大规模ASON中路由协议优化的研究

路由协议是自动交换光网络(ASON)控制平面的重要组成部分,其负责泛洪网络的链路状态信息,并进行路由计算.在ASON的实际运行过程中,路由协议存在一些不足,如占用大量数据通信网(DCN)带宽以及链路状态数据库同步时延过大等,这些问题对网络的可扩展性有较大影响.文章针对上述问题提出了路由协议的优化方案,包括为路由信息的泛洪设定阈值,以及给路由协议增加数据库自更新功能.     

自动交换光网络的控制平面路由技术

自动交换光网络（ASON）控制平面的路由协议是由传统的路由协议结合光网络的特点扩展而来的。传统的路由协议包括了OSPF，IS-IS和P-NNI协议，这里则讨论了光层路由协议的模型，对传统路由协议的扩展，以及路由协议的具体设计三个方面。对传统路由协议的扩展，主要包含了如下几个方面的扩展：光链路相关的定义、带外控制信道的支持、对光网络中保护和恢复功能的支持；对分层次路由的支持；对传送网分配地址的支持。在具体设计中，讨论了协议数据包和链路广播两个方面的内容。     

分层ASON网络中路由计算和连接管理策略的比较研究

本文比较研究了分层结构自动交换光网络(ASON)中四种路由计算和连接管理策略：基于链路状态的分层路由和前向资源预留(LS-HRFR)、基于链路状态的源路由和前向资源预留(LS-SRFR)、基于本地信息的分层路由和沿路径探测、后向资源预留(P-HRBR)以及基于本地信息的源路由和沿路径探测、后向资源预留(P-SRBR)．离散事件仿真的结果表明：采用基于本地信息进行路由计算并通过沿路径探测资源使用信息来选取空闲波长的策略(P-HRBR和P-SRBR)相对基于链路状态的路由计算和空闲波长选取策略(LS-HRFR和LS-SRFR)来说，在分层路由情况下，其对网络总阻塞率的改善微乎其微，但在源路由的情况下．其对网络总阻塞率的改善十分明显．     

分层路由-新一代智能光网络的路由技术

近几年数据业务正在持续快速地增长,为了满足日益增长的带宽需要和不断提高的服务质量要求,光网络正朝着智能化的方向不断发展.智能光网络,特别是自动交换光网络(ASON)的提出代表了光网络的发展方向,成为下一代光网络结构的研究焦点.为了提高网络的可扩展性和灵活性,满足ASON面向连接的网络特性,ASON网络采用了分层路由技术,通过拓扑抽象将ASON网络的路由结构层次化,利用聚合的路由信息简化选路过程.分层的路由结构使得运营商能够屏蔽网络的内部细节,提高网络的安全性,并且可以任意配置网络内部结构,使整个光网络具有高度的灵活性和可扩展性.本文深入分析了ASON网络的分层路由体系结构和分层路由对域间接口的功能要求,详细地介绍了适用于ASON分层路由的DDRP路由协议,并讨论了基于DDRP的ASON分层路由的组网实现方案.     

分层路由——新一代智能光网络的路由技术

近几年数据业务正在持续快速地增长，为了满足日益增长的带宽需要和不断提高的服务质量要求，光网络正朝着智能化的方向不断发展。智能光网络，特别是自动交换光网络(ASON)的提出代表了光网络的发展方向，成为下—代光网络结构的研究焦点。为了提高网络的可扩展性和灵活性，满足ASON面向连接的网络特性，ASON网络采用了分层路由技术，通过拓扑抽象将ASON网络的路由结构层次化，利用聚合的路由信息简化选路过程。分层的路由结构使得运营商能够屏蔽网络的内部细节，提高网络的安全性，并且可以任意配置网络内部结构，使整个光网络具有高度的灵活性和可扩展性。本文深入分析了ASON网络的分层路由体系结构和分层路由对域间接口的功能要求，详细地介绍了适用于ASON分层路由的DDRP路由协议，并讨论了基于DDRP的ASON分层路由的组网实现方案。     

新的ASON路由实现方案

提出了一种新的基于OSPF的ASON路由实现方案,扩展了波长链路状态公告和网络节点链路状态公告,用于在全网分发波长和网络拓扑信息。实现了拓扑的自动发现和路由信息的可靠分发,并提供了友好的RWA接口以便引入各种RWA算法和动态连接建立信令协议。通过仿真对本方案进行了验证,比较了若干RWA算法的性能,分析了两类路由信息更新触发策略和在全网分发波长信息的可行性。     

