G729 Voice Decoder Design

Embedded digital signal processing (DSP) systems are usually associated with real time constraints and/or high data rates such that fully software implementations are often not satisfactory. In that case, mixed hardware/software implementations are to be investigated. This paper presents the design of a HW/SW G.729 voice decoder dedicated to embedded systems. The decoder has been built around, on the one hand a reconfigurable digital circuit (FPGA) to achieve the so called IP hardware part—the autocorrelation computation—using a linear systolic array, and on the other hand a digital signal processor (DSP) for the remainder of the algorithm. Apart such an implementation is typically driven by the use of reusable component (IP) it is of great interest for new G729-based applications such as Voice over IP (VoIP) for example. It results in an overall reduction of the execution time per frame. Another interesting point is the design of a parameterizable autocorrelation block which can be useful for a wide range of applications such as GSM 13 Kbit/s, APC 9.6 Kbit/s and G723 6.3 Kbit/s and 5.3 Kbit/s. In the G729 context and using a V50 Virtex FPGA, the execution time of this function is 10 times faster than a TMS320C6201 DSP implementation.     

基于Linux的互联网视频监控系统

为使监控系统小型化、通用性以及具有较好的交互性,分别以ARM9处理器为硬件和Linux操作系统为软件的平台方案开发出了一个互联网视频监控系统服务器。通过拨号软件接入互联网,视频服务器将USB摄像头采集到的图像数据通过有线或无线网络传输系统上传到互联网上,客户端使用Java开发的相应软件或浏览器输入服务器的IP地址就可实...     

Videoconferencing on the Internet

This paper describes the INRIA videoconferencing system (IVS), a low bandwidth tool for real-time video between workstations on the Internet using UDP datagrams and the IP multicast extension. The video coder-decoder (codec) is a software implementation of the ITU-T recommendation H.261 originally developed for the integrated services digital network (ISDN). Our focus is on adapting this codec for the Internet environment. We propose a packetization scheme, an error control scheme and an output rate control scheme that adapts the image coding process based on network conditions. This work shows that it is possible to maintain videoconferences with reasonable quality across packet-switched networks without requiring special support from the network such as resource reservation or admission control     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

Software superglue [Web services]

It is still early days for Web services but they have recently become one of the hottest issues within the software industry. In a nutshell, Web services are a set of standards based technologies that allow software engineers to connect up a multitude of proprietary IT systems quickly and flexibly. They provide a neutral 'glue' that, in effect, makes lots of different technologies look the same. Based on these standards, software engineers are able to build reusable software components that can reside on any device and communicate with any service (regardless of its native technology) across any Internet protocol (IP) based network.     

Security of industrial sensor network-based remote substations in the context of the Internet of Things

The main objective of remote substations is to provide the central system with sensitive information from critical infrastructures, such as generation, distribution or transmission power systems. Wireless sensor networks have been recently applied in this particular context due to their attractive services and inherent benefits, such as simplicity, reliability and cost savings. However, as the number of control and data acquisition systems that use the Internet infrastructure to connect to substations increases, it is necessary to consider what connectivity model the sensor infrastructure should follow: either completely isolated from the Internet or integrated with it as part of the Internet of Things paradigm. This paper therefore addresses this question by providing a thorough analysis of both security requirements and infrastructural requirements corresponding to all those TCP/IP integration strategies that can be applicable to networks with constrained computational resources.     

A framework for building intelligent manufacturing systems

The paper describes a systematic approach to design and development of software for intelligent manufacturing systems. The approach is based on a multilevel, general object oriented model of intelligent systems. Current methods and software design and development tools for intelligent manufacturing systems either stress particular components of intelligence (e.g., high level domain expertise, or learning capabilities, or fuzziness of decisions), or their domain dependence (e.g., monitoring and control systems, or CAPP systems). It is usually difficult to make extensions of such methods and tools, nor is it easy to reuse their components in developing intelligent manufacturing systems. Considerable efforts are being dedicated to the development of interoperable software components, distributed object environments, and flexible and scalable applications to overcome some of these problems. The approach described in the paper starts with a well founded software engineering principle, making clear distinction between generic, low level intelligent software components, and domain-dependent, high level components of an intelligent manufacturing system. It is extensible and adjustable. It also suggests some steps toward design of future software development tools for intelligent manufacturing systems. Several intelligent systems have been developed using the approach. One of these systems, in the cement manufacturing domain, is briefly overviewed, illustrating how the approach is used in practice. Finally, some informal discussion on the performance and complexity of the approach is presented     

Design and Implementation of Embedded Transmission Control Protocol/Internet Protocol Network Based on System-on-programmable Chip

A scheme of transmission control protocol/Internet protocol（TCP/IP） network system based on system-on-programmable chip（SOPC） is proposed for the embedded network communication. In this system, Nios processor, Ethernet controller and other peripheral logic circuits are all integrated on a Stratix Ⅱ field programmable gate array （FPGA） chip by using SOPC builder design software. And the network communication is realized by transplanting MicroC/OS Ⅱ （uC/OS Ⅱ ） operation system and light weight Internet protocol（LwIP）. The design idea, key points and the structures of both software and hardware of the system are presented and ran with a telecommunication example. The experiment shows that the embedded TCP/IP network system has high reliability and real-time performance.     

