Data Communications in Japan

Aspects of data communications in Japan are broadly summarized in this paper. First, various networks for data communication are described and some examples of data communication services using these networks are mentioned. Next, some topics in data communication technology are outlined. Topics include two large-scale computer projects and R&D on pattern recognition techniques in the data-processing field, standard modems now in use and new modems for PCM transmission and other uses in the data transmission field, optical character readers (OCR) and an audio-response unit, as well as various printers in the data terminal equipment field.     

Terminals

The rapid development of several different kinds of terminals and the greater ease that they offer for the use of real-time on-line systems are having a major impact on the computer industry and on computer applications. Trends that influence the increasing utilization of terminals are identified. The major subsets of the terminal market include keyboard/printer terminals, CRT terminals, "smart" terminals, remote-batch terminals, real-time data acquisition and control terminals, transaction and point-of-sale terminals, and several miscellaneous types of less frequently used terminals. Applications, characteristics, and some design considerations are discussed for each of these types of terminals. The important relationship between terminal capability and communications requirements is analyzed. To the extent that stored program capability in the terminal permits part of the task to be performed locally, communication of data between terminal and central communication can be reduced with a consequent reduction in communication costs and increase in overall system reliability.     

Power Efficient SDR Implementation of IEEE 802.11a/p Physical Layer

Software defined physical layer modems can be considered the new trend in the field of communications. Differently from dedicated hardware, software can be easily modified to implement a large variety of standards on the same platform. The use of software can significantly reduce development costs, but generally comes at the price of an increase in silicon area and power consumption. For different reasons, this price is something that is not always convenient or even possible to pay, as in the case of low-cost ICs implementing a single waveform, or even multi-mode modems embedding legacy IPs already available in hardware. In particular, power consumption overhead can be prohibitive for mobile terminals or in general for battery-powered devices. The very first challenge for a computing fabric to be competitive is to find and implement the right trade-off between flexibility and performance. This was the guideline for the design of the Block Processing Engine (BPE), a template architecture conceived for power-efficient baseband processing. The BPE core feature is a mixed-grain instruction set balancing general-purpose fine-grain instructions with more specific coarse-grain instructions wrapping custom hardware modules. To further limit the power consumption, the BPE also implements instruction-pipelining, variable-size SIMD and multi-task support. To prove the efficiency of such an approach, a dual-mode IEEE 802.11a/p receiver has been implemented.     

The first decade of personal computers

The first decade of personal computers is characterized by three generations of these man-made devices. During the last six years alone, the number of personal computers purchased has increased by two orders of magnitude. This rapid growth has been catalyzed by innovations in computing and communication technology and by the advent of systems with friendlier human-machine interfaces geared towards individual needs. As the microelectronics revolution progresses and better software methodologies evolve, the personal computer will find widespread use in nontraditional application areas involving computing operations on information of many different types. This paper discusses the key features of contemporary personal computers. Four different market niches are delineated and their characteristics analyzed.     

A new direction in personal computer software

The "personalization" of computers is made possible by three major factors--advances in microelectronics, the availability of inexpensive software for a spectrum of applications, and the increased user-friendliness of computer systems. This paper examines the trends in software development, and presents estimates of the escalating costs involved in such development. Major studies by AT & T and by others stress that the true need is for more sophisticated and effective communication tools rather than for more computing power. Effective communication often pivots around the impact of diverse types of information--numeric, textual, and pictorial. Current endeavors are towards refining and integrating several existing technologies to implement software that enables programmers and non-programmers alike to readily manipulate images comprised of different types of information. This paper examines the emerging field of presentation graphics software and presents details of a new product in this nascent field. The conclusion emphasizes the impact of graphic computing in enlarging the spectrum of personal computer applications.     

内嵌TPM的视频监控服务器安全方案

可信计算技术是目前计算机安全的研究热点之一。采用可信计算技术。可大大提高终端和网络通信的可信性。本方案通过视频监控服务器内嵌可信计算平台模块TPM，将可信计算技术引入到视频监控系统中。利用TPM的密码运算引擎和存储保护功能，结合可信计算的相关思想，能够使视频监控服务器的安全性有一定的提高，而且这种基于硬件的安全技术，相对于基于软件的安全技术来说效率更高。     

Computer-communication network reliability: Trends and issues

People working in Computer-communication networks usually distinguish between the entire system and the communications subnet. The former includes the latter plus the terminals, devices and computer intercommunication via the subnet. This logically includes the resident processes that control or interface with the subnet. Greater computer communication network reliability can obviously be achieved by maximizing the reliability of its constituent components i.e. hardware, software, and communication network. The network reliability can be improved by exploiting the redundancies that are either inherent due to network topology or can be provided in the network. This paper presents a comprehensive discussion of issues involved and trends prevailing in producing reliable hardware; reliable software; and reliable computer communication network while reviewing techniques available for preventing, detecting, diagnosing, correcting and recovering from malfunctions.     

