A Novel Outage Capacity Objective Function for Optimal Performance Monitoring and Predictive Fault Detection in Hybrid Free-Space Optical and RF Wireless Networks

This study develops an optimal performance monitoring metric for a hybrid free space optical and radio wireless network, the Outage Capacity Objective Function. The objective function—the dependence of hybrid channel outage capacity upon the error rate, jointly quantifies the effects of atmospheric optical impairments on the performance of the free space optical segment as well as the effect of RF channel impairments on the radio frequency segment. The objective function is developed from the basic information-theoretic capacity of the optical and radio channels using the gamma-gamma model for optical fading and Ricean statistics for the radio channel fading. A simulation is performed by using the hybrid network. The objective function is shown to provide significantly improved sensitivity to degrading performance trends and supports of proactive link failure prediction and mitigation when compared to current thresholding techniques for signal quality metrics.

A survey of free space optical networks

Free Space Optical （FSO） networks, also known as optical wireless networks, have emerged as viable candidates for broadband wireless communications in the near future. The range of the potential application of FSO networks is extensive, from home to satellite. However, FSO networks have not been popularized because of insufficient availability and reliability. Researchers have focused on the problems in the physical layer in order to exploit the properties of wireless optical channels. However, recent technological developments with successful results make it practical to explore the advantages of the high bandwidth. Some researchers have begun to focus on the problems of network and upper layers in FSO networks. In this survey, we classify prospective global FSO networks into three subnetworks and give an account of them. We also present state-of- the-art research and discuss what kinds of challenges exist.

Implementation of access controller for Ethernet passive optical network

This paper presents the design and implementation of access controller used for Ethernet passive optical network （ EPON）. As a first step to develop an ASIC product, the entire system is designed on a field programmable gate array （FPGA） with an embedded CPU. To reduce working frequency of the FPGA, the byte-to-word conversion is proposed. Propagation delays are equalized by ranging procedure so as to avoid data collision. Implementations of synchronization, classification, as well as Linux porting are illustrated in detail. The interface between the FPGA and CPU are also presented. Experimental results show that the proposed system can properly function in a relatively low cost FPGA.

Optical wireless network in home area based on white LED lights

A new optical wireless network based on white LED lights in home area is proposed. It is a duplex channel communication system utilizing signal emitters of white LED lights in the downlink and infrared devices in the uplink. Strategies for the system construction are given. Performance for users＇ mobile access of different kinds of optical concentrators is investigated. Indoor channel band-width is analyzed considering white LED light distribution, wall reflection, and receivers field of view （FOV）. Various modulation methods are discussed. A demo point-to-point system for surfing the net is constructed using a new line code of 4B6B which is developed to stabilize the optical output, and a peak data rate of 1 Mbps is achieved. This system is built into the lighting infrastructure, therefore decreasing the cost and offering a solution for wireless access in places which are sensitive to radio frequency like hospitals.

Wireless Communication Networks' Planning in Underdeveloped Countries

The planning of wireless communication networks in underdeveloped countries is studied for landline telephone, fixed broadband wireless access and PLMN systems via investigation and discussion of the LDC networks＇ characteristic, technology selection, deployment consideration, network configuring, civil work evaluation and investment estimation. An example is embedded all through providing a general

近距无线通信组网拓扑技术

针对精确制导武器的新质作战需求,文中以无线电气设计为核心技术方向实现产品模块化设计,以解决灵活组网、抗毁重构和动态拓扑等问题。采用Ad Hoc组网架构、广义编码和无源多址接入技术,实现快速、灵活、稳定的信息交互。通过混合式路由设计,在金属舱网络中划分子网并实施先应式路由和反应式路由,并引入地界标思想以减少多制式通信影响。通过提前规定所有事件的时序和优先级,建立简易事件类型库,并在节点间备份存储,同时采用边界广播协议实现目的节点快速抵达网关节点。研究结果表明,所提方案满足了武器功能模块化设计的需求,通过无线通信网络的组网和路由协议设计,实现了灵活组网、抗毁重构、动态拓扑和多制式通信等能力特点。

广播电视宽带网络光纤入户方案设计及技术分析

广播电视宽带网络光纤入户方案集成了万兆网际互连协议(Internet Protocol,IP)广播、掺铒光纤放大器(Erbium Doped Fiber Amplifier,EDFA)、分光器、吉比特无源光网络(Gigabit Passive Optical Network,GPON)等关键技术,并将光网络单元ONU(Optical Network Unit,ONU)作为关键桥梁实现了光纤网络与用户设备的连接,满足有线直播和互联网视频点播平台的双向传输需求,通过测试验证了方案的可行性。该方案为广播电视宽带网络光纤入户提供了高效可行的解决方案,从而为用户提供了更优质的观看体验和更强大的网络支持。

