光设备中嵌入式测控网络模块的设计与实现

文章提出了一种基于UIP（嵌入式传输控制协议／网际协议）协议栈的光设备中的测控模块的设计方案。测控模块作为低成本的测控网络接入方案，可以将具有RS-232／RS-485（串行通信接口）等接口的测控设备简单又直接地连接到局域网上，利用现有的丰富的局域网资源，组成一系列局域网的分布式测控系统。     

光纤通信网络在高速数据采集系统中的应用

基于光纤通信网络对一种高速数据采集系统进行了设计。通过多路数据采集方式,并与光纤通信网络相结合,使得高速数据采集能力得到大幅提高。该系统主要由处理系统、采集模块及光纤网络共同构成,光纤通信网络前端采集模块在模拟滤波、采样完成后,通过处理器实现信号的传输。此外,通过光数据采集系统实验,证明了在高速数据采集系统中应用光纤通信网络能实现速率在10 Gbit·s-1以下的光数据接入采集。     

Space-Time Receiver for Multi-Rate CDMA Systems: Multi-Code and Variable Spreading Length Access Methods Comparison

This work proposed the linear minimum mean square error (LMMSE) space-timereceivers for synchronous multi-rate direct sequence code devision multipleaccess (DS/CDMA) systems. The performance of the proposed receivers isanalyzed. The high-rate (HR) LMMSE space-time receiver with combiningtechnique can provide essentially the same performance for low-rate (LR) usersas LR LMMSE space-time receiver while eliminate the time delay for the HRusers. The performance of the proposed multi-rate LMMSE space-time receiversare studied in the context of two multi-rate access methods: multi-code (MC)access where high data rate users multiplex their information streams ontomultiple codes, and variable spreading length (VSL) access where signaturesequences of different lengths are assigned to users with different datarates.Through the simulation results, we show that: (a) the proposed multi-rateLMMSE space-time receivers are optimum near-far resistant; (b) the proposedmulti-rate LMMSE space-time receivers have a clear performance improvementcompared to the time only LMMSE dual rate receiver; (c) there is a performancegain of the proposed multi-rate LMMSE space-time receivers compared to themulti-rate decorrelating space-time receiver when near-far ratio (NFR) is low;(d) The performance difference between MMSE combining and MRC in multi-ratesystem is much more pronounced than in single-rate system. Simulations alsoshow that the VSL access method is more robust than MC access methodconsidering changing rate-ratio in multi-rate systems.     

Blind Channel Estimation for Multi-Rate Multicarrier DS/CDMA Communications

Multi-rate multicarrier DS/CDMA is a potentially attractive multiple access method for future wireless communications networks that must support multimedia, and thus multi-rate, traffic. Several receiver structures exist for single-rate multicarrier systems, but little has been reported on multi-rate multicarrier systems. Considering that high-performance detection such as coherent demodulation needs the explicit knowledge of the channel, based on the finite-length chip waveform truncation, this paper proposes a subspace-based scheme for timing and channel estimation in multi-rate multicarrier DS/CDMA systems, which is applicable to both multicode and variable spreading factor systems. The performance of the proposed scheme for these two multi-rate systems is validated via numerical simulations. The effects of the finite-length chip waveform truncation on the performance of the proposed scheme is also analyzed theoretically.     

Operating Penalties in Single-Fiber Operation 10-Gb/s, 1024-Way Split, 110-km Long-Reach Optical Access Networks

We report for the first time optical signal-to-noise penalties which lead to performance degradations in single-fiber long-reach optical access networks when compared to identical dual-fiber systems. A simplified architecture, with reduced optical amplifier count compared to previous work, for single-fiber operation of a symmetrical 10-Gb/s, 1024-way split, 110-km long-reach optical access network is presented and demonstrated. In addition, a possible solution to remove the optical signal-to-noise penalty is suggested     

Performance analysis of an optical network employing waveband and traffic grooming

This paper analyses an optical network architecture composed by an arrangement of nodes equipped with multi-granular optical cross-connects (MG-OXCs) in addition to the usual optical cross-connects (OXCs). Then, selected network nodes can perform both waveband as well as traffic grooming operations and our goal is to assess the improvement on network performance brought by these additional capabilities. Specifically, the influence of the MG-OXC multi-granularity on the blocking probability is evaluated for 16 classes of service over a network based on the NSFNet topology. A mechanism of fairness in bandwidth capacity is also added to the connection admission control to manage the blocking probabilities of all kind of bandwidth requirements. Comprehensive computational simulation are carried out to compare eight distinct node architectures, showing that an adequate combination of waveband and single-wavelength ports of the MG-OXCs and OXCs allow a more efficient operation of a WDM optical network carrying multi-rate traffic.     

