Services, architectures, and protocols for space data systems

The author presents a comprehensive discussion of three major aspects of the work of the Consultative Committee for Space Data Systems (CCSDS), a worldwide cooperative effort of national space agencies. The author examines the CCSDS space data communications network concept on which the data communications facilities of future advanced orbiting systems will be based. He derives the specifications of an open communications architecture as a reference model for the development of services and protocols that support the transfer of information over space data communications networks. Detailed specifications of the communication services and information transfer protocols that have reached a high degree of maturity and stability are offered. The author also includes a complete list of currently available CCSDS standards and supporting documentation     

You'll never talk alone [cellular radio networks]

The transition in the 1990s from analogue to digital technology in cellular radio networks marked a turning point in mobile telephony, heralding a future of ubiquitous, low-cost, personal communications. The global growth of personal communications has continued at an incredibly rapid pace. The commercial pressures in today's markets are such that the development of future standards and systems are driven not simply by technology, but by commercial opportunity and market pull. In this respect personal communications has gone up a gear since the development of the early GSM digital cellular standards. The opportunities to apply PCS technology into adjacent markets and applications are huge, with new products and services limited only by imagination     

Test yourself: how much do you know about internationalcommunications? [International numbering systems]

We like to think of international telephone communications as `transparent', the successful outcome of 100 years of technical progress and standards setting, but the author shows us that it is not. The user still has to be something of an expert to understand how to make international calls, and there are chaotically differing numbering systems for telephony, telex, and electronic mail. We should be reminded that usability of services, not just their usefulness, is a critical component of communications. Simplicity, consistency, and rationality of service features and the `human interface' that allows users to invoke them should be a high priority for communications engineers as they work toward the integrated services networks of the future     

Wireless mobile communications at the start of the 21st century

At the start of the 21st century, the wireless mobile markets are witnessing unprecedented growth fueled by an information explosion and a technology revolution. In the radio frequency arena, the trend is to move from narrowband to wideband with a family of standards tailored to a variety of application needs. Many enabling technologies including wideband code-division multiple access, software-defined radio, intelligent antennas, and digital processing devices are greatly improving the spectral efficiency of third-generation systems. In the mobile network area, the trend is to move from traditional circuit-switched systems to packet-switched programmable networks that integrate both voice and packet services, and eventually evolve toward an all-IP network. Furthermore, accompanied by wireless mobile location technology, wireless mobile Internet is expected to revolutionize the services that can be provided to consumers in the right place and at the right time. Wireless mobile communications may not only complement the well established wireline network; it may also become a serious competitor in years to come. We review the history of the wireless mobile communications, examine the current progress in standards and technologies, and discuss possible trends for wireless mobile solutions     

Applications of voice processing to telecommunications

The ways in which people communicate are changing rapidly. The options are many and diverse, ranging from voice calls over wireless networks, to video calls over the conventional wired network, ISDN video, FAX, e-mail, voice mail, beeper services, data services, audio teleconferencing, video teleconferencing, and so-called scribble phone service (transmission of arbitrary handwritten input). This revolution in communications is being fueled by several sources, including the availability of low-cost, low-power, computation in both DSP and RISC chips, larger and cheaper memory chips, improved algorithms for communications (e.g., modems, signaling) and signal processing, and finally the creation of world-wide standards for transmission, signal compression, and communication protocols. The broad goal of the communications revolution is to provide seamless and high-quality communications between people (or groups of people), anywhere, anytime, and at a reasonable price. Although there are many technologies that form the bases for the communications environment of the twenty-first century, one of the key technologies for making the vision a reality is voice processing. In this paper we attempt to show, by example, how voice processing has been applied to specific problems in telecommunications, and how it will grow to become an even more essential component of the communications systems of the twenty-first century     

Developments and Constraints in 802.11-Based Roadside-to-Vehicle Communications

Vehicular communication has recently become popular for delivering traffic information and broadband services to the commuters. The feasibility of using the opportunistic short interval connections between vehicles and between vehicles and the roadside infrastructure is under scrutiny. The main motivation behind writing this review is that several survey works addressing inter-vehicle communications are available in literature but hardly any survey article on roadside-to-vehicle (R2V) communication is known to the authors. Here, we discuss the latest standards and protocols which can allow the use of already available WLAN infrastructure in the vehicular context. The use of roadside WLAN APs would provide the same services as those envisaged by the intelligent transportation systems using the dedicated roadside base stations. In this paper, we give an overview of the recent developments, limitations, standards and protocols that can facilitate 802.11-based R2V communication.     

