Fibre to the home – infrastructure deployment issues

To date the use of optical fibre in the access network has typically only proved cost effective for supplying the high-bandwidthdemands of large corporate companies. For new and established network operators, however, the increasing demand forbandwidth to deliver bearer, interactive and bundled services to business and residential customers is requiring them to seriouslyconsider the high volume roll-out of optical-fibre-based systems. Network operators therefore face some major decisions, notonly in terms of the type of fibre transmission systems to deploy, but also on how to install a cost-effective network of fibrecables, ducting and joints to connect to the customers they wish to serve. Installing fibre in the ground represents a majorcommitment and a long term investment. Network operators can typically expected the fibre infrastructure to equate to at least60% of the cost of the overall access transmission system. Planning and building such networks involves major investment at theoutset, and, in todays highly competitive markets, operators are faced with the added complications of uncertain take-up ofservices by customers and the likelihood of high customer churn.This paper focuses on fibre to the home (FTTH) and the deployment options and challenges for the physical fibre infrastructure.The key difference associated with connecting optical fibre to residential properties instead of business properties is not technicalbut commercial. There is typically a much smaller potential revenue from a residential property than from a business property.This leads to a need for cost optimisation of both the transmission system and the fibre infrastructure. This paper examines thefibre infrastructure issues that need to be considered for an FTTH deployment and describes the fibre access network modellingactivities carried out by BTexact's Broadband Network Engineering unit. The aim of this modelling is both to automate theplanning of, and to optimise the costs of deploying, access networks based on real geographical and demographic data.     

FTTH与LTE在农村部署的投资对比

本文首先给出了FTTH和LTE在农村宽带部署的两种接入模型,针对农村复杂地形地貌抽象出了大村模型和小村模型。具体细化了FTTH和LTE在农村部署时的成本因素,提出了FTTH和LTE的投资模型。分别在大村模型和小村模型下,对FTTH和LTE的单用户投资进行了比较。在大村模型下,FTTH接入模型投资小于LTE;而在小村且人口稠密的地方,LTE接入模型投资小于FTTH。     

基于10G EPON的广电FTTH跨越式升级策略

随着数字化、高清化技术的发展,传统的HFC网络面临着巨大的挑战。利用10G EPON技术对广电HFC网络实施FTTH升级改造,可有效兼顾现有网络的光纤资源,以低成本投入实现从光进铜退到千兆入户的跨越式升级。文中分析了基于10G EPON技术的广电HFC向FTTH跨领域迁移的技术方案及应用现状,并结合实际工程建设情况,经过系统性的测试,验证了所提方案的可靠性和实用性。     

基于EPON/GPON的FTTH接入网OAM研究

本文结合国内ADSL宽带接入网运维的实际情况和国外FTTH网络运维方面的成功经验,根据中国电信FTTH现场试验取得的一些成果,面向将来大规模建设FTTH接入网的实际需要和运维技术的发展趋势,系统地分析了FTTH网络运行维护的内容和特点、维护体制与流程、维护手段和方法.     

Modelling of LDMOS transistor using artificial neural networks: DC and RF performances

This article presents an accurate method based on artificial neural networks (ANNs) for DC and RF modelling of laterally diffused metal oxide semiconductor (LDMOS) transistors, under various temperature conditions. In LDMOS transistors, temperature is an effective factor, so the proposed models include this parameter. Two neural networks‐based procedures have been proposed for LDMOS transistor modelling, first for DC and second for RF modelling. In each case, two kinds of neural networks have been used, multilayer perceptron and radial basis function neural networks. Two models are compared to each other in terms of accuracy, and for both of them, an excellent agreement between modelled and measured data is obtained. The ANN model is developed and trained with the help of data obtained by simulation of a Si‐LDMOS transistor using ADS software.     

FTTH网络互通性与运维管理

FTTH网络在我国以及全球都已进入规模部署、广泛应用的阶段，其中局端设备和用户端设备的互通性对于降低组网成本、方便系统管理具有重要意义。本文介绍了目前FTTH网络中异厂商设备互通性的进展，并针对FTTH网络规模部署后运维管理系统架构进行探讨，提出了在FTTH网络中应使用双模管理架构，并详细分析了网络中各种设备的管理方案。     

