一种有线无线一体化的集团用户接入系统及其实现

有线无线一体化技术是通讯网的发展趋势。介绍了如何对现有的有线接入系统进行改进,并增加对无线业务的处理,从而实现了针对集团用户的有线无线一体化的综合接入系统。     

一种集成无线和有线信号的混合接入系统研究

为了满足不同高带宽业务的需求,提出一种同时传输有线和无线信号的混合接入网系统。在下行链路中,无线信号以相位调制格式在光载波上传输,有线信号以强度调制格式重调制在光载波上,在ONU(光网络单元)采用不同的解调方案进行解调接收;在上行链路中,通过载波重用技术再调制有线基带信号并将其传输至OLT(光线路终端),简化了系统的器件配置。利用光学软件Optisystem验证了系统的可靠性和有效性。仿真结果显示,无线链路信号和有线基带信号经过正交调制传输后,在用户端仍能得到较好效果的眼图,说明它们能被准确地接收。采用载波重用技术的上行基带信号也能被OLT准确地接收。     

有线无线混合接入RoF系统的Optisystem实验仿真

随着光纤无线(Radio-over-Fiber,RoF)技术逐渐成熟,下一代光接入网致力于提供有线和无线双重服务.采用Optisystem光通信仿真软件搭建了加载差分相移键控(DPSK)相位调制数据格式的有线与无线混合接入RoF系统模型,利用光分插复用器(IL)实现毫米波与基带信号的同时调制与传输.毫米波和基带信号的频谱图和眼图的仿真结果验证了该系统的有效性与可靠性.     

The wired/wireless, instant access, data, and media trial at IEEE NOMS 2000

The networking infrastructure provided at the IEEE NOMS 2000 conference in Honolulu in April 2000 was a field trial of new electronic technologies and services for hotels, conference centers, and meeting events. Its essential elements were immediate and transparent network access, both wired and wireless physical access, and media services including an online database of keynote presentations, proceedings papers, and audio/visual multicasts. This article introduces the services concepts, the technology behind them, and the lessons learned from the NOMS 2000 field trial.     

有线无线混合接入RoF系统结构分析与验证

随着用户需求的不断增加,能提供有线无线混合接入的光纤无线(RoF)系统成为了新的研究热点.在分析比较国内外混合接入技术的基础上,设计了一种波长交织(WI)密集波分复用( DWDM)的全双工混合接入RoF系统,实验仿真初步证实了该系统的有效性.     

Multi-service small-cell cloud wired/wireless access network based on tunable optical frequency comb

In this paper, we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network (C-RAN) based on radio-over-fiber passive optical network (RoF-PON) system, which utilizes scalable multiple-frequency millimeter-wave (MF-MMW) generation based on tunable optical frequency comb (TOFC). In the baseband unit (BBU) pool, the generated optical comb lines are modulated into wired, RoF and WiFi/WiMAX signals, respectively. The multi-frequency RoF signals are generated by beating the optical comb line pairs in the small cell. The WiFi/WiMAX signals are demodulated after passing through the band pass filter (BPF) and band stop filter (BSF), respectively, whereas the wired signal can be received directly. The feasibility and scalability of the proposed multi-service wired/wireless integrated C-RAN are confirmed by the simulations.     

多种用户接入方式和综合认证平台建设

本文论述了基于RADIUS协议的认证平台的现状和多用户接入情况下的综合认证需求，并对宽带接入的业务属性和业务流程对认证的需求进行了分析。     

对光纤用户接入设备的探讨

介绍了用户接入网的发展, 光纤用户接入设备的组成和功能, 光纤用户接入设备与交换机远端用户模块、用户数字环路设备的比较,以及光纤用户设备引入对本地网建设的影响。     

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。     

Fixed broadband wireless access: state of the art, challenges, andfuture directions

This article provides an overview of fixed broadband wireless access technology. Focusing on the band below 3 GHz, we describe BWA service and carrier needs, deployment scenarios, architectural requirements, physical layer, medium access control, and radio link protocol requirements. We characterize fixed BWA channels, outline the major challenges of fixed BWA, and study requirements for future BWA systems. Finally, we show that the use of multiple antennas at both ends of a fixed wireless link provides significant leverages     

QoS issues in the converged 3G wireless and wired networks

The Internet evolution delineated through the last years has urged the wireless network community to support the deployment of IP multimedia services with guaranteed quality of service (QoS) in 3G wireless networks. This article copes with the interoperability between 3G wireless networks and wired next-generation IP networks, for the provision of services with an a priori known quality level over both environments. More specifically, the UMTS architecture as well as a prototypical implementation of the next-generation Internet based on DiffServ are considered. The article focuses on the mapping among the traffic classes of the two networks at the point where the networks converge, and discusses the requirements and possible solutions for their proper interworking at the signaling and user levels. Simulations prove that proper mapping among the traffic classes of each world is necessary in order to achieve the desired end-to-end traffic characteristics.     

