A Solution to Optimizing Access Networks

1　ＴｈｅＰｒｅｓｅｎｔＳｉｔｕａｔｉｏｎｏｆＡｃｃｅｓｓＮｅｔｗｏｒｋｓ　　Ｉｎｔｅｒｎａｔｉｏｎａｌｃｏｍｍｕｎｉｃａｔｉｏｎｉｎｆｏｒｍａｔｉｏｎｔｅｃｈ ｎｏｌｏｇｉｅｓａｒｅｎｏｗａｄａｙｓｉｎｎｏｖａｔｉｎｇｇｒｅａｔｌｙ .Ａｎｄｔｈｅｈｉｇｈ ｔｅｃｈｉｓｗｅｌｌｉｎｇｕｐｃｏｎｔｉｎｕｏｕｓｌｙ .Ｔｈｅｔｅｌｅｃｏｍ ｍｕｎｉｃａｔｉｏｎｎｅｔｗｏｒｋｉｓｅｖｏｌｖｉｎｇｉｎｔｈｅｄｉｒｅｃｔｉｏｎｏｆｔｈｅｓｔｒａｔｉｆｉｃａｔｉｏｎｄｉｍｉｎｕｔｉｏｎａｎｄｔｈｅａｕｇｍｅｎｔｏ…     

A Distributed Intranet/Web Solution to Integrated Management of Access Networks

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＡｃｃｅｓｓＮｅｔｗｏｒｋｉｓａｓｅｒｉｅｓｏｆｔｒａｎｓｆｅｒｅｎｔｉ ｔｉｅｓｂｅｔｗｅｅｎｓｅｒｖｉｃｅｎｏｄｅｉｎｔｅｒｆａｃｅｓａｎｄｔｈｅｒｅｓｐｏｎ ｄｅｎｔｕｓｅｒｎｅｔｗｏｒｋｉｎｔｅｒｆａｃｅｓ,ｐｒｏｖｉｄｉｎｇｔｒａｎｓｆｅｒ ｒｉｎｇ ,ｍｕｌｔｉｐｌｅｘｅｒ,ｃｒｏｓｓ ｃｏｎｎｅｃｔｉｏｎａｎｄｏｔｈｅｒｌｏａｄｔｅｌｅｃｏｍｍｕｎｉｃａｔｉｏｎｓｅｒｖｉｃｅｓ[1 ] .ＡｓｔｈｅＣｏｍｍｕｎｉｃａ ｔｉｏｎＴｅｃｈｎｏｌｏｇｉｅｓｄｅｖｅｌｏｐ…     

一种简易的局域网拨号接入服务配置与网络资源共享方案

本文介绍一种简易的局域网拨号接入服务配置与网络资源共享方案。该方案是在局域网内以Windows98为系统平台的PC上实现的，使工作人员可在家中或其他有电话线的地方方便地通过实验室的局域网连接到校园网乃至互联网并使用其中的资源，从而可以有效的缓解目前普遍存在的拨号上网困难的问题。     

Single-Fiber Access/Metro WDM Ring Architecture for Asymmetric Traffic Applications in Next Generation Networks

The next generation network (NGN) and the speed-up of access lines will sharply increase the demand for one-way applications such as internet protocol television (IP TV) and video on demand (VOD). One-way applications make the downlink bandwidth much larger than the uplink bandwidth. Asymmetric traffic is best supported by using different numbers of wavelengths in the uplink and downlink, which presumes the use of a wavelength division multiplexing (WDM) network. Unfortunately, the existing 2- or 4-fiber ring network architecture is symmetric, and so it cannot efficiently accommodate asymmetric paths. This paper proposes a novel 1-fiber WDM protection ring that offers a cost-effective optical network architecture for asymmetric traffic as well as symmetric traffic. It also proposes a new 1:1 protection switching scheme and automatic protection switching (APS) control protocol that can reduce capital expenditures for optical-electro-optical termination cards and provide nonrevertive protection switching with extra traffic and APS with end-to-end supervision including optical switching fabrics. Moreover, this paper shows that the proposed wavelength switching scheme offers much better network survivability after multiple wavelength failures than the existing bidirectional switching scheme can offer.     

