A network management and control scenario for multimedia applications

Emergence of multimedia applications requires that appropriate management and control activities be provided and organized in a somewhat integrated framework. Such issues as coordination of operations on the shared information, provision of the user requirements in terms of quality of service and efficient handling of the available network resources result in more critical problems when they regard multimedia objects. Mainly this is due to the time-constrained requirements that arise from the need of synchronization among multiple streams of information which are different in their nature and granularity. This paper discusses the impact of the above issues on network management and control and proposes an architectural model for the management and control of broadband applications that require handling of multimedia information.     

A CMOS analog front-end circuit for an FDM-based ADSL system

A CMOS analog front-end circuit for an FDM-based ADSL system is presented. The circuit contains all analog functions including AGC amplifiers, continuous-time band pass filters, ΣΔ AD/DA converters, and digital decimation and interpolation filters. On-chip automatic tuning of the bandpass filters provides more than 300% center frequency range with 1% frequency accuracy. The higher-order ΣΔ AD/DA converters achieve 12-b data conversion at 1.54 Msamples/s with an oversampling ratio of only 32. The 0.7 μm CMOS circuit measures 65 mm² and consumes 1.9 W from a single 5 V power supply     

A BiCMOS analog front-end circuit for an FDM-based ADSL system

This BiCMOS analog front-end (AFE) integrated circuit contains the analog transmit function and a low-noise receiver for FDM-based ADSL systems. The IC includes a current steered 14-bit 5-Msps D/A converter, laser trimmed third-order reconstruction and anti-alias filters, a programmable attenuator with 200-ohm output drive capability, 60-dB of RX programmable gain, and a serial interface. Trimmable thin-film resistors allow ±4% filter cutoff frequency and absolute gain accuracy. The multitone power ratio performance of the part is approximately 65 dB with a spurious free dynamic range >70 dBc. The CMRR of the RX channel is >90 dB@1.1 MHz. PSRR for transmit and receive are greater than 60 dB. The isolation features of the 1.2-μm BiCMOS technology allow transmit and receive to operate in full-duplex mode with greater than 80 dB of cross-talk isolation. The chip size is 25.8 mm² which includes bond pads and electrostatic discharge protection devices     

ESTER: an expert system for management of respiratory weaningtherapy

The withdrawal of mechanical ventilation generally presents no problems if carried out when the values of certain predictive physiological variables suggest that the patient will be able to breathe for him or herself. In certain cases, however, a more gradual weaning procedure is necessary, in which the amount of mechanical assistance provided is in some way reduced little by little. One of the usual means of achieving this gradual reduction is by intermittent mandatory ventilation (IMV), in which short bursts of mechanical ventilation are separated by progressively longer periods of "ventilator silence" which stimulate the patient's endogenous respiration. ESTER is an expert system in which the most widely accepted criteria are systematically called upon to supply advice to the clinician who has to prescribe a respiratory therapy regime suited to the needs of the patient. After effecting a preliminary prognosis of the patient's condition, ESTER asks for certain physiological parameters to be keyed in. Analysis of these parameters reveals the patient's condition and allows a recommended respiratory therapy to be designed.     

机载多传感器管理专家系统设计方法探索

未来航空电子系统的一个主要特点就是智能化,利用专家系统可以达到机载多传感器智能管理的目的.简要介绍了多传感器管理的内容和目的以及飞行员助手,提出了一种机载多传感器管理专家系统结构方案,对知识库和推理机的设计方法进行了探索.     

Wireless network resource management for Web-based multimedia document services

Advances in wireless technology and availability of portable devices with networking capabilities have enabled ubiquitous Web accessibility. This has created the need to provide advance Internet services to mobile users without causing service failures due to connection migration or handoffs. However, scarcity of wireless resources restricts the provision of multimedia services in wireless networks. We address the issue of managing wireless resources to support Web-based multimedia document services including MPEG-4-based applications, in wireless networks with a high degree of user mobility. In particular, we formulate the resource management problem in wireless networks as an optimization problem with an objective function comprising different quality of presentation parameters.     

基于IP网的自主式多媒体远程教学系统

本文在简要分析多媒体远程教学需求的基础上,提出了一种包括教师T、学生P、课件资源R、协作教学环境E和网上教学管理M等表示远程教学的五元组结构模式,进一步设计了基于IP网的支持教学现场直播和按需点播的多媒体远程教学系统,并在校园网上进行了同步时授课以及按需点播的实验。     

Rule-based expert systems for network management and operations: anintroduction

The functions that can be performed by an integrated communication network management expert system are identified. Expert systems are defined, and knowledge representation, knowledge acquisition, and inference engines are discussed. A sample application problem using OPS5 is presented     

ExPro-an expert system based process management system

The design, development and preliminary testing of ExPro, an expert-system-based process management system, is reported. This system is designed to provide process setup, monitoring, and supervisory control capabilities for applications in a real-time semiconductor manufacturing environment. ExPro is a rule-based system developed using the OPS-83 expert system language in a personal computer environment. It features a modular structure and includes an integrated analytical process simulator. The simulator is used to predict process parameters prior to processing and provide wafer state information from real-time (measured) process information when direct measurement of the state is impractical. The process selected for development and demonstration purposes was rapid thermal oxidation (RTO). Testing revealed that the accuracy of the system was within 1% of goal for the case of Si(100) wafers, but the less accurate Si(111) simulation led to much larger errors     

