WDM光网络中OXC结构对带内串扰积累的影响

串扰是波分复用(WDM)光网络中光交叉连接(OXC)投入实用的最大障碍。理论分析了基于扩展Benes(DB)结构和改进扩展Benes(GMDB)结构的3种典型OXC节点结构中的带内串扰,并数值模拟了基于两种结构的OXC节点中带内串扰的积累特性。结果表明,基于DB结构和GMDB结构的OXC节点可以完全消除低于二阶的各类串扰。发现基于GMDB结构的OXC节点能大大减少带内串扰的积累,与基于DB结构的OXC节点相比,基于GMDB结构的OXC节点对光开关串扰系数的要求放宽了5dB,说明OXC节点结构的选择对消除串扰尤为重要。     

与偏振相关和无关的4×4自由空间光开关

设计了一种由相位型空间光调制器(PSLM)、偏振光分束器(PBS)、反射镜、半波片(HWP)和四分之一波片(QWP)构成的2×2光开关。该光开关所用器件少,具有结构紧凑规整、功能的实现与信号光的偏振态无关以及可以完成双向交换等特点。在此基础上通过2×2光开关的级联,设计了一种与偏振无关的4×4光开关的实验模块,根据其路由控制表对该实验模块功能的实现进行了分析。为与之作比较,还提出了一种与偏振相关的4×4光开关,该光开关利用对信号光偏振态的控制进行路由选择,以实现所需的交换和排序。     

与偏振相关和无关的4×4自由空间光开关

设计了一种由相位型空间光调制器（PSLM）、偏振光分束器（PBS）、反射镜、半波片（HWP）和四分之一波片（QWP）构成的2×2光开关。该光开关所用器件少,具有结构紧凑规整、功能的实现与信号光的偏振态无关以及可以完成双向交换等特点。在此基础上通过2×2光开关的级联,设计了一种与偏振无关的4×4光开关的实验模块,根据其路由控制表对该实验模块功能的实现进行了分析。为与之作比较,还提出了一种与偏振相关的4×4光开关,该光开关利用对信号光偏振态的控制进行路由选择,以实现所需的交换和排序。     

基于STM32F078和LTC2662的硅基光开关阵列参数标定控制器设计与实现

随着科技的发展,光纤通信大量使用,硅基光开关阵列的使用场景越来越多,当前基于硅基的光开关阵列技术得到了发展.但由于技术还不够成熟,光开关阵列中每个开关节点的控制参数还不能做到一致,需要的电压在4～6 V.为了能够准确控制和使用硅基光开关阵列,必须对硅基光开关阵列中的每个开关节点控制参数进行准确标定,标定其控制电压或电流.为了实现控制参数的高效标定,设计一种高效的硅基光开关阵列参数标定控制器.     

波分复用光控相控阵雷达的控制技术

为了设计波分复用光控相控阵雷达的完整结构,提出基于光开关控制的光控相控阵雷达发射与接收前端的基本组成,描述光控相控阵雷达的工作原理。介绍光开关控制的波分复用光延时网络结构,设计并分析光控相控阵雷达工作的开关控制流程。测试光开关的性能,分析其对光控相控阵雷达时序设计的影响。制作开关控制的三级光纤真时延迟线结构,实现并验证8个扫描角度的可编程波束成形延迟网络。开关控制光延时网络的实现,证明了基于光开关控制的相控阵雷达工作的有效性和可行性     

基于双面反射镜的N×N光开关的特性分析和实验研究

报道了基于双面反射镜的N×N光开关器件。介绍了使用双面反射镜的2×2，4×4光开关的集成光路设计和工作原理；采用Benes网络，以2×2和4×4光开关为基本单元的N×N光开关器件的整体结构，并根据“一笔画”原理，分析了4×4，8×8和16×16光开关矩阵的可重排无阻塞特性和光开关矩阵的光路选择算法。最后，基于2×2，4×4光开关技术制备了16×16光开关矩阵。测试表明，该器件具有良好的插入损耗、回波损耗、串扰和开关时间等性能，从而验证了设计思想和工艺的可行性。在基于双面反射镜的光开关矩阵中，双面反射镜的使用大大减少了光开关矩阵中运动镜片的数量，简化了控制程序，并有利于提升光开关器件的可靠性能，有望在中小型光交换机、网络管理和光路测量中获得应用。     

