最后将从底层的无线传感器收集的数据交付到顶层必要的接入点进行必要的存储和处理,从而实现整个传感器网络的数据获取;理论分析和仿真实验结果表明,提出的基于移动运输代理的传感器网络模型不仅具有较好的鲁棒性和可扩展性,而且相比于基站网络模型和Ad-hoc网络模型,在传感器功率消耗、数据成功率和基础设施投入成本方面有明显的优势。     

光纤综合宽带接入网技术

阐述了光纤综合宽带接入网的特点和构成，研究了系统结构、业务类型、主要接口以及光纤分配网的结构，比较了光纤综合宽带接入网与光纤数字网的系统性能，举例说明了光纤综合宽带接入网在电力系统的应用情况。     

Feasibility study on a highly mobile microwave-band broad-bandtelecommunication system

A prototype of a wireless transmission system has been developed that can transmit multimedia-information data at a maximum rate of 4.608 Mb/s in the 5.2-GHz carrier frequency band. It is based on a multicode transmission scheme that uses cyclic shifted-and-extended M-sequences and is designed for applications such as intelligent transport systems (ITS) and future broadband mobile communication systems. The proposed scheme is highly robust against high-speed multipath fading. The transmission performance of the prototype system was measured in field trials at an outdoor ITS experimental course. The real-time data-transmission rate between the base and mobile stations was 4.608 Mb/s at a vehicle speed of 80 km/h     

慈溪电力应急指挥通信系统的建设

在国家电网公司应急指挥通信系统规划设计的背景下,慈溪供电局结合自身需求组织搭建了一套基于宽带无线专网的应急指挥通信系统。该系统由区域传输网络和指挥调度平台两部分组成。其无线传输网络通过4个基站,结合终端中继实现了全市范围的无线信号覆盖,具备语音、视频及IP数据等综合业务传输能力。系统具有实用性强、业务兼容性好、扩展能力强及数据安全性高等特点。     

Microwave exposure and safety associated with personal wireless telecommunication base stations

There are considerable public concerns regarding the biological effects and safety of microwave exposure from wireless base stations. There have been repeated calls for measures and tools that would reduce the exposure to microwave radiation from cellular mobile telephone operations. The radiated power from a base station antenna can vary from less than 1 to as high as 500 W per channel (or transmitter), depending on the location and type of the antenna used for a cellular communication system. The level of public exposure to microwave energy from any base station varies depending on antenna type, location, and distance from the base station. The microwave exposure a person receives from a base station thus depends on both the distances from the antenna, and the angle below the direction of the main beam.     

一种有效的具有负载意识的按需路由协议

移动Ad hoc网络是由一组无线移动终端构成的临时性网络,不依赖于固定的基站或现有的有线骨干网。由于网络拓扑结构动态变化的特性和网络资源的有限性,开发一种性能优越的Ad hoc网络路由协议是一项具有挑战意义的工作。在本论文中,提出了一种有效的具有负载意识的按需驱动路由方案。该方案将网络负载信息作为路由选路的主要标准。对提出的方案作了仿真,并且和Dynamic Source Routing（DSR）协议进行了比较。结果表明网络负载在总体上得到了平衡,包传递率和平均端到端时延的性能也得到了有效的改善。     

Wireless nomad: Pioneer in an urban residential environment

As wireless Internet use has vastly increased over the last several years, numerous cities, community groups, and individuals have been part of the rapid growth and experimentation with wireless connectivity. Wireless Nomad (WN) is a Toronto, Canada, based Internet Service Provider (ISP) dedicated to converting existing wireless broadband backhaul into services designed to benefit communities. Wireless Nomad's development since 2005 has provided insight into several key areas of wireless Internet deployment: wireless connectivity and shared services, spectrum management, and broadband competition.     

接入网技术的分析与选择

宽带接入网技术是未来通信网发展的关键,并成为近期开发和建设的热点。首先简要介绍宽带接入网技术的发展现状和主要应用,重点介绍了无源光网络(PON)的特点和发展前景;结合电力通信网的现状探讨了电力通信接入网的技术选择,指出将有源和无源宽带光纤接入技术相结合,可以作为电力通信建设接入网的技术策略,对电力通信网的光纤化起到积极的推动作用。