全业务经营下的接入光缆演进方案研究

随着全业务运营的竞争,移动运营商已开始向全业务经营转型,在满足全业务发展的过程中,接入层光缆网络资源是否充足以及结构是否合理已成为重要因素。文章在全面分析了全业务经营各类型业务的接入光缆需求后,探讨研究了全业务经营下本地接入光缆网的演进方案及业务承载方式。     

A WDM-based optical access network for wide-area gigabit access services

This article proposes and demonstrates a WDM-based access network that directly connects end users over a wide area to the center node and provides guaranteed full-duplex Gigabit Ethernet access services to each of over 100 users. The center node employs an optical carrier supply module that generates not only the optical carriers for the downstream signals but also those for the upstream signals. The latter are supplied to optical network units (ONUs) at users' homes/buildings via the network. Since the ONUs simply modulate the optical carriers supplied from the center node via the network, they are wavelength-independent.     

Photonic transport network OAM technologies

The optical path concept was proposed to realize ubiquitous B-ISDN. It can make quantum leaps in both transmission capacity and cross-connect throughput simultaneously by exploiting WDM (wavelength division multiplexing) transmission and the wavelength routing capabilities of paths. Since the optical path is a new concept, new operation and management (OAM) systems and related technologies need to be developed before it can be fully utilized. This article discusses some of the key OAM-related issues and identifies the technical points necessary for future developments. The issues include optical path realization technologies, optical path accommodation design problems, a newly proposed optical transport network layer architecture, and the optical transport module for the network node interface     

Blind channel estimation in multi-rate CDMA systems

Multi-rate CDMA is a potentially attractive multiple access method for future broad-band multimedia wireless networks that must support integrated voice/data traffic. The primary impairment for such multi-rate systems is the multipath nature of radio channels that results in intra-user inter-chip interference (ICI) and multi-user interference (MUI) between different users' symbols. Explicit knowledge of the channel is typically needed for high performance detectors (such as coherent demodulation). We propose a subspace method for channel estimation in multi-rate CDMA systems. A unified signal model that applies to three multi-rate CDMA schemes proposed in the literature is developed. The computational complexity for multi-rate scenarios is large and variable-accordingly, a modified approach is devised that offers performance/complexity trade-offs. Performance analysis is conducted based on a close-form expression for the mean square error of the estimator, supported by simulation results that investigate the effectiveness of our method     

IEEE 802.11中多速率多节点公平的数据分组长度调整策略

在深入剖析多速率机制导致不公平性根源的基础上,提出了基于传输速率的数据分组长度调整(TRPSA)策略,该策略保证了传输速率不同的节点能公平地占用无线信道。理论证明和仿真验证了该策略能有效实现多速率多节点情况下的公平性,显著提高网络性能。该策略只需对IEEE 802.11做细小修改,易于在实际网络中实现和推广。     

OCDMA系统中多码长地址码的设计及性能研究

为了满足光码分多址系统中不同用户能够获得不同发送速率的需求,根据所需地址码的容量和码重,通过MATLAB编程,设计出没有重复数字的间隔集,得到具有理想相关性的多码长地址码。根据该地址码的构造特点推导计算出该地址码的误比特率,并绘制出误比特率随同步用户数变化图。设计并仿真了多速率光码分多址系统,分析了误比特率和系统性能。结果表明,该多码长地址码具有良好的相关性和误比特率性能,能够满足各种速率需求的用户。通过系统编解码后能够理想地恢复出原始信号,得到优良的眼图。此研究对光码分多址多速率系统的进一步发展是有帮助的。     

用Bayes网络对光纤接入网供电系统故障的监控

供电是光纤接入网中的一个重大技术问题。文中讨论了供电的两种方式,即网络供电方式和本地供电方式。对于光纤接入网,本地供电结构是一种较为理想的方案,但对本地供电网络监控则又是一个技术难点。文中设计了一种采用Ｂａｙｅｓ网络的电源监控系统网络结构,对网络进行了理论分析,并给出具体的实现方案。     

