Optimizing offset times in Optical Burst Switching networks with variable Burst Control Packets sojourn times

In this paper, we consider the case of an Optical Burst Switching (OBS) network where the Switch Control Units (SCU) do not work at the peak rate. As a consequence, some Burst Control Packets (BCPs) will have to wait in queue to be processed, and then the BCP sojourn time will be variable. On the contrary, the optical burst does not leave the optical domain and the delay suffered is close to the propagation delay. Hence, chances are that the BCP arrives late to a given switch and, in that case, the optical burst will be dropped. We propose a Load-adaptive Offset Time algorithm (LOT) that takes into account the BCP variable sojourn time for the offset time calculation. The algorithm performs on-line calculation of the Discrete Fourier Transform (DFT) of the BCPs waiting time pdf. Our findings show that this procedure is very efficient both in terms of bandwidth usage and processing load. For example, considering a Gaussian service time for the BCPs, it turns out than less than 45 coefficients are necessary to calculate the offset time for a SCU utilization factor larger than 0.1.     

MPLS技术在唐山有线电视综合信息网数据平台中的设计与应用

MPLS技术是一项具有多协议支持的技术，它综合利用了网络核心的交换技术和网络边缘的IP路由技术各自的优点，它将标记分配给多协议的数据桢以便在基于我展品信元的网络中传输。它能够提供现有传统IP路由技术所不能支持的要求保障QoS的业务，通过MPLS技术，我们可以提供各种新兴的增值业务，有效的实施流量工程和计费管理措施，扩展和完善更高等级的基础服务。     

LOBS技术研究

光突发交换技术(OBS)是一种新出现的光交换技术,它综合了光波长路由和光分组交换的优点。本文的LOBS又将MPLS 和OBS这两大技术结合在一起,利用MPLS强大的控制能力为OBS网络在QoS、流量工程和网络恢复等方面提供良好的支持。文章根据LOBS的基本原理,提出并详细阐述了它的网络构成和工作机制,最后指出了LOBS网络在流量工程和网络生存性方面相对其他光网络的优越性。     

基于开关信号理论的四值ECL电路

从一个有效的多值代数系统应能反映多值电路中的物理过程的这一原则出发,本文提出了一组可以描写多值ECL电路中信号与开关元件间相互作用的运算。讨论了这些运算的物理对应及有关性质,并由此建立了适用于ECL电路的开关信号理论。本文设计了若干基本四值ECL电路,用SPICE程序模拟证明了它们均具有正确的逻辑功能与理想的DC特性。     

自扫描光电二极管列阵的均匀性研究

本文主要从自扫描光电二极管列阵SSPD的电路设计、版图结构、工艺和材料等几个方面,研究了导致这种图像传感器视频输出信号呈现非均匀性的种种原因,提出了解决问题的措施。提高了SSPD器件CL128、CL256的均匀性,其视频输出信号不均匀性NV由小于±10％提高到±7％。     

用于光信息处理的表面垂直光电子器件的现状

评论用于光信息处理表面垂直光电子器件的近期进展。同时,讨论改善器件性能的几种方案。     

Optimum component switching for systems that operate and idle

Whilst the selection of optimum redundancy designs, in the presence of opposite failure modes, has received much attention in the literature, the associated problem of optimum management of such redundant systems has hitherto been ignored.This note considers the determination of the optimum switching policy for redundancy designs in terms of a cost formulation which weights each of the two failure modes and allows for a cost associated with the repeated switching of components. The integrated design and switching problem is also discussed. By considering all possible three component series — parallel systems, it is demonstrated that the optimum switching policy is critical in the determination of the optimum redundancy design.     

A broadband central office for ATM

Recently, a growing interest has been shown towards fast packet switching, ATD (asynchronous time division), or the more general term ATM (asynchronous transfer mode) in a number of companies and organizations such as CCITT and RACE. In Belgium a broadband experiment is planned using this technique. This paper focuses its attention on the central office (switching exchange). This exchange is a multistage network constructed with independent switching elements based on the self-routing principle. The load control in the exchange is provided by a static load control mechanism applied to the logical connections granted on these links. Simulation results show that this load control mechanism can work perfectly if used in the proper environment.     

高速脉宽调制器的原理及应用

本文介绍了ＳＷ１８２５高速脉宽调制器的特点和原理，列举了典型应用的接线图；并对电路应用中的功耗、工作稳定性等进行了讨论。     

New insight into phase change memories

The switching mechanism in phase change memories was described on the basis of minimum switching unit: the commuton. A commuton is a minimum cluster of atoms that supports a reversible phase change from high to low electrical conduction state and back under the influence of an external signal. The switching process in a phase change chalcogenide film was modeled using two dimensional cellular automata approach. A system of 50 × 50 cells, each cell containing a commuton, was simulated. In the particular case of Ge₂Sb₂Te₅ (investigated here) this system corresponds to a 30 × 30 nm area. The formation of the percolation path as a function of phase change induced in commutons explains the switching phenomenon. The influence of the percent of defects in the material on the percolation threshold has been studied.