Applications of 40-Gb/s Chirp-Managed Laser in Access and Metro Networks

We investigate 40-Gb/s cost-efficient transmitter for access and metro networks. This 40-Gb/s transmitter comprises a standard directly modulated distributed-feedback (DFB) laser and a subsequent optical filter. Large dispersion tolerance of this transmitter is realized by chirp control through the phase correlation between adjacent bits for the destructive interference in order to erase the power of “0” bits while enhancing the extinction ratio. The chirp model of the DFB laser and the optimum parameters of the optical filter have been numerically analyzed. The chirp-managed 42.8-Gb/s transmission over 20-km standard single mode fiber (SSMF or SMF-28) without dispersion compensation and a centralized lightwave WDM-PON system are experimentally demonstrated. We have also realized the transmission over 100-m graded index plastic optical fiber (GI-POF). Moreover, the application in the metro network over 240-km SSMF or SMF-28 has also been investigated in this paper.      

移动城域网数据业务接入解决方案

文章根据移动城域网数据业务接入的两个发展阶段,探讨了两种接入模式下移动城域网的建设方案,分析了在网络转型时期,移动城域网的发展方向及建设重点。     

A Simple and Closed-Form Access Delay Model for Reliable IEEE 802.11-Based Wireless Industrial Networks

With the ongoing popularity of the IEEE 802.11 standard, many analytical studies for the distributed coordination function (DCF) have been reported but due to lack of a comprehensive model, the research has been going on. In this paper, three probabilistic analytical access delay models have been proposed for the IEEE 802.11 DCF mechanism in saturated traffic and noisy industrial applications. The first and second one provide an accurate packet delay model by solving non-linear equations at low and high Signal to Noise Ratios (SNRs) respectively. The third one on the other hand offers an approximate and simple closed-form model which does not need solving any non-linear equation and therefore can easily be utilized in the distributed adaptive network quality of service provisioning algorithms for industrial nodes which usually have limited processing capabilities. Delay-reliability, delay-packet payload and delay-data rate tradeoffs has also been studied. Simulation results match the theoretical derivations in most SNRs, confirming the effectiveness of the proposed models.     

随时随地远程安全访问网络升级方案——Cylan(赛蓝)SSL VPN成功应用于天津财政系统

用户需求天津市财政局是天津市人民政府综合管理经济的职能部门。为了扎实做好"有为、务实、高效、和谐、廉政"工作,财政局安全信息化在经济建设过程中发挥的作用也越来越明显,财政局也相当重视。信息交流不断网络化、信息化,保障信息数据在公网上的安全传输已成为天津市财政局急待解决的问题。如何在不影响现有网络正常使用的情况下平滑升级现有网络,且达到相应的安全标准,使下属单位及出差员工能够随时随地访问天津财政系统,成为天津市财政局安全信息化升级的一个难点。     

A Low-Cost Inband FEC Scheme for SONET/SDH Optical Metro Networks

A novel inband forward-error correction (FEC) method, devised for the electronic-mitigation of physical optical transmission impairments, is implemented and experimentally demonstrated. The proposed inband-FEC scheme, Free-Of-Charge Uniform Shield (FOCUS), is an inherently low-cost approach, applicable to standard synchronous digital hierarchy/synchronous optical network rates, allowing optically transparent signal propagation over longer distances. The performance/efficiency of the FOCUS method is evaluated in terms of tolerance against optical signal-to-noise ratio degradation and chromatic-dispersion, associated with the signal transmission over standard single-mode fiber. Bit-error-rate measurements and coding gain calculations at the standard STM-64 rate (9.953 Gb/s) reveal significant coding-gain improvement for all cases examined     

三网融合的几种接入技术

用户接入网(AN:Access Network,简称“接入网”)是泛指用户网络接口(UNI)与业务节点接口(SNI)间实现传送承载功能的实体网络,是从本地交换机到用户终端之间的实施系统,主要连接的相关设备包括交换机和用户终端设备。为了适应信息业飞速发展的新形势,接入网的宽带接入技术也呈现了新的发展态势。XDSL系统(包括HDSL、ADSL、VDSL、UADSL、EDSL)、HFC网技术、基     

解决接入网"瓶颈"的有效方案--宽带无线接入系统

本文介绍了宽带无线接入系统 3 .5G、2 6GLMDS技术特性及市场应用     

A Directory Service for Perspective Access Networks

Network fragmentation occurs when the accessibility of a network-based resource to an observer is a function of how the observer is connected to the network. In the context of the Internet, network fragmentation is well known and occurs in many situations, including an increasing preponderance of network address translation, firewalls, and virtual private networks. Recently, however, new threats to Internet consistency have received media attention. Alternative namespaces have emerged as the result of formal objections to the process by which Internet names and addresses are provisioned. In addition, various governments and service providers around the world have deployed network technology that (accidentally or intentionally) restricts access to certain Internet content. Combined with the aforementioned sources of fragmentation, these new concerns provide ample motivation for a network that allows users the ability to specify not only the network location of Internet resources they want to view but also the perspectives from which they want to view them. Our vision of a perspective access network (PAN) is a peer-to-peer overlay network that incorporates routing and directory services that allow network perspective-sharing and nonhierarchical organization of the Internet. In this paper, we present the design, implementation, and evaluation of a directory service for such networks. We demonstrate its feasibility and efficacy using measurements from a test deployment on PlanetLab.     

