A Distributed Experimental Communications System

The packet experimental communications system (packet XCS) is a new experimental voice and data switch. It uses a local-area network (LAN) for digital voice transmission, with local intelligence for switching. The packet XCS also has highly distributed control. The individual sites cooperate to provide user services as well as internal data management. We have learned that several local networks, including CSMA/CD networks, can be made to work well for voice transmission and that highly distributed control is practical in such a system. A system has been constructed which is used as a testbed for distributed voice and data communications experiments. This system is purely for experimentation and does not indicate a direction for future Bell System product offerings.     

UMTS — the mobile part of broadband communications for the next century

This paper outlines the path from developing broadband ISDN/ATM systems towards the European vision of the next generation mobile system — Universal Mobile Telecommunications System (UMTS).The capabilities of UMTS in terms of services and features compared to the second generation mobile system GSM, and the network technologies behind N-ISDN and B-ISDN, are discussed with proposals for technical developments to satisfy the UMTS requirements. The UMTS radio interface aspects are described and considerations on the network requirements to support these radio aspects are discussed.The requirements within the network for control, switching and transport to support the mobility, service and interconnecting network aspects of UMTS are outlined in conjunction with the technical solutions currently under discussion and some latest thoughts on a potential high-level architecture     

Future Local Telephone Network Configurations

This paper presents the concept of dividing a local office service area under the present telephone network into blocks of switching areas to make up a local network with small, distributed switching nodes because switching costs will become much cheaper relative to cable laying costs due to LSI technology progress. In this paper, cable laying cost and switching cost are taken as the two main factors in determining future local network configurations. First, the cable laying cost is formulated using cable duct and circuit length. Next, the switching system cost is formulated based on the relation between capability and cost of components such as gates and memories. Finally, local telephone network cost is calculated, using the cost formulas obtained and data available at present. The conclusion is that from the cost-effective point of view, conventional local network office service areas should be divided into 9 to 16 blocks.     

Design of transmission and multiplexing systems for broadbandpacket networks

Dynamic time-division multiplexing (DTDM) is a flexible network transport technique capable of handling both continuous and bursty traffic effectively. By using three different multiplexing architectures in the network, DTDM permits graceful evolution of the existing circuit switching network into a flexible broadband packet communications network supporting integrated voice, data, and video traffic. The first multiplexing stage uses a packet assembler to multiplex different broadband services into a common DTDM-format serial bit stream. The second multiplexing stage uses a statistical packet multiplexer to concentrate network traffic for more efficient use of transmission facilities. The third multiplexing stage uses a synchronous time-division multiplexer for high-speed point-to-point transparent transmission. The multiplexer uses a simple tributary synchronization scheme based on positive and negative block justification, which combines the concept of controlled-slip and bit-stuffing techniques while maintaining information integrity. A generic CMOS LSI chip has been designed for use in the three-stage multiplexing system     

T-dipole arrays for mobile applications

This paper describes the work of the Antenna Department of France Telecom R&D (Research and Development) - formerly CNET (Centre National d'Etudes des Telecommunications) - on base-station antennas. The goal of this development work was to study new signal processing systems, or to characterize propagation within the frequency band of the following new wireless systems: GSM, Global System for Mobile Communications; UMTS, Universal Mobile Telecommunications System; HIPERLAN, high performance radio local area network. However, the results presented concern only the antennas, in many different configurations. All of them are based on the T-dipole antenna.     

基于B/S网络结构的嵌入式视频监控系统

针对视频监控领域的需求,采用TI公司C6000系列DSP芯片TMS320DM642作为核心处理芯片,搭建了一套基于B/S网络结构的嵌入式视频监控系统。系统包括多路视频采集、多路视频本地显示、系统存储器扩展、和视频网络传输部分。系统的软件编写采用了TI的嵌入式实时操作系统DSP/BIOS和网络开发套件NDK,对系统各个线程进行有序调度。试验证明该系统满足了视频图像采集和网络视频传输的实时性要求。     

Progress Towards Digital Subscriber Line Services and Signaling

With digital connectivity, future subscribers will be able to exercise local and network services involving the routine delivery, management, and processing of information. Accelerated by rapidly advancing technology, the evolutionary process towards digital connectivity and integrated voice and data services in the network is underway. This paper describes the methods of integrating voice and information capability into the telecommunications network. The attributes of this network will include the availability of digital connectivity directly to the subscriber, the availability of a robust signaling means between the subscriber and his local switching office, and common channel signaling to implement all interexchange signaling. Issues of interest include an overview of digital subscriber connectivity, signaling and information structures for these kinds of lines, communications protocols, and general network considerations for the provision of information services. Partitioning of intelligence between intelligent subscriber terminals and controllers and their switching system is investigated. The use of message and virtual channel switching facilities to handle limited information rate services is discussed. Finally, an exploratory digital subscriber line under investigation at Bell Laboratories is described.     

