International Telecommunication Union

This paper brings together evolutionary economics and resource-based approaches to the study of the firm and focuses them upon the issue of technological diversification. Despite the empirical observations that the world is increasingly technologically complex, technological ...

The implementation of the 58th World Health Assembly resolution on e-health will pose a major challenge for the Member States of the World Health Organization (WHO) African Region due to lack of information and communications technology (ICT) and mass Internet connectivity, compounded by a paucity of ICT-related knowledge and skills. The key objectives of this article are to: (i) explore the key determinants of personal computers (PCs), telephone mainline and cellular and Internet penetration/connectivity in the African Region; and (ii) to propose actions needed to create an enabling environment for e-health services growth and utilization in the Region. The effects of school enrolment, per capita income and governance variables on the number of PCs, telephone mainlines, cellular phone subscribers and Internet users were estimated using a double-log regression model and cross-sectional data on various Member States in the African Region. The analysis was based on 45 of the 46 countr...

Unprecedented impacts of climate change on agricultural systems around the world coupled with increasing food demand underlie the urgency of building a more productive, resilient, and low-emission agricultural development model - one that is climate-smart. Establishing climate-smart agriculture (CSA) systems requires investment in concrete on-farm practices and broader programs to establish implementation at scales that will transform systems to address food security and development goals in the face of climate change. The CSA Prioritization Framework (CSA-PF) was designed by scientists at CIAT and CCFAS to guide actors at multiple levels in their effort to identify best-bet CSA investment portfolios through scientific and participatory evaluation of the broad set of applicable practices for a given context. The CSA-PF is a CSA implementation planning and policy support tool aimed at governments, donors, non-governmental organizations, and local actors. The framework explicitly targ...

This paper addresses a fundamental question: Is there a standard way of creating standards? Based on our first-hand experience of creating a technical ICT standard called H.350, we pondered over the process and reflected on what really happened. H.350 is a Directory Services for Multimedia standard ratified by the International Telecommunications Union in September 2003. Resulting from an Internet2 Video Middleware working group the new H.350 standard provides a uniform way to store and locate information related to video and voice over IP (VoIP) in directories that are linked seamlessly to enterprise directories. There were many socio-economic-technical factors that led to the creation of H.350 and we were able to organize the process into a framework, which we present here. We have combined the ''public policy good'' model and the ''stakeholder analysis model'' in standards creation into a comprehensive framework that can help the research community to better understand what goes on in standards creation. We conducted in-depth interviews with the core H.350 team to learn more about the entire process and their experience. The findings from these interviews further validate our framework. We apply the case of H.350 to our framework and help understand the forces that affect development of ICT standards.

The focus in this review paper for new technology about to satellite, it's similar to satellite but its station is stratosphere. Firstly introduces the wireless communications and then switches to fourth generation in wireless communications. Then discusses about High Altitude Airships, the "STRATELLITES" which are actually unmanned Kelvar balloons filled with helium gas which are used instead of towers for wireless communication, each of which replace hundreds of towers and reduce the cost of wireless communications. They also overcome the disadvantage of simple towers which could not provide proper coverage in the hilly areas.

The focus in this review paper for new technology about to satellite, it’s similar to satellite but its station is stratosphere. Firstly introduces the wireless communications and then switches to fourth generation in wireless communications. Then discusses about High Altitude Airships, the “STRATELLITES” which are actually unmanned Kelvar balloons filled with helium gas which are used instead of towers for wireless communication, each of which replace hundreds of towers and reduce the cost of wireless communications. They also overcome the disadvantage of simple towers which could not provide proper coverage in the hilly areas. Keyword – Unmanned Kelvar Balloons, High Altitude Airship INTRODUCTION Wireless communication is a simply data communication without the use of landlines. This may include cellular telephone, two-way radio, fixed wireless (broadband wireless), laser (free space optics) or satellite communication systems. Mobile wireless technologies are going to act as glue ...

The telecommunications landscape is undergoing a period of dramatic change. A near term next generation network (NGN) is emerging characterized by a rich set of services and a dynamic and competitive marketplace where innovation and time to market will be critical success factors. Changing consumer-provider relationships, competitive pressures and new e-commerce technologies will accelerate the use of real time payment and prepayment techniques. This will increase the demand for real-time processing of charging data. Powerful, new, charging support systems will be needed to enable real time charging of these new services. Policy based management appears to offer potential solutions.

