光分组交换网络结构

光分组交换技术日益成为世界各国研究的重点，光交换的结构设计是光分组交换技术的关键。文中详细介绍了目前正在研究的空间光开关、广播选择和波长路由三种光分组交换结构。随着光网络、光器件和光系统技术的发展，光分组交换必会走向实用化。     

光分组交换技术的研究

光分组交换技术的引入，改善了带宽的利用率和网络的灵活性，延伸了光的透明性。在光分组交换层中光分组的产生、同步、缓存、再生，分组头重写及分光组之间挑功率的均衡成为实现光分组产换的基本技术，而多波长方案并不是光分组交换的唯一模式，光时分分组交换、光标签交换、波分及混合分组交换、多协议标签交换、光突发分组交换等交换方式的出现必将对未来的通信网产生重要的影响。     

光分组交换技术

光分组交换以其大容量、高速化、无电磁干扰等优良特性受到世界各国的重视。尽管目前对光交换的研究尚处于起始阶段，但随着宽带通信业务的发展和对光交换技术的深入研究，光交换技术将不断进步和完善。对光分组交换的特点及其与电分组交换的区别进行了讨论，并介绍了两处比较典型的光交换结构，最后对几种光分组编码方法进行了介绍和比较。     

未来光网络中的LOBS技术

光突发交换技术和MPLS的迅速发展产生了一种更加灵活、紧凑的IP／DWDM集成方案LOBS。它综合了光路交换和光分组交换的优点及最先进的MPLS的强大控制能力，是下一代因特网的理想光交换方案，并且为光分组交换的实现奠定了基础。文中在全面介绍LOBS交换网络结构和控制协议的基础上，分析了LOBS流量工程和QoS机制，最后初步讨论了LOBS时延和阻塞率特性。     

光突发交换与下一代互联网

光突发交换与交换粒度介于光电路交换（即波长交换）和光分组交换之间的一种光交换模式，因为它克服了光电路交换和光分组交换的缺点，具有很大的技术优势，很有可能成为下一代互联网骨干网络的核心技术，真正实现光子互联网。本介绍光突发交换技术的基本原理，讨论了光突发交换的协议，突发封装和在IP骨干网中的应用等问题，并指出在这项技术得到应用之前需要解决的诸多课题。     

光分组交换网络结构

光分组交换技术日益成为世界各国研究的重点 ,光交换的结构设计是光分组交换技术的关键。文中详细介绍了目前正在研究的空间光开关、广播选择和波长路由三种光分组交换结构。随着光网络、光器件和光系统技术的发展 ,光分组交换必会走向实用化     

光分组交换节点技术

文章首先介绍了光分组交换网络的分类和光分组交换节点的基本结构，接着详细讨论了全光分组交换节点设计和实现中的关键问题，交换结构的设计，光存储的实现以及分组拥塞问题的解决方案。     

光突发交换网关键技术及发展

本主要介绍了光突发交换网的关键技术，并在同光波长交换网络和光分组交换网络相比较的基础上，对光突发交换的发展前景做了乐观的估计。     

光突发交换控制卡电路的设计与实现

光突发交换(OBS)是兼顾光电路交换和光分组交换优点的一种折衷方案，是未来光互联网的一种实现形式。在我们即将组建的光突发交换试验网中，IP(因特网协议)数据在边缘节点被组装成突发包，需要使用数据卡和控制卡分别处理数据分组和控制分组。因此，对处理控制分组的控制卡电路的优化设计和实现进行了描述。     

核心网中的光分组交换

光分组交换（OPS）是光交换技术的长远发展目标，其研究工作在上世纪90年代取得了很大进步。本文主要介绍OPS的一些基本概念和相关使能技术的进展情况，最后对OPS的前景做一些分析。     

Traffic models for slotted optical packet switched networks

Optical packet switching (OPS) has emerged as a promising architecture for the future all-optical network scenario. In order to have a successful deployment of OPS networks, several networking issues must be resolved, e.g., how to resolve contentions and how to provide Quality-of-Service (QoS) differentiation. Such networking studies often rely on teletraffic analysis in order to quantify the performance of the OPS network. In this paper, we introduce new and review existing traffic models for slotted buffer-less OPS networks. In particular, we present a novel asymmetric traffic model, suitable for studying the effects of non-uniform traffic. Optical packet switches with and without wavelength conversion are studied. Numerical evaluations and a comparison study of the presented traffic models are reported. The main contributions of this paper are to advance the field of establishing a theoretical framework for slotted OPS networks and to act as a tutorial for teletraffic engineering in such networks. http://www.item.ntnu.no/~haraldov.     

On the performance of different node configurations in multi-fiber optical packet-switched networks

With the development of optical packet-switching (OPS) technologies, multi-fiber OPS networks will play an important role in the future data transmissions. In such networks, instead of constructing some extremely expensive node configurations with strictly non-blocking switching function, a more practical solution is multi-board switches that contain a number of small-sized switching boards. In this article, we have evaluated the performance of several different multi-board switches, based on the following two main objectives: (i) better understanding the effects of different connection schemes between switching boards and optical buffers and (ii) investigating possible schemes for achieving comparable performance to that of the ideal, strictly non-blocking switches. Extensive simulation results have shown that unlike circuit-switched net- works, multi-board OPS cannot easily perform comparably to the strictly non-blocking switch by having slightly more fibers per link. Also, such a problem can be tackled by several different approaches. The most efficient one is to equip the switch with more buffers rather than to increase the switching-board size or to enhance the buffer sharing between different switching boards.     