基于偏振的光矩阵开关

提出了一种新型的基于偏振的光矩阵开关方法 ,通过控制光的偏振态实现严格无阻塞连接。以 4× 4光矩阵开关为例 ,详细给出了其节点开关和交换网络的实现方案。并对该 4× 4光矩阵开关进行实测 ,证明该方法制作的小规模光矩阵开关具有插损低 ,串话小 ,开关时间中等 ,性能稳定 ,工艺成熟等特点。     

基于双面反射镜的N×N光开关的特性分析和实验研究

报道了基于双面反射镜的N×N光开关器件。介绍了使用双面反射镜的2×2,4×4光开关的集成光路设计和工作原理;采用Benes网络,以2×2和4×4光开关为基本单元的N×N光开关器件的整体结构,并根据“一笔画”原理,分析了4×4,8×8和16×16光开关矩阵的可重排无阻塞特性和光开关矩阵的光路选择算法。最后,基于2×2,4×4光开关技术制备了16×16光开关矩阵。测试表明,该器件具有良好的插入损耗、回波损耗、串扰和开关时间等性能,从而验证了设计思想和工艺的可行性。在基于双面反射镜的光开关矩阵中,双面反射镜的使用大大减少了光开关矩阵中运动镜片的数量,简化了控制程序,并有利于提升光开关器件的可靠性能,有望在中小型光交换机、网络管理和光路测量中获得应用。     

一种新的与偏振无关的双向2×2光开关的设计

设计了一种由偏振光分束器(PBS)、位相型空间光调制器(PSLM)、反射镜、半波片(HWP)和1/4波片(QWP)构成的2×2光开关.该光开关所用器件少,具有结构紧凑规整、功能的实现与信号光的偏振态无关以及可以完成双向交换等特点.进而通过2×2光开关的级连,设计了一种与偏振无关的4×4光开关的实验模块.     

聚合物热光光开关器件驱动与控制单元的研制

在分析了聚合物热光光开关工作特点以及集成光开关器件的工作状态矩阵的基础上,设计了一种新的简洁可靠的聚合物热光光开关器件驱动与控制单元,有效的提高了光开关器件的工作效率。     

基于通用改进型扩展Benes型光开关的智能光交换模块

分析了基于通用改进型扩展Benes型光开关的动态交换特性,阐述了核心光交换控制电路的设计,并组建了实验网络.采用一种巧妙的编程方法,实现了GDMB光开关矩阵的动态光路交换,利于实现高速、可靠的数据交换.     

面向智能路由的多级哈希网络数据存储结构

网络数据的采集和存储是智能路由控制的基础,为智能路由提供了大量的网络流量数据进行模型训练和决策。然而,作为网络数据存储系统中的核心设备,交换机的存储空间非常有限,且设计灵活性低,无法满足智能路由控制对全面高精度的数据存储和轻量级存储系统的需求,进而影响智能路由控制的效果。提出一种面向智能路由控制的多级哈希网络数据存储结构,高效利用交换机有限的存储空间,实现低碰撞率的网络数据存储。该结构通过多级哈希表增加数据的可存储空间数量,从而降低存储冲突率并提高存储空间利用率。同时,该结构使用基于低开销时间戳的LRU算法解决哈希冲突：在发生哈希冲突时总是保存最新的网络数据,清除陈旧数据,以尽可能减少后续的存储冲突。基于真实网络流量数据的实验证明了相比目前普遍使用的单级哈希存储结构,多级哈希存储结构在存储碰撞率和负载率两方面存在显著的性能优势。     

NS2中扩展新路由算法的研究

NS2是网络研究与设计中广泛使用的一个网络仿真模拟器。讨论了NS2网络仿真软件的结构及其功能扩展原理,着重分析了其中路由模块的功能和实现,提出在NS2中扩展一个新路由算法的方法,并给出了一个具体的模拟实例。     

A reconfigurable ATM switch fabric for fault tolerance and trafficbalancing

A large-scale asynchronous transfer mode (ATM) switch fabric that can be constructed with currently feasible technology is proposed. Based on analysis of the technology, it is found that module interconnection becomes the bottleneck for a large fast packet switch. Fault tolerance for the switch is achieved by dynamic reconfiguration of the module interconnection network. The design improves system reliability with relatively low hardware overhead. An abstract model of the replacement problem for the design is presented, and the problem is transformed into a well-known assignment problem. The maximum fault tolerance is found, and a fast replacement algorithm is given. The reconfiguration capability can also be used to ameliorate imbalanced traffic flows. The authors formulate this traffic flow assignment problem for the switch fabric and show that the problem is NP-hard. A simple heuristic algorithm is proposed, and an example is given     