For reliable data transmission using single-carrier signaling over multi-path fading channels, multi-layer hybrid automatic repeat request (HARQ) protocols is a promising technique for high data throughput communication systems. In this paper1, we propose a joint equalization scheme for multilayer packet retransmission over a frequency-selective fading channel. We first derive the equivalent MIMO channel model for multi-layer retransmission. Then, we present the corresponding receiver implementing a successive interference cancellation scheme with integrated joint equalization for each layer. We evaluate, by computer simulations, the frame error rate performance and the throughput performance of a retransmission based multi-layer HARQ protocol using the proposed combining scheme. Simulation results show a significant performance gain in comparison with post-combining methods based on separate detection and packet combining at the bit level.

This article examines the topic of Ukrainian Istanbul in the interwar period of 1929-1935. The author focuses on the life stories and multifaceted heritage of the Ukrainian emigration -people who shaped not only their own present and life, but also the future of their stateless nation: they nurtured the historical cultural and political continuity of Ukrainian-Turkish relations; tried to gain autocephaly for the Orthodox Ukrainian Church and fought for Ukrainian statehood. The researcher calls into question the exclusivity and comprehensiveness of the definitions traditional for Russian historiography, such as 'Russian Beloemigration' and 'Russian Exodus', which, without exception and taking into account historical realities, label all emigrants who arrived on evacuation ships during the so-called Wrangel and Denikin evacuations. For example, the future founder of the Committee for the Rescue of Ukraine in Istanbul, O. Adiyassevych, the future deputy of V. Murskyi, M. Zabello, and many other ethnic Ukrainians were among the emigrants of the Wrangel wave of emigration to the Bosphorus. In 1929, the head of the Central Committee of the Ukrainian People's Republic in exile, V. Murskyi, arrived in Istanbul with his family. Despite a number of obstacles, he tried to carry out intelligence, representative, public, and anti-Soviet educational work in Turkey and the Middle East with great success. The article makes a crude attempt to prove that the so-called 'Russian white emigration' was also represented by other nations, in particular ethnic Ukrainians, whom foreign scholars, guided by pro-Russian narratives, baselessly reduce to the general term 'beyazrus' -'white Russians'.

The Automatic Identification System (AIS) is a ship born VHF transponder to automatically provide exchange of identification (MMSI), position, speed, course and other information between ships and with coastal stations. Initially designed for collision avoidance, it allows ship-to-ship monitoring and coastal tracking by port authorities or coast guards. But the reception by costal sensors is limited to approximately 50 nm so that traffic on the open ocean disappears into vast blind spots. AIS signals can propagate much further in the vertical direction; thus it is still possible to implement space-based ship monitoring systems based on constellations of LEO’s (Low Earth Orbit) satellites, with the key potential advantage of a worldwide coverage. Space-based AIS reception systems are going to become a reality in the next few years. Several pilot space systems have already been launched; being incomplete constellations, they still are limited in term of revisit frequency but they give...

The Automatic Identification System (AIS) is a ship born VHF transponder to automatically provide exchange of identification (MMSI), position, speed, course and other information between ships and with coastal stations. Initially designed for collision avoidance, it allows ship-to-ship monitoring and coastal tracking by port authorities or coast guards. But the reception by costal sensors is limited to approximately 50 nm so that traffic on the open ocean disappears into vast blind spots. AIS signals can propagate much further in the vertical direction; thus it is still possible to implement space-based ship monitoring systems based on constellations of LEO’s (Low Earth Orbit) satellites, with the key potential advantage of a worldwide coverage. Space-based AIS reception systems are going to become a reality in the next few years. Several pilot space systems have already been launched; being incomplete constellations, they still are limited in term of revisit frequency but they give...

age caused by minute debris particles. 2 In addition, different shuttle missions have been forced to alter their courses, sometimes quite dramatically, to avoid collisions with larger space debris objects.' This Comment addresses several important aspects of the problem of space debris. First, it provides an overview of the space debris problem, including the origins of debris and the specific risks associated with space debris. Second, the Comment examines current international law provisions governing space debris, followed by a survey of individual countries' policies regarding debris. Finally, it explores some of the proposed solutions and provides a recommendation. A. AMouNr OF DEBRIS At first glance, space debris would appear to pose little or no danger to missions in orbit. After all, outer space is a large area, and the objects mankind has launched are small in comparison. As is often the case, however, appearances can be deceiving. Space debris poses a very serious threat to human activities in outer space. 4 Although mankind only ventured into outer space thirty years ago, we have launched approximately 18,000 objects into space since that time. 5 While not all of these objects have remained in orbit, there are currently approximately 7100 objects in orbit capable of being tracked from Earth. 6 Trackable objects, however, are not the greatest hazard because they often can be avoided by utilizing the maneuvering capabilities of satellites. Untrackable objects represent the most serious threat to space activities. Estimates of the current 2