A comprehensive DCF performance analysis in noisy industrial wireless networks

The use of wireless technology in industrial networks is becoming more popular because of its flexibility, reduction of cable cost, and deployment time. Providing an accurate model to study the most important parameters of these networks, the timeliness and reliability, is essential in assessing the network metrics and choosing proper protocol settings. The Institute of Electrical and Electronics Engineers (IEEE) 802.11 is a common and established wireless technology, and several analytical models have been proposed to assess its performance; however, most of them are accurate only for a limited network situation, especially data networks that have large packet payloads and are used at high signal to noise ratios, and cannot be applied to study the performance of industrial networks that have short packet lengths and are used in harsh and noisy environments. In this paper, a novel three‐dimensional discrete‐time Markov chain model has been proposed for the IEEE 802.11‐based industrial wireless networks using the distributed coordination function as the medium access control mechanism in the worst‐case saturated traffic. It considers both causes of the backoff freezing: busy channel and the successive interframe space waiting time. In this way, it provides a much more accurate estimation of the channel access and error probabilities, resulting in a more accurate network parameter calculation. Also, based on the proposed model, a comprehensive packet delay analysis, including average, jitter, and cumulative distribution function, has been provided for the near 100% reliable industrial scenario and error‐prone channel condition, which in comparison with similar pieces of work provides much more accurate results. Copyright © 2014 John Wiley & Sons, Ltd.     

Geography- and infrastructure-aware topology design methodology for broadband access networks (FTTx)

We present a topology design methodology for broadband (FTTx) access networks. The calculations are based on real geographic data (digital maps) and infrastructural information of the targeted area, using detailed and realistic cost models in order to provide results of practical interest. The developed heuristics offer low time consumption and nearly optimal solutions for the highly complex problem of minimal cost network deployment, due to the properly chosen and customized heuristic algorithms for the various network technologies. We review the specific properties of the FTTx network technologies, present a formal representation of the problem including a detailed cost function and network model and discuss complexity issues. The various solution techniques are presented along with case studies of real-life scenarios in order to show the potential of the methodology. The developed heuristic algorithms offer an approximation of the optimum within 10–15%, while time consumption remains in the range of a few minutes, even for large-scale scenarios with 10,000s of customers. Beyond topology design, the results provided by these methods are useful for a preliminary CAPEX estimation and techno-economic comparison.     

一种旋转、尺度变换和平移鲁棒水印算法

几何攻击是目前困扰数字水印领域发展的问题,现有的抗几何攻击的水印技术存在诸多缺陷和不足.本文提出一种基于时域的抗几何攻击水印技术,利用边框这一简单的图形通过对其检测和提取,完成对几何失真参数的检测.考虑到实际应用中存在噪声的影响,用中值滤波和锐化增加了几何参数估计的鲁棒性.利用检测获得的几何失真参数对图像进行校正,使图像基本恢复原图从而无失真地提取水印.同时本文探讨了诸多文献尚未提及的几何失真恢复问题,提出一种模板匹配的方法恢复图像.仿真实验证明,该方法在含水印图像受到几何攻击后,仍可无失真地提取水印.     

SOI-KF: Distributed Kalman Filtering With Low-Cost Communications Using the Sign of Innovations

When dealing with decentralized estimation, it is important to reduce the cost of communicating the distributed observations-a problem receiving revived interest in the context of wireless sensor networks. In this paper, we derive and analyze distributed state estimators of dynamical stochastic processes, whereby the low communication cost is effected by requiring the transmission of a single bit per observation. Following a Kalman filtering (KF) approach, we develop recursive algorithms for distributed state estimation based on the sign of innovations (SOI). Even though SOI-KF can afford minimal communication overhead, we prove that in terms of performance and complexity it comes very close to the clairvoyant KF which is based on the analog-amplitude observations. Reinforcing our conclusions, we show that the SOI-KF applied to distributed target tracking based on distance-only observations yields accurate estimates at low communication cost     

电力光纤到户光缆监测系统的设计

电力光纤到户工程是国家电网公司智能电网建设的重要组成部分,随着智能电网建设的不断推进,光纤到户部署的规模将不断扩大,网上光缆数量急剧增加,如何维护这些光缆是迫切需要解决的问题。电力光纤到户光缆监测系统采用了PON网络通信、光学测量、地理信息系统等技术,很好地解决了FTTx网络中PON光纤资源的监控,同时能兼顾对接入、汇聚、骨干层光缆网络的监测管理。通过集中的自动维护方式,系统能及时地反映光缆的运行状况,在光缆出现故障时,能够快速测试、准确定位。     

建设灵活的低成本的FTTH网络

针对FTTH建设中存在的问题、成本构成进行了分析,提出了建设灵活的、低成本的FTTH网络的思路和技术措施;结合实际场景分光器的应用对端口利用率的影响进行了探讨,对FTTH设计、建设提供参考。     

Cost and quantity analysis of passive double-star optical-access-network facilities for broadband service multiplexing

In this paper, the authors propose the most suitable passive double-star network (PON) configuration for multiplexing more than two kinds of broadband service by wavelength division multiplexing (WDM) in optical access networks. They calculate the cost and number of facilities in outside plant and central offices by using the latest cost trend and investigate their dependence on certain structural conditions such as the number of splits, network configuration, and fiber structure, and service conditions such as multiplexing service number and service penetration. Moreover, the required network configuration for multiplexing more than three services was investigated. As a result, the most suitable PON network for cost-effective service provision and fiber to the home (FTTH) deployment was determined.     

