Traditional Communication Systems Research Articles

Institutional Repositories, Open Access, and Scholarly Communication: A Study of Conflicting Paradigms

The Open Access movement of the past decade, and institutional repositories developed by universities and academic libraries as a part of that movement, have openly challenged the traditional scholarly communication system. This article examines the growth of repositories around the world, and summarizes a growing body of evidence of the response of academics to institutional repositories. It reports the findings of a national survey of academics which highlights the conflict between the principles and rewards of the traditional scholarly communication system, and the benefits of Open Access. The article concludes by suggesting ways in which academic libraries can alleviate the conflict between these two paradigms.

Introduction of a Guide to Enhance Risk Communication Among Low-Income and Minority Populations

Low-income populations, especially those belonging to minority groups, are among the most vulnerable groups before, during, and after a natural disaster. One of the factors that can be attributed to their vulnerability is the ineffectiveness of traditional risk communication systems in reaching this population. Many low-income populations are distrustful of government agencies and those who typically communicate risk messages. Consequently, traditional systems are not as effective in reaching these communities. Furthermore, traditional systems have been based on the social media that the general population uses and not based on social networks of disadvantaged populations which are more important than formal channels in these communities for dissemination of information. To bridge the gap, an approach is needed that relies on trusted agencies and leaders to educate and warn low-income communities about possible public health threats. A grassroots approach can enhance the capacity of the risk communication systems to more effectively reach vulnerable populations by engaging grassroots organizations in risk communication activities. The Guide to Enhance Grassroots Risk Communication Among Low-Income Populations provides strategies and guidance that can assist agencies in upgrading their systems for risk communication by building partnerships with local community stakeholders.

UWB for multi-gigabit/s communications beyond 60 GHz

The recently allocated 71---76 GHz and 81---86 GHz bands provide an opportunity for realizing Line Of Sight (LOS) links for directional point-to-point "last mile" applications. An efficient use of this spectrum may allow wireless to finally "catch up" with wires, leading to systems such as "multi-Gigabit wireless Ethernet," and "wireless fiber." However, the transmission at such a frequency range is characterized by several additional challenges compared to lower frequency bands, from both technological and propagation point of view, which makes difficult to use them efficiently. In this scenario, IR (Impulse Radio) UWB (Ultra Wide Band) technology might offer some more degrees of freedom for the design of a highly integrated and low cost transceiver. This work has at its core the design and BER (Bit Error Rate) performance evaluation of an IR-UWB architecture based on an 85 GHz up-conversion stage of train of Gaussian pulses having duration lower than 1 ns. Finally, we compare performance of this architecture with the ones of a more traditional continuous wave communications system with FSK (Frequency Shift Keying) modulation. Simulation results show that BER performance, in presence of RF non-linearities, for an IR-UWB transceiver architecture operating at 85 GHz (with same data rate and bandwidth) are better than a coherent BFSK scheme working in a similar scenario. Finally, some conclusions are reported, pointing out the UWB antenna design and the future works related to the modeling of the channel at frequencies beyond 60 GHz and the implementation of the test bed.

Guest editorial: embedded and real-time computing systems and applications

Real-time computing systems are those systems in which correctness of the system depends not only on the logical result of computation but also on the time at which the results are produced. This implies that, unlike more traditional information and communication systems, where there is a separation between correctness and performance, in real-time computing systems correctness and performance are very tightly interrelated. Only a few decades ago, real-time computing systems were an important but narrow niche of computer systems, consisting mainly of military systems, air traffic control and embedded systems for manufacturing and process control. This association caused that real-time systems problems did not attract widespread interest from the computer community. Meanwhile, the emergence of large scale distributed systems, enabled by advances in networking technology, has broaden real-time concerns into a mainstream enterprise, with clients in a wide variety of industries and academic disciplines. Terms such as “Cooperating-Objects”, “Cyber-Physical Systems” or “Internet of Things” have come to describe the research and technological effort that will ultimately efficiently allow interlinking the real world physical objects and cyberspace. The integration of physical processes and computing is however nothing dramatically new: embedded systems have been in place since a long time to denote systems that combine physical processes with computing. The revolution is coming from extensively networking embedded computing devices, in a blend that involves sensing, actuation, computation, networking, pervasiveness and physical processes. And interaction with the physical world always implies timeliness as a main concern in the design process. This tendency has been establishing real-time technology as a priority for commercial strategy and academic research for the foreseeable future and also for a wider

