Existing Communication Systems Research Articles

Robust Digital Retrodirective Beamforming Technique for Multipath Channel Environment

Abstract In this paper, we describe the effect of temporal and spatial focusing obtained by using the digital retrodirective beamforming (DRDB) system and analyze BER performance of DRDB in multipath channel. There is a problem with reception performance degraded due to inter symbol interference (ISI) in multipath channel. In order to reduce ISI, the existing communication system use complex equalizer. In order to reduce ISI, we propose a DRDB system which can retransmit data information toward direction as the received signal without any prior information. Also, we explain ISI mitigation by temporal and spatial focusing of the proposed system. Simulation results show that the proposed system has better BER performance than that without DRDB becauseof ISI mitigation effect in multipath channel environment.

Friendly Spectrally Shaped Radar Waveform With Legacy Communication Systems for Shared Access and Spectrum Management

In this paper, we investigate a friendly spectrally shaped radar waveform design that can be used in a spectral band being utilized by one or more communication systems. We specifically consider legacy communication systems as opposed to cooperative communication systems to address the ever present problem of legacy technologies. This radar waveform is able to share the spectrum with the existing communication systems such that its detection performance is not compromised while trying to help the legacy systems maintain their own symbol error rates (SERs). We show with various scenarios that the spectrally shaped radar waveform outperforms the traditional wideband pulse waveform in terms of detection performance with the communication signals acting as interference to the radar. Moreover, SERs of the legacy systems employing quaternary phase-shift keying modulation in the presence of the shaped radar waveform (acting as interference) outperform SERs of systems under traditional radar pulse interference. These SERs are very close to theoretical noise-only SERs.

Capacity Scaling of Cognitive Networks: Beyond Interference-Limited Communication

The capacity scaling laws of two overlaid networks are investigated, which are located in the same area sharing the same wireless resources with different priorities. The primary network can be regarded as an existing communication system operated in a licensed band and, therefore, is assumed to operate in an order-optimal fashion to achieve its standalone capacity scaling law. The secondary cognitive network must keep its interference to the primary network below a certain threshold while at the same time maximizing its own throughput scaling law based on cognition information. The existing scaling results for cognitive networks inherently assume multihop communication, which is a restricted coding model. By contrast, in this paper, a general coding model is considered without any specific physical layer coding assumptions. The capacity scaling exponents for both networks are analyzed when the numbers of primary nodes n, primary base stations l, which support the communication between primary nodes, and secondary nodes m increase with the relations m = n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</sup> , β > 1, and l = n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γ</sup> , 0 ≤ γ ≤ 1. For the extended network model, the capacity scaling exponents are completely characterized as max {2-α/2, 1/2, γ} and max{2-α/2, 1/2} for the primary and secondary networks respectively, where α > 2 denotes the path-loss exponent. That is, the capacity scaling laws for the primary and secondary networks are represented, respectively, by n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max{2-α/2,1/2,γ}±∈</sup> and m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max{2-α/2,1/2}±∈</sup> for α > 0 arbitrarily small. For the dense network model, when the primary network achieves its standalone capacity scaling exponent of 1, the secondary network is shown to achieve a scaling exponent of 1 - 1/(2β), which improves the previous scaling exponent of 1/2 achieved by multihop. For both models, it turns out that the conventional multihop approach is in general quite suboptimal.

Optical peaking enhancement in high-speed ring modulators.

Ring resonator modulators (RRM) combine extreme compactness, low power consumption and wavelength division multiplexing functionality, making them a frontrunner for addressing the scalability requirements of short distance optical links. To extend data rates beyond the classically assumed bandwidth capability, we derive and experimentally verify closed form equations of the electro-optic response and asymmetric side band generation resulting from inherent transient time dynamics and leverage these to significantly improve device performance. An equivalent circuit description with a commonly used peaking amplifier model allows straightforward assessment of the effect on existing communication system architectures. A small signal analytical expression of peaking in the electro-optic response of RRMs is derived and used to extend the electro-optic bandwidth of the device above 40 GHz as well as to open eye diagrams penalized by intersymbol interference at 32, 40 and 44 Gbps. Predicted peaking and asymmetric side band generation are in excellent agreement with experiments.