基于物联网的智能家居服务网关的设计

为了实现智能家居系统中的远程及近程控制,从物联网的概念出发,设计实现了一个嵌入式的WEB网关服务器,将基于Zigbee协议的无线传感器网络与基于TCP/IP协议的Internet相联。该设计采用STM32F107VC为主控制器,通过串口实现与WSN协调器的通信,外接一个网卡芯片实现与Internet的连接。在软件设计上重点实现智能家居通信控制系统,并引入嵌入式操作系统uCOS-II对系统资源进行管理,移植LwIP协议栈实现TCP/IP的基本功能。     

Broadband wide-area networking via IP/ATM over SATCOM

A concept for broadband wide-area networking based on the use of the Internet Protocol (IP) over asynchronous transfer mode (ATM) broadcast over extremely high-frequency (EHF) 30/20 GHz Ka-band satellite communication (SATCOM) is presented. It is primarily intended to support applications such as broadcast of data and video, fast Internet access, and teleconsultation with interactive white board. Operation from midsize terminals located at a corporate headquarters to small highly transportable terminals at remote facilities is envisioned     

An end-to-end transmission architecture for the remote control of robots over IP networks

Teleoperation via the Internet is attracting more and more attention from both academia and industry. Physical interaction with remote environments over IP networks, however, poses many technical challenges that are still outstanding, such as time delay, limited bandwidth, and unreliable transmission. To deal with these problems, the majority of current work is concentrated on developing advanced remote control algorithms or interface techniques whereas data transmission between the human operator and the remote robot through the Internet is often treated as a given condition. This paper describes a novel data transmission architecture, for which the core is the trinomial transport protocol, to facilitate the remote control of Internet robots. The trinomial protocol is analyzed theoretically and its advantages over other existing protocols are verified by simulation and experimental studies.     

Storage area network extension solutions and their performance assessment

Several solutions are proposed to extend storage area networking solutions over distances of hundreds to thousands of kilometers. Native fibre channel or end-to-end fibre channel-based solutions can be offered over long distances using SONET-based networks. Protocols such as Internet SCSI (iSCSI), Internet fibre channel protocol (iFCP) and fibre channel over TCP/IP (FCIP) are being proposed to enable storage area networking solutions over networks that use IP as their transport protocol. Performance analysis of these solutions in terms of application throughput under variable network conditions of packet loss, bandwidth availability, extension distance, and TCP implementations in the sender and receiver is presented based on analytical modeling of different solutions.     

A real-time video transport system for the best-effort Internet

It is a challenging problem to design an efficient real-time video transport system for the present best-effort Internet because of the strict bandwidth, loss and time constraints and the lack of quality of service (QoS) guarantees from the present IP networks. This paper presents an end-to-end system architecture based on the MPEG-4 Delivery Multimedia Integration Framework (DMIF) for transporting real-time live video over the Internet. The key features of the system include: (1) MPEG-4 DMIF-based terminal architecture; (2) combination of an end-to-end feedback control mechanism and a rate-adaptive encoding algorithm for the best use of the Internet; (3) a robust and efficient packetization scheme for the MPEG-4 bit-stream by using the resynchronization marker approach specified in the MPEG-4 standard; and (4) efficient error control algorithms adopted at the end systems for visual quality enhancement. Simulation and test results using the actual Internet showed that our system is capable of utilizing the available network resource and achieve good perceptual quality at the application level.     

PriQoS:priority-differentiated flow control mechanism based on SDN

It was difficult to meet the increasing demand of quality of service (QoS) for the best-effort IP network,so it was urgent to develop a kind of QoS control mechanism that was compatible with the existing IP software and hardware resources.Therefore,a priority-differentiated control mechanism based on the software defined networking called PriQoS was proposed.When the network resource was scarce,a multi-queue bandwidth allocation algorithm based on the inte-grated priority of service flow was used to meet the bandwidth requirement with high priority flows.PriQoS was deployed on the network edge,which was no need to modify applications in the end systems and routers in the core network.The mechanism has advantages such as easy to deploy and being compatible with the IP applications and devices.Experimental results show that the PriQoS mechanism can guarantee the QoS of higher priority services.     