Pathways for telecommunications: a European outlook

The factors driving the transformation of telecommunication systems are used as the basis for describing major trends in network architecture and access structures, intelligent networks (INs), mobile and personal communications, and management functions. The factors include network digitization, the widespread use of optical fibers, and the increase in the range and demand for high-speed services. The interplay between technologies, markets, and standards is analyzed, and the need to identify consistent and harmonized patterns of development for network architectures and services is considered. In particular, telecommunications products, services, and regulations in Europe are discussed     

Digital video coding standards and their role in videocommunications

The efficient digital representation of image and video signals has been subject of considerable research over the past 20 years. With the growing availability of digital transmission links, progress in signal processing, VLSI technology and image compression research, visual communications has become more feasible than ever. Digital video coding technology has developed into a mature field and a diversity of products has been developed-targeted for a wide range of emerging applications, such as video on demand, digital TV/HDTV broadcasting, and multimedia image/video database services. With the increased commercial interest in video communications the need for international image and video coding standards arose. Standardization of video coding algorithms holds the promise of large markets for video communication equipment. Interoperability of implementations from different vendors enables the consumer to access video from a wider range of services and VLSI implementations of coding algorithms conforming to international standards can be manufactured at considerably reduced costs. The purpose of this paper is to provide an overview of today's image and video coding standards and their role in video communications. The different coding algorithms developed for each standard are reviewed and the commonalities between the standards are discussed     

IPv6 networks over DVB‐RCS satellite systems

Satellite plays an important role in global information infrastructure (GII) and next generation networks (NGNs). Similarly, satellite communication systems have great advantages to support IPv6 (Internet Protocol version 6) networks as a technology that allows universal access to broadband e‐services (audio, video, VPN, etc.). In the context of DVB‐S2 (digital video broadcast‐satellite) and DVB‐RCS (digital video broadcast‐return channel via satellite) standards, this paper presents the current SatSix project (satellite‐based communications systems within IPv6 networks) within the European 6th Framework Programme, which is implementing innovative concepts and effective solutions (in relation with the economical cost) for broadband satellite systems and services using the technology presented above. This project is promoting the introduction of the IPv6 protocol into satellite‐based communication systems. Moreover, through SatSix, the industry is addressing the next generation Internet, IPv6. It also enhances its competitive position in satellite broadband multimedia systems by exploiting the common components defined by the European DVB‐S2 and DVB‐RCS satellite broadband standards. Copyright © 2007 John Wiley & Sons, Ltd.     

Satellite Scenarios and Technology for the 1990's

Commercial satellite communications continues to undergo changes arising not only from advancing technology but also from new service offerings and regulatory activities. As the communications industry grows more competitive, future directions in satellite communications will become more economically than technologically motivated. This paper addresses the future of satellite communications, emphasizing fixed satellite services but also covering maritime mobile and broadcast satellite services. Following a brief recapping of the past, current services are discussed and future services are projected for the above service categories. A projection is made of the economics of satellite communications systems using gateway and varying degrees of distribution of earth stations, for both INTELSAT VI and future multibeam satellites and the TAT-8 fiber-optic undersea cable. After a brief allusion to systems design considerations, the anticipated technology projections towards the year 2000 for satellite communication services (including satellite antennas, transmitters and receivers, and on-board interconnection subsystems) are presented in some detail. Finally, it is concluded that satellite communications will have a major role in this epoch, and widespread use of low-cost customer premise earth station may justify more sophisticated and more expensive spacecraft.     

UMTS universal mobile telecommunications system: development ofstandards for the third generation

The standards for the universal mobile telecommunications system (UMTS) are being developed by the European Telecommunications Standardization Institute (ETSI), UMTS is a set of standards aimed at the global market. It will be a real third-generation global system for mobile communications, adding new features and introducing relevant technological innovations while evolving from both a global system for mobile communications (GSM) and integrated services digital networks (ISDNs), UMTS standardization is a market-driven process, and UMT standards are based on the carefully selected market requirements developed in close cooperation with the UMTS Forum and GSM Memorandum of Understanding Association (MoU), UMTS belongs to the IMT-2000 family and, while supporting existing services, will be capable of offering new and revolutionary services including multimedia and access to the Internet, offering a speed of 2 Mb/s for a single user at a radio-access network. This paper attempts to give an objective view of the UMTS standardization in Europe     

TDD-CDMA for the 4th generation of wireless communications

This article discusses an evolutionary TDD mode of CDMA-based path for 3.5G/4G systems. This technology has already been the basis of two 3G standards: TD-CDMA and TD-SCDMA with a synchronous uplink. Several techniques have been developed that allow TDD-CDMA-based systems to transmit at rates usually associated with 3.5G to 4G, up to 10-20 Mbit/s with wide area coverage. The present TDD-CDMA-based 3G standards are evolving to provide these higher rates, while fully retaining the coverage and mobility associated with, and expected from, the present mobile communications systems. This article discusses how TDD-CDMA specific techniques facilitate delivering services at data rates associated with 3.5G and 4G. We review how TDD-CDMA can provide for asymmetric uplink and downlink transmissions, facilitate deployment of advanced antennas for improved downlink coverage, and enable provision of advanced receiver techniques in base stations and mobiles. We also discuss how these techniques affect systems capacity in full packet-switched IP-based systems. We then discuss 4G TDD CDMA systems: those with different modulation techniques for uplink and downlink communications. These are generally based on a multicarrier mode of CDMA, and may incorporate OFDM technique.     