END: an expert network designer

Professional designers with intensive knowledge and experience are needed for large computer network design and optimization. Such designers must be well informed about the most recent up-dates in this rapidly advancing field to be able to handle the available state-of-the-art technologies. Since designers of such caliber are difficult to find and usually very expensive, the present authors propose the use of expert systems to play their role and/or assist them in their task. The authors discuss: system architecture and functionality, the OPNET network simulation package. They also present various network design examples     

AUTOREC: an automated error recovery system for network management

The system, which was developed and is being used by AT&T to do error detection and recovery on a packet switching network, is described. Some of the major design issues that were addressed in developing AUTOREC are examined. These include system scope, hardware considerations, language selection, the multiple vendor problem, device recovery capability, and expansion. AUTOREC's modular architecture is described, and how an operator would interface with the system is explained. Some of the benefits that have resulted from the project and some of the lessons learned are discussed     

A video conference network management system

Setting up either one or multiple conferences and managing the various devices can be a very difficult task. In this article a newly developed distributed video conference management system is explained and tested. © 1998 John Wiley & Sons, Ltd.     

A 2.4-GHz sub-mW CMOS receiver front-end for wireless sensors network

A 2.4-GHz fully integrated CMOS receiver front-end using current-reused folded-cascode circuit scheme is presented. A configuration utilizing vertically stacked low-noise amplifier (LNA) and a folded-cascode mixer is proposed to improve both conversion gain and noise figure suitable for sub-mW receiver circuits. The proposed front-end achieves a conversion gain of 31.5dB and a noise figure of 11.8dB at 10MHz with 500-/spl mu/A bias current from a 1.0-V power supply. The conversion gain and noise figure improvements of the proposed front-end over a conventional merged LNA and single-balanced mixer are 11dB and 7.2dB at 10MHz, respectively, with the same power consumption of 500/spl mu/W.     

A resource management strategy for multimedia adaptive-rate traffic in a wireless network with TDMA access

One of the challenges today for wireless network operators is to find techniques which will make it possible to introduce multimedia capabilities into mobile communications. The application of a wireless network structure made up of pico-cells to solve this problem will cause an increase in the handover rate. Therefore, a major requirement in a wireless environment is to design an effective call admission control (CAC) strategy to minimize the handover drop probability. Another important requirement is to maximize network utilization in terms of the mean number of channels used. The goal of this paper is to define a resource management strategy for heterogeneous adaptive-rate traffic. The proposed strategy is actually a combination of two: a CAC management strategy and a bandwidth management one. The CAC management strategy extends the Guard Channel strategy to obtain priority-based CAC management for adaptive-rate sources; the bandwidth management strategy allows channels to be assigned proportionally to the throughput window declared by users. In order to assess the effectiveness of the proposed CAC strategy, two Markov models of the system are introduced: one, from the network point of view, to evaluate global system performance, and another, from the user point of view, to evaluate the performance each user is provided with by the network. Numerical examples conclude the paper to analyze which factors most affect performance when the source rate is adaptive and the proposed admission strategy is applied.     

基于神经网络的电子设备故障诊断专家系统

对复杂的电子设备的故障进行快速准确的诊断和维护是一个急待解决的重要问题。在分析了单独应用专家系统和神经网络的优缺点的基础上,提出了一种集成式诊断专家系统模式,将神经网络与传统的专家系统进行有机结合。经实验证明,系统的推理效率明显提高,且具备良好的鲁棒性、启发性和透明性。由此可见,该集成方法对故障诊断十分有效。     

Call admission control for an adaptive heterogeneous multimedia mobile network

A novel call admission control (CAC) scheme for an adaptive heterogeneous multimedia mobile network with multiple classes of calls is investigated here. Different classes of calls may have different bandwidth requirement, different request call holding time and different cell residence time. At any time, each cell of the network has the capability to provide service to at least a given number of calls for each class of calls. Upon the arrival (or completion or hand off) of a call, a bandwidth degrade (or upgrade) algorithm is applied. An arriving call to a cell, finding insufficient bandwidth available in this cell, may either be disconnected from the network or push another call out of the cell toward a neighboring cell with enough bandwidth. We first prove that the stationary distribution of the number of calls in the network has a product form and then show how to apply this result in deriving explicit expressions of handoff rates for each class of calls, in obtaining the disconnecting probabilities for each class of new and handoff calls, and in finding the grade of service of this mobile network     

A low-power multi-band CMOS RF receiver front-end for ubiquitous sensor network applications

This paper presents the design and experimental results of a low-power multi-band RF receiver including a multi-band low-noise amplifier (LNA) and a down-conversion mixer based on the IEEE 802.15.4 standard for sensor node applications. A multi-band LNA with two inputs is tuned to two resonant frequencies by controlling the voltage on a switched MOS. The implemented RF receiver front-end achieves a maximum voltage conversion gain of 38 and 30 dB, NF of 6.2 and 9.2 dB at the 868/915 MHz and the 2.45 GHz bands, respectively. The RF receiver front-end dissipates total 3.0 mA (including I/Q mixers) under supply voltage of 1.8 V at both operation bands.     

A proposal of an ATM wireless access system for tetherless multimedia services

This paper proposes an ATM wireless access system for tetherless multimedia services. The proposed system is intended to provide ATM-based high-speed transmission capability for tetherless multimedia services by wireless media in private LAN/WAN environments as well as public environments. To enable high-speed transmission, this paper proposes the utilization of the SHF band taking advantage of its wide frequency spectrum availability. However, the propagation feature of the SHF band limits the wireless terminal mobility in the proposed system compared with current cellular phone systems. This paper discusses the concept and system architecture of the proposed ATM wireless access system, including its ATM transport based on ATM/TDMA conversion using a time stamp scheme.