Wireless LANs and mobile networking: standards and futuredirections

The emerging widespread use of wireless LAN systems together with the users' desire for such systems to interoperate has created a requirement for standards. Many standards bodies are currently defining standards for wireless systems that relate to different layers of the networking protocol stack. Of these, two influential physical and data link layer standards, IEEE 802.11 and the European HIPERLAN, are described. The article then considers the network layer by discussing extensions that are being made to the widely used Internet protocol (IP) to deal with mobility (wired or wireless). The final standards that are discussed relate to wireless link management. The article concludes by speculating on future directions for wireless LAN systems     

智能建筑系统的控制论描述及其优化

随着我国经济不断的发展,科技水平也不断地提高,互联网与信息通信技术发展迅猛,各种各样的高新技术广泛的应用于各个领域,建筑行业里高新技术的运用非常常见。建筑技术、计算机技术以及自动化技术相互结合发展,从而促使智能建筑系统的发展。随着智能建筑的发展,在建筑过程中,突发事故时常发生,对人们的生命财产安全造成了重大影响。本文通过对智能建筑系统的控制理论进行详细的说明,利用控制理论来处理智能建筑系统,以及分析研究对智能建筑系统进行优化,从而使得智能建筑系统更加有利于建筑行业的发展,减少事故的发生率,从而降低人们的生命财产的损失。     

A case for end system multicast

The conventional wisdom has been that Internet protocol (IP) is the natural protocol layer for implementing multicast related functionality. However, more than a decade after its initial proposal, IP multicast is still plagued with concerns pertaining to scalability, network management, deployment, and support for higher layer functionality such as error, flow, and congestion control. We explore an alternative architecture that we term end system multicast, where end systems implement all multicast related functionality including membership management and packet replication. This shifting of multicast support from routers to end systems has the potential to address most problems associated with IP multicast. However, the key concern is the performance penalty associated with such a model. In particular, end system multicast introduces duplicate packets on physical links and incurs larger end-to-end delays than IP multicast. We study these performance concerns in the context of the Narada protocol. In Narada, end systems self-organize into an overlay structure using a fully distributed protocol. Further, end systems attempt to optimize the efficiency of the overlay by adapting to network dynamics and by considering application level performance. We present details of Narada and evaluate it using both simulation and Internet experiments. Our results indicate that the performance penalties are low both from the application and the network perspectives. We believe the potential benefits of transferring multicast functionality from end systems to routers significantly outweigh the performance penalty incurred.     

Mobile IP-DECT internetworking architecture supporting IMT-2000applications

Realistic realization and mass acceptance of mobile data services require networking architectures offering acceptable quality of service and attractive tariffs. A novel strategy for this goal is maximum integration of popular data networking standards and their infrastructure into wireless networks. This article discusses a Mobile IP-based network architecture to provide IP services in DECT to support IMT-2000 applications. DECT offers micromobility within multicell subnets, while Mobile IP supports macromobility between multicell subnets. Incorporating Mobile IP into the DECT handoff mechanism in this way extends DECT micromobility with IP macromobility. Also, utilizing fast, seamless DECT handoff management reduces Mobile IP handoff delay to circumvent TCP throughput degradation during handoff and reduce frequency of Mobile IP signaling over the ether to conserve spectral efficiency. This feature seamlessly unifies DECT with the global Internet. Seamless integration of DECT with the Internet is crucial due to the continuing phenomenal popularity of the Internet and wireless communications, and ubiquity of DECT systems. To achieve the above DECT/IP interworking efficiently, the architecture introduces a network entity called a DECT service switching point, which is an extended DECT central control fixed part. DECT network-level services are mapped onto those of the IETF integrated services architecture to maintain QoS provided by DECT in the backbone Internet. Mobile Resource Reservation Protocol, an extended RSVP tailored to mobile networking, is adopted to provide the needed signaling in IntServ. The proposed architecture preserves traditional non-IP based services such as PSTN voice     

NetScope: traffic engineering for IP networks

Managing large IP networks requires an understanding of the current traffic flows, routing policies, and network configuration. However, the state of the art for managing IP networks involves manual configuration of each IP router, and traffic engineering based on limited measurements. The networking industry is sorely lacking in software systems that a large Internet service provider can use to support traffic measurement and network modeling, the underpinnings of effective traffic engineering. This article describes the AT&T Labs NetScope, a unified set of software tools for managing the performance of IP backbone networks. The key idea behind NetScope is to generate global views of the network on the basis of configuration and usage data associated with the individual network elements. Having created an appropriate global view, we are able to infer and visualize the networkwide implications of local changes in traffic, configuration, and control. Using NetScope, a network provider can experiment with changes in network configuration in a simulated environment rather than the operational network. In addition, the tool provides a sound framework for additional modules for network optimization and performance debugging. We demonstrate the capabilities of the tool through an example traffic engineering exercise of locating a heavily loaded link, identifying which traffic demands flow on the link, and changing the configuration of intradomain routing to reduce the congestion     

基于TCP/IP的嵌入式WebServer网络测控系统设计

本文研究基于TCP/IP协议栈的嵌入式系统在网络智能设备中的测控应用设计。以Rabbit2000网络微处理器和Dynam ic C软件开发环境为例,阐述构建嵌入式W ebServer的具体技术及相关的实现方案;详细介绍了实现TCP、UDP报文进行网络通信、串行口数据通信和对网络智能设备的测控技术等,并给出系统硬件原理框图和有关软件实现的程序代码及流程图。