Implementation of the ITU-R P.1546-4 and ITM propagation models for SEAMCAT prepared and developed in the National Institute of Telecommunications Poland is presented. Results of our research encompasses methodology, implementation and verification of plug-ins into the SEAMCAT software are shown. Keywords—electromagnetic compatibility, interferences, propagation, SEAMCAT, spectrum engineering.

Analyses have shown that there is an increasing interest on Ka-Band usage for satellite missions. In addition to the usage of Ka-Band for a geostationary relay satellite there are already plans to install a Ka-Band terminal on the European module (Columbus) of ISS. An own Ka-Band antenna at Weilheim Ground Station of DLR (German Aerospace Center) assures a direct access to satellites using Ka-band and offers an opportunity to co-operate with international partners in a worldwide Ka-Band antenna network. One of the responsibilities of DLR is to provide continuous and reliable high data rate links to/from spacecrafts and the ISS. Since the high data rate communication link is one of the initial requirements of future space missions, the Ka-band was decided to be used in near future for communications to a potential geostationary relay satellite. In addition to the geostationary mission it is envisaged to analyse the Kaband usage for potential moon missions. This paper covers a study of Ka-band attenuation due to rain and atmospheric gases and implements the ITU model in Matlab code for Weilheim Ground Station.

Analyses have shown that there is an increasing interest on Ka-Band usage for satellite missions. In addition to the usage of Ka-Band for a geostationary relay satellite there are already plans to install a Ka-Band terminal on the European module (Columbus) of ISS. An own Ka-Band antenna at Weilheim Ground Station of DLR (German Aerospace Center) assures a direct access to satellites using Ka-band and offers an opportunity to co-operate with international partners in a worldwide Ka-Band antenna network. One of the responsibilities of DLR is to provide continuous and reliable high data rate links to/from spacecrafts and the ISS. Since the high data rate communication link is one of the initial requirements of future space missions, the Ka-band was decided to be used in near future for communications to a potential geostationary relay satellite. In addition to the geostationary mission it is envisaged to analyse the Ka- band usage for potential moon missions. This paper covers a study...

Standards for modern digital CDMA communication systems specify limits on the error vector magnitude (EVM) of the transmitted signal at the transmitter, whereas performance at the receiver is characterized by the bit error rate (BER). Traditionally, RF receiver specification defines limits on amplitude-and phase ripple over a certain bandwidth, IP3, IQ-mismatch, DC-offset, etc. Unfortunately, these parameters lack an obvious relation to BER. In this paper, we show that the EVM offers remarkable advantages when used as a conceptual figure of merit to characterize the distortions caused by the elements of the receiver's RF frontend. The use of the EVM as a parameter for the optimization of the RF receiver and for the description of the RF-BB (radio frequencybaseband) interface leads to a simple design process and avoids over-specification. For CDMA systems, we give an explicit relation between the EVM and the BER. Furthermore, the benefits of using the EVM in RF receiver design are illustrated by examples and verified by simulations.

Activity modeling is known as a powerful technique for designing and specifying the flow logic of a process. Due to the complexity of the described process, activity models may involve multiple activities that are tangled with each other. Such activities are known as crosscutting concerns that are difficult to modularize using existing activity modeling constructs. This paper presents an aspect-oriented approach to supporting separation of crosscutting concerns in activity models. An extension to activity modeling is introduced for encapsulating crosscutting activities in well-modularized aspects, which are in turn composed with base activities by a specialized aspect weaver in a systematic way.

