宽带有线接入网技术及其比较

从基于双绞线的ADSL技术，基于HFC网的Cable Modem技术，基于五类线的以太网接入技术及光纤接入技术等方面，详细介绍和分析比较了宽带有线接入网技术。     

Economics of residential broadband access network technologies andstrategies

This article presents a techno-economic assessment of the evolution of the access network segment toward broadband data service delivery, including in-depth sensitivity analysis of key issues faced by the infrastructure providers. The line costs and payback periods of different access network technologies for infrastructure broadband upgrades are examined, subject to variation in parameters like the existing infrastructure, the broadband take rate, civil work costs, revenues, and rollout year. The work should enable establishment of guidelines for broadband infrastructure upgrade strategies     

PON与无线接入网协同发展关键技术研究

随着全业务的发展和中国移动“4+1网络协调发展”战略的提出,作为有线宽带接入主流技术的PON与无线接入网的结合更加紧密.本文结合中国移动WLAN、C-RAN和TD Femto无线接入需求,分析了PON与无线接入网协同发展的关键技术、发展策略和后续研究方向,主要包括PON支持WLAN回传、C-RAN传输和UniPON技术...     

下一代多波长光接入网关键技术分析

介绍了WDM-PON系统的基本结构以及运行原理,重点分析和探讨了其中涉及到的关键技术,主要包括多波长光源、波分复用器、ONU光源、接收机等光器件方面的问题.此外,还对光网络的保护和恢复以及如何承载广播业务等关键问题进行了深入探讨.最后,分析了WDM-PON未来的研究方向,并提出了应用前景.     

固定无线宽带接入技术

1无线接入网概述 无线接入网又称为无线本地环路(WLL),由无线基站和用户单位组成.无线基站包括基站收发信机、基站控制器,它提供一个面向程控交换机的标准网络接口V5接口和面向用户侧的空中接口,并完成无线接口的认证和保密、无线资源管理、用户单位登记、路由选择、计费维护以及协议转换、语言与数字的代码转换等功能.用户单元包括收发信机,并提供一个面向基站的无线接口和而向用户的传统接口.传统接口实现协议转换、代码转换、认证、本地供电等功能.交换机与基站之间用数字传输系统相连.基站把网络侧进来的复合网络标准的数字信号,转换成数字空中接口信号.用户单元接收机站送来的无线信号,并将其转换成为模拟信号或者标准数字信号,再用有线手段与用户设备相连.     

Broadband access using wireless-over-fibre technologies

This paper describes a number of wireless-over-fibre technologies for broadband access which are being investigated in the Photonics Group at University College London (UCL). In particular, the paper will report the asymmetric Fabry-Perot modulator/detector (AFPM), functioning not only as an optical modulator in the uplink direction, but also as a conventional photodetector in the downlink direction in a single device. Compared to the existing waveguide type electro-absorption modulator, the AFPM is polarisation-insensitive to light, simpler to fabricate and uses only a single optical fibre for both uplink and downlink transmissions, and therefore has the potential to lower the costs of future picocell deployments. Direct modulation of a semiconductor laser is the simplest way to generate modulated optical signals. In the presence of multiple large modulation signals, however, intermodulation or inter-channel distortion can easily be generated in the semiconductor laser and affect other lower power neighbouring channels. A feed-forward linearisation technique for directly modulated semiconductor lasers, capable of operating at frequencies above 5 GHz, has been developed and will be described in detail in this paper. Most modern commercial buildings already have a multimode optical fibre (MMF) infrastructure for carrying the Ethernet data. To provide cost-effective and reliable indoor cellular and wireless local area network (WLAN) coverage without dependence on the radio penetration from outside base-stations, it is highly desirable that the same MMF infrastructure be used to carry these additional services between the equipment room and the remote antenna units around the building. Although not previously regarded as having sufficient bandwidth, it has now been shown that MMF can successfully carry microwave modulated optical signals, including GSM1800 and UMTS cellular radio. Use of MMF for multiservice, multioperator in-building radio coverage has been demonstrated in a collaboration between UCL and the University of Cambridge and will be described in this paper. As the number of cellular and broadband WLAN devices increases, the lower parts of the radio spectrum are becoming more and more congested. To meet the demand for ever higher data transmission rates, other parts of the radio spectrum are being considered for these applications, particularly the millimetre-wave region (30 GHz and above). One of the challenges facing such systems is the generation and delivery of a low phase noise precisely synchronised local oscillator signal. In this paper, a simple optical heterodyne source with two injection locked slave lasers and a more environmentally robust source using an optical injection phase lock loop will be described, together with signal distribution using a bidirectional semiconductor optical amplifier in a coarse wavelength division multiplex fibre ring architecture. Finally it will be argued in the conclusions that future broadband wireless-over-fibre access networks will be required to provide multiservice and multi-operator coverage for buildings, and having the required technologies at sufficiently low cost will be the key factor to success.     