基于无线宽带技术的智能配网通信接入方式

针对智能配网通信接入的需求,探讨点对点接入方式、点对多点接入方式、网格网络接入方式等无线宽带技术的智能配网通信接入方式,并提出无线宽带技术在智能配网通信接入中的应用方案。通过研究无线宽带技术在配网终端设备通信、配网集中控制中心和配网分布式控制中的应用,为智能配网通信接入提供一种高效、可靠的技术选择。

光纤传输接入网络中OTN技术的运用研究

为优化光纤传输质量,满足宽带接入的可控化管理需求,要严格遵循光纤传输应用控制的技术规范,有效建立基于光传送网(Optical Transport Network,OTN)技术的光纤传输接入网络,从而维系信息传输的及时性,搭建完整的技术运行框架。应从大颗粒信息传输处理、城域核心网和干线网络、宽带用户接入、长途网应用交叉设备等方面对OTN技术的具体应用内容进行系统化分析,更好地实现网络性能的平滑升级,从而满足城域网建设的具体需求。因此,系统研究光纤传输接入网络中OTN技术的应用要点具有现实意义。

50 GHz optical true time delay beamforming in hybrid optical/mm-wave access networks with multi-core optical fiber distribution

We propose and experimentally validate an optical true time delay beamforming scheme with straightforward integration into hybrid optical/millimeter（mm）-wave access networks. In the proposed approach, the most complex functions, including the beamforming network, are implemented in a central office, reducing the complexity and cost of remote antenna units. Different cores in a multi-core fiber are used to distribute the modulated signals to high-speed photodetectors acting as heterodyne mixers. The mm-wave carrier frequency is fixed to 50 GHz（VBand）, thereby imposing a progressive delay between antenna elements of a few picoseconds. That true time delay is achieved with an accuracy lower than 1 ps and low phase noise.

Optical SDMA for applying compressive sensing in WSN

In order to apply compressive sensing in wireless sensor network, inside the nodes cluster classified by the spatial correlation, we propose that a cluster head adopts free space optical communication with space division multiple access, and a sensor node uses a modulating retro-reflector for communication. Thus while a random sampling matrix is used to guide the establishment of links between head cluster and sensor nodes, the random linear projection is accomplished. To establish multiple links at the same time, an optical space division multiple access antenna is designed. It works in fixed beams switching mode and consists of optic lens with a large field of view（FOV）, fiber array on the focal plane which is used to realize virtual channels segmentation, direction of arrival sensor, optical matrix switch and controller. Based on the angles of nodes＇ laser beams, by dynamically changing the route, optical matrix switch actualizes the multi-beam full duplex tracking receiving and transmission. Due to the structure of fiber array, there will be several fade zones both in the focal plane and in lens＇ FOV. In order to lower the impact of fade zones and harmonize multibeam, a fiber array adjustment is designed. By theoretical, simulated and experimental study, the antenna＇s qualitative feasibility is validated.

SCMA-D2D混合网络卷积自编码器

为满足物联网通信大连接、低功耗的需求,高效利用有限的频谱资源成为一项重要的挑战。在应用了稀疏码分多址接入(SCMA)技术的蜂窝网络中增加设备对设备(D2D)用户对,两者共享频谱资源,可以进一步提高频谱利用率,满足大规模连接和低功耗的通信需求。然而,当不同类型的用户共享相同的频谱资源时会导致严重的用户间干扰,导致多用户检测精度降低,译码复杂度增高。本文使用卷积神经网络(CNN)进行SCMA-D2D混合网络自编码器设计,通过端到端的联合训练,设计出合适的神经网络结构。用CNN单元实现混合网络的编码,学习SCMA蜂窝用户和D2D用户的有效码本;将混合网络的多用户检测问题建模为一个基于共享层机制的多任务分类解码问题,建立多用户分类解码器。实验结果表明,本文提出的自编码器能够生成对系统适应性更强的码本,结合接收端的多任务分类解码器能够有效地提高整个混合网络系统的误码率性能,同时减小译码计算复杂度。

下一代毫米波无线局域网:愿景与关键使能技术

随着信息通信技术的快速发展和广泛部署,人类的生产生活以及社会治理向数字化、信息化、智能化方向不断深入演进。作为应用最广泛的无线通信技术之一,无线局域网(WLAN,wireless local area network)需要在吞吐量、可靠性、时延等关键性能上进一步突破,同时还需要具备感知、智能等新特性。毫米波(mmWave,millimeter wave)巨大的频率资源为无线局域网发展注入了新动能,但同时也带来了新的技术挑战和需求。首先,回顾了无线局域网的发展历程;其次,描述了未来无线局域网的网络结构、典型应用、发展方向和性能指标要求;然后,分析了毫米波频段无线信道特性及其对无线网络设计的新要求、新挑战;最后,对能够适应这些挑战和要求的一些潜在关键技术进行了探讨和展望。