Improving communication between emergency department staff.

During redevelopment of the emergency department at the Royal Sussex County Hospital, Brighton, it was deemed vital that its internal communication system should be as effective as possible. An audit of staff perceptions of the existing communication system and a relevant literature review were undertaken, therefore, to inform a proposal for the development of a new online system. This article describes the development and implementation of the system.

Harmonization of critical result management in laboratory medicine

Unsafe medical care is a major source of disabling injuries and death throughout the world. The failure to notify, follow up, and action critical results, which signify life threatening situations, is of particular concern and may cause avoidable morbidity and mortality. International accreditation standards require pathology laboratories to have a system for the timely and reliable communication of critical results to clinical personnel responsible for patient care. In response, various practices and a number of different terminologies have been described in the literature. Increased attention to patient safety standards and multinational surveys, however, highlighted shortcomings and inefficiencies in existing communication systems. These failures and variations in practice call for clear guidance and harmonization of approaches in order to improve communications and to provide safer patient care. The objectives of this review are to create a harmonized terminology and to learn from international practices by systematically reviewing the best available evidence on existing approaches. Based on literature review findings we highlight key areas where harmonization is necessary and feasible and offer a conceptual framework and methods for designing better and more evidence-based systems for the timely notification of laboratory results that represent potential patient safety hazards.

Analyses of Optical Emitter Performance in Terehertz Wireless Communication System

To resolve the limitation of information safety and transmission speed in existing communication system, it applied the modular design method to design optical-electric combined THz wireless communication system framework, and determined 125GHz carrier frequency. Aiming at the core component optical emitter uni-traveling-carrier photodiode (UTC-PD) in THz wireless communication system, it analysed the relationship between output power, bandwidth and input signal types, and determined the emitter bandwidth by experiment. The result shows that the transmission speed in the system is able to reach 3.0Gbps when BER is less than 10-10.

Planar ultra‐wideband antenna with five notched stop bands

A printed ultra-wideband (UWB) antenna with five notched stop bands is presented. By introducing a pair of arc-shaped slots, two defected ground structures and an open-loop resonator, five sharp notches are achieved at frequencies of 2.4, 3.2, 5.2, 5.8 and 7.5 GHz. The proposed antenna has been fabricated and tested. The measured results indicate that the proposed design not only supports UWB bandwidth requirements but rejects five narrow bands to avoid possible interference with existing communication systems. In addition, the proposed antenna has relatively omnidirectional radiation patterns in passbands.

Digital Radio Broadcasting for Community Radios Using Pseudo-random Codes

This paper aims to present a digital radio broadcasting system that explores the advantages of pseudo-random codes. In this context, a transmitter and its dual receiver are able to reuse frequency spectrum bands without interfering on other existing communication systems. It is proposed a communication system that allows radio broadcasting with the following characteristics: lower transmission power, new communication channels and digital signal processing techinques to add positioning services in two dimensions.

A Model for the Allocation of Limited Resources for Technological Improvement: A Case of Courier Service