非线性光电延时反馈混沌同步复用通信系统研究

A hyper dimensional multiplexed chaos communication system was proposed based on nonlinear delayed feedbacks of electrooptical modulator.Different from traditional chaos communication system,the chaotic waveform is not produced by the semiconductor but by the electro-optical modulator.The scheme is advantageous of high nonlinear dimension,easily reproduced and manipulated accurately.The encryption method of signals modulating feedback delays and cross-correlation decryption method were illustrated.High rates of multiplexing and demultiplexing were numerically simulated for three channels.The main factor for error bit rate was analyzed.The influence of optical fiber on the multiplexed chaos communication system was further investigated.The research results indicate that the influence of optical fiber on chaos synchronization can be reduced significantly and the original signals can be recovered successfully as long as corresponding gain compensation schemes are adopted.

A survey of cross-layer design for VANETs

Recently, vehicular communication systems have attracted much attention, fueled largely by the growing interest in Intelligent Transportation Systems (ITS). These systems are aimed at addressing critical issues like passenger safety and traffic congestion, by integrating information and communication technologies into transportation infrastructure and vehicles. They are built on top of self organizing networks, known as a Vehicular Ad hoc Networks (VANET), composed of mobile vehicles connected by wireless links. While the solutions based on the traditional layered communication system architectures such as OSI model are readily applicable, they often fail to address the fundamental problems in ad hoc networks, such as dynamic changes in the network topology. Furthermore, many ITS applications impose stringent QoS requirements, which are not met by existing ad hoc networking solutions. The paradigm of cross-layer design has been introduced as an alternative to pure layered design to develop communication protocols. Cross-layer design allows information to be exchanged and shared across layer boundaries in order to enable efficient and robust protocols. There has been several research efforts that validated the importance of cross-layer design in vehicular networks. In this article, a survey of recent work on cross-layer communication solutions for VANETs is presented. Major approaches to cross-layer protocol design is introduced, followed by an overview of corresponding cross-layer protocols. Finally, open research problems in developing efficient cross-layer protocols for next generation transportation systems are discussed.

A new call control scheme of Push-To-Talk system

For Push-To-Talk (PTT) system based on Public Mobile Data Network (PMDN), the end-to-end time delay is the key aspect of the user’s experience. The Push-Over-Cellular (POC) scheme defined by Open Mobile Alliance (OMA) is based on the VoIP phone model and use SIP protocol as the call control scheme. The call setup time delay in SIP may reach to several seconds, which is unacceptable for the PTT service. In this paper, we provide a new call control scheme for PTT system based on PLMN network. By combining the apriority knowledge of PTT call model and the priority control scheme, we encapsulate the signaling message and the voice data into a same data packet, when the user push the button, the voice and the call control signaling are sent to the server at the same time. So the long time delay of call setup procedure of POC scheme can be eliminate. The end-to-end call delay can be decreased significantly. The experiment result based on the commercial CDMA2000 1X network of China Unicom shows that the call delay can be decreased to 600 ms, which approach to the traditional trunk communication system’s requirement.

Energy model for communication via diffusion in nanonetworks

Abstract Molecular communication is a new communication paradigm that uses molecules for information transmission between nanomachines. Similar to traditional communication systems, several factors constitute limits over the performance of this communication system. One of these factors is the energy budget of the transmitter. It limits the rate at which the transmitter can emit symbols, i.e., produce the messenger molecules. In this paper, an energy model for the communication via diffusion system is proposed. To evaluate the performance of this communication system, first a channel model is developed, and also the probability of correct decoding of the information is evaluated. Two optimization problems are set up for system analysis that focus on channel capacity and data rate. Evaluations are carried out using the human insulin hormone as the messenger molecule and a transmitter device whose capabilities are similar to a pancreatic β -cell. Results show that distance between the transmitter and receiver has a minor effect on the achievable data rate whereas the energy budget’s effect is significant. It is also shown that selecting appropriate threshold and symbol duration parameters are crucial to the performance of the system.