职业学院有线无线网络融合设计

随着无线网络技术的发展,职业学院在网络的规划和建设中需要充分考虑无线网络的重要性和无线网络建设需求。文章就职业学院网络建设进行分析和设计。     

Experimental assessment of RED in wired/wireless networks

The Internet is a heterogeneous environment comprising wired and wireless components, and transport protocols with different error recovery strategies. We use simulations to study the behaviour of random early detection (RED) gateways in such heterogeneous environments. We investigate two issues: (i) the performance trade‐offs of the dropping policy of RED over Drop‐Tail's, and (ii) the impact of RED's active queue management on more sophisticated protocols such as TCP‐SACK. Some of our results indicate that RED does not deal adequately with heterogeneity. In particular, it may happen that RED applies congestion avoidance techniques even when wireless errors force some senders to back off prior to actual congestion. Our scenarios involve a non‐monotonic transmission behaviour of transport protocols within one and the same congestion epoch; RED may escalate further bandwidth under‐utilization by applying false congestion avoidance tactics. Furthermore, our results indicate that RED's dropping policy of ‘proportional’ fairness, which is realized through a Send‐more/Drop‐more scheme, can also penalize sophisticated protocols like TCP‐SACK, which attempt to recover more aggressively from wireless losses. In summary, our results call for further investigation of RED's efficiency in heterogeneous networks and naturally raise the concern of RED's compliance with the end‐to‐end argument. Copyright © 2004 John Wiley & Sons, Ltd.     

太赫兹无线和有线融合通信技术的研究与展望

随着5G的移动互联及物联网相交织等新型业务的蓬勃发展,对未来通信系统传输容量、传输速度以及误码率等要求愈来愈高。介于毫米波与远红外光之间的太赫兹频段兼有微波和光波的特性,具有低量子能量、大带宽、良好的穿透性。近年来太赫兹通信系统成为研究热点之一,但太赫兹无线通信存在视距传播以及较大路径损耗缺点,太赫兹无线和有线融合传输则兼具两者优点。本文分析了光子太赫兹信号产生、光子太赫兹无线链路传输和光子太赫兹光纤链路传输过程中涉及的器件和技术,重点介绍了太赫兹有线传输的研究现状,并通过基于强度调制直接检测实现1.485 GBaud 350 GHz的1 m太赫兹光纤有线实时传输视频实验,展现了太赫兹有线传输巨大的发展潜力。     

Broadband access using subcarrier multiplexing and asymmetric digital subscriber lines

A broadband access system using subcarrier multiplexing on optical fibre and asymmetric digital subscriber lines (ADSL) or very high‐speed digital subscriber lines (VDSL) on unshielded twisted‐pair is proposed to provide broadband access. In this hybrid‐fibre/twisted‐pair (HFTP) system, the digital multiplexing/demultiplexing process is moved back to the central office by using subcarrier multiplexing for fibre transmission. Instead of installing in remote node, ADSL/VDSL transceivers are installed at the central office to greatly reduce the remote node complexity. The local node simply down‐converts the subcarrier multiplexed ADSL/VDSL signal to the baseband, suitable to send directly into the twisted‐pair. The reduction of complexity could result in a lower initial installation cost, especially for a low service penetration rate. Copyright © 2000 John Wiley & Sons, Ltd.     

Wide-band digital subscriber access with multidimensional blockmodulation and decision-feedback equalization

The author investigates the potential transmission performance of pair-wire subscriber lines at the higher rate of 800 kb/s, with particular reference to digital subscriber line transmission for ISDN (integrated services digital network) basic access. Block modulation schemes of 1-4 dimensions, at a rate of 2 bits per dimension, are considered. Time-division multiplexing is used to combine the multiple dimensions for transmission over a single-waveform channel, namely, the subscriber line. The channel noise is assumed to be additive and dominated by near-end crosstalk. MMSE (minimum mean-squared error) decision-feedback equalization is used to deal with the noise and the intersymbol interference. Using the theory developed, the potential performance of some simple lines is calculated. The coding gain of a multidimensional modulation scheme is found to be fully preserved after transmission if the equalizer is infinite in length. However, the gain realized can be much lower, or none at all, if the equalizer is only moderate in length. This latter phenomenon is due to the fact that the noise at the decision point is coloured, due to the inability of the equalizer to whiten it sufficiently