One of the basic questions in the field of microeconomics is how to make decisions about allocation of limited resources for technological improvement. The aim of this study is exactly to propose a model that will help firms in making this kind of decisions. The model puts employees’ stress level in the central place. There was a hypothesis introduced that based on stress level analyses in correlation with particular parameters of business, the recommendations for improvements can be reached.As a data collection tool, two questionnaires were used. First questionnaire was related to stress test. In this paper BHC test was used (Behavioral Health Concepts team, 2000). It is a standardized questionnaire containing 27 questions. The other questionnaire contained 12 questions of which 6 was related to defining employees attitudes about predefined business parameters.In order to get information about what should be changed first Work Stress Index – WSI is introduced. Higher value of WSIi indicates that in the case of the lack of resources for comprehensive changes, higher priority in improvement should be given to business parameter i.The examinees in this study were couriers that work in courier service sector in Serbian Post. There were 29 of them included in this research. Since there were a small number of examinees in this study, Fisher's exact test was used in order to examine the correlation between stress level of employees and particular parameters of the business process. In the case of a large number of examinees (above 100) other methodology should be used (see Dobrodolac et al., 2010). To calculate correlation, a frequency distribution of appearance in some of the stress categories should be analyzed (well adjusted, stressed, very stressed and extremely stressed). In the case of WSI calculation, we treated the average values of overall scores obtained from BHC stress testOne of the improvement points that were indicated as a result of the model’s implementation was the communication between dispatcher and couriers. This segment of courier service is further analyzed in this paper.The existing communication system that was the part of public network has not met the expectations. Therefore, a new communication system should be introduced. As a possible solution, Private Mobile Radio systems, also known as communication systems for closed user groups, were proposed for implementation. In the process of communication system design it is necessary to take into account the economic parameter, i.e. the overall costs. In that sense, good characteristic of Professional Mobile Radio system is that more departments or services using communication for closed user groups may use a common infrastructure, but to have a separate functioning. Thus, the introduction of such system should involve coordinating the various administrations interested in the use of communication system for closed user groups.Finally, the main contributions of this paper are: the design of a new model for the allocation of limited resources for technological improvement, a manifestation of model’s applicability and a proposal of new communication system for courier service in Serbian Post.The advantage of the proposed model lies in its simplicity of realization and the possibility of wide application. It could be applied to different types of businesses, to both manufacturing and service industries, and also to various positions, from low working levels to highest management level.DOI: http://dx.doi.org/10.5755/j01.ee.23.4.1502

FUNDAMENTALS OF A CLASSICAL CHAOS-BASED CRYPTOSYSTEM WITH SOME QUANTUM CRYPTOGRAPHY FEATURES

We present the fundamentals of a cryptographic method based on a hyperchaotic system and a protocol which inherits some properties of the quantum cryptography that can be straightforwardly applied on the existing communication systems of nonoptical communication channels. It is an appropriate tool to provide security on software applications for VoIP, as in Skype, dedicated to voice communication through Internet. This would enable that an information packet be sent through Internet preventing attacks with strategies similar to that employed if this same packet is transferred in an optical channel under a quantum cryptographic scheme. This method relies on fundamental properties possessed by chaotic signals and coupled chaotic systems. Some of these properties have never been explored in secure communications.

NIOSH-Sponsored Research in Through-the-Earth Communications for Mines: A Status Report

This paper presents the results of recent contractual research sponsored by the National Institute for Occupational Safety and Health that aimed at demonstrating the feasibility of through-the-earth (TTE) wireless communication in mining. TTE systems, developed by five different contractors, are discussed with a focus on technical approach, prototype hardware, and field test results. System features include both magnetic and electric field sensing, loop and line antennas, digital and analog processing, noise filtering and cancelation, and direction finding. The systems were demonstrated at commercial mine sites. The results of these tests are characterized by transmission range and power levels. This paper concludes with a discussion of issues that remain to be resolved as TTE communications are implemented. These include text versus voice format, acceptable time delays, portability, ease of deployment, an interface with existing communications systems, permissibility, and the effect of geological variations.

The European External Action Service:A Pivotal Actor in EU Foreign Policy Communications?

Summary This article analyses the role of the European External Action Service (EEAS) in EU foreign policy communications. Having cumulated a number of pre-existing functions, the EEAS is situated at the centre of the existing communication systems used in the European Union in relation to matters of foreign policy. Moreover, the EEAS is contributing to the expansion of the existing practice of foreign policy communications in three ways. First, it has affected the direction of communication flows in the most well-established (but now declining) communication system — the COREU/CORTESY network — as a growing proportion of messages now originate in Brussels. Second, the EEAS is developing an autonomous EU capacity for information gathering, as EU delegations regularly draft political reports. Third, the EEAS has contributed to the expansion of information sharing in consular affairs, which is an area of mixed and contested competences. The EEAS is thus a key actor in EU foreign policy communications, although practices are forever shifting and its role is still under construction.