A study of spam filtering using support vector machines

Electronic mail is a major revolution taking place over traditional communication systems due to its convenient, economical, fast, and easy to use nature. A major bottleneck in electronic communica...

The Nonlinear Impairments Due to the Data Correlation Among Sub-Carriers in Coherent Optical OFDM Systems

Resulted from the narrow frequency interval, the nonlinear impairments are strongly related with the data correlation of the optical orthogonal frequency division (OFDM) symbol in coherent optical OFDM (CO-OFDM) system, which is very different from the traditional WDM optical communication systems. The concept of normalized accumulative correlation coefficient (NACC) is proposed to evaluate the data correlation of the OFDM symbol. The parameter phi is presented to describe the influence of the systematic physical configuration on the nonlinear impairments. The dependence of the nonlinear impairments on the data correlation is investigated and revealed analytically. Closed form expressions are presented to calculate the noise spectrum, total nonlinear noise energy and noise signal ratio (NSR) under the condition that phi les 0.2, which is valid for most practical CO-OFDM system. The NSR is proportional to the NACC and phi2. Simulation results are well consistent with analytical calculations when phi les 0.2.

A method of modulating signals with space-time encoding using non-linear iteration algorithm

In the conditions of limited frequency resource and along with increasing requirements towards transmission data rates in radio communications systems a demand for increasing their spectral characteristics arouses. One of technologies increasing the channel capacity by many times (compared to traditional radio communications systems with one transmitting antenna) is the space-time encoding technique. The absence of effective signal processing algorithms, having acceptable computational complexity, at the receiving side appears to be limiting factor for systems with space-time encoding. A new algorithm for demodulating signals with space-time encoding, which exceeds the known algorithm in interference immunity and possesses moderate computational complexity, is suggested.

100-Gb/s optical communications

Optical communications is a quickly evolving field, driven by the ever increasing need for communication bandwidth. Over the next decade, the field is expected to mature substantially as high-speed components enable more advanced modulation and digital signal processing. With the standardization of 100-Gb/s Ethernet well in progress, terabit Ethernet is just over the horizon. As data rates continue to increase above 100 Gb/s, the role of the microwave engineer will become more and more critical to the success of next-generation optical communications gear. There is a tremendous opportunity for the radio engineer to migrate his or her skills to work in the field of microwave signal integrity. This is an up-and-coming field with lots of room for innovative research. In this article, the current state of the art and the research frontiers of 100 G optical communication systems is explained, and various optical modulation approaches are illustrated. Furthermore, comparison with traditional microwave communication systems is presented as well as the increasing role of the microwave engineer in high-speed optical communication design.

Orfeo Tv: Street Television Breaks the Italian Regimented Broadcasting Network

In developed societies open access to media system is considered a sign and a symbol of freedom and democracy, given the role media play in orienting public's understanding of important issues and choices. From this perspective, traditional broadcasting communication system, in particular the television, has evolved in the opposite direction. Because of its technology and the close regulations adopted in the western countries, television is usually conceived and institutionalized as a centric, inaccessible and regimented system of communication. People do not consider broadcasting medium as a one to use to communicate directly with other people. The relation between broadcasting stations and people is unidirectional: people are receivers, passive viewers in front of a television set. In the last years, a radically different television network is emerged: it is open, it is free ('free as in speech', as Richard Stallman would say) and it brakes with the institutionalized separation between production and consumption that characterized the traditional television. The aim of this paper is to describe and analyze the experience of the first Italian open television station (also called 'tv di strada', street television), Orfeo Tv, and the network it created, Telestreet. Orfeo Tv begins its activity in the summer of 2002 in Bologna. From the beginning, the founders were aware that the survival and the power of the initiative depended on the possibility of multiplication and they compared their project to a virus to spread on the Italian cultural life. This story shows a) how institutions and technologies, like the television, can be reframed and institutionalized under completely different assumptions, b) how the institutional evolution and technology innovation are intertwined, c) the relevance of critical mass for the survival of emergent initiatives. Technological innovation that has been used by the Orfeo Tv people is mainly a new combination of different existing technologies that have been purposively used. It is true that street televisions become possible because the technological innovation lowered the entry barriers and made widely accessible to everyone to produce and broadcast television programs. Finally, this is a story where technology points out the limitations of the institutional context. The experience of Orfeo Tv, is interesting because it underlies how far people are from having free access to broadcasting media system and how far is the legal framework from let free the access to this important medium. Institutional regulations were not ready to manage the people use of the broadcasting medium and in fact the new technologies that have been chosen to be implemented (i.e. digital terrestrial television service) are meant to keep the television close and regulated.

