Satellite-based Networks Research Articles

Deadline-constrained multi-commodity flow routing and scheduling optimization with consideration of edge lengths and capacities

With the emergence of satellite communications, meeting deadline requirements for data flow has become more challenging due to the trade-off between route lengths and capacities, as traversal delay becomes more prominent in satellite networks. To address the transmission optimization problems of multi-commodity flow with deadlines in satellite-based networks like networks considering edge lengths and capacities, we propose a new traffic model of flow conservation with the delay of edge lengths and then construct the deadline-constrained multi-commodity flow routing and scheduling optimization based on the proposed traffic model. Besides, for priority scheduling of multi-commodity flow, admission control is studied to schedule the commodities according to the priority level based on the proposed deadline-constrained flow optimization model. To solve the proposed models, we utilize the time-slicing approach and decomposition methods. Flow optimizations and admission control are discretized into linear programming and mixed 0–1 linear programming, respectively, which are suitable for Benders and Dantzig–Wolfe decomposition. We provide numerical examples using the Iridium satellite network to demonstrate the effectiveness of our routing and scheduling methods compared to those without consideration of edge delays.

Uncertainties in Clear-Sky Solar Irradiance Modeling Induced by the Limited Availability of the Atmospheric Parameters

Abstract In the recent years, great progress has been made in developing terrestrial and satellite-based networks for the measurement of atmospheric parameters, which serve as inputs in clear sky parametric models. However, some parameters may still be missing from the model input due to small temporal sampling or lack of in situ data. This paper presents a case study on the accuracy of the clear-sky solar irradiance estimation by a parametric model, when the availability of inputs is limited. The study was conducted with high-quality radiometric and atmospheric data recorded by the INOE-Magurele station, Romania. Seven different scenarios were studied. In each scenario the clear-sky solar irradiance model was run assuming that certain parameters are missing from the input. The results quantitatively confirm the dominant role of aerosols in establishing the accuracy of solar irradiance estimation under clear sky conditions. The unavailability of the measured Ångström turbidity coefficient may lead to a twofold/threefold increase in the uncertainty of direct-normal/diffuse solar irradiance estimation.

Survey on Optimization Methods for LEO-Satellite-Based Networks with Applications in Future Autonomous Transportation.

Future autonomous transportation is one of the most demanding application areas in terms of connectivity, as it has to simultaneously meet stringent criteria that do not typically go hand in hand, such as high throughput, low latency, high coverage/availability, high positioning and sensing accuracies, high security and robustness to interferences, etc. In order to meet the future demands of challenging applications, such as applications relying on autonomous vehicles, terrestrial networks are no longer sufficient and are to be augmented in the future with satellite-based networks. Among the emerging satellite networks, Low Earth Orbit (LEO) networks are able to provide advantages over traditional Medium Earth Orbit (MEO) and Geo-Stationary Earth Orbit (GEO) networks in terms of signal latency, cost, and performance. Nevertheless, several challenges exist in LEO system design, which have not been fully addressed in the existing literature. In particular, the problem of LEO-system optimization of design parameters is a multi-dimensional problem with many aspects to be considered. This paper offers a comprehensive survey of the LEO-system design parameters, of the challenges in LEO system design process, and of the optimization methods for satellite communication, positioning, and sensing applications, as well as a summarizing discussion on the design considerations for LEO-based networks to support future autonomous transportation.

An efficient signcryption scheme for vehicular satellite-based networks

With the widespread of the vehicular ad-hoc network (VANET), a huge number of vehicles are connecting to networks. To provide the position of these vehicles, the global position system (GPS) is required. Usually, the GPS is commoned with internal sensors mounted inside the vehicle. Thus, the communication with this sensor is needed when we need to specify the position of vehicle through the satellite. This communication is done by using a secure channels. However, the authentication and privacy are deemed as the main goal of the network communication. Therefore, an efficient signcryption scheme for vehicular satellite-based network (SVSN) is proposed in this paper. The proposed scheme meets the security demands for VANETs, for instance authentication, unforgeability, confidentiality, and integrity. Based on the Discrete Logarithm (DL) problem, the presented scheme is secure. Compared with the existing signcryption schemes, the performance analysis show that our proposed scheme is more suitable for vehicular satellite networks.

SatNetLab

The space industry is moving rapidly towards offering low-latency and high-bandwidth global Internet coverage using low Earth orbit satellites. Such networks represent "one giant leap" in Internet infrastructure, both in their goals and the underlying technology. Due to their unique characteristics, they open up new opportunities, and pose new research challenges. I thus lay out a case for networking researchers to collaboratively undertake the construction of SatNetLab, a research platform that enables experimentation across upcoming satellite-based networks.