Inter-organisational communication for patients being case managed by community matrons.

Background Poor communication between community matrons (CMs), in-hours and out-of-hours (OoH) general practitioners (GPs) causes uncertainty and inefficiencies. Setting A practice-based commissioning group in West London and the associated CMs who case manage high users of hospital services. Question What helps good communication between CMs, GPs and OoH services to ensure that the right patients are case managed and hospital admissions are avoided? Methods Whole system participatory action research, with four stages: 1) identify communication problems as perceived by a wide range of stakeholders; 2) draw a diagram of the existing communication system, and with stakeholders redraw this to overcome its weaknesses; 3) pilot the changes proposed; 4) gain consensus among stakeholders about policy. Results Stakeholders agreed that standards should be adopted to improve communication for the care of patients who are case managed by CMs. Routine passage of information between GP, CMs and the OoH services would achieve this, and is feasible. Specifically: routine information (termed Special Patient Notes) should be sent to the OoH service about vulnerable patients, including those who are case managed by CMsclear information about CM attachment to general practices and how to refer to them should be easily accessibleGPs and CMs should meet quarterly for mutual learning and to discuss patientsthe OoH service electronically should cascade information to GPs, CMs and others named in the Special Patient Notescommissioners should routinely gather data to compare clusters of general practices for i) referrals to CMs, ii) posting Special Patient Notes, iii) unscheduled consultations and hospital admissions of all patients including those being case managed. Discussion This project revealed system-wide communication problems for the care of patients being case managed by CMs, and ways to overcome these. Commissioners could insist that these are adopted locally, and gather data to prompt compliance and evaluate the consequential cost savings.

Basic Study of Orthogonal Signal Division Multiplexing for Underwater Acoustic Communication: A Comparative Study

Underwater acoustic (UWA) communication in shallow water has been challenging owing to multipath-induced signal distortion and motion-induced Doppler distortion. In this study, we investigate the performance of a UWA communication system using orthogonal signal division multiplexing (OSDM) on intersymbol interference (ISI) and Doppler shift in a simulation, by comparing it with an existing communication system that uses coherent modulation with an adaptive filter, to clarify whether OSDM is suitable for UWA communication in shallow water. The obtained results clarify that OSDM is robust to heavy ISI, and it is expected to be suitable for a rapidly time-varying channel. For example, OSDM can improve the output signal-to-noise ratio (SNR) of 9.4 dB in a shallow water channel with a multipath delay time dispersion of 20 symbols, compared with the UWA communication system with decision feedback equalizer (DFE). However, it is also clarified that OSDM is more sensitive to the Doppler effect compared with the existing communication system, and there is the necessity of applying frequency-offset compensation, because the permissible Doppler shift, when the output SNR falls to -3 dB, for OSDM is less than half that for the UWA communication system with DFE.

Industrial powerline communication for machine tools and robotics

Nowadays, machining systems worldwide are on a very high level, regarding mechanics as well as control technology. Therefore, in the case of challenging sub-assemblies like drive and control systems and technological components (e.g. high-frequency spindles and processing heads) the emphasis should be placed on the integration of these components in specialised machine and plant configurations, especially by reducing the interfaces with a new communication system. In the future, technological innovations can be primarily expected from the introduction of highly integrated mechatronic machine modules. The concept of this new powerline communication system is the transmission of data and power for a drive unit over a common power cable. This can be achieved by high-frequency modulation of the data onto the cable. In this paper, the basic conditions for the industrial powerline communication are presented. First an overview is given on the existing communication systems in production technology. As an essential requirement the transfer function of the transmission channel is analysed. Further, the disturbances on the transmission channel are discussed. The final essential requirement is the compliance with the standards regarding elimination of disturbances, conducted as well as radiated. For proof of functionality the Orthogonal Frequency Division Multiplex- (OFDM-) transmission method is applied. This is implemented in two modems which have been set up within a demonstration system.