The National Telecommunications and Information Administration (NTIA) General Model for estimating video quality and its associated calibration techniques were independently evaluated by the Video Quality Experts Group (VQEG) in their Phase II Full Reference Television (FR-TV) test. The NTIA General Model was the only video quality estimator that was in the top performing group for both the 525-line and 625-line video tests. As a result, the American National Standards Institute (ANSI) adopted the NTIA General Model and its associated calibration techniques as a North American Standard in 2003. The International Telecommunication Union (ITU) has also included the NTIA General Model as a normative method in two Draft Recommendations. This paper presents a description of the NTIA General Model and its associated calibration techniques. The independent test results from the VQEG FR-TV Phase II tests are summarized, as well as results from eleven other subjective data sets that were used to develop the method.

This paper presents a new reduced reference (RR) video quality monitoring system that utilizes less than 10 kbits/s of reference information from the source video stream. This new video quality monitoring system utilizes feature extraction techniques similar to those found in the NTIA General Video Quality Model (VQM) that was recently standardized by the American National Standards Institute (ANSI) and the International Telecommunication Union (ITU). Objective to subjective correlation results are presented for 18 subjectively rated data sets that include more than 2500 video clips from a wide range of video scenes and systems. The method is being implemented in a new end-to-end video quality monitoring tool that utilizes the Internet to communicate the low bandwidth features between the source and destination ends.

AISSat-1 was launched on July 12, 2010 and is believed to be the first high performance nano-satellite to provide an observational service to governmental authorities. The primary mission objective is to perform maritime observation in the Norwegian High North and High South, thereby making a con siderable contribution to the maritime situational awareness (MSA) of these areas.

AISSat-1 was launched on July 12, 2010 and is believed to be the first high performance nano-satellite to provide an observational service to governmental authorities. The primary mission objective is to perform maritime observation in the Norwegian High North and High South, thereby making a con siderable contribution to the maritime situational awareness (MSA) of these areas.

The Automatic Identification System (AIS) is a ship born VHF transponder to automatically provide exchange of identification (MMSI), position, speed, course and other information between ships and with coastal stations. Initially designed for collision avoidance, it allows ship-to-ship monitoring and coastal tracking by port authorities or coast guards. But the reception by costal sensors is limited to approximately 50 nm so that traffic on the open ocean disappears into vast blind spots. AIS signals can propagate much further in the vertical direction; thus it is still possible to implement space-based ship monitoring systems based on constellations of LEO’s (Low Earth Orbit) satellites, with the key potential advantage of a worldwide coverage. Space-based AIS reception systems are going to become a reality in the next few years. Several pilot space systems have already been launched; being incomplete constellations, they still are limited in term of revisit frequency but they give...

The modern trend in communication process is shifting from traditional audio to audiovisual pattern including video telephony and multimedia communications. The consumption trend in television applications has also deviated from traditional linear television to flexible applications including Video-on-Demand (VoD), Internet Protocol Television (IPTV) and interactive television applications. However, these applications require reasonable bandwidth for immersive received quality. It becomes challenging under constrained wireless network resources to satisfy users demand efficiently. Thus, the aim of this research work which presents a ‘Hybrid Approach for Efficient Distribution of Television applications over wireless channel’. The discussed approach harnesses the dynamic nature of video content in the design process. The experimental results show enhancement in the distribution process in terms of improved received quality.

Rain, snow, gaseous, cloud, fog, scintillation and other atmospheric properties can have a distorting effect on signal fidelity of Ku and Ka bands, thus resulting in excessive digital transmission error. This loss of signal is commonly referred to as signal attenuation. Signal attenuation impacts the QoS in wireless and satellite networks. Accurately predicting channel attenuation due to atmospheric conditions can enable mitigation planning by adaptively selecting appropriate modulation, coding, transmitted power level, transmission rate and configured frame size. The aim of this paper is to estimate different attenuations using predicted signal-weather correlated database in collaboration with ITU-R propagation models combined with interpolation methods, gateway, and ground terminal characteristics. A three dimensional relationship is proposed among these attenuations with respect to propagation angle and rainfall rate [l]-[8]. The outcome is key factor in diagnosing, adjusting and...