The UniMIN switch architecture for large-scale ATM switches

A general expansion architecture is proposed that can be used in building large-scale switches using any type of asynchronous transfer mode (ATM) switch. The proposed universal multistage interconnection network (UniMIN) switch is composed of a buffered distribution network (DN) and a column of output switch modules (OSMs), which can be any type of ATM switch. ATM cells are routed to their destination using a two-level routing strategy. The DN provides each incoming cell with a self-routing path to the destined OSM, which is the switch module containing the destination output port. Further routing to the destined output port is performed by the destination OSM. Use of the channel grouping technique yields excellent delay/throughput performance in the DN, and the virtual FIFO concept is used for implementing the output buffers of the distribution module without internal speedup. We also propose a “fair virtual FIFO” to provide fairness between input links while preserving cell sequence. The distribution network is composed of one kind of distribution module which has the same size as the OSM, regardless of the overall switch size N. This gives good modular scalability in the UniMIN switch. Performance analysis for uniform traffic and hot-spot traffic shows that a negligible delay and cell loss ratio in the DN can be achieved with a small buffer size, and that DN yields robust performance even with hot-spot traffic. In addition, a fairness property of the proposed fair virtual FIFO is shown by a simulation study     

Fault tolerance design for large-scale optical switches

In this paper, we present an enhanced fault tolerance in large-scale optical switches through innovations in architecture and control logic design. A large-scale switch is constructed from a network of 2×2 optical switch elements (SEs). Classic switch network architectures, such as the Benes, are not designed with fault tolerance in mind. There are three major contributions in this paper: (1) we developed an analytical method, referred to as the probability accumulation method, to calculate the average connection blocking probability in a faulty switch network; (2) we provided a failure-aware routing algorithm to effectively circumvent connections from defected SEs in a dilated Benes switch; and (3) we improved the connectivity pattern of the Benes network to further reduce the blocking probability, especially when the SE failure rate is low.     

SDH多业务传输平台(MSTP)路由算法

多业务传输平台(MSTP)的出现使得同步数字体系(SDH)网络可以传输多种业务.路由和保护模块是网络管理软件的核心模块之一.由于网络成本的限制,在网络中往往会出现多种工作方式不完全一致的设备,增加了路由的复杂性.文章对多设备多业务的SDH网络的路由和保护进行了分析,分别给出了电路业务和数据业务的路由算法.此算法已成为华环公司网络管理系统的核心模块.     

Performance of a large multicast ATM switch

In this paper, we present the design of a large self-routing multicast ATM switch. The switch consists of a sorting network followed by a 3-stage routing network. We first present a simple design of a large sorting network built using small sized shared memory that can be used as a building block for a large sorting network. Small sized shared memory is also used in the 3-stage routing network making the switch modular and easy to implement using current VLSI technology. As the network uses shared memory modules, multicasting functionality is easily built into the network. The performance of the proposed network is compared with an equivalent completely shared memory switch using computer simulations under bursty traffic model. The results show that the proposed network has better performance in terms of cell loss ratio than the completely shared memory switch under moderate to heavy traffic load (0.6 ≤ effective offered load ≤ 1.2). Furthermore, multicast cell delays are drastically improved. This revised version was published online in June 2006 with corrections to the Cover Date.     

A general packet replication scheme for multicasting withapplication to shuffle-exchange networks

Multicasting in broadband packet switches and metropolitan networks can be achieved by first replicating the packets and then routing them to their destinations. This paper studies a simple but general replication scheme that can be applied to arbitrary interconnection-network topologies. The replication process of a packet adapts itself according to the network topology and the traffic condition. Hot spots of replication activities are diffused by this scheme which automatically migrates the replication efforts to less active network regions. The scheme can potentially be used in networks (e.g., the Manhattan-street network) in which multicasting was thought to be inherently difficult. This paper, however, focuses on the shuffle-exchange copy network for a detailed study of the replication algorithm and its implementation at the logic-diagram level. It is found that the performance of the algorithm improves with the increase in network dimensions. Cascading the copy network with a point-to-point switch makes a multicast switch. A novel strategy for reducing the memory size of its routing tables is proposed