The internet of ideas

As researchers we have a duty to communicate our ideas. As communications researchers, we are privileged to study the technology and phenomena that are so transforming human society. We seek to understand and enhance the very tools with which we can convey our contributions to human knowledge. In Japan there is a mode of presentation called, Pecha Kucha, where speakers present 20 images for 20 seconds each, as a way to convey new experimental thoughts effectively. I am going to present 12 ideas, each one in that spirit. Rather than a retrospective of my work, or a vision for a possible future Internet Architectures, I want to engage in what I do in my daily work with graduate students, thinking of problems that need solving in existing communications systems, or simply new ways to build communications systems. I do not expect more than one or two of these ideas to make it past first base, but there is value in learning how to apply one's critical faculties even when filtering out bad ideas. Metcalfe's law is that the value of the network is the square of the number of participants since each participant contributes new input for all other participants. In an Internet of ideas, then, this value is only achieved if we contribute our ideas freely. Researchers censor ideas for various reasons, including that a new communications system must have a business case. The Internet itself (the Web, Facebook and Twitter) was created without any business case. Many startups end up in a business that is nothing to do with the one-pager or elevator pitch they presented to the venture capitalists. We have no business filtering out ideas except if they are simply bad. So here are my twelve research elevator pitches.

Substantiation of communication infrastructure selection in newly developed territories

Mobility needs, especially for motorized transport, have significantly increased in recent decades with the public becoming more and more dependent on the means of communication. Transport has become an inseparable part of the way of life of modern human being which helps to satisfy some needs but creates new needs. With undoubted benefit these changes caused the new problems, such as traffic congestion, time loss, or increased noise and pollution. These arguments made it necessary to look for new ways to bring under control the existing communication system processes in the newly planned urban territories and to develop new innovative tasks for the EU urban communication systems to ensure effective and uninterrupted functioning of communication systems and implementation of the main communication objectives. This scientific work analyzes the need for communication systems in the newly developed territories, describes the worldwide software packages used for modeling of junctions, gives an illustrated example on how to select the type of intersection for the territory planned to be built-up in Molėtai city, and describes advantages of the selected type of junction.

Disciplinary differences in the use of internet discussion groups: differential communication needs or trust problems?

This paper tests empirically the claim that the successful application of information and communication technologies (ICTs) depends on the social context of their use. There are striking differences in the prevalence of ICT use between researchers in different academic disciplines. Nevertheless it is unclear whether and how they depend on disciplinary differences of the academic communication system. This paper presents several existing and new hypotheses that specify how disciplinary differences in communication systems influence whether researchers make use of so-called internet discussion groups (IDGs). The hypotheses either argue that specific trust problems inhibit IDG subscription or that IDGs fulfil discipline-specific communication needs, which gives incentives for subscription. They are tested with data of a sample of university researchers in the natural and social sciences and the humanities. The trust hypotheses are not confirmed. The idea that IDGs have a distinct orientation function that diminishes deficiencies in the existing communication systems of some disciplines finds support. Scholars who work in research fields that are difficult to overview, that is fields with a high number of journals, have a special incentive to subscribe to IDGs.

Strategies to reduce interruptions from mobile communication systems in surgical wards

We conducted interviews with two surgeons from the department of gastrointestinal surgery at the University Hospital of North Norway. The results confirmed that interruptions from mobile devices were a problem, especially in surgical theatres, outpatient wards, emergency wards and inpatient rooms. Users in hospitals, especially surgeons and physicians, need a better communication system. Our proposed system would intercept the signals from the existing communication system before they are sent out to the mobile devices. The signals would then be routed through a context-aware system, paired with context information and available rules defined by the doctor, which will decide what to do with the call/page. A single device which integrates both the pager and the phone system, and makes use of context information to control interruptions automatically yet allow the caller to decide whether to interrupt, would be highly appreciated by the users.