Free Space Optics (FSO) has become a viable, high-bandwidth wireless alternative to fiber optic cabling. The primary advantages of FSO over fiber are its rapid deployment time and significant cost savings. The disadvantage of FSO over fiber is that laser power attenuation through the atmosphere is variable and difficult to predict, since it is weather dependent. This factor limits the distance at which FSO should be deployed. Using historical weather data collected at airports, the link availability as a function of distance can be predicted for any FSO system. These availability curves provide a good indication of the reasonable link distances for FSO systems in a particular geographical area. FSO link distances can vary greatly from desert areas like Las Vegas to heavy-fog cities like St. Johns NF. Another factor in determining FSO distance limitations is the link availability expectation of the application. For enterprise applications, link availability requirements are generally greater than 99%. This allows for longer FSO link ranges, based on the availability curves. The enterprise market is where the majority of FSO systems have been deployed. The carriers and ISPs are another potential large user of FSO systems, especially for "last-mile" metro access applications. If FSO systems are to be used in telecommunication applications, they will need to meet much higher availability requirements. Carrier-class availability is generally considered to be 99.999% ("5 nines"). An analysis of link budgets and visibility-limiting weather conditions indicates that to meet carrier-class availability, FSO links should normally be less than 140 m (there are cities like Phoenix and Las Vegas where this 99.999% distance limitation increases significantly). This calculation is based on a 53 dB link budget. This concept is extended to the "best possible" FSO system, which would have a 10 W transmitter and a photocounting detector with a sensitivity of 1 nW. This FSO system would have a 100 dB link margin, which would only increase the 99.999% link distance to 286 m. A more practical solution to extending the high availability range would be to back-up the FSO link with a lower data rate radio frequency (RF) link. This hybrid FSO/RF system would extend the 99.999% link range to longer distances and open up a much larger metro/access market to the carriers. It is important to realize that as the link range increases, there will be a slight decrease in overall bandwidth. To show the geographical dependence of FSO performance, the first map of FSO availabilities contoured over North America is presented. This map is the first step to developing an attenuation map for predicting FSO performance, which could be used in a similar fashion to the International Telecommunication Union (ITU)/Crane maps for predicting microwave performance.

Agent-oriented models are frequently used in disciplines such as requirements engineering and organizational process modelling. i* is currently one of the most widespread notations used for this purpose. Due to its strategic nature, instead of a single definition, there exist several versions and variants, often not totally defined and even contradictory. In this paper we present a comparative study of the three most widespread i* variants: Eric Yu's seminal proposal, the Goal-oriented Requirement Language (GRL) and the language used in the TROPOS method. Next, we propose a generic conceptual model to be used as reference framework of these three variants and we show its use for generating specific models for the three mentioned variants, as well as for other existing proposals.

In this poster we show how to use Specification and Description Language (SDL) to represent cellular automata models. To achieve that we use a generalization of the common cellular automata, named m:n-CA k. Also we add some extension to SDL language to simplify the representation of these automata. Thanks to SDL and m:n-CA k the behavior of the cellular automata model can be defined in a graphical way allowing the complete and unambiguous description of the simulation model that uses it. SDL is a modern object oriented language that allows the definition of distributed systems. It has focused on the modeling of reactive, state/event driven systems, and has been standardized by the International Telecommunications Union (ITU) in the Z.100.

Subjective assessment methods have been used reliably for many years to evaluate video quality. They continue to provide the most reliable assessments compared to objective methods. Some issues that arise with subjective assessment include the cost of conducting the evaluations and the fact that these methods cannot easily be used to monitor video quality in real time. Furthermore, traditional, analog objective methods, while still necessary, are not sufficient to measure the quality of digitally compressed video systems. Thus, there is a need to develop new objective methods utilizing the characteristics of the human visual system. While several new objective methods have been developed, there is to date no internationally standardized method. The Video Quality Experts Group (VQEG) was formed in October 1997 to address video quality issues. The group is composed of e xperts from various backgrounds and affiliations, including participants from several internationally recognized organizations working in the field of video quality assessment. The majority of participants are active in the International Telecommunications Union (ITU) and VQEG combines the expertise and resources found in several ITU Study Groups to work towards a common goal. The first task undertaken by VQEG was to provide a validation of objective video quality measurement methods leading to Recommendations in both the Telecommunications (ITU-T) and Radiocommunication (ITU-R) sectors of the ITU. To this end, VQEG designed and executed a test program to compare subjective video quality evaluations to the predictions of a number of proposed objective measurement methods for video quality in the bit rate range of 768 kb/s to 50 Mb/s. The results of this test show that there is no objective measurement system that is currently able to replace subjective testing. Depending on the metric used for evaluation, the performance of eight or nine models was found to be statistically equivalent, leading to the conclusion that no single model outperforms the others in all cases. The greatest achievement of this first validation effort is the unique data set assembled to help future development of objective models.