优化EPON对本地P2P业务承载能力的研究

P2P流量已成为网络中的主要流量,但现有EPON系统不能很好的承载本地P2P业务.文中从MPCP协议的角度对逻辑链路标签及其过滤规则进行扩展,使本地P2P数据包不需经OLT端二层交换即可实现下行转发,从而大大改善了P2P业务的QoS.并以此方案为基础,提出改进EPON的DBA算法,设置专门的P2P时隙,实现P2P业务的全光域转发.两种方案的建模仿真结果表明,两者均能明显改善EPON对本地P2P业务的承载能力.     

Transmission Planning for an Evolving Local Switched Digital Network

This paper examines the major issues associated with transmission planning for an evolving local switched digital network. Three general topics are discussed. First is the need to establish various "receive" levels within the digital switch in order to maintain existing toll loss and level plans. These are required because the integration of the interface between digital switching and transmission facilities has eliminated the channel bank, traditional location of the pad which controls trunk losses. The second area examined is the inherent fourwire nature of a digital switch. In order to maintain existing loss-noise grade of service, a nominal 0 dB cross office loss has been proposed for the switch. The 0 dB loss operation must be attained while experiencing little or no degradation due to singing or near-singing distortion. Acceptable listener echo performance can be obtained in a zero loss office with existing outside plant if an appropriate impedance balance technique, such as segregation of balance networks for loaded and nonloaded loops, is adopted. The third topic is the increasing use of remote vehicles in a local digital network. The basic rule of thumb applied is that transmission performance for customers at a "remote" location should be equivalent to transmission performance for customers at the "host" office. Transmission plans can then be applied accordingly.     

支持普适服务的一体化网络研究

现有信息网络的原创模式基本上是多种网络完成多种服务,要从根本上解决现有信息网络存在的严重弊端,必须创建新的网络体系基础理论.本文在归纳总结、分析研究传统各种信息网络交换路由理论的基础上,创造性的引入接入标识和交换路由标识,创建接入标识与交换路由标识的分离聚合映射理论,建立新型网络体系结构下的广义交换路由理论与机制,从而形成一体化网络模型与理论,在有效保证移动性和安全性的同时,解决了异质异构网络的一体化问题;构建了一体化网络与现有网络的过渡方案与机制,保证了传统网络到新网络的平滑过渡;给出了一体化网络的设计与实现方案,并通过原型系统验证了一体化网络的可行性、有效性和正确性.     

Simulation of the performance of a Ka‐band VSAT videoconferencing system with uplink power control and data rate reduction to mitigate atmospheric propagation effects

The purpose of this paper is to evaluate the impact of propagation effects at 20/30 GHz on the performances of the radio interface of a VSAT videoconferencing system and to demonstrate the interest to implement Fade Mitigation Techniques in order to improve the link availability. Specifications and system requirements of the VSAT network are briefly described. System performances of the physical layer are simulated using time‐series data measured with the ESA's OLYMPUS satellite. The simulations enable to implement and optimize Up‐Link Power Control and Data Rate Reduction, and to assess the related link performance improvement. Moreover, the introduction of propagation data sets allows to have a better idea of some system parameters which directly impact on the quality of service such as the switching rate or the link availability that such a system should have when deployed in operational conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

局域网视频传输系统的设计与实现

介绍了在局域网上利用TCP/IP协议实现视频传输系统的设计,给出了视频传输系统方案,设计了按客户/服务器网络通信模型,利用Visual C 中的多线程设计思想和Winsock套接字,设计了网络通信软件,最后给出了系统运行结果.本系统在江苏沙集闸站调试运行,通过局域网传输实时图像,实现对水利设施的远程监控,在局域网的各个站点计算机上都能接收到实时图像,并能进行实时操作,图像清晰,控制方便,效果良好.     

