A Novel Radio-Over-Fiber System With Wavelength Reuse for Upstream Data Connection

We have experimentally demonstrated a novel wavelength reuse scheme for up-link connection in a radio-over-fiber (ROF) system. The dual-mode lightwave generated by optical carrier suppression modulation is separated by an optical interleaver. One of the dual-mode lightwaves is modulated with a baseband data at 2.5 Gb/s. The other lightwave will be used for the optical carrier for the up-link data modulation. There is no additional laser source for the upstream data generation in the base station. By this method, we simplify the configuration of the ROF system and reduce the cost of the system     

光分组交换网络的冲突解决：用光纤延迟线还是波长转换器

该文研究了光分组网络的冲突处理问题,提出了两种异于传统设计方法的交换结构．研究表明：对于非突发性业务,非简并排列方式的光纤延迟线是成本聚低的解决手段;而对于突发业务,将波长转换器和延迟线结合使用是兼顾分纽丢弃性能,系统体积和成本的较好策略．文中基于此给出了系统设计原则,该原则可确保系统节约大量的波长转换器和延迟线。对改善系统的整体性能十分有利．     

Experimental Facsimile Communication System on Packet Switched Data Network

The use of the public data network for facsimile communication has remarkable advantages with regard to high speed and reliable transmission and, in addition, it is well applicable to provide value added facilities for future service extension. The Research and Development Laboratories of Kokusai Denshin Denwa (KDD) Company, Ltd. have developed an experimental facsimile communication system on the packet switched data network (PSDN). The system is composed of packet switching exchanges (PSE), high speed digital facsimile terminal equipment, a facsimile communication processor (FCP), and facsimile packet assembly/ disassembly equipment (FAX-PAD). The facsimile equipment in the system adopts a two-dimensional modified READ code and has the interface protocol to the PSDN. The FCP provides the store-and-forward facilities to provide such services as delayed delivery, multiaddress delivery, and mailbox service. The FAX-PAD realizes the interworking between facsimile equipments on the public switched telephone network (PSTN) and those on PSDN. After various experiments including international field tests, it was confirmed that the system is useful for future advanced facsimile service.     

波长交换光网络中路由波长分配技术

路由波长分配问题是在给定连接的情况下,为该请求分配适当的光路进行传输。在无波长转换能力的情况下,需要为光路在其传输的链路上分配相同的波长,这就是波长连续性问题。物理层的光损伤极大的限制了光网络的能力,因此需要可感知损伤的路由波长分配算法来保证传输的质量。对于不同的感知损伤的路由波长分配方式,相应地,有不同的控制平面结构。     

Packet Pacing in Small Buffer Optical Packet Switched Networks

In the absence of a cost-effective technology for storing optical signals, emerging optical packet switched (OPS) networks are expected to have severely limited buffering capability. To mitigate the performance degradation resulting from small buffers, this paper proposes that optical edge nodes “pace” the injection of traffic into the OPS core. Our contributions relating to pacing in OPS networks are three-fold: first, we develop real-time pacing algorithms of poly-logarithmic complexity that are feasible for practical implementation in emerging high-speed OPS networks. Second, we provide an analytical quantification of the benefits of pacing in reducing traffic burstiness and traffic loss at a link with very small buffers. Third, we show via simulations of realistic network topologies that pacing can significantly reduce network losses at the expense of a small and bounded increase in end-to-end delay for real-time traffic flows. We argue that the loss-delay tradeoff mechanism provided by pacing can be instrumental in overcoming the performance hurdle arising from the scarcity of buffers in OPS networks.      

分组网络中同步标准的进展及分析

如何解决同步信号地面链路传递问题,是目前分组传送网络中研究的一个重要课题。传统同步体系中的标准仅适用基于电路交叉技术的网络,并不适用于指导分组传送网络中面临的问题。目前虽已有运营商应用1588v2,满足移动回传网络中的时间同步需求,但随着网络复杂性的逐步增强,以及对设备时间(时钟)能力要求的不断提高,亟待相关标准的出台及完善。文章对分组网络中的同步标准进行了讨论,并就当前包交换技术实现频率和时间同步的热点应用给出了建议。     