In this paper we analyze the response of a non-ideal optical beamforming system which employs true-time delays based on fiber Bragg gratings. Effects regarding deviation of the Bragg wavelengths, instabilities of the laser source wavelength and misalignment of the fiber path lengths, were studied. We show how these deviation parameters affect the irradiation pattern of linear phased-array antennas.

Since the i* (i-star) framework was adopted by the requirements engineering community, different groups have formulated variations of the language proposed therein with the purpose of adapting the framework to the specific needs of its users. Whilst this flexibility is helpful from many perspectives, it poses some challenges, remarkably the difficulty of sharing a common model knowledge base, and tool incompatibility. In earlier works, we have formulated the iStarML interchange format as a mediator between these different variations. In this paper, we present a particular experience we have carried out, namely the interconnection of two existing tools, jUCMNav and HiME. We have provided the adequate mappings to transform models that correspond to the two metamodels adopted by these tools, we have identified the conflicting cases in the transformation, and we have implemented the mapping as import/export facilities in the tools. This case has not just an intrinsic value as proof of concept (i.e., the ability of these two tools to interchange models) but also sets the basis for a general solution to the i* tool interoperability problem.

Rainfall and temperature studies were conducted on selected Nigerian stations using data from the HelioClim website archive. This study investigates the relationship between temperature fluctuations and rainfall variations across selected Nigerian stations from 1980 to 2022 using statistical tools and Machine Learning Algorithms (MLA). The used data were analyzed using the Kolmogorov-Smirnov test, Spearman's rank correlation, and five regression models: linear, logarithmic, inverse, quadratic, and cubic regression models. The models were fitted and their performances were evaluated using R 2 , MSE, and RMSE as performance metrics. Moreover, the data were analyzed with E-view 7.0 and the Statistical Package for Social Sciences (SPSS version 20.0). 20% of the data was tested, while the remaining 80% was trained using 24 MLA. The statistical analysis revealed that the maximum rainfall and temperature for the stations ranged from 200 to 240 mm and 25.8 to 26.8℃. In comparison, the minimum rainfall and temperature ranged from 110 to 140 mm and 24.2 to 24.6℃. The Kolmogorov-Smirnov shows that rainfall was not normally distributed in all locations (p < 0.05) while temperature followed normal distribution in Ibadan (p = 0.182, p > 0.05), Akure (p = 0.200, p > 0.05) and Abeokuta (p = 0.107, p > 0.05). More so, a negative relationship was more pronounced in Ikeja (r =-0.408, p = 0.000, p < 0.01) and Abeokuta (r =-0.408, p = 0.000, p < 0.01), compared with what was obtained in other locations. The MLA of regression type revealed that temperature has its highest R 2 (1.00) in 15 models while rainfall has its highest in 5 models. As a result, it is demonstrated that temperature affects rainfall. The findings suggest that temperature fluctuations significantly influence rainfall patterns. The research recommended that necessary agencies be required to establish more data collection centres for improved climate monitoring and forecasting.

The advancement of e-business applications and IT infrastructure has had massive impact on construction business processes over the last decade. The added effects of globalisation coupled with global economic recession have forced businesses to implement e-business applications within their organisations. It is clear in all industries, that e-business technologies have become a key strategic vehicle in improving performance. In Construction, e-business applications complement most of the business functions and have removed geographical boundaries resulting in a global construction market with increased competition, increased collaboration and have helped reducing the fragmentation of the industry. However, even though the successes are inevitable, it is scrutinized that the advancement is still constrained within the industry. Thus there is a need to undertake an analysis of current construction e-business usage and attitude of construction professionals towards ebusiness trends to ensure a productive and beneficial implementation of construction e-business tools within organisations. This study acknowledged the niche for research into current e-business usage in UK construction organisations and aimed to determine and map the use of ICT in construction cost management activities, and explore the attitudes of professionals towards e-business approaches. Initially a comprehensive literature review was carried out together with an online web search to identify what ICT and software packages are being used for construction cost management activities. Results from this review aided in developing the research questionnaire and a detailed an online structured survey was carried out using the chartered quantity surveying organisations within the UK. This paper presents the findings of the survey and discusses the ICT usage within construction organisations for cost management activities and the attitude of construction professionals towards BIM and construction e-business trends.