Adoption of e-procurement in Hong Kong: An empirical research

For the past 5 years, a large number of procurement articles have appeared in the literature. E-procurement solutions make purchasing activities more effective in terms of both time and cost. E-procurement is changing the way businesses purchase goods. Since most products and services are procured using electronic data interchange and the Internet, the application of e-procurement is inevitable in both manufacturing and services. There are limited empirical studies in the literature on the adoption of e-procurement in a country, that is, at the macro-level. Nevertheless, such a study will help companies in other countries to develop policies, strategies, and procedures to implement e-procurement. Understanding the importance of such a study, we have conducted a questionnaire-based survey about the adoption of e-procurement in Hong Kong. The main objective of this study is to identify the perceived critical success factors and perceived barriers regarding the implementation of e-procurement. A conceptual framework has been developed for the adoption of e-procurement, and this subsequently has been tested with data collected from companies in Hong Kong. Also, this study examines the current status of e-procurement adoption in Hong Kong. Finally, a framework is proposed based on the conceptual and empirical analysis for the adoption of e-procurement. The results indicate that educating companies in both long- and short-term benefits would encourage the application of e-procurement. Some critical success factors include adequate financial support, availability of interoperability and standards with traditional communication systems, top management support and commitment, understanding the priorities of the company, and having suitable security systems.

Assessing the impact of ICT on UK general haulage companies

This paper focuses on the road freight transport industry, using the UK as a case study. It examines the extent to which Internet freight exchanges and the use of information and communication technology (ICT) processes are affecting general haulage. Recent surveys suggest that there is scope within the road transport industry to improve efficiency in terms of fill rates and empty running. Any improvements may also help to alleviate the pressures faced in many developed countries by the haulage industry, which include driver shortages, new legislation, such as the Working Time Directive in Europe, increasing road congestion, as well as to support improvements desired for sustainability. A background summary of the UK road haulage industry and the potential impact of e-commerce are provided before the results of a survey from 49 general haulage operators in their attitude to and adoption of ICT developments are analysed and assessed. The study concludes that a split picture is emerging. While many of the smaller haulage operators remain dependent upon traditional communication and process systems, the larger logistics companies, who control the majority of vehicles and freight movements, are progressively developing new ways of working supported by ICT adoption.

Resource allocation and performance analysis of wireless video sensors

Wireless video sensor networks (WVSNs) have been envisioned for a wide range of important applications, including battlefield intelligence, security monitoring, emergency response, and environmental tracking. Compared to traditional communication system, the WVSN operates under a set of unique resource constraints, including limitations with respect to energy supply, on-board computational capability, and transmission bandwidth. The objective of this paper is to study the resource utilization behavior of a wireless video sensor and analyze its performance under the resource constraints. More specifically, we develop an analytic power-rate-distortion (P-R-D) model to characterize the inherent relationship between the power consumption of a video encoder and its rate-distortion performance. Based on the P-R-D analysis and a simplified model for wireless transmission power, we study the optimum power allocation between video encoding and wireless transmission and introduce a measure called achievable minimum distortion to quantify the distortion under a total power constraint. We consider two scenarios in wireless video sensing, small-delay wireless video monitoring and large-delay wireless video surveillance, and analyze the performance limit of the wireless video sensor in each scenario. The analysis and results obtained in this paper provide an important guideline for practical wireless video sensor design.