FTTR场景下空间复用与速率联合优化

随着网络技术的飞速发展,用户对家庭场景内网络体验的要求日益增加。FTTR能够在一定程度上解决无线网络连接不稳定的问题。在FTTR架构基础上,介绍了集中式光无线网接入架构,探讨了下一代Wi-Fi协同空间复用技术与速率控制的主要原理,并对当前面临的挑战以及未来的研究方向进行了分析和展望。

面向千兆宽带光纤接入网的网络架构设计

为了探讨面向千兆宽带光纤接入网的网络架构设计及相关挑战,分析关键问题,以提供对未来网络发展趋势的理解。通过对千兆宽带光纤接入网的网络架构设计等关键问题的分析,得出千兆宽带光纤接入网是未来网络发展的趋势,能够提供高速的数据传输和更好的用户体验。在设计千兆宽带光纤接入网的网络架构时,需要考虑网络的可扩展性、灵活性和高效性。千兆宽带光纤接入网的发展是未来网络的趋势,但在实现这一目标时,需要解决网络架构设计、组网、网络安全和隐私保护等关键问题和挑战。通过合理规划和有效措施,建立稳定、高效、安全和隐私保护的千兆宽带光纤接入网,为用户提供更好的网络体验。

PON 技术在接入网中的设计与应用

科学技术带动了宽带网络的发展,宽带网络不仅改变了信息传播的方式,也改变了人们的生活习惯和方式。无源光网络(Passive Optical Network,PON)技术已成为接入网的主流技术,应用PON技术优势,可以进行业务创新、提升运营效率、引领至简体验、实现多方共赢,目前已被广泛应用于小区、楼宇、商务写字楼、校园、企业以及酒店等多种场景,PON技术的大规模使用使接入业务类型的多样化、宽带的速度以及容量都发生了巨大变化。重点阐述PON技术在接入网中的设计与应用,并对PON技术在接入网的发展进行了展望。

宽带光接入网与用户驻地网支持边缘计算的部署方式和关键技术

计算型网络逐步兴起,网络架构向“设备、边缘和云”转型发展。其中,边缘距离用户最近,是网络演进的重要一环。在宽带光接入网和用户驻地网提供边缘计算能力成为重点研究方向之一。首先介绍了在宽带光接入网和用户驻地网支持边缘计算的算力部署位置和部署方式,之后讨论了支持边缘计算需要具备的关键技术。

GPON技术在宽带接入网中的有效应用

千兆无源光网络(Gigabit Passive Optical Network,GPON)技术在宽带接入网中具有广泛的有效应用。首先介绍了GPON技术的基本原理,包括光纤传输基础知识、GPON网络结构以及下行上行传输机制。其次探讨了GPON技术的应用优势,如高带宽和高速率、长距离传输能力、共享网络资源以及低成本和高效率。最后介绍了GPON的应用模式,包括光纤到户(Fiber to the Home,FTTH)和光纤到楼(Fiber to the Building,FTTB)等。在此基础上,详细阐述了GPON技术在宽带接入网中的应用,包括提供高速宽带接入、支持多种业务和服务、实现高质量的视频和音频传输以及支持远程办公和云服务。另外,展望了GPON技术的发展趋势和未来展望,GPON技术在宽带接入网中发挥着重要的作用,并具有广阔的应用前景。

拓展宽带接入的无线Mesh网技术

无线Mesh网(wirelessmeshnetwork,WMN)作为一种新的网络结构,正在成为下一代无线接入研究中的一个热点。本文首先介绍了无线Mesh网的一些基本概念,然后讨论了无线Mesh网中的关键技术,并在此基础上分析了其应用前景,最后介绍了当前的主要商用无线Mesh系统和该技术的标准化进展。

高速铁路公众宽带通信接入体制与关键技术综述

为高速列车旅客提供稳定的宽带无线接入网络服务是需要解决的问题。本文首先比较国内外现有的几种高速铁路宽带无线接入方案,指出它们各自的优缺点;然后阐述在高速铁路特殊场景下公众宽带通信接入网络建设面临的主要难题,包括多普勒频移、多径效应、穿透损耗和快速切换等;最后探讨认知无线电、压缩感知、OFDM、MIMO和RoF等技术在高速铁路公众宽带通信接入网络上应用的可行性。