In this paper, we present the first version of a simulator that allows executing models defined using Discrete Event System Specification and models defined using Specification and Description Language. Specification and Description Language (SDL) is a graphical language, standardized under the ITU Z.100 recommendation, widely used to represent telecommunication systems, process control and real-time applications in general. Discrete Event System Specification (DEVS) is a formalism widely used on the simulation field to represent Discrete Event Systems. The execution of the DEVS models is based on a transformation of the simulation model DEVS representation to an equivalent SDL representation. To do this, we propose a XML representation for the DEVS models, and a XML representation for SDL models. Also, we implement an algorithm capable to perform this transformation.

This work addresses the problem of performing a formal modelling of the processes related to the surgical pavilions and an anaesthesia unit on a Chilean hospital. To perform this modelling we used Specification and Description Language (SDL). The model was very successful in order to document and to understand the tacit knowledge of the unit and facilitates the simulation.

This study examines patterns in international telephone communications, documenting a close relationship between international call volume aggregated by nation and indicators of global connectivity including volume of international trade, tourism and migration. In addition, the analysis documents the existence of a set of national "communities" of callers. The clear orientation of large portions of the world to former colonial powers (e.g., West Africa and North Africa to France), and the separation of the Muslim Middle East and the Chinese-speaking nations of East and Southeast Asia from other calling communities suggest the importance of continuing historic and cultural influences on information flows.

The Automatic Identification System (AIS) is a ship born VHF transponder to automatically provide exchange of identification (MMSI), position, speed, course and other information between ships and with coastal stations. Initially designed for collision avoidance, it allows ship-to-ship monitoring and coastal tracking by port authorities or coast guards. But the reception by costal sensors is limited to approximately 50 nm so that traffic on the open ocean disappears into vast blind spots. AIS signals can propagate much further in the vertical direction; thus it is still possible to implement space-based ship monitoring systems based on constellations of LEO’s (Low Earth Orbit) satellites, with the key potential advantage of a worldwide coverage. Space-based AIS reception systems are going to become a reality in the next few years. Several pilot space systems have already been launched; being incomplete constellations, they still are limited in term of revisit frequency but they give...

Rain and snow can have a distorting effect on Ku and Ka bands signal fidelity resulting in excessive digital transmission errors. This loss of signal attenuation is commonly referred to as rain fade. Rain fade impacts the Quality of Service (QoS) in wireless and satellite networks. Accurately predicting rain fade can enable mitigation planning by adaptively selecting appropriate power level, coding and modulation. This paper computes rainfall rate and Rain Attenuation (RA) at any location on earth using ITU-R models combined with bi-linear interpolation and frequency extrapolation. In addition since RA is considered a dominant impairment for wireless signal [1]-[6], we are introducing a novel method for accurately determining RA as function of frequency based on proceeding results from a predicted weather database. Finally, a three dimensional relationship is proposed among RAs with both frequency and rainfall rate, which is a function of probability. These results are key factors in adjusting and improving satellite signal power, modulation and coding schemes, and frame size, monitored and controlled altogether by a powerful and efficient intelligent system in order to improve QoS.

Weather attenuations can have a distorting effect on signal fidelity above 10 GHz that lead to excessive digital transmission error. This loss of signal is commonly referred to as signal attenuation. Signal attenuation impacts QoS in wireless and satellite networks. An intelligent decision support system is therefore necessary for service providers by accurately calculating rain, gaseous, cloud, fog, and scintillation attenuations using predicted signal-weather correlated database in collaboration with ITU-R propagation models combined with gateway, and ground terminal characteristics. The effect becomes a key feature in adjusting and improving satellite signal power, modulation and coding schemes, monitored and controlled altogether by a powerful and efficient intelligent-based attenuation countermeasure system. A three dimensional relationship is proposed among these attenuations with respect to propagation angle and rainfall rate [1]-[9]. The result pilots an enhanced back propagation-learning algorithm that is used to iteratively tune the intelligent controller based on fuzzy logic technique with returned SNR values for activating the weighted Modulation/ Codepoint to its optimal values, depending on actual or predicted weather conditions, configuration settings and tolerance/safety margins for SLA commitment.

