网络自相似业务模型进展

综述了目前国内外在自相似业务建模研究方面所获得的主要成果，分析了各种模型的特点，并进行了分类和评价，指出了几种重要模型的参数获取的复杂度，并对模型的意义进行了初步的探讨，提出了有待进一步研究的问题，对自相似业务的分析和处理具有一定的指导意义。     

Addressing self-similarity in optical switching networks by means of ant colony optimization

In this work, we propose the use of an Ant Colony Optimization (ACO) algorithm to mitigate packet loss in an optical packet switching network that carries self-similar traffic, which is known to have a great impact in the buffer performance in terms of loss probability as exemplified in this work. By adaptively routing the packets and balancing the network load, we demonstrate by some simulations the effectiveness of this approach when compared with a shortest-path routing scheme, achieving a performance that is comparable to the Poisson traffic scenario in some cases. The proposed algorithm can be used as a viable alternative to traffic shaping techniques.     

HDTV communication systems in broadband communication networks

Two high-definition television (HDTV) communication systems created for broadband communication networks are discussed. Nationwide HDTV transmission and distribution services and HDTV subscriber distribution services are examined. A network architecture for high-quality HDTV transmission is described. The transmission bit rates of HDTV services, which are the basic factors in constructing the network frame, are considered. Two HDTV coding algorithms, subband discrete cosine transform (DCT) and subband differential pulse-code modulation (DPCM) are described, and their coding bit rates discussed. A synchronous-digital-hierarchy-based synchronous transfer mode network design suitable for the transmission of HDTV signals in broadband communication networks are described     

Some complexity results about packet radio networks (Corresp.)

It is shown that the decision problem regarding the membership of a point in the capacity region of a packet radio network is nondeterministic polynomial time hard (NP hard). The capacity region is the set of all feasible origin-to-destination message rates where feasibility is defined as the existence of any set of rules for moving the data through the network so that the desired rates are satisfied.     

通信网电话会议技术研究

从多种角度对通信网中电话会议进行了分类,并将其实现方式归结为分离结构和综合结构2种实现框架。提出了分布式会议桥的思路,与传统的集中式会议桥相比,在某些应用场合下可减少电话会议局间信道资源占用量,并可扩展会议桥的容量。     

通信的传媒属性

介绍了通信与传媒(媒体)的概念,通信与传播的界定,以及从技术、业务和产业发展的角度详细分析了通信的传媒属性.认为传媒是传播的渠道,通信技术的创新促进了传媒的演变,通信业务已具有传媒属性,凸显了丰富的传媒功能.认为通信产业正在融合传媒产业的内容资源.在技术进步、业务创新以及产业融合的驱动下,通信的范围会进一步向传媒延伸.     

Cooperative communication in wireless networks

Transmit diversity generally requires more than one antenna at the transmitter. However, many wireless devices are limited by size or hardware complexity to one antenna. Recently, a new class of methods called cooperative communication has been proposed that enables single-antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenna transmitter that allows them to achieve transmit diversity. This article presents an overview of the developments in this burgeoning field.     

Data communication in ATM networks

An increasing number of customers require LAN access with high bandwidth and low delay over long distances. To satisfy these needs, several high-speed network techniques have been developed. Asynchronous transfer mode (ATM) is superior compared to other networking technologies, as it offers high bandwidth and is scalable in the sense that the bandwidth capacity of an ATM system is not fundamentally limited to the technology itself. Initial ATM installations will operate as subnetworks of existing networks and MAC layer protocols. One of the main challenges in ATM is the transparent support of existing connectionless LAN services. Several activities have been launched within international standard bodies and forums to specify ways of providing data communication services over ATM. Most notable examples are Switched Multimegabit Data Service (SMDS) and the similar Connectionless Broadband Data Service (CBDS) supported mostly by public network service providers. But also other approaches such as IP over ATM, and LAN emulation that show more adherence to the existing local and campus area networking paradigms. The article presents the requirements and architecture of the LAN emulation service. It describes the alternative methods for carrying IP packets over ATM, a public broadband service architecture and CBDS. The traffic management aspects of the data communication services are also discussed     

