PERFORMANCE ANALYSIS OF AN INPUT-BUFFERED ATM SWITCHING FABRIC WITH INDEPENDENT WINDOW-ACCESS SCHEME

In this paper, an Independent Window-Access(IWA) scheme is proposed, and the performance of an input-buffered ATM switching fabric with the IWA scheme is analysed by means of a probability generating function approach, the closed formulas of the average cell delay and the maximum throughput are given, and results show that the IWA scheme makes the switching fabric have better performances than traditional window-access scheme. The computer simulation results are in good agreement with these analytical results.     

Design of a non-blocking shared-memory copy network for ATM

The design of a copy network is presented for use in an ATM (asynchronous transfer mode) switch supporting BISDN (broadband integrated services digital network) traffic. Inherent traffic characteristics of BISDN services require ATM switches to handle bursty traffic with multicast connections. In typical ATM switch designs a copy network is used to replicate multicast cells before being forwarded to a point-to-point routeing network. In such designs, a single multicast cell enters the switch and is replicated once for each multicast connection. Each copy is forwarded to the routeing network with a unique destination address and is routed to the appropriate output port. Non-blocking copy networks permit multiple cells to be multicasted at once, up to the number of outputs of the copy network. Another critical feature of ATM switch design is the location of buffers for the temporary storage of transmitted cells. Buffering is required when multiple cells require a common switch resource for transmission. Typically, one cell is granted the resource and is transmitted while the remaining cells are buffered. Current switch designs associate discrete buffers with individual switch resources. Discrete buffering is not efficient for bursty traffic as traffic bursts can overflow individual switch buffers and result in dropped cells, while other buffers are under-used. A new non-blocking copy network is presented in this paper with a shared-memory input buffer. Blocked cells from any switch input are stored in a single shared input buffer. The copy network consists of three banyan networks and shared-memory queues. The design is scalable for large numbers of inputs due to low hardware complexity, O (N log₂ N), and distributed operation and control. It is shown in a simulation study that a switch incorporating the shared-memory copy network has increased throughput and lower buffer requirements to maintain low packet loss probability when compared to a switch with a discrete buffer copy network.     

An adaptive reservation scheme for VBR voice traffic in wireless ATM networks

A reservation scheme, named dynamic hybrid partitioning, is proposed for the Medium Access Control (MAC) protocol of wireless ATM (WATM) networks operating in Time Division Duplex (TDD) mode. The goal is to improve the performance of the real-time Variable Bit Rate (VBR) voice traffic in networks with mixed voice/data traffic. In most proposed MAC protocols for WATM networks, the reservation phase treats all traffic equally, whether delay-sensitive or not. Hence, delay-sensitive VBR traffic sources have to compete for reservation each time they wake up from idle mode. This causes large and variable channel access delays, and increases the delay and delay variation (jitter) experienced by ATM cells of VBR traffic. In the proposed scheme, the reservation phase of the MAC protocol is dynamically divided into a contention-free partition for delay-sensitive idle VBR traffic, and a contention partition for other traffic. Adaptive algorithms dynamically adjust the partition sizes to minimize the channel bandwidth overhead. Simulation results show that the delay performance of delay-sensitive VBR traffic is improved while minimizing the overhead.     

图像识别技术在银行ATM监控的应用

分析了银行原有自动柜员机监控的方式和原理。对ATM的监控方式、配置做了基本的描述,并对银行为提升ATM安防管理水平,而采取的监控联网措施和功能性做了分析。对现有ATM监控系统出现的主要问题、存在的缺点和目前我国ATM安保管理问题的严重性做了详细说明。文中介绍了图像识别技术在ATM监控系统中的应用,以及在ATM监控中所起...     

基于ATM的宽带多媒体通信卫星系统运维管理技术研究

随着卫星网络以及通信系统的逐渐研发,宽带多媒体通信卫星系统在通信领域中备受关注.宽带多媒体通信卫星系统能够实现全球无缝隙覆盖的网络互连,在通信系统研发中发挥着重要的作用.基于宽带多媒体通信卫星系统运行维护管理是保障通信卫星系统稳定运行的基础.在本文中对基于ATM的宽带多媒体通信卫星系统运维管理技术进行研究.     

A simple bandwidth management scheme for multiservice ATM networks

In this paper we outline a simple strategy to manage bandwidth allocation and congestion control and to guarantee service requirements in a multiservice ATM (asynchronous transfer mode) network. We propose a network architecture based on a core network, making available a limited number of quality of service profiles, and an access network, made of edge adapters in charge to match the user's requirements with the network's available quality of service profiles and to shape input traffic to achieve high network throughput. The connection admission rule is presented, and edge adapter architecture and design examples are given. The effectiveness of the scheme is demonstrated by numerical results which report the network utilization performance when the proposed core network policies and edge adapter design apply.     

Evolutionary architecture for an all-services ATM access network

This paper presents a flexible concept for a broadband subscriber access network which minimizes investment costs by predominantly using the existing network infrastructure. The target network may consist of either a coaxial tree-and-branch structure or symmetrical copper pairs to the subscriber, and is connected to the central head station with the aid of optical feeder lines which can be implemented or enhanced by a passive optical network (PON). In the event of an increase in bit rate requirements, the coaxial network can be expanded by dividing it into smaller, optically fed subnetworks or by supplementing it with optical overlay systems. Flexibility, expandability and low costs are achieved through the standard ATM format implemented for the signals of all interactive services down to the network termination units on the subscriber side. Those signals are transmitted in the coaxial network in frequency bands above the CATV band in accordance with a multiple of the CATV channel width to ensure that the modulation and demodulation is implemented in a cost-efficient manner while providing ‘bit rate on demand’ for a suitably high number of subscribers. Separation of the network termination unit from the customer premises equipment enables a flexible, cost-efficient subscriber configuration to be selected, existing domestic wiring to be used and several completely different subscriber terminals to be simultaneously connected.     

医院信息网络维护管理系统的设计与实现

探讨如何提高医院信息部门的信息化管理水平。结合医院信息维护需求和特点,设计并实行了医院信息网络维护管理系统,包括坐班登记子系统、下科维护登记子系统和值班日志登记子系统。实现了对坐班故障记录、人员流动和重要设备的信息化管理和实时监管。本系统的使用有利于提高信息部门服务质量和管理水平,值得进一步推广。     

ADSL网络从ATM向IP的演进

本文简要介绍了ADSL发展情况，承载网从ATM向IP演进，ATM DSLAM向IP DSLAM溶进以及宽带业务发展的一些问题。     

Policing of realistic VBR video traffic in an ATM network

ATM has been accepted by CCITT as the transport mechanism for the future BISDN and will also be widely used in future customer premises networks. Networks based on the ATM principle are expected to provide a very flexible communications infrastructure allowing customers to make effective use of a wide variety of offered services. To provide this flexibility with an acceptable quality of service while operating the network in an economic way, elaborate traffic management functions will be necessary to control the traffic flows within the network. This paper will study one of these functions—the so-called ‘usage parameter control’ or ‘policing’ function—in some detail to illustrate some of the problems that arise and point out possible solutions. The mechanisms chosen to implement the policing function will be the ‘leaky bucket’ mechanism, the ‘jumping window’ mechanism and the ‘moving window’ mechanism. The input streams used to assess the mechanisms represent different types of video communication—videophone, video conference and entertainment video—coded according to different variable bit-rate (VBR) algorithms. In contrast to most of the previous studies, where artificial, statistical traffic sources have been used, the sources used in this paper are directly based on measured ‘real-life’ video data. This ensures that all the statistical properties of the actual traffic stream are preserved and allows identification of the different factors that influence the dimensioning and the performance of the policing mechanism. The results of this study show that the uncertainty about the key parameters at call set-up and the considerable impact of single scenes make the proper dimensioning of policing mechanisms difficult. Furthermore, it seems not to be practical to use the long term mean bit-rate as the key traffic control parameter for these sources. Results indicating that the long-term cell loss ratio is not a sufficient measure for the quality of service are also presented. A comparison of the mechanisms shows that from a performance perspective, the ‘leaky bucket’ mechanism is superior to the two window mechanisms. This work is relevant to evolving standards for both BISDN traffic management and variable bit-rate video coding.     

Implementation of multipoint connections in an ATM switching network

This paper presents the problems in the implementation of multipoint connections at switching level using the example of an ATM switching network. By choosing the proper routeing mechanism and the appropriate architecture of the switching element, a switching network can gradually be adapted to an increasing share of multipoint traffic. The first section describes the problems with the handling of multipoint connections within a multiple stage connection oriented switching network. In particular this refers to the routeing of the cells through the switching network. Several alternatives on this issue are discussed. Both, the selected approach based on a differentiated self-routeing mechanism and the corresponding cell format are introduced. In the second part of this article several switch architectures are compared in respect of their multipoint capability. It is demonstrated that at present the most promising solution are switching elements based on the principle of central buffering. A single chip solution using this concept is employed in the presented switching network.     