Data communications needs

Present and future computer communications requirements are considered. Present computing is characterized primarily by three well-established paradigms: timesharing, transaction, and mainframe. Each of these is examined. To understand future needs, trends in computer paradigms and technology are examined. Innovative uses of data communications are considered under circumstances in which voice orientation is not a factor, a computational perspective is operative, and new communications options are available. Developments in processor power and system software are briefly considered, and client-server systems and the networks that make them possible are covered in depth. The much more demanding data communication requirements of client-server systems are stressed     

Building open programmable multimedia networks

Recent advances in distributed systems and transportable software and increasing demand for better quality of service (QoS) control in multiservice networks are driving a reexamination of network software architectures. We established the Comet (Control, Management, and Telemedia) Group at Columbia University's Center for Telecommunications Research to provide comprehensive understanding of network software architecture for the 1990s and beyond. This research focuses on developing new network architectures that support service creation, QoS control, and the joint allocation of computing and communications resources. This provides an opportunity to reconcile the perspectives of the computing and communication communities. Future multiservice (multimedia) networks will carry traffic such as video, audio, and computer data with diverse QoS requirements. Such networks will thus require that we develop ways to manage many physical and logical entities, services, and users     

Low earth orbit satellite communications experiments using the digital signal processing payload on the PoSAT-1 microsatellite

There is a growing interest in using networks of small satellites in low Earth orbit (LEO) to provide a variety of communications services in conjunction with small ground terminals. The only ’little LEO’ microsatellite digital store-and-forward communications network (HealthNet) in commercial operation at the time of writing uses microsatellites, communications payloads, and protocols designed and built at the University of Surrey, U.K. In order to provide an in-orbit research test-bed for improving communications with microsatellites in LEO by optimizing modulation and demodulation techniques, an advanced DSP payload, the digital signal processing experiment (DSPE), was included on board the latest Surrey microsatellite (PoSAT-1). In-orbit experiments using the PoSAT-1 DSPE first optimized the existing non-coherent CPFSK communication systems and then investigated the use of coherent MSK to provide a potential 3dB advantage while remaining compatible with the spacecraft systems. A novel DSP implementation of the Hodgart-Massey coherent MSK demodulator/decoder was developed by the authors and its behaviour compared with the classical de Buda demodulator undertypical LEO conditions through a sequence of rigorous computer simulations and laboratory bench tests. The simulations and bench tests quantified a practical 2dB improvement in BER performance when compared with non-coherent CPFSK, while also exhibiting considerable tolerance to the frequency and amplitude variations which are encountered in an LEO environment. These characteristics were subsequently confirmed by in-orbit demonstrations using the PoSAT-1 DSPE. The microsatellite, payload, modems and experimental results are presented in this paper and discussed with a view towards implementing an adaptable DSP-based communications system capable of optimizing data throughput with LEO microsatellites.     

无线通信领域的“下一个大事件”——认知无线电

认知无线电是在软件无线电基础上发展而来的能够自适应外界环境变化的智能无线通信系统,其核心思想是使无线通信设备具有发现"频谱空穴"并合理利用所发现的"频谱空穴"的能力。认知无线电的提出为从根本上解决日益增长的无线通信需求与有限的无线频谱资源之间的矛盾开辟了一条行之有效的新途径。从认知无线电技术的研究背景入手,综合阐述了认知无线电的定义及其特点、实现认知无线电的关键技术以及超宽带与认知无线电相结合的认知超宽带通信技术。     

The 220 MHz ITS spectral allocation: potential, pitfalls, andapplications

In 1992 five narrowband frequency pairs in the 220-222 MHz band were allocated for intelligent transportation system (ITS) applications. These allocations are capable of supporting low-rate digital communications (4-30 kb/s). This article examines potential applications within the ITS program which can effectively use the low data rate that these allocations can provide. An overview of the narrowband wireless data communication challenges and the communication theoretic techniques likely to be employed on high-performance modems is provided. An experimental system was built, and preliminary field test results are presented which demonstrate that spectral efficiencies in excess of 3 b/s/Hz are achievable in practical modems     

Control, Computing and Communications: Technologies for the Twenty-First Century Model T

In the early twentieth century, the Model T Ford defined the desirable, affordable automobile, enabled by new technologies in mechanics, materials, and manufacturing. Control, computing, communications, and the underlying software are the technologies that will shape the personal mobility experience of the twenty-first century. While the Model T was self-contained, the external reach of wireless communication technologies will define the boundaries of the twenty-first century automobile, which will be only one component in a large intelligent transportation infrastructure. This paper reviews advances in control for safety, fuel economy and reduction of tailpipe emissions, and new directions in computing, communication and software, including the interaction of the automobile with consumer electronic devices and the intelligent transportation infrastructure     

Software-defined radio technology in the problem concerning with the successive sounding of HF ionospheric communication channels

The problem concerning new software-defined radio technology is investigated as applied to the successive sounding of HF ionospheric communication radio channels. The algorithm for quadrature processing of chirp signals subjected to elementwise compression in the frequency domain is developed. It is established that a channel scattering function and a delay power profile are related to a compressed-signal spectrum and their basic parameters. Data on the key characteristic of HF communications modems are presented. The efficiencies of different modems are estimated using the experimental data on channel parameters. It is demonstrated that the aforementioned technology can be used to estimate not only HF communication channel parameters from the pass band of a radio line but also select the optimal one and, furthermore, makes it possible to combine communications and radio sounding systems in the single device.     

The telephone network of the 1960s

In 1960 the transmission technology of the public switched telephone network was ordinary cable pairs, carrier systems on both paired and coaxial cable, and point-to-point microwave radio systems. Voice signals were frequency multiplexed for efficient transmission, but remained in analog form from end to end of a connection. Electromechanical switching systems provided circuit-switched connections, and about half of the customers could directly dial long distance calls. The following decade saw the beginnings of electronic switching and direct distance dialing on a global basis. Meanwhile, applying digital technology to achieve lower costs and better quality for voice transport began in earnest, and the interconnection of data terminals and computer centers became an increasingly important communications need. The initial data communications approach, still used with ever increasing sophistication and speed, was to convert data to speech-like form with data modems. Later, the direct connection of digital data to digital network facilities became the method of choice for building computer communications networks and the backbone of the Internet. It now appears likely that one day all signals, including voice, will be transported by unified high-speed digital networks with a common set of protocols     

IN architectures for implementing universal personaltelecommunications

This article focuses on architectures for providing universal personal telecommunications (UPT) service to wireline users. Although UPT services could be provided to users of wireless phones, thereby giving those users personal communication services (PCS), the wireline environment introduces certain important complications. Unlike "smart" cellular phones, which can register themselves and the user automatically, wireline telephones are unable to automatically detect and register a UPT user. UPT therefore includes a manual registration procedure to associate a PTN with the phone where calls will be received or placed. Also, unlike personal communications terminals that are typically used by only one person, wireline phones are likely to be shared among other users. Therefore, the network must keep track of who is using the phone, so it can provide the appropriate telecommunications services. It would be difficult or impossible to implement UPT as a switch-based service. Fortunately, an intelligent network (IN) architecture that is well suited for implementing UPT is being deployed by many local exchange (LECs) and interexchange carriers (IXCs)     

Software radio: The challenges for reconfigurable terminals

The Software Defined Radio (Sdr) has always been considered as a promising solution for the future of wireless communications because of its ability to provide flexible architecture, enabling multimode and multistandard devices. On the network side, this technology seems to be achievable in a short-term visibility (we even are currently knowing the very beginnings ofSdr solutions in the field of network equipments), but applied to terminals, this technology is likely to reach later its maturity because the embedded issue is synonymous with high constrained architecture. The implementation of software radio terminals requires, for instance, the use of high calculation capability Digital Signal Processors (Dsp) or deeply integrated multiband rf transceiver, whose power consumption quality acts as a brake for the current development of such solutions. Nevertheless, the microelectronic industry will still provide more and more powerful components and, within a few years, theSdr dream will come true for terminal manufacturers. Furthermore, software radio is also a good opportunity to merge computer science and telecommunications technologies, in order to develop smart terminals, which may integrate software components like an operating system or Java virtual machine, etc. Hence, the software radio concept within mobile terminal is still an R&D issue, which requires effort combination in different fields but which also represents a great opportunity for the future of terminals.     

用MC145442实现多点通信

大部分单片调制解调器芯片都是依据电话线路设计制造的，即在一条信道上只能实现点对点的通信。文中简要论述了实用ＭＯＴＯＲＯＬＡ公司生产的单片调制解调器ＭＣ１４５４４２如何实现多点通信的基本思想和具体实现方法，并以一台主机和两台分机通信为例介绍了整个通信流程。     

Optimal dynamic transport selection for wireless portable devices

Recent technological advances in mobile computing and wireless communication have made portable devices, such as PDA, laptops, and wireless modems to be very compact and affordable. On the other hand, wireless networks have gained such wide popularity that new network infrastructure is continually introduced. It is thus likely that many of the future portable devices will be equipped with multiple wireless modems such as Bluetooth and 802.11 WLAN, in order to increase device inter‐operability. The availability of multiple modems can leverage the performance of the communication traffic generated by the applications, for example Internet access. We envision a tool for managing the device connection through these modems. At the core of this tool is an optimization engine that splits packet traffic across a subset of the available transports so that user's performance metrics are maximized. This paper describes a mathematical model for such an optimization problem considering its applicability to small portable devices. Relevant quality of service (QoS) parameters such as bandwidth, average delay, and energy consumption are covered in the model. The mathematical formulation is validated using a simulated environment. The experimental results have demonstrated the effectiveness of our model and captured the inter‐relationship among the quality parameters. Copyright © 2006 John Wiley & Sons, Ltd.     

Protocol architecture for universal personal computing

This paper presents a new paradigm for network computing over the Internet called universal personal computing, where mobile users can access computing resources, network services, and personalized computing environments anywhere using any available terminals. The user and system requirements are defined, and an agent-based protocol architecture required to manage different mobile objects, i.e., users and terminals, in this computing environment is presented. Modifications of connection setup procedures between user application programs to enable addressing based on a global user identity are considered. The use of personal agents to facilitate interworking and management functions is proposed