自动交换光网络路由技术

主要讨论自动交换光网络（ASON）中的路由技术。首先介绍了ITU－T关于ASON路由技术体系结构的要求，然后讨论了ASON路由技术与IP网络路由的不同之处，接着分析了IETF GMPLS对IP路由协议的扩展，包括OSPE－TE和ISI－TE。最后介绍了光互连论坛（OIF）在网络－网络接口（NNI）路由协议方面的进展情况。     

自动交换光网络(ASON)分级路由技术的研究

路由技术是自动交换光网(ASON)的核心技术之一．文章在分析ASON的层网络结构、路由结构以及路由功能部件相互作用的基础上，重点讨论了ASON的分级路由技术，包括分级路由的网络结构及其详细的操作步骤．     

自动交换光网络的分层路由体系及其路由实现方法

本基于国际电信联盟电信标准化组织(ITU-T）相关标准及光互联论坛(OIF)有关草案，阐述了路由域分层的一般原则，给出了层次路由体系下实现路由功能的一般性原理，提出了分层路由体系下路由的实现方法。     

ASON动态路由解决方案浅析

以自动交换光网络(ASON)标准路由模型为基础,介绍了域间路由协议在ASON路由中的实现方法,并针对其动态路由算法的不足进行分析,结合ASON控制平面发展趋势提出了初步的解决方法.     

多媒体通信的吉比特HMR协议

本文介绍了一个ＨＭＲ（高速多媒体通信环网）协议。这个协议建立在吉比特的ＬＡＮ／ＭＡＮ（局域网／城域网）上，并以ＭＡＣ（媒体存取控制）协议和ＡＴＭ（异步转移模式）来传送信息。为了使最大的存取延迟和存储媒体带宽损失达到最小，ＨＭＲ协议采用多窗口标记算法，这种算法的每个优先级都有它自己的最好控制窗口标记。     

IEEE 802.11 medium access control enhancements based on simultaneous multiple‐input multiple‐output bandwidth sharing

The demand for higher data rate has spurred the adoption of multiple‐input multiple‐output (MIMO) transmission techniques in IEEE 802.11 products. MIMO techniques provide an additional spatial dimension that can significantly increase the channel capacity. A number of multiuser MIMO system have been proposed, where the multiple antenna at the physical layer are employed for multiuser access, allowing multiple users to share the same bandwidth. As these MIMO physical layer technologies further evolve, the usable bandwidth per application increases; hence, the average service time per application decreases. However, in the IEEE 802.11 distributed coordination function‐based systems, a considerable amount of bandwidth is wasted during the medium access and coordination process. Therefore, as the usable bandwidth is enhanced using MIMO technology, the bandwidth wastage of medium access and coordination becomes a significant performance bottleneck. Hence, there is a fundamental need for bandwidth sharing schemes at the medium access control (MAC) layer where multiple connections can concurrently use the increased bandwidth provided by the physical layer MIMO technologies. In this paper, we propose the MIMO‐aware rate splitting (MRS) MAC protocol and examine its behavior under different scenarios. MRS is a distributed MAC protocol where nodes locally cooperate with one another to share bandwidth via splitting the spatial channels of MIMO systems. Simulation results of MRS protocol are obtained and compared with those of IEEE 802.11n protocol. We show that our proposed MRS scheme can significantly outperform the IEEE 802.11n in medium access delay and throughput. Copyright © 2012 John Wiley & Sons, Ltd.     

Next generation hierarchical CWDM/TDM-PON network with scalable bandwidth deliverability to the premises

Long haul optical networks have been on focus for more than two decades. With the advent of dense wavelength division multiplexing technology, optical long haul fiber networks have been so successful in delivering an unprecedented amount of bandwidth that they outperformed the traffic deliverability from/to the access network by orders of magnitude. The reason was a cost-efficiency mismatch; long haul ultra-high bandwidth networks can take advantage of state of the art and costly technology, which cost-sensitive access networks cannot. The result was an unbalanced traffic flow from/to access points to the network if one compares the aggregate flow of the long haul network with that of the access. Nevertheless, over the last decade technology at the access advanced and new standards have been developed so that in the access layer of the overall communications network the focus has shifted onto fiber optic access again. Thus, in the optical regime, two proposals have prevailed. One uses a time division multiplexing (TDM) scheme over a single wavelength and a comprehensive timing protocol, and the other uses coarse wavelength division multiplexing (CWDM) technology. Each technology has advantages and disadvantages, and the one attempts to address the disadvantages of the other. In this paper we describe a hierarchical CWDM/TDM passive optical network (PON). Our access network architecture is scalable, it is flexible to accommodate one of several topologies simultaneously, and it delivers any type of payload, synchronous and asynchronous that spans from DS0 to Gbps. We discuss the bandwidth flexibility, versatility, resiliency and cost efficiency of the access network. We also demonstrate that our network can deliver payload to more than 16,000 end-users using simple and existing optical technology. Thus, if one considers cost per bandwidth or per user, the cost-efficiency outperforms any previous PON access network. Moreover, we provide simulation results to support the viability of our network architecture.     

