EPON系统承载TDM业务解决方案分析与研究

数据网承载TDM业务是目前业界关注的焦点.EPON作为新一代的宽带接入技术,为满足网络发展与融合的客观要求,必须要实现多种业务包括TDM业务的综合接入.文章对TDM over EPON的基本机制、时钟实现方式以及XPON的QoS机制进行了分析与研究,提供了教种有效的EPON承载TDM的业务解决方案.     

IEEE1588协议及其在路由交换平台中的实现技术

下一代网络（NGN）是一种融合了IP技术和多媒体通信技术的全新网络,然而当涉及到传统TDM业务应用及需要进行时钟同步分配时,基于IP技术的全新网络则需要具备完善的时钟同步能力来满足相关业务的同步需求。IEEE1588协议标准的出现正好解决了在新一代路由交换平台中的时钟同步问题。这里分析了IEEE1588协议的偏移测量和延时测量时钟同步过程,并给出了IEEE1588协议在路由交换平台中的具体实现过程。     

PON系统承载TDM技术研究

作为综合接入系统,PON系统不仅要能承载数据、视频和语音等业务,还应能承载TDM业务。本文结合TDM业务的传输特性,研究了TDM over EPON/GPON的各种电路仿真协议,提出了TDM over EPON/GPON的协议参考模型,详细分析了PON系统承载TDM业务的关键技术。     

E1 over EPON的时钟同步技术

文章介绍了E1 over 基于以太网的无源光网络(EPON)的关键技术中时钟同步的实现方法,通过对自适应法的研究和改进,优化了时钟输出抖动的指标,有效地保障了EPON系统的服务质量(QoS)指标.相对于时间标签法,自适应法在分组网络中进行时钟同步方面具有更广泛的适用空间.     

同步以太网测试方法

得益于移动宽带业务的强劲增长,许多移动网络运营商已经或正在把移动回传网络从传统同步传输(如SONET/SDH和T1/E1)迁移到运营级以太网。传统TDM网络不仅提供数据传输,而且能实现频率同步。这样,原来由TDM网络提供的时钟同步也同样必须在以太网络中实现,并且同步的质量和网络性能不能受到影响。再者,3G/LTE无线网络不仅需要频率同步,还需要时间/相位的同步。所以,在部署前对以太网络各个部件作同步性能的验证就显得非常必要。本文介绍了实现以太网同步的各种方式和原理、同步精度测量面临的挑战。结合IXIA业界领先的同步测试工具Anue 3500,重点对PTP技术中的路径支持设备(如边界时钟和透明时钟)的测试方法进行了探讨。     

下一代宽带接入技术--10 Gbit／s EPON

10 Gbit／sEPON基于EPON标准并加以发展，使EPON与10 Gbit／sEPON系统能够通过粗波分复用（CWDM）和时分多路复用（TDM）技术相结合，在同一网络上实现共存。EPON与10 Gbit／sEPON可通过VoIP技术进行语音通信，并通过电路仿真业务（CES）传输其他TDM客户端信号。     

GPON系统承载TDM业务的技术分析

对GPOIN系统承载TDM业务的两种具体实现方式TDM-over-GEM和CESoP-over-GEM进行了详细的技术分析,并介绍了三种可能的定时同步时钟恢复方式,最后介绍了评估分组网上TDM业务QoS的指标。     

一种TDM／TDMA点地多点系统时钟同步方法

针对TDM/TDMA点对多点系统传输信号特点,提出了一种系统时钟同步方法,介绍了电路的组成及原理。该方法能有效地抑制多级中继时系统的时钟抖动,提高TDM/TDMA通信系统的传输性能。     

EPON系统中的E1电路仿真

EPON系统采用PON的网络拓扑结构、以太帧结构,实现数据业务的高速接入。如何增强以太网的能力,构筑多业务平台,实现实时音视频和IP数据在单一平台上传输是EPON研究中的关键问题之一,本文对EPON中E1电路仿真技术及实现方案进行了研究。     

TDM在EPON中的传输方案分析

以太网光无源网络（EPON）在国内发展很快,如何在EPON传输以太网数据外的其他业务,如传统的时分多路（TDM）信号,将对EPoN的发展有着重要影响。文章从VOIP技术、分组网电路仿真（CESOP）技术,分析比较了EPON进行话音的传输以及其他TDM信号的方案。     

A 200 Mbit/s Synchronous TDM Loop Optical LAN Suitable for Multiservice Integration

This paper describes a 200 Mbit/s multiservice optical local area network (LAN) using a synchronous TDM loop structure. The LAN consists of a central supervisory node and multiple service nodes connected by an optical fiber loop. Each service node supports communication channels which have access to allocated time slots in TDM frames continuously circulating on the loop. Multiple independent communication paths of various speeds up to 140 Mbits/s and various modes including point-to-point, ring, and multicast, can be provided between the channels on the loop. The ring will be useful to support ring networks, such as a token ring. The structure of this LAN is quite suitable for integration of multiple services, including video, image, data, and voice, since each service can independently choose its own speed, access method, and mode. In this development, various LSI-based high-speed hardware technologies including compact E/O and O/E modules, GaAs 4 × 4 matrix switch LSI's, and high-speed TDM-processor LSI's, which are versatilely applicable to high-speed LAN's ranging from 100 Mbits/s up to 560 Mbits/s, have been successfully introduced and compact LAN equipment has been obtained. This paper deals mainly with the system and hardware structure of this LAN, together with high-speed hardware technologies. An outline of firmware and network operation, and an application example are also described.     