A C/L-Band Gain-Clamped SOA-Raman Hybrid Amplifier for CWDM Access Networks

We demonstrate an 83-nm flat gain-bandwidth gain-clamped semiconductor optical amplifier-Raman hybrid amplifier for coarse wavelength-division-multiplexing (CWDM) access networks. Four channels of 2.488-Gb/s CWDM signals were amplified and the input dynamic range for 1-dB bit-error-rate power penalty exceeds 17.3 dB.     

Polarization-Insensitive All-Optical Upconversion for Seamless Integration Optical Core/Metro/Access Networks With ROF Systems Based on a Dual-Pump FWM Scheme

We have proposed and experimentally demonstrated a novel scheme to realize polarization-insensitive all-optical upconversion for single-channel or wavelength-division multiplexing signals. This scheme is based on the copolarized-pump four-wave mixing effect in nonlinear media. The copolarized pump is generated by using optical carrier suppression in an external intensity modulator; therefore, the two pumps are always parallel and phase locked. This scheme has some unique advantages for the integration between optical transport networks and radio-over-fiber systems, such as a polarization-insensitive, low-frequency bandwidth requirement for optical and electrical components, and high wavelength stability.      

面向数字接入的高速Modem解决方案

简单介绍了AD公司面向网络的高速ModemA开发芯片－ADSP－21mod870的结构和特点,继而详细阐述了基于其的面向数字接入的高速Modem解决方案,并对开结构体系和工作流程进行了具体的简述,最后进行了总结和展望。     

地铁公网泄漏电缆四缆接入方案

随着5G技术的发展,地铁中公网通信也需要考虑5G覆盖,地铁公网通信是采用泄漏电缆来实现的,相应的泄漏电缆数量也要是4根.本文对三大运营商进入地铁的十几个系统进行了互调干扰分析,给出了各系统在4根漏缆中分配的建议.     

宽带无线接入网中的RS编译码硬件解决方案

提出了欧氏算法和IDFT相结合的RS码流式解码方案,并在FPGA芯片上予以实现。计算机仿真和实测表明,该方案在GF(28)的符号速率可达50MHz以上,最大延时为640ns,满足了高速宽带无线接入网中抗干扰编译码的需求。     

A New Solution for Simple Cooperative Relaying

In this paper we present a new simple cooperative relaying scheme. The proposed scheme is compared with simple cooperative schemes with virtual orthogonal space time block coding (OSTBC) and quasi orthogonal space time block coding (QOSTBC). Every of these three schemes includes one base station with two antennas, two relay stations each with a single antenna and one mobile station with a single antenna. The aim of the proposed scheme is to preserve, as much as it is possible bit error rate (BER) performance of the cooperative scheme with virtual OSTBC, but with increased code rate. It is shown that the presented scheme obviously outperforms simple cooperative scheme with virtual QOSTBC, while in comparison with simple cooperative scheme with virtual OSTBC has very similar BER performance and increased code rate.     

一种全业务宽带接入的实现方案

该方案把CWDM技术应用于光接入网,能够实现语音、数据、视频全业务的接入。方案中通过复用器的级联, 很方便的兼容现有的SDH系统。对光通路作了细致的分析并提出相关的对策。     

一种适用于IBSS网络的无线接入认证协议

针对目前无线局域网接入认证协议WAPI与RSNA在IBSS模式下运行复杂及密钥管理协议存在DoS攻击等问题,该文采用实体认证角色的自适应选择策略,对密钥管理协议进行改进,提出了一种安全性更强、执行效率更高的适用于IBSS网络的无线接入认证协议,并利用CK模型对其进行了分析。分析结果表明：在密钥加密算法是CCA安全及密钥导出算法是伪随机的前提下,协议在UM下是SK-secure的。最后,以WAPI协议为例,给出新协议与原始协议的性能对比。