Enhanced MAC Protocol and Scheduling Algorithm for High Rate WPANs

The demands for higher data rate in Wireless personal area network （WPAN） than one in Bluetooth has been completed with IEEE 802.15.3 standard. The standard, named High-rate WPAN （HR-WPAN）, adopts TDMA-based Medium access control （MAC） protocol. In this paper, we propose novel MAC protocol and scheduling algorithm to achieve efficient time-slots allocation. Time slots for data transmissions are allocated by two steps. In the first step, the time slots are initially allocated using a proposed allocation algorithm based on statistical packet inter-arrival time. Then, the initial allocation is dynamically adjusted by utilizing feedback information coming from each device. Performance evaluations are carried out through extensive simulations and significant performance enhancements are observed.     

NEAX61∑交换机简易实现800号业务的方法

介绍了NEAX∑交换机不需要增加智能网的硬件设备，而只通过数据的设定来实现800号增值业务的方法，以及针对目前NEAX∑交换机还不能完全实现被叫付费这一问题的补救方法。     

An interconnection architecture for network-on-chip systems

Network on Chip (NoC) is a discipline research path that primarily addresses the global communication in System on Chip (SoC). It is inspired and uses the same routing and switching techniques needed in multi-computer networks. Current shared-bus based on-chip communication architectures generally have limited scalability due to the nature of the buses especially when complex on-chip communication SoC is needed. The main goal is to have a dedicated communication infrastructure in the system that can scale up while minimizing the area and power. The selected topology of the components interconnects plays prime rule in the performance of NoC architecture as well as routing and switching techniques that can be used. In this paper, we introduce a new NoC architecture by adapting a recursive topology structure. An experimental study is performed to compare this structure with basic NoC topologies represented by 2D mesh and Spidergon. The analysis illustrates the main features of this topology and its unique benefits. The simulation results show that recursive network outperforms 2D mesh and Spidergon in main performance metrics.     

Multi-domain architecture for policy management inumts ip multimedia subsystem

The Universal Mobile Telecommunications System (UMTS) offers IP-based multimedia applications and services with end-to-end Quality of Service (QoS) guarantee. The key component providing these services is the IP Multimedia Subsystem (IMS) that uses Service-Based Local Policy (SBLP) management for QoS control. To support end-to-end QoS, the UMTS IMS network should be scalable, reliable and flexible in policy deployment and enforcement, characteristics that are not found in single-domain policy architecture. A hybrid policy architecture is proposed, in which a hierarchical architecture is applied to the multi-domain environment in a single operator UMTS IMS network, while a peering architecture is employed in a multi-operator UMTS IMS network. The proposed multi-domain policy architecture potentially minimizes the session setup delay and policy exchange traffic while maximizing network scalability.     

Optimal Modernization Policies for Telecommunications Facilities

This paper considers a problem of telecommunications network modernization. The model presented provides the cost criterion corresponding to a general network evolution strategy which may consist of a combination of three basic policies: expansion of existing facilities; overlay of existing facilities with modern equipment to serve the growth; or replacement of existing facilities with modern equipment. The cost criterion is basically defined as the cumulated sum of all inflated discounted cash flows. Two major problems are discussed: 1) the single location or local facility evolution problem applicable to single transmission links or switching nodes and 2) the multilocation problem involving several nodes. An application of the second problem described here concerns the selection of switching equipment types for a telephony network (including remote concentrators). For both problems, simple necessary and sufficient conditions are derived for pure strategies to be optimal. Pure strategies involve events occurring at the beginning and/or end of the study horizon.     

UMTS the next generation of mobile radio

Europe's third-generation mobile communication system will transform the capabilities of cellular networks. The authors describe some of the implications for users, network operators and would-be licence holders of UMTS (Universal Mobile Telephone System)     

Reduction of wireless signals in indoor environments by using an active frequency selective wall based on spectrum sensing

This paper presents a wireless local area network (WLAN) spectrum control system that uses active frequency selective shielding walls to selectively reduce or pass WLAN signals in the 5 GHz band indoors. The proposed system utilizes a well‐known active frequency selective structure based on a rectangular loop with PIN diodes and is thus capable of either reducing or passing the WLAN frequency by using the on/off switching of the PIN diode based on the measured electric field strength in indoor. We designed and simulated the proposed active frequency selective shielding wallpaper by using commercial electromagnetic simulation software and confirmed that the proposed structure can reduce the WLAN signal by switching the PIN diode by applying the manufactured prototype on the exterior of an experimental apparatus containing a WLAN receiver antenna that is capable of measuring the received electric field strength. Extension of the results presented herein can be applied to reduce the wireless signal to enhance the spectrum efficiency of an indoor space.