Effects of selected noises on the quantum memory satellite based quantum repeaters

Quantum repeaters are a key part of long-range free-space quantum key distribution. They allow us to circumvent the negative effects of the no-cloning theorem. Quantum repeaters are also a key point in point-to-point communication since otherwise, a direct line of sight would be necessary. In our simulation, we examined the QKD capabilities of quantum repeaters in a satellite-based network, along with selected types of noises.

Resource Allocation in Satellite-Based Internet of Things Using Pattern Search Method

The emergence of Internet of Things (IoT) and high throughput satellite communication networks enables the capability of anytime, anywhere environment monitoring and sensing. A key challenge of satellite-based IoT is to enhance spectrum and energy efficiency so as to meet the ever-increasing demand for satellite bandwidth and dynamic access of a massive number of IoT terminals. In this paper, we propose a novel power control algorithm for IoT terminals being deployed in satellite-based IoT systems where some terrestrial base station is available to acquire IoT devices' information as well as to perform resource management. We adopted the Poisson point process (PPP) theory to formulate the model for this power optimization problem. The PPP theory is applied to evaluate the distance distribution of random IoT devices in this satellite-based networks. Optimal power control scheme can be obtained by taking into consideration user distribution and signal interference plus noise ratio (SINR) demand for various IoT terminals. In addition, due to the complexity of the objective function of power control deduced by the PPP theory, we utilize the pattern search method to identify an optimal solution in global area. Furthermore, we provide numerical results from various perspectives including user rates and energy efficiency to testify the performances of our power proposal.

Analysing and securing the sustainability of e-Government projects from technical aspect using employees perspective approach

Sustainability of eGovernment projects in developing countries is an evolving area, in 1987 India has started its major computerization in government sector by launching the national satellite-based computer network (NICNET). Subsequently in 2006 government has approved National eGovernance plan, with projects classified under Centre, State and Integrated. The aim of plan is citizen centric with anywhere anytime access, increased efficiency and reduced cost. These high aiming and crucial projects face various challenges and hence it’s working team plays a pivotal role in their sustainability. In this research using employee perspective approach an algorithm and a model has been developed for conducting studies of similar nature. Further the determinant named as Backend, Frontend and Best Practices has been identified and analysed in Indian context. We have conducted a survey on a sample size of more than 400 employees working in these projects. The results and findings have revealed that continuous learning and training plays a key role for project sustainability. As per the research conducted it has been identified that the backend factors are of eminent importance at all stages in project except conceptualisation phase.

A Telephone for the World: Iridium, Motorola, and the Making of a Global Age by Martin Collins

Reviewed by: A Telephone for the World: Iridium, Motorola, and the Making of a Global Age by Martin Collins Rebecca Slayton (bio) A Telephone for the World: Iridium, Motorola, and the Making of a Global Age. By Martin Collins. Baltimore: Johns Hopkins University Press, 2018. Pp. 280. Hardcover $44.95. Iridium was an ambitious business and engineering venture that aimed to provide telecommunications services to the entire world. Using both published sources and oral history interviews, Martin Collins's new book situates Iridium in the transition from the Cold War era, in which U.S. military interests played a dominant role in shaping technological research and development, to an era in which neoliberal philosophy and free markets seemed ascendant. Collins argues that Iridium represented corporate, technological, and ideological conceptions of "the global." Launched by the U.S.-based multinational corporation Motorola, Iridium was part of a broader globalization of Western businesses that characterized the late twentieth century. Technologically, Iridium was literally global; initial proposals envisioned seventy-seven satellites (hence "Iridium," the element with atomic number seventy-seven), providing communications to any place on earth. And ideologically, the project drew upon and amplified the notion that global markets were a force for social progress. Iridium grew out of the Systems Engineering Group within Motorola's Government Electronics Division, which aimed to move beyond the division's traditional work as a subcontractor for military, intelligence, and space projects by becoming a prime contractor for commercial as well as government customers. Iridium eschewed new technology and instead focused on the organizational innovations needed to achieve "manufacturability" in a globally-dispersed workforce. This meant focusing on "quality," as epitomized for example in Motorola's Six Sigma method of reducing errors to 3.4 per million opportunities (the fraction of instances more than six standard deviations from the mean of a normal distribution). Whereas previous satellite manufacture had focused on designing single vehicles for worst-case-scenarios, Iridium focused on the timely production of an entire constellation of satellