SNA Function Management

The path control network of Systems Network Architecture (SNA) supports communication between pairs of network addressable units called logical units, usually referred to as LU's. When communicating, information flows between LU's over a logical connection called a session. SNA defines three categories of messages which flow on LU-to-LU sessions-- session control, data flow control, and function management data. Thispaper discusses the structui'e and semantics of messages and protocols used by one LU to manage functions performed by a remote LU. The relatio.nship between distribution of function, the nature of the information, the technology, and the architecture of the data stream will be discussed. The data Streams used by SNA printers and 3270 displays will be used as examples. The paper concludes with a discussion of the possible impact of advancing electronic technology on data stream architecture.     

控制器局域网简化小型网络的构成

控制器局域网(CAN)最初由Robert Bosch公司(一家汽车制造厂)于1986年提出,其目标是设计一种非常可靠的网络,使得车辆内部各个电子模块之间能很容易地进行通信.Bosch公司达到了目标-在新型奥迪(Audi)A8轿车内部共安装了80个CAN器件,分布在5个网络中.     

Design of EBG Power Distribution Networks With VHF-Band Cutoff Frequency and Small Unit Cell Size for Mixed-Signal Systems

Hybrid electromagnetic bandgap (EBG) power distribution networks (PDNs) with VHF-band cutoff frequency, small unit cell size, and wideband noise suppression characteristics are proposed. Commercial lumped chip inductors are used to implement inductive bridges between neighboring metal patches instead of conventional microstrip lines. A 1D analysis model of the EBG structure is developed to find a mathematical ground for the use of the lumped chip inductors in the EBG PDN designs. From 158 MHz to 4528 MHz a measured stopband bandwidth of 4.37 GHz is achieved with over -60 dB noise suppression levels.     

Wireless Infrared Communication Systems and Networks

International Journal of Wireless Information Networks -     

UWB Systems for Wireless Sensor Networks

Wireless sensor networks are emerging as an important area for communications. They enable a wealth of new applications including surveillance, building control, factory automation, and in-vehicle sensing. The sensor nodes have to operate under severe constraints on energy consumption and form factor, and provide the ability for precise self-location of the nodes. These requirements can be fulfilled very well by various forms of ultra-wide-band (UWB) transmission technology. We discuss various techniques and tradeoffs in UWB systems and indicate that time-hopping and frequency-hopping impulse radio physical layers combined with simple multiple-access techniques like ALOHA are suitable designs. We also describe the IEEE 802.15.4a standard, an important system that adopts UWB impulse radio to ensure robust data communications and precision ranging. In order to accommodate heterogeneous networks, it uses specific modulation, coding, and ranging waveforms that can be detected well by both coherent and noncoherent receivers.      

Modeling Communication Networks With Hybrid Systems

This paper introduces a general hybrid systems framework to model the flow of traffic in communication networks. The proposed models use averaging to continuously approximate discrete variables such as congestion window and queue size. Because averaging occurs over short time intervals, discrete events such as the occurrences of a drop and the consequent reaction by congestion control can still be captured. This modeling framework, thus, fills a gap between purely packet-level and fluid-based models, faithfully capturing the dynamics of transient phenomena and yet providing significant flexibility in modeling various congestion control mechanisms, different queueing policies, multicast transmission, etc. The modeling framework is validated by comparing simulations of the hybrid models against packet-level simulations. It is shown that the probability density functions produced by the ns-2 network simulator match closely those obtained with hybrid models. Moreover, a complexity analysis supports the observation that in networks with large per-flow bandwidths, simulations using hybrid models require significantly less computational resources than ns-2 simulations. Tools developed to automate the generation and simulation of hybrid systems models are also presented. Their use is showcased in a study, which simulates TCP flows with different roundtrip times over the Abilene backbone.     

Discrete-Time Queueing Systems and Their Networks

Queueing systems in descrete time that can model certain computer communication systems are considered. First, a single-resource model consisting of a geometric server with feedback facility, to which packets arrive in independent bulks, is analyzed. Then, it is shown that a network of such geometric resources with packets arriving in independent Bernoulli streams (which, in a sense, is a discrete analog of Jackson's network) does not possess the independence property. A byproduct of this result is the fact that output of a geometric resource fed by two or more independent Bernoulli streams is not an independent Bernoulli stream.     

EPON系统在有线宽带网中的应用

分析了EPON和CATV光网络结构的相似性,特别是EPON软件、硬件技术的发展创新,使得EPON技术和HFC技术得以结合,从而为EPON系统在有线宽带网中的大规模应用奠定了坚实基础。     

High-Capacity PCM Transmission Systems for Toll Networks

High-capacity pulse code modulation (PCM) transmission systems have made little impact despite the availability of suitable technology and the rapid growth of low-capacity systems. It is shown that high-capacity systems can now be introduced into toll telephony networks without short-term economic or compatibility disadvantages and with considerable long-term advantages. A 120Mbits/s coaxial cable system compatible with 12-MHz systems is described in outline.     

Adaptive Control of Mechanical Systems Using Neural Networks

In this paper, we consider the decentralized adaptive control design problem for uncertain mechanical systems, where uncertainty may arise due to isolated subsystem and/or interconnections among subsystems. Radial basis function neural networks are used to approximate the nonlinear functions to include both dynamic and interconnection uncertainties in each subsystem. The stability of the thus designed control system can be guaranteed by a rigid proof. Finally, a simulation example is given to illustrate the effectiveness of the proposed algorithm.     

Location Verification Systems in Emerging Wireless Networks

As location-based techniques and applications have become ubiquitous in emerging wireless networks, the verification of location information has become more important. In recent years, there has been an explosion of activity related to lo- cation-verification techniques in wireless networks. In particular, there has been a specific focus on intelligent transport systems because of the mission-critical nature of vehicle location verification. In this paper, we review recent research on wireless location verification related to vehicular networks. We focus on location verification systems that rely on for- mal mathematical classification frameworks and show how many systems are either partially or fully encompassed by such frameworks.     

Operational Support Systems for Carrier-Scale IP Networks

The operational support systems (OSS) of any major telecommunications operator are the underlying resource for the management and delivery of all its communications services. It is used for handling direct customer interactions (helpdesk, orders, fault handling, billing, etc) and for the processes involved in managing the services and the networks on which they are supported. Many such services and networks are rapidly evolving in the Internet protocol (IP) era with a consequent requirement for radical improvements and streamlining in the design of the OSS. This paper describes some of the challenges faced by BT in the quest to design IP OSS for future operations.     

CATV宽带网络反向传输通道的设计

在CATV宽带网络反向传输通道的设计中比较突出的问题是反向噪声的积累和数据传输的误码率。介绍反向传输通道的设计方法；如何降低反向传输通道的噪声、误码率；抑制反向传输通道噪声的5个主要措施。     

Integrally Small Perturbations of Linear Nonautonomous Systems

Let A(t) and B(t) (t≥0) be variable n×n-matrices. Assuming that the system [(x)\dot]=A(t)x\dot{x}=A(t)x is exponentially stable and the matrix norm of the integral ò₀^t (B(s)-A(s)) ds\int_{0}^{t} (B(s)-A(s))\,ds is sufficiently small, for the system [(x)\dot]=B(t)x\dot{x}=B(t)x we derive explicit stability conditions, which improve the well-known ones in appropriate situations. The results are illustrated by a numerical example.     

一种适应小型网络向未来智能网络演进的方法

随着信息化时代的到来,宽带应用为关系国计民生的基础设施,但目前有线网络的宽带覆盖不够,缺少稳定的移动信号,区域之间的"信息化鸿沟"依然存在,为此提出一种针对地域广、用户基数少、通信质量差地区的全面提升网络质量、直接向5G演进、低成本易维护的网络架构模型。     

Stochastic Power Saving for Macrocell-Assisted Small Cell Networks

Journal of Signal Processing Systems - In this paper, a power saving scheme is investigated for macrocell-assisted small cell networks in the downlink, in which small cells are selected to stay in...     

Distributed Sensor Networks Deployment Using Fuzzy Logic Systems

The effectiveness of distributed wireless sensor networks highly depends on the sensor deployment scheme. Given a finite number of sensors, optimizing the sensor deployment will provide sufficient sensor coverage and ameliorate the quality of communications. In this paper, we apply fuzzy logic systems to optimize the sensor placement after an initial random deployment. We use the outage probability due to co-channel interference to evaluate the communication quality. Fenton–Wilkinson method is applied to approximate the sum of log-normal random variables. Our algorithm is compared against the existing distributed self-spreading algorithm. Simulation results show that our approach achieves faster and stabler deployment and maximizes the sensor coverage with less energy consumption. Outage probability, as a measure of communication quality gets effectively decreased in our algorithm but it was not taken into consideration in the distributed self-spreading algorithm.