ATM网络业务恢复机制研究

提出了基于网管控制下的层次化ATM网络业务恢复管理机制，指出了在网络维护管理过程中采用多种恢复机制并进行层次化技术处理的重要性。ATM网络的正常可靠运行需要从网络各个层次，运用各种恢复管理机制对业务进行管理维护。在网络实际运行过程当中，联合应用网络各层次上的恢复管理机制是非常重要的。描述了该技术具体应用以及基于网管控制的业务恢复策略。     

在基于MPLS的ATM交换机上的RIO分组丢弃算法性能研究

如何利用基于多协议的标签交换（ＭＰＬＳ）机制来支持有差别的业务类型,是目前研究的热点。本文研究了在基于多协议标签交换机制的ＡＴＭ交换机上支持有差别业务类型的一种实现算法。经研究表明：ＲＩＯ算法通过有效的活动缓存管理机制,在采用最简单的ＦＩＦＯ排队策略的情况下,能够较好地支持有差别的业务类型。     

基于CPLD的ATM安全警示系统设计

介绍了以CPLD（复杂可编程逻辑器件）为核心的ATM（自动柜员机）安全警示系统的设计。该系统由CPLD开发平台、红外检测单元、超声波测距单元、语音提示单元、激光封锁单元和闪光预警单元组成。当有人存取款时，系统显示等候人的距离，同时LED（发光二极管）显示屏实时模拟等候人的靠近情况。语音模块会根据等候人的位置做出相应的提示。如果有人强行闯入激光封锁线，则闪光灯闪光，同时语音模块发出报警。     

光缆通信传输网络维护系统的设计与实现探究

通信工程是我国现代化重要的枢纽工程,光缆通信是我国目前主要的传输形式与传输设备,在我国科学技术水平不断提高的同时,光缆通信传输网络系统在我国的通信工程中得到广泛的应用,曾庆了光缆通信网络传输的可靠性,减少网络故障发生.为了满足现代化网络通讯设施的使用与运行,需要对光缆通信传输网络系统进行必要的维护工作,在光缆通信的传输阶段避免出现故障问题.     

综合业务接入ATM网络的资源共享

本文提出了一种在ATM网络中传输综合业务的资源共享方案,该方案中,每一VP只传输一类业务,并根据各业务的带宽,各VP传输的业务量和链路的剩余带宽动态分配各个VP占用的宽带,在保证各类业务呼损率的前提下,可获得提高传输效率和降低节点归一化处理负荷的良好折衷。本文还引入了迟滞和资源预留两个概念,并分析了它们对呼损率和节点的归一化处理负荷的影响,最后给出了详细的理论分析和计算机模拟结果。     

基于ZigBee技术的电源网络监控系统设计

随着日常生活和生产中设备对用电的要求,电源的管理越来越重要,电源的稳定性不仅影响设备的正常工作,还会带来相应的安全隐患.在系统设计中对电源要进行必要的监测和控制,电源监控系统中终端设备单独对电源模块进行监控,对电源的控制采用快速响应继电器来减少延迟,从而保证系统安全.本文提出了基于ZigBee无线传感网的电源监控系统软件设计和硬件设计方案.系统中的ZigBee无线模块节点采用CC2430芯片为核心,优点是成本低、协议简单和组网容易等.     

8端口ATM工作组交换机设计与性能分析

本文概述了基于FPGA的8端口155Mbit/s(25Mbit/s)ATM工作组交换机的设计,对其关键部分如输入输出端口处理,交换结构等进行了阐述,并对其性能进行了分析,试验运行表明各项指标均满足设计要求。     

关于智能化变电站监控与运维的研究

电力是我们国家社会发展的基础动力,所以电力维护也是我们现今电力发展的重要目的.藉此,本文对智能化变电站监控与运维技术进行了探索,并讨论了智能化变电站监控方法.     

SDH网络中网管监控优化方案设计

随着通信行业的高速发展和人力成本的提高,通信网管网络的稳定运行已成为运营商关注的焦点。本文通过对SDH网络中的ECC通信的特点、通信原则、组网能力等方面进行分析,结合实际应用中SDH网管有时会出现的网元大面积脱管、网元数据及告警信息提取更新速度慢等隐患,提出了解决的几个有效方法,并通过应用于实际日常维护工作中,使SDH传输设备网管的有效性和可靠性得到了大幅的提高。