A US perspective on standards development

The foundation for the interconnected society of the 21st century is being built today. The key to having this become a reality is the availability of compatible national, regional, and global communications standards. Committee T1 Telecommunications has played increasing important standards development roles in the US and global telecommunications industries. Committee Tl's dual roles of a US standards developer and an initiator of global standards harmonization contribute to satisfying the users' desires that it be as easy to communicate across the country or around the world as it is to communicate across the street. The key technologies of asynchronous transfer mode (ATM), personal communications services (PCS), and synchronous optical network (SONET) are but a few of the topics for which standards have been developed in Committee T1, and for which standardization of extensions and enhancements continue. These areas have also been among the topics Committee T1 has targeted for standards harmonization     

White broadband power line communication: Exploiting the TVWS for indoor multimedia smart grid applications

Balancing the energy production and consumption in smart grids influences the integration of new high‐speed communication technologies, to support monitoring services. Sharing the television white space (TVWS) spectrum between licensed and unlicensed users has been recommended by the federal communications commission in 2004. Federal communications commission allows the unlicensed users to access both the very high frequency (VHF) and the ultra‐high frequency channels in TVWS. On the other hand, broadband power line communication (BPLC) has drawn the researchers' attention over the last decade as a high‐speed indoor communication technology. One application for BPLC is the multimedia service in smart grid applications. In this article, we present an overview of the standards, regulations, and channel models of the TVWS and BPLC as 2 separate technologies. We then propose the deployment of the BPLC technology in the TVWS VHF band to build up the white BPLC (WBPLC) communication systems. The WBPLC incorporates the TVWS and the BPLC technologies into multiple‐input multiple‐output communication systems in the VHF band. The simulation results show significant throughput enhancement in the WBPLC over both the TVWS and BPLC communication systems, indicating that WBPLC can be a promising technology to serve the growing needs for the multimedia services in future smart grids.     

H.323多媒体通信系统的组成和运作

从介绍ＩＴＵ－Ｔ已经制定的适合于各种通信网络应用的Ｈ．３２Ｘ系列多媒体通信标准开始，继而叙述基于ＴＣＰ／ＩＰ的 Ｈ．３２３标准多媒体通信系统的组成和运作，包括 Ｈ．３２３终端结构、终点协议库、多点控制器（ＭＣＵ）、网关泅闸、边界单元等分量。最后介绍 Ｈ．２２５和 Ｈ．２４５两个协议的操作过程。Ｈ．３２３多媒体通信系统正获得越来越广泛的应用。     

Present State and Future of Telecommunications in Turkey

The public telecommunication network of Turkey is briefly discussed in this paper. The existing telephone, telegraph, data, and other related services are summarized, and future trends in some of these services are indicated. These trends suggest that capital investments on the telecommunication services must be at least doubled in order that the standards in the country compete with those of the world averages. Finally, some of the research in communications is cited.     

飞速发展的香港数据通信业务

本文根据赴港参观学习所见所闻，详细介绍了香港电讯数据通信业务发情况，资费标准和服务特点，并描述了北京电信与香港电讯的合作概貌及前景。     

Applications of antenna arrays to mobile communications. I.Performance improvement, feasibility, and system considerations

The demand for wireless mobile communications services is growing at an explosive rate, with the anticipation that communication to a mobile device anywhere on the globe at all times will be available in the near future. An array of antennas mounted on vehicles, ships, aircraft, satellites, and base stations is expected to play an important role in fulfilling the increased demand of channel requirement for these services, as well as for the realization of the dream that a portable communications device the size of a wristwatch be available at an affordable cost for such services. This paper is the first of a two-part study. It provides a comprehensive treatment, at a level appropriate to nonspecialists, of the use of an antenna array to enhance the efficiency of mobile communications systems. It presents an overview of mobile communications as well as details of how an array may be used in various mobile communications systems, including land-mobile, indoor-radio, and satellite-based systems. It discusses advantages of an array of antennas in a mobile communications system, highlights improvements that are possible by using multiple antennas compared to a single antenna in a system, and provides details on the feasibility of antenna arrays for mobile communications applications     

Mobile satellite services for travellers

The services offered by INMARSAT are described. INMARSAT is the only organization providing satellite communications services worldwide to all modes of transportation by air, land, and sea. At the same time the wide range of its membership, comprising 64 countries (including both the United States and the Soviet Union) has meant that the technical standards adopted by INMARSAT are recognized internationally. The supporting infrastructure is described. The future of satellite communications is briefly examined     

Why are ISDN standards important?

The advantages offered by the integrated services digital network (ISDN) to US Department of Defense (DoD) communications in terms of interoperability provides a framework for a discussion of ISDN standards. The standards organizations working on ISDN and network protocol standards are described, and their relationship to each other is delineated. The status of the standards being developed is discussed, and those that would be of special interest to the US DoD are examined