Fixed wireless routes for Internet access

The author discusses the use of fixed radio access in urban and rural locations for Internet access. The costs involved are discussed and compared to wired access costs. The frequency bands available are considered as are the propagation conditions and antenna aspects     

Fixed wireless access: An overview

This paper is intended to provide an overview of wireless local loop (wll) today, i.e. the access to final customers through radio systems; this domain covers a wide range of applications, from telephony in rural areas or in developing countries to broadband access offered by alternate carriers in developed countries. A number of technical concepts are common to all these applications (radio transmission, radio access control, management of active devices in the distribution network, propagation, spectrum issues), but actual products and services are very different - from cheap, well-proven DECT equipment for basic telephony to expensive broadband LMDS prototypes for 2 Mbit/s (or ? ? 64 kbit/s) services and fast internet access.     

An overview of broad-band access technologies

The provision of broad-band services based on either the Internet or the asynchronous transfer mode (ATM) technique requires a new generation of access networks. In the short term, solutions such as x-digital subscriber line (DSL) and hybrid fiber coaxial (HFC), allowing the reuse of existing infrastructures look very promising. For the longer term, new infrastructures based either on radio or on optical access links seem preferable. Three x-DSL techniques aiming at high-bit-rate transmission over twisted pairs are presented: high-bit-rate DSL, asymmetrical DSL, and very-high-bit-rate DSL. An extension of existing cable television networks known as HFC is also described. Two other prospective approaches, wireless in the loop (WITL) and fiber in the loop (FITL), are then presented. Several techniques are considered for WITL: digital enhanced cordless telecommunication local multipoint distribution service, wireless ATM, and low Earth orbit satellite constellations. The various architectural alternatives for the FITL approach are discussed, a special interest being dedicated to the synchronous digital hierarchy self-healing loop and the ATM over a passive optical network. We mention the main experiments and the standardization activities inherent to the domain     

FSO与其它接入技术的比较

光纤是目前最新的宽带接入方式,使用光纤技术的网络速度不断提高,但在解决“最后一公里”接入问题时,存在着许多局限性,如施工成本较高;初装费用高,灵活性差,升级费用高;扩展性差,施工周期长等。自由空间光通信技术(FSO: FreeSpace Optical)是一种新型无线接入技术。FSO能在空气中用激光或光脉冲在THz光谱范围内传输分组数据。因无需申请无线频率,起始投资低,运营费用低,且可以提供与光纤系统相似的传送带宽。尤其在有难以逾越的布线障碍或对建网速度要求快的情况下,或对经常需搬迁的机动性单位,FSO能在楼宇之间成为替代光纤的一种网…     

Fixed low-frequency broadband wireless access radio systems

This article provides an overview of a fixed low-frequency broadband wireless access system for point-to-multipoint voice and data applications. The operating frequency bands are from 2 to 11 GHz, and the base station can use multiple sectors and will be capable of supporting smart antenna technology. The product system requirements, design of the radio subsystem specification, as well as an analysis of microwave transmission related to current radio technologies are presented. Examples of BWA technology are provided courtesy of Harris Corporation     

城域光网络的实现技术

城域多业务传输平台是新一代城域网发展的必然产物,它集光/电,传输,交换/路由一体化于一身,可简化网络,降低成本,降低功耗,使管理和维护更加容易。构建城域多业务传输平台的不同技术在运用范围和演进方式上有很大的不同,不同运营商在城域网的建设中可以组合不同的技术实现各自不同的方案。新一代SDHNG SDH是建立在传统SDH上,增强SDH处理TDM业务,特别是分组业务的能力。NG SDH除保持传统SDH的能力外,大大改善了分组的带宽管理,具有比传统SDH更大的灵活性。NG SDH使用新的复用技术组合多协议业务进入标准或级联的SDH虚容器中。…     

光网络热点技术综述

目前光网络的发展已从狂热追捧回归到理性发展,逐渐集中到切实解决阻碍光网络发展普及的技术障碍的正确轨道上来了。本文综述了近期光网络研究的热点:关键器件、网络控制与管理、故障管理、光组播技术、IP over WDM、流量整合疏导、光分组交换和智能自动交换光网络等。