An All-Optical Access-Metro Interface for Hybrid WDM/TDM PON Based on OBS

A new all-optical access-metro network interface based on optical burst switching (OBS) is proposed. A hybrid wavelength-division multiplexing/time-division multiplexing (WDM/TDM) access architecture with reflective optical network units (ONUs), an arrayed-waveguide-grating outside plant, and a tunable laser stack at the optical line terminal (OLT) is presented as a solution for the passive optical network. By means of OBS and a dynamic bandwidth allocation (DBA) protocol, which polls the ONUs, the available access bandwidth is managed. All the network intelligence and costly equipment is located at the OLT, where the DBA module is centrally implemented, providing quality of service (QoS). To scale this access network, an optical cross connect (OXC) is then used to attain a large number of ONUs by the same OLT. The hybrid WDM/TDM structure is also extended toward the metropolitan area network (MAN) by introducing the concept of OBS multiplexer (OBS-M). The network element OBS-M bridges the MAN and access networks by offering all-optical cross connection, wavelength conversion, and data signaling. The proposed innovative OBS-M node yields a full optical data network, interfacing access and metro with a geographically distributed access control. The resulting novel access-metro architectures are nonblocking and, with an improved signaling, provide QoS, scalability, and very low latency. Finally, numerical analysis and simulations demonstrate the traffic performance of the proposed access scheme and all-optical access-metro interface and architectures     

我国光接入网发展影响因素分析及广电对策思考

本文阐述了光接入网、当前主流及下一代无源光网络技术。同时,基于国内外光接入网及FTTH发展情况,分析了影响我国光接入网发展的主要因素,提出了广电如何发展光接入网的几点对策建议。     

对中国发展宽带接入及光纤的思考

宽带接入发展趋势正从传统的铜线接入向。有线铜退光进,无线宽带移动化,有线无线相互补充。实现无缝接入。的目标演进。光纤宽带是固网宽带接入发展的必然选择。光接入面临多重挑战,需要综合考虑建设与运营维护、无源光网络光线路终端容量设置、光纤宽带对无源光网络（PON）光网络单元的要求、光纤宽带设备的管理、综合业务承载能力、多业务承载对业务控制层的影响等问题。     

光码分多址（OCDMA）应用于接入网的研究

基于光码分多址技术应用于接入网具有异步接入、用户分配的灵活性、支持不同业务、系统的安全性等优点成为下一代接入网的最佳候选方案之一。首先介绍了OCDMA应用于接入网的相干和非相干两种系统结构、接着介绍了基于光素数码和光正交码两种编码方式的地址码的选择和构造、最后分析了在用户数较多和较少时两种情况下的系统误码率,得出了影响系统性能的3个参数：用户数、码长和码重。     

基于ExpressCard接口的光网卡设计

结合ExpressCard和以太网光纤通信技术的诸多优点设计了一款光网卡,解决便携式PC机与网络测试设备的远距离通信问题。在设计中采用Real t ek的RTL8111DL和RTL8211DN芯片技术,实现PCI E到以太网及MDI接口到PECL电平接口的转换,最后接入光电转换模块完成光纤信号的收发。     

基于PON技术光接入网的运行、管理和维护

无源光网络是当今宽带接入网领域中最为热门的技术之一。在使用PON进行大规模宽带接入网建设和改造的同时,如何提高接入网的运行维护效率已经成为运营商必须解决的问题。本文介绍了在基于PON技术宽带接入网的运行和维护过程中,运营商所面临的一些问题:如何实现快速业务开通,如何进行接入网的故障诊断等。     

Adaptive Optical Network Unit for Point-to-Point and PON Systems Based on Gigabit Ethernet

This paper proposes an optical network unit (ONU) that works in point-to-point (P2P) optical access systems as well as passive optical network (PON) systems and so reduces the operational expenditure of optical access networks in the full FTTH era. First, we discuss its design and implementation; after clarifying the requirements for the adaptive ONU, we describe how it should work while focusing on Gigabit-Ethernet-based P2P and PON systems. Next, we study its feasibility through experiments on a prototype. Also, we provide some additional considerations regarding the implementation and future application of the adaptive ONU.