Alfabetización en la comunicación mediática: la narrativa digital

The generalization of a technological and digital screen world shows a complex reality. Traditional communication systems and new unknown relation with other novel and strangers converge in this reality. The television already has entered the digital world. The digital technologies define a new universe of languages, of interactions and systems of relation. A new reality that is located between the real thing and the virtual thing. This world of «screens» has numerous edges that are necessary to analyze in all their dimensions and individual influences, social and cultural. All solution happens through a process of alphabetization in the new technologies of the communication. La conformación y generalización de un mundo tecnológico y digital, «de pantallas», presenta una realidad compleja. Convergen en esta realidad sistemas de comunicación y de relación tradicionales con otros novedosos y desconocidos. La televisión ya ha entrado en el mundo digital. Las tecnologías digitales definen un nuevo universo de lenguajes, de interacciones y sistemas de relación. Una nueva realidad que se sitúa entre lo real y lo virtual. Este mundo de «pantallas» tiene numerosas aristas que es necesario analizar en todas sus dimensiones e influencias individuales, sociales y culturales. Toda solución pasa por un proceso de alfabetización en las nuevas tecnologías de la comunicación.

A multicamera setup for generating stereo panoramic video

Traditional visual communication systems convey only two-dimensional (2-D) fixed field-of-view (FOV) video information. The viewer is presented with a series of flat, nonstereoscopic images, which fail to provide a realistic sense of depth. Furthermore, traditional video is restricted to only a small part of the scene, based on the director's discretion and the user is not allowed to "look around" in an environment. The objective of this work is to address both of these issues and develop new techniques for creating stereo panoramic video sequences. A stereo panoramic video sequence should be able to provide the viewer with stereo vision at any direction (complete 360-degree FOV) at video rates. In this paper, we propose a new technique for creating stereo panoramic video using a multicamera approach, thus creating a high-resolution output. We present a setup that is an extension of a previously known approach, developed for the generation of still stereo panoramas, and demonstrate that it is capable of creating high-resolution stereo panoramic video sequences. We further explore the limitations involved in a practical implementation of the setup, namely the limited number of cameras and the nonzero physical size of real cameras. The relevant tradeoffs are identified and studied.

General consumer communication tools for improved image management and communication in medicine.

We elected to explore new technologies emerging on the general consumer market that can improve and facilitate image and data communication in medical and clinical environment. These new technologies developed for communication and storage of data can improve the user convenience and facilitate the communication and transport of images and related data beyond the usual limits and restrictions of a traditional picture archiving and communication systems (PACS) network. We specifically tested and implemented three new technologies provided on Apple computer platforms. (1) We adopted the iPod, a MP3 portable player with a hard disk storage, to easily and quickly move large number of DICOM images. (2) We adopted iChat, a videoconference and instant-messaging software, to transmit DICOM images in real time to a distant computer for conferencing teleradiology. (3) Finally, we developed a direct secure interface to use the iDisk service, a file-sharing service based on the WebDAV technology, to send and share DICOM files between distant computers. These three technologies were integrated in a new open-source image navigation and display software called OsiriX allowing for manipulation and communication of multimodality and multidimensional DICOM image data sets. This software is freely available as an open-source project at http://homepage.mac.com/rossetantoine/OsiriX. Our experience showed that the implementation of these technologies allowed us to significantly enhance the existing PACS with valuable new features without any additional investment or the need for complex extensions of our infrastructure. The added features such as teleradiology, secure and convenient image and data communication, and the use of external data storage services open the gate to a much broader extension of our imaging infrastructure to the outside world.

Can PACS benefit from general consumer communication tools?

Some emerging consumer technologies can be adopted to improve and facilitate image and data communication in medical and clinical environment. The wide adoption of new communication paradigm such as instant messaging, chatting and direct emailing can be integrated in specific applications. The increasing capacity of portable and handheld devices such as iPod music players offer an attractive alternative for data storage that exceeds the capabilities of traditional off-line storage media such as CD or even DVD. We elected to develop an image display and manipulation software called OsiriX to integrate different innovative technologies facilitating the communication and data transfer between remote users. We integrated email and instant messaging features to the program allowing users to instantaneously email an image or a set of images that are displayed on the screen. Using iChat instant messaging application from Apple a user can share the content of his screen with a remote correspondent and communicate in real time using voice and video. To provide convenient mechanism for exchange of large data sets the program can store the data in DICOM format on CD or DVD, but was also extended to use the large storage capacity of iPod hard disks as well as Apple's online storage service “.Mac” that users can subscribe to benefit from scalable secure storage that is accessible from anywhere on the internet. The adoption of these innovative technologies is likely to change the architecture of traditional picture archiving and communication systems and provide more flexible and efficient means of communication.