Buffering management schemes for optical variable length packets under limited packet sorting

This paper studies several buffering strategies for optical packet switching (OPS) under limited packet sorting. Three schemes, which are able to sort newly arrived packets based on packet’s length as well as capability of finding the minimum buffer occupancy, are analyzed and compared. Results show that all three proposed schemes could improve OPS performance considerably in terms of probability of packet loss (PPL) and probability of information loss (PIL). In addition, the simulation results show that not all the newly arrived packets need to be sorted in order to obtain minimum packet loss probability. Since the amount of packets and thus the packet processing time is significant in OPS, it is possible that not all the packets can be processed using one of the buffering strategies. An important finding of this paper is that if only 10% of the packets are sorted, the PPL is comparable to the minimum packet loss value obtained when 100% of the packets are sorted.     

The impact of synchronization on the performance of FDL buffers

Circumventing the speed bottleneck of electronic switching, novel switching approaches like optical burst switching (OBS) and optical packet switching (OPS) handle the switching of bursts (or packets) in backbone nodes optically, and include a set of fiber delay lines (FDLs) for optical buffering. While previous work acknowledges the performance difference between optical FDL buffers and electronic RAM buffers, the important role of synchronization herein has received little attention to date.     

An effective buffering architecture for optical packet switching networks

A novel optical buffering architecture for Optical Packet Switching (OPS) networks is proposed in this article. The architecture which adopts a fiber-sharing mechanism aims at solving the problem of using a large number of fiber delay lines that are used to solve resource contention in the core node in OPS networks. The new architecture employs fewer fiber delay lines compared to other simple architectures, but can achieve the same performance. Simulation results and analysis show that the new architecture can decrease packet loss probability effectively and achieve reasonable performance in average packet delay.

The study of QoS guarantee in the optical burst switching internet backbone

Optical switching technology can be categorized into optical circuit switching (OCS), optical packet switching (OPS) and optical burst switching (OBS). OCS is suitable for large amounts of data transmission; however, the channel utilization is inefficient when the traffic flows are intermittent. OPS can be easily adapted to any higher layer and is suitable for bursty traffic, but it requires a highly complex technology and optical buffer. The new switching paradigm, OBS, can provide higher bandwidth utilization and meanwhile avoid the complexity in OPS technology.In this paper, we investigate how the quality of service (QoS) can be guaranteed and reliable transmission can be supported in the OBS-based Internet backbone. We propose the adjustable-time-counter-based (ATCB) burst assembly and the non-real time packet retransmission mechanisms and apply them in the ingress router of the OBS Internet backbone to guarantee the quality of real time applications and lossless requirement of non-real time services. Moreover, traffic shaped is performed for real time packets in the egress router so that the real time property is preserved with a low jitter. Simulation results show that the burst blocking probability using the ATCB burst assembly is improved, compared with the time-counter-based (TCB) and burst-length-threshold-based (BLTB) mechanisms. The delay, loss and jitter of real time service conform to the QoS requirement. Meanwhile, the delay of non-real time service also falls in the acceptable range.     

Performance analyses of serial-mode multicasting scheme in optical packet switched networks

The serial-mode multicasting scheme (SM), which can achieve duplication, buffering, and serial export of optical multicast packets in Optical Packet Switched (OPS) networks, is experimentally studied in this paper. Based on the experimental results, several limitations of this scheme, such as the multicast latency and signal impairment, are discussed. In addition, its performance in OPS networks is investigated by computer simulations. From the simulation results, a conclusion can be drawn that compared with the parallel-mode multicasting scheme (PM) producing multiple simultaneous copies of the optical packets by an optical power splitter or other devices, the SM scheme can increase the multicast success ratio and reduce the multicast retransmission times at the costs of some signal impairments and some extra transmission latency.

OPTIMIZATION OF WDM OPTICAL PACKET SWITCHES WITH SPARSE WAVELENGTH CONVERTERS AND NON-DEGENERATE FIBER DELAY-LINES

This paper investigates the untraditional approach of contention resolution in Wavelength Division Multiplexing (WDM) Optical Packet Switching (OPS). The most striking characteristics of the developed switch architecture are: (1) Contention resolution is achieved by a combined sharing of Fiber Delay-Lines (FDLs) and Tunable Optical Wavelength Converters (TOWCs); (2) FDLs are arranged in non-degenerate form, i.e., non-uniform distribution of the delay lines; (3) TOWCs just can perform wavelength conversion in partial continuous wavelength channels, i.e., sparse wavelength conversion. The concrete configurations of FDLs and TOWCs are described and analyzed under non-bursty and bursty traffic scenarios. Simulation results demonstrate that for a prefixed packet loss probability constraint, e.g., 10-6, the developed architecture provides a different point of view in OPS design. That is, combined sharing of FDLs and TOWCs can, effectively, obtain a good tradeoff between the switch size and the cost, and TOWCs which are achieved in sparse form can also decrease the implementing complexity.     

氧化多孔硅上制作Cu电感的研究

给出了一种厚膜氧化多孔硅(OPS)层上制作Cu电感的新型工艺技术。由于OPS是一种低损耗的材料,铜的电阻率很低,采用OPS隔离硅衬底和Cu线圈能够降低电感的寄生损耗,提高电感Q值。实验过程中将孔隙度>56%的多孔硅厚膜利用两步氧化法氧化为OPS厚膜,通过种子层溅射/光刻/电镀Cu/刻蚀种子层的方法完成了Cu线圈的电镀。获得了1nH的电感,其Q值在10GHz的频率下达到了9,电感的自谐振频率超过20GHz。