The Data Vortex Optical Packet Switched Interconnection Network

A complete review of the data vortex optical packet switched (OPS) interconnection network architecture is presented. The distributed multistage network topology is based on a banyan structure and incorporates a deflection routing scheme ideally suited for implementation with optical components. An implemented 12-port system prototype employs broadband semiconductor optical amplifier switching nodes and is capable of successfully routing multichannel wavelength-division multiplexing packets while maintaining practically error-free signal integrity (BER $ ≪ {hbox{ 10}}^{ - 12}$ ) with median latencies of 110 ns. Packet contentions are resolved without the use of optical buffers via a distributed deflection routing control scheme. The entire payload path in the optical domain exhibits a capacity of nearly 1 Tb/s. Further experimental measurements investigate the OPS interconnection network's flexibility and robustness in terms of optical power dynamic range and network timing. Subsequent experimental investigations support the physical layer scalability of the implemented architecture and serve to substantiate the merits of the data vortex OPS network architectural paradigm. Finally, modified design considerations that aim to increase the network throughput and device-level performance are presented.      

Experimental Demonstration of 1.25-Gb/s Radio-Over-Fiber Downlink Using SBS-Based Photonic Upconversion

We experimentally demonstrate a radio-over-fiber downlink system using a stimulated Brillouin scattering (SBS)-based photonic upconversion technique. The Brillouin selective amplification characteristic of SBS is incorporated to generate the 11-GHz band radio-frequency (RF) carrier. The dual-electrode Mach-Zehnder optical modulator, which is used to carry the broadband data in the optical carrier instead of the optical sideband, is adopted along with the SBS-based carrier generation setup. To vindicate the broadband capabilities of the proposed scheme, 1.25-Gb/s pseudorandom bit sequence data is carried in the optical carrier. Error-free operation of the 1.25-Gb/s downlink is achieved without critical power penalties after the 13-km fiber transmission.     

QoS Differentiation in Asynchronous Bufferless Optical Packet Switched Networks

Optical Packet/Burst Switched networks (OPS/OBS) have emerged as promising all-optical network architectures for future core networks due to good resource utilization and the ability to handle high line speeds in a cost-efficient way. Regarding these networks, Quality of Service (QoS) differentiation should be provided in order to give sufficient QoS to real-time applications, and to utilize network resources optimally. In this paper, we present three fundamental different QoS differentiation schemes suitable for asynchronous bufferless OPS. We present analytical models and derive explicit results for the packet loss rates. We then present a general evaluation framework followed by a comparison study of the considered QoS differentiation schemes. Simulation and analytical results show that QoS differentiation schemes based on preemption have better performance than drop based and access-restriction based QoS differentiation schemes.     

基于3G网络PS域的传真通信研究

传真通信在PSTN网上得到了广泛的应用,在3G网上虽然制定了CS域传真的相关标准,却并未开展应用。而PS域虽然提供了透明的数据传输通道,但在端到端通信和传输的实时性方面与固定IP网有较大差别。针对3G网CS域不能进行传真通信的现状,对PS域传真的可行性进行了研究,分析了PS域信道的特点,对实时传真模式和存储转发模式进行了比较,提出在PS域建立VPN实现端到端通信和存储转发的传真工作模式。     

分组交换网上的增值业务

本文介绍了公用和专用分组交换数据网的现状后，说明了开展标准的增值业务系统的重要性。论述了典型的增值业务系统－电子邮件和传真存储转发系统。     

Quality of Service in Asynchronous Bufferless Optical Packet Switched Networks

Optical Packet Switching (OPS) is a promising technology for future core networks due to the ability to handle bursty traffic, adaptability to changes in the network infrastructure and good network utilization. In order to provide sufficient Quality of Service (QoS) to the emerging range of real-time and critical business applications, service differentiation should be present in future OPS. This paper presents the Preemptive Drop Policy (PDP), which provides service differentiation in asynchronous bufferless OPS. Based on time-continuous Markov chains, we introduce an analytical model of the PDP for switches with and without wavelength conversion. We extend the PDP into the Adaptive PDP (APDP), which provides absolute QoS guarantees in OPS. Simulations performed validate our analytical model and show that the APDP operates properly in a dynamic changing system load scenario.     

3G分组域核心网设备性能评估研究

由于无线带宽的增加,在3G网络中可以实现更多的数据业务,这些数据业务的逐渐引入将会对分组域核心网设备产生更多的性能压力;另外,业务种类的增多以及业务部署的周期逐渐缩短也会导致话务模型的复杂度和时变性增大,对设备在不同情况下的性能表现提出了新的挑战.这些都要求对3G分组域核心网设备进行科学的评估,以推动设备性能的优化,最大程度地保障网络和业务质量.本文对3G分组域核心网设备的性能评估方法做了系统的描述,并结合实际测试中发现的问题,对今后工作提出了参考建议.     