This article is a survey on communication aspects of High Altitude Platforms (HAPs), namely airships or aircraft positioned in the stratosphere between 17 and 22 km. HAPs can be considered as a novel solution for providing telecommunications services. This survey begins with an introduction to HAPs, that is, some historical information and advantages of HAPs compared to terrestrial and satellite networks, followed by information about suitable airships and aircraft, frequency bands allocated to HAPs, possible architectures, and some points on the system structure. We continue with the studies that have been carried out on channel modeling and interference, antennas, transmission and coding techniques. We also refer to access and resource allocation techniques that have been performed so far. Finally, the survey concludes with the types of applications that HAPs are suitable for, in addition to some related projects.

ITU-R recommends a global rain-attenuation prediction model for satellite link, but it lacks a physical meaning because it is an empirical model and the effective path-length model is frequency dependent. In this paper, a global effective path-length model, which can be used for total attenuation prediction in satellite link, is proposed. The proposed model is a physical model based on rain-cell concept. The test for the proposed model was performed against the data in the ITU-R SG3 DB, using the procedures in the recommendation ITU-R P. 311 and the Fascicle. The test results show that the prediction error of the proposed model is less than the existing ITU-R model. In addition, the proposed model is a physical model and simple compared to the current ITU-R model.

Funding information European Union and Belgian, French, Italian, Portuguese and Swiss funding agencies. Details are provided in the Acknowledgements section. Guaranteeing interoperability between devices and applications is the core role of standards organizations. Since its first JPEG standard in 1992, the Joint Photographic Experts Group (JPEG) has published several image coding standards that have been successful in a plethora of imaging markets. Recently, these markets have become subject to potentially disruptive innovations owing to the rise of new imaging modalities such as light fields, point clouds, and holography. These so-called plenoptic modalities hold the promise of facilitating a more efficient and complete representation of 3D scenes when compared to classic 2D modalities. However, due to the heterogeneity of plenoptic products that will hit the market, serious interoperability concerns have arisen. In this paper, we particularly focus on the holographic modality and outline how the JPEG committee has addressed these tremendous challenges. We discuss the main use cases and provide a preliminary list of requirements. In addition, based on the discussion of real-valued and complex data representations, we elaborate on potential coding technologies that range from approaches utilizing classical 2D coding technologies to holographic content-aware coding solutions. Finally, we address the problem of visual quality assessment of holographic data covering both visual quality metrics and subjective assessment methodologies.

In this paper, we present a new Joint Source-Channel Coding (JSCC) architecture to extend the coverage of H.264/AVC High Definition (HD) video delivery over Digital Subscriber Line (DSL). The proposed solution combines low complexity H.264/AVC transrating as well as multi-carrier transmission and takes into account realistic ADSL2 specifications including all OSI layers. Both transrating and bit and power loading transmission parameters are automatically optimized in terms of end-user perceived quality, with respect to the characteristics of the given subscriber’s loop. Several originalities have been included: a new optimization algorithm has been developed, as well as a full rate-distortion modelling of the H.264/AVC transrater’s performances. Simulation results show that the proposed solution can extend the coverage area of HD video delivery up to more than one kilometre. It should allow the widespread distribution of HD video contents and increase the number of eligible subscrib...

Weather attenuations can have a distorting effect on signal fidelity above 10 GHz that lead to excessive digital transmission error. This loss of signal is commonly referred to as signal attenuation. Signal attenuation impacts QoS in wireless and satellite networks. An intelligent decision support system is therefore necessary for service providers by accurately calculating rain, gaseous, cloud, fog, and scintillation attenuations using predicted signal-weather correlated database in collaboration with ITU-R propagation models combined with gateway, and ground terminal characteristics. The effect becomes a key feature in adjusting and improving satellite signal power, modulation and coding schemes, monitored and controlled altogether by a powerful and efficient intelligent-based attenuation countermeasure system. A three dimensional relationship is proposed among these attenuations with respect to propagation angle and rainfall rate [1]-[9]. The result pilots an enhanced back propagation-learning algorithm that is used to iteratively tune the intelligent controller based on fuzzy logic technique with returned SNR values for activating the weighted Modulation/ Codepoint to its optimal values, depending on actual or predicted weather conditions, configuration settings and tolerance/safety margins for SLA commitment.

Protocol testing is a very important field nowadays, because it provides a way to detect different kinds of errors in a communicating environment. Communicating Sequential Processes (CSP) could be efficiently applied for creating a process-based model for the test system. In this article we attempt to provide a CSP module for the most frequently used formal language in testing, the TTCN-3, which could make the testing process easier and cheaper. Another important question is the manufacturing time cost of the product. This article presents a test practise where time can be saved during this period.