Real-time communication in packet-switched networks

The dramatically increased bandwidths and processing capabilities of future high-speed networks make possible many distributed real-time applications, such as sensor-based applications and multimedia services. Since these applications will have traffic characteristics and performance requirements that differ dramatically from those of current data-oriented applications, new communication network architectures, and protocols will be required. In this paper we discuss the performance requirements and traffic characteristics of various real-time applications, survey recent developments in the areas of network architecture and protocols for supporting real-time services, and develop frameworks in which these, and future, research efforts can be considered     

A survey on industrial communication networks

Industrial communication networks differ from other types of networks because these applications are responsible for the control and monitoring of a physical process. In this paper, we will summarise the requirements that users specify for these networks, present the state of art on field buses, factory and cell communication networks and indicate current research directions.     

Multiservice optical video communication networks — first results and ongoing developments in france

Since 1986, the first operating video communications systems developed by ALCATEL, have been commercially opened in the cities of Rennes, Saint-Cloud, Mantes and Toulon; other plants are under installation in the cities of Evry, Marseille, Massy, Gennevilliers, Lille and Montpellier. The basic infrastructures already installed permit the connection of several tens of thousands of households. Compared with conventional coaxial system, the ALCATEL video communications system presents the following main advantages:

• (a) More efficient operating facilities for audiovisual services offering built-in access control functions, without any additional descrambling terminal on the user's premises, allowing easy introduction of pay-per-view programming, and providing advertising people with adequate audience measurements.
• (b) Flexible and continuous implementation of additional telecommunication services such as telephony, videotex, home security, bidirectional data transmission and professional specialized applications.

Those advantages are a direct consequence of the switched-star network structure, based on fibre-optic technologies. After a brief overview of the architecture, the paper will present design principles and the main technical choices related to the ALCATEL system. The second part of the paper will describe the different subsystems constituting the switched-star network such as the subscriber subsystem and the operating and maintenance organization. Lastly, different evolving schemes for future introduction of narrowband and the broadband telecommunication services will be proposed.     

Some experimental and modeling results of widely varying urban environments on train mobile radio communication

A comparative study of urban mobile radio wave propagation characteristics in the UHF band has been carried out based on the field strength measurements conducted inside a moving train in two widely varying urban environments. Various prediction techniques are employed to compare the observed path losses with those of predicted ones in both the environments. The major fall out of the present study is the modification of Xia's model, which gave better agreement with the observed results. The deviations of the prediction techniques and their suitability have been discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

移动通信网络下通信最优节点自动选择方法研究

现有通信最优节点的选择方法,不能在保证误码率的前提下完成节点自动选择。为了解决上述问题,通过LTE网络架构、统一核心网络,从根本上降低因用户移动而造成数据分组丢失可能性,完成移动通信网络环境的搭建;应用通信误码率的计算与最优节点的自动选择,搭建基于移动网络的EBCPS通信最优节点自动选择方法。模拟应用环境设计对比实验结果表明,EBCPS通信最优节点自动选择方法,既能在保证误码率的前提下,完成节点自动选择,也能提高最小剩余量,缩短竞争接入时间。     

机载认知通信网络架构研究

为了满足作战人员对机载通信网络高移动性、高容量、保障多种业务服务质量（ QoS )、多链互通互操作等需求,考虑到机载网络包含多个异构链路的特点,借鉴商用认知网络思想,提出了一种新的基于认知的网络层收敛分层架构。分析了该架构的特点和优势,给出了该网络架构的认知流程,阐述了涉及到的关键技术。基于认知的网络层收敛分层架构,容易实现多个异构链路资源集成和应用,并在所有协议层认知的基础上,智能地适配动态环境来满足用户端到端指标和提升网络性能。