An AWG-based WDM-PON architecture employing WDM/TDMA transmission for upstream traffic with dynamic bandwidth allocation

In this article, we examine a candidate architecture for wavelength-division multiplexed passive optical networks (WDM-PONs) employing multiple stages of arrayed-waveguide gratings (AWGs). The network architecture provides efficient bandwidth utilization by using WDM for downstream transmission and by combining WDM with time-division multiple access (TDMA) for upstream transmission. In such WDM-PONs, collisions may occur among upstream data packets transmitted simultaneously from different optical networking units (ONUs) sharing the same wavelength. The proposed MAC protocol avoids such collisions using a request/permit-based multipoint control protocol, and employs a dynamic TDMA-based bandwidth allocation scheme for upstream traffic, called minimum-guaranteed maximum request first (MG-MRF), ensuring a reasonable fairness among the ONUs. The entire MAC protocol is simulated using OPNET and its performance is evaluated in terms of queuing delay and bandwidth utilization under uniform as well as non-uniform traffic distributions. The simulation results demonstrate that the proposed bandwidth allocation scheme (MG-MRF) is able to provide high bandwidth utilization with a moderately low delay in presence of non-uniform traffic demands from ONUs.     

PON与OBS网络互连结构的研究

光突发交换(OBS)网络的城域网应用需要解决与接入网的互连问题。针对基于集成节点的PON与OBS网络互连方案,研究了集成节点的功能与组成结构,分析了模块之间的信息交互,给出了集成节点结构的一种设计方案,并简单讨论了基于这一方案的汇聚机制和动态带宽分配算法。     

Review on Dynamic Bandwidth Allocation of GPON and EPON

The passive optical network (PON) technology has been drastically improved in recent years. In spite of using the optical technology, the utilization of the entire bandwidth is a very challenging task. The main categories of PON are the Ethernet passive optical network (EPON) and gigabit passive optical network (GPON). These two networks use the dynamic bandwidth allocation (DBA) algorithm to attain the maximum usage of bandwidth, which is provided in the network dynamically according to the need of the customers with the support of the service level agreement (SLA). This paper will provide a clear review about the DBA algorithm of both technologies as well as the comparison.     

Experimental investigation on slow light via four-wave mixing in semiconductor optical amplifier

Optical buffer is a key component in all optical information processing systems.Slow light at room temperature via four-wave mixing (FWM) in semiconductor optical amplifier (SOA) is experimentally investigated.Time delay of 0.40ns is achieved for a sinusoidal modulation signal at 0.1 GHz, corresponding to a delay bandwidth product (DBP) of 0.04.Factors that affect the experimental results are discussed.It is found out that the variable optical delay via FWM in SOA can be controlled either electrically by changing the SOA bias or optically by varying the pump power or pump-probe detuning.     

传输网DCC通道带宽瓶颈及优化

传统SDH网络DCC通道带宽无法满足日益增长的需求,文章提出了通过将ML-PPP协议应用于SDH网络DCC通道管理的方式.实验结果表明,通过ML-PPP协议将多个物理链路结合到一起,形成一个高带宽的虚拟链路,可以成倍提高DCC通道带宽,从而有效解决传统传输网DCC通道带宽瓶颈问题.     

Inter‐ONU Bandwidth Scheduling by Using Threshold Reporting and Adaptive Polling for QoS in EPONs

I dynamic bandwidth allocation (DBA) scheme, an inter–optical network unit (ONU) bandwidth scheduling, is presented to provide quality of service (QoS) to different classes of packets in Ethernet passive optical networks (EPONs). This scheme, referred to as TADBA, is based on efficient threshold reporting from, and adaptive polling order rearranging of, ONUs. It has been shown that the network resources are efficiently allocated among the three traffic classes by guaranteeing the requested QoS, adaptively rearranging the polling orders, and avoiding nearly all fragmentation losses. Simulation results using an OPNET network simulator show that TADBA performs well in comparison to the available allocation scheme for the given parameters, such as packet delay and channel utilization.     

Optimal transmissions for space-time coded OFDM UWB systems

1 Introduction Recently, the high rate short range wireless personal area network (WPAN) is considered. When the inverse of the sampling rate is significantly shorter than the total delay spread, as is the case for most UWB communication systems, OFDM systems are more attractive than a single-carrier system. The multi-band OFDM physical layer proposal has been adopt by IEEE 802.15.3a Task Group[1]。 Combing STC and OFDM have the properties to achieve high data rate and mitigate int…