共享RAM的E1/SDH映射算法

在同步数字体系(SDH)网中,E1是一种重要且常见的业务类型,大量的接入设备需要完成E1到SDHTU 12的映射/解映射.文章通过对SDH帧结构和E1映射机制的分析,提出了一种时分复用共享RAM的E1映射算法,该算法能够大大减少先进先出(FIFO)的使用和逻辑资源的占用,尤其适于在接入网设备中利用专用集成电路实现低成本的E1接入.     

Clock synchronization for packet networks using a weighted least‐squares error filtering technique and enabling circuit emulation service

Circuit emulation service (CES) allows time‐division multiplexing (TDM) services (T1/E1 and T3/E3 circuits) to be transparently extended across a packet network. With circuit emulation over IP, for instance, TDM data received from an external device at the edge of an IP network is converted to IP packets, sent through the IP network, passed out of the IP network to its destination, and reassembled into TDM bit stream. Clock synchronization is very important for CES. This paper presents a clock synchronization scheme based on a double exponential filtering technique and a linear process model. The linear process model is used to describe the behaviour of clock synchronization errors between a transmitter and a receiver. In the clock synchronization scheme, the transmitter periodically sends explicit time indications or timestamps to a receiver to enable the receiver to synchronize its local clock to the transmitter's clock. A phase‐locked loop (PLL) at the receiver processes the transmitted timestamps to generate timing signal for the receiver. The PLL has a simple implementation and provides both fast responsiveness (i.e. fast acquisition of transmitter frequency at a receiver) and significant jitter reduction in the locked state. Copyright © 2006 John Wiley & Sons, Ltd.     

以太网电路仿真技术及其应用

在无连接的分组交换网络中,仿真电路交换业务可以采用电路仿真技术。时分复用(TDM)业务对时延、抖动以及分组丢失等特性非常敏感,因此电路仿真要解决的根本问题就是确保仿真业务的服务质量特性要求。由于以太网具有廉价、简单、扩展性强和分布广泛等特点,通过以太网传送TDM业务的需求变得越来越明显。以太网电路仿真技术可以实现以太网透明地传输TDM业务(E1/T1和E3/T3等)。文中主要介绍了TDMoverEthernet技术的基本概念、技术要点及面临的主要技术挑战;通过与TDMoverIP、VoIP和ATM等相关技术的比较,指出了该技术的优势;最后,给出了TDMoverEthernet技术的一个应用实例。     

光纤水听器时分复用系统串扰的理论分析与仿真研究

串扰是困扰光纤水听器阵列时分复用技术应用发展的重要问题之一.对时分复用系统中通道之间存在的串扰从理论上进行了深入分析,并运用仿真方法研究了系统中的串扰与光开关消光比、复用通道数等因素的关系.     

An Architecture for TSI-Free Nonblocking Optical TDM Switches

One of the key elements in building a time-division- multiplexed (TDM) switch is the time slot interchange (TSI). Given the current optical switching and buffer technologies, TSI-based TDM architectures have many implementation drawbacks, including severe signal attenuation. Some studies showed that some space-time equivalence diagrams can be converted into a delay-unit-based (TSI-free) TDM. This type of architecture is attractive for optical TDM switches, but the techniques discussed in those studies are for rearrangeable switches. Many applications require nonblocking switches where adding a new connection (or a flow) will not cause rearrangement of existing connections. In this paper, we present the design principle for building strictly nonblocking delay-unit-based (TSI-free) optical TDM switches.     

Efficient time slot assignment algorithms for TDM hierarchical andnonhierarchical switching systems

Two efficient time slot assignment algorithms, called the two-phase algorithm for the nonhierarchical and the three-phase algorithm for the hierarchical time-division multiplex (TDM) switching systems, are proposed. The simple idea behind these two algorithms is to schedule the traffic on the critical lines/trunks of a traffic matrix first. The time complexities of these two algorithms are found to be O(LN²) and O(LM²), where L is the frame length, N is the switch size, and M is the number of input/output users connected to a hierarchical TDM switch. Unlike conventional algorithms, they are fast, iterative and simple for hardware implementation. Since no backtracking is used, pipelined packet transmission and packet scheduling can be performed for reducing the scheduling complexity of a transmission matrix to O(N²) and O(M²), respectively. Extensive simulations reveal that the two proposed algorithms give close-to-optimal performance under various traffic conditions     

A Novel Dynamic Bandwidth Assignment Algorithm for Multi-Services EPONs

1IntroductionIt seems that providing broadband services is thesaver of telecom industry. Long-haul and Metro corenetworks are capable of carrying broadband servicessince they have experienced a dramatic i mprovement inbandwidth capacity and efficiency with the advent oftechnologies such as Dense Wave length Division Multi-plexing (DWDM)[1 ~3]and other newtechnologies .Buta clear bottleneckexistsinthe“first mile”of access net-work[4]. Without eli minationthe bandwidth bottlenecksthat exis…     

A high capacity metropolitan area network using lightwavetransmission and time multiplexed switching

The technical feasibility of a lightwave communication system capable of providing service to thousands of subscribers within cities or large suburban areas is examined. Each subscriber in this system has available upon demand an aggregate bit rate of up to 100 Mb/s. The aggregate bit rate of the entire network is on the order of 5 Tb/s. The network topology is that of a star-on-star wherein each subscriber line terminates on one of a multitude of remote concentrators. Each high-speed link from a remote concentrator to a centrally located time-multiplexing photonic switch consists of a single-mode fiber carrying several wavelength-division multiplexed (WDM) channels. Each channel operates in a time-division multiplexed (TDM) mode at a data rate of 2 Gb/s and is powered by a multimode laser. No regeneration is required at the central switch, and at the remote concentrators, each channel is terminated by a direct-detection receiver. The approach achieves high throughput by reusing the same channels, that collectively occupy a tiny fraction of the optical band, among all interconnecting links and, with the exception of large-dimensional switch arrays, employs readily available technology