FTTx用光纤光缆

FTTx是光通信发展的必然趋势,也是当前光网络发展的最大推动力.FTTx用光缆根据其在网络中的不同位置,总体上可划分为馈线光缆、配线光缆、入户光缆.对这三类光缆的特点、典型的结构和技术进展分别进行了介绍.此外,具有优异弯曲性能的G.657光纤是FTTH系统的核心产品之一,对其国内外技术和标准的发展也进行了对比分析.     

A statistical modeling approach to location estimation

Some location estimation methods, such as the GPS satellite navigation system, require nonstandard features either in the mobile terminal or the network. Solutions based on generic technologies not intended for location estimation purposes, such as the cell-ID method in GSM/GPRS cellular networks, are usually problematic due to their inadequate location estimation accuracy. In order to enable accurate location estimation when only inaccurate measurements are available, we present an approach to location estimation that is different from the prevailing geometric one. We call our approach the statistical modeling approach. As an example application of the proposed statistical modeling framework, we present a location estimation method based on a statistical signal power model. We also present encouraging empirical results from simulated experiments supported by real-world field tests.     

Constraint-Based Geolocation of Internet Hosts

Geolocation of Internet hosts enables a new class of location-aware applications. Previous measurement-based approaches use reference hosts, called landmarks, with a well-known geographic location to provide the location estimation of a target host. This leads to a discrete space of answers, limiting the number of possible location estimates to the number of adopted landmarks. In contrast, we propose Constraint-Based Geolocation (CBG), which infers the geographic location of Internet hosts using multilateration with distance constraints to establish a continuous space of answers instead of a discrete one. However, to use multilateration in the Internet, the geographic distances from the landmarks to the target host have to be estimated based on delay measurements between these hosts. This is a challenging problem because the relationship between network delay and geographic distance in the Internet is perturbed by many factors, including queueing delays and the absence of great-circle paths between hosts. CBG accurately transforms delay measurements to geographic distance constraints, and then uses multilateration to infer the geolocation of the target host. Our experimental results show that CBG outperforms previous geolocation techniques. Moreover, in contrast to previous approaches, our method is able to assign a confidence region to each given location estimate. This allows a location-aware application to assess whether the location estimate is sufficiently accurate for its needs     

FTTH网络中的ONT管理方案探讨

FTTH网络是宽带光接入网的发展方向,可以为用户提供更高的带宽,但在FTTH网络建设中,ONT设备的管理是需要关注的一个问题。本文介绍了目前PON网络ONT的管理机制和家庭网关的管理机制,并在此基础上对FTTH网络中PONONT与家庭网关功能融合的ONT设备的远程管理机制进行了探讨。     

Optical amplifiers for video distribution

The promise of a broadband fibre communications network has attracted the interest of CATV and Telco concerns. Various networks and topologies have been discussed. Cost is a drawback in some of the proposed networks, particularly those networks which require switching. This paper discusses a low cost broadcast tree and branch network which uses optical amplifiers to extend the network penetration. Recent work in the development of optical amplifiers suggests that the Erbium fibre amplifier may be compatible with VSB-AM. The characteristics of such an amplifier will be discussed. This scenario allows an orderly transition from the present-day AM backbone system to the tree and branch fibre architecture. Once the broadband fibre plant is in place new services can be implemented that exploit the broadband nature of fibre.     

On Accurate Energy Consumption Models for Wireless Ad Hoc Networks

Energy conservation is important for ad hoc networks. However, little effort has been made to carefully study the energy cost metrics upon which the design of various energy efficient algorithms is based. More specifically, most existing energy consumption models only considered energy cost of exchanging data packets, although common wireless protocols also need control packets (e.g., ACK) for reliable data transmissions. Without considering the energy cost of exchanging control packets, these existing models tend to underestimate the actual energy consumption, and thus leading to suboptimal energy efficient designs. In this paper, we develop energy consumption models that take into account energy consumption due to data packets, control packets and retransmission. We verify by simulations that our models match the actual energy consumption much better than existing models. In addition, we show that a minimum energy routing protocol based on an accurate model of ours performs much better than those based on existing models     

Traffic modeling for telecommunications networks

As new communications services evolve, professionals must create better models to predict system performance. The article provides an overview of computer simulation modelling for communication networks, as well as some important related modelling issues. It gives an overview of discrete event simulation and singles out two important modelling issues that are germane to extant and emerging networks: traffic modelling and rare event simulation. Monte Carlo computer simulation is used as a performance prediction tool and Markov models are considered