同步光分组交换网核心节点光分组长度分析

研究了同步光分组交换网中光分组长度的设计及其对一些网络性能参数的影响,分别推导了光分组中开销所占比率、时延及光纤延时线长度与光分组长度的关系,并给出各自相应的理论分析和数值解析,为光分组中分组长度的设计做了基础工作。     

An Optical Packet Addressing Scheme for Optical Packet Switched Networks Using RF Frequency Carrier Assignment

We propose an efficient optical packet addressing technique for optical packet-switched networks, where the pre-assigned RF frequency carriers are used to represent the packet addresses. It can simplify the control process of optical packet switching so that it results in reduced address processing time and smaller complexity of the packet address processor due to simple extraction of address information. We also analyze the performance of the proposed packet addressing scheme in the transmission aspect taking into account packet address wavelength beating and laser nonlinearity.     

一种单光源ROF系统的分析

降低基站的建设成本,实现低成本的ROF系统.采用光载波抑制调制产生光毫米波,利用光纤光栅的滤波特性,将毫米波上下边带分离.在中心站,将5Gbit/s下行数据只调制到上边带.在基站,将从天线接收下来的上行数据信号经过混频后调制到下边带.本文给出了系统关键点的眼图、频谱,及系统的误码曲线.利用该方法实现了单光源ROF系统,上行数据传输30km的功率代价为0.33dB,下行数据传输30km的功率代价足1.1dB.单光源ROF系统由于基站不需要另外安装光源而变得更简单,而且效率增加.     

A Genetic Algorithm for Routing in Packet—Switched Communication Networks

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A Novel All-Optical Routing Architecture for Optical Packet Switched Networks

Increasing bandwidth demand, mostly driven by the Internet Protocol (IP), has made researchers consider to deploy all-optical devices into packet switched networks. Despite huge bandwidth of the optical communication links (optical fiber) the usable capacity is limited due to bottlenecks (congestions) at the switching nodes. In this paper, a novel all-optical routing architecture is proposed for optical packet switched networks. In the design, practical optical devices (gratings, threshold elements, optical delays, and couplers) have been improved and exploited in order to integrate into an all-optical routing device. The system has been implemented and simulated by using an photonics simulation package (VPI-Virtual Photonics). The packets conveying a three-bit routing information tag at the bit rate of 10 Gbps have been successfully routed between two links. Some of the components are standard tools of the simulation package and some needed to be designed using the transfer function or theory developed in the literature. Noise and losses associated to the nonideal nature of the components are considered in the simulation as well.     

基于多重光正交码光标签的光分组交换系统实验研究

采用多个光正交码串行排列组成的多重光正交码(MOOC)标签格式,提高了可用标签的数目;构建了基于MOOC标签的光分组交换系统(OPS),对该系统中的各项关键技术,包括光分组信号产生单元、光标签处理单元、交换控制单元,光交换矩阵等进行了分析和研究;完成了光分组交换系统演示实验,并对实验结果进行了讨论.     

Routing Strategies to Minimize Packet Loss in an Optical Packet Switched Network with Recirculating FDL Buffers

The major goal of optical packet switching (OPS) is to match switching technology to the huge capacities provided by (D)WDM. We study optical packet switches with recirculating fiber delay line (FDL) buffers. Through simulation, we have assessed the logical performance of a single optical packet router (OPR), focusing on packet loss rate (PLR). By verifying that our scheduling algorithm does not alter the traffic profile characteristics from in- to output, we illustrate how the single node results can be used to assess network-wide performance. We use the capability of assessing end-to-end PLRs to develop network-wide routing algorithms designed to minimize the maximal PLR occurring in the network. In case studies on pan-European networks, we first compare two algorithm variants and thereafter we compare the PLR-based routing algorithm with both load balancing and shortest path routing. While load balancing achieves PLRs that are multiple orders of magnitude lower than shortest path routing, the PLR-based algorithm can reach PLRs up to two orders of magnitude better. The improvement in PLR comes at the price of only a small increase in used bandwidth (a few percent). Subsequently we show that the discussed PLR-based routing algorithm can be easily extended to multiple priorities. By introducing multiple priorities we can keep the loss rates for high priority traffic very low. However, it may lead to an increase of the obtained minimal max-PLR value for low priority traffic. But as we prove this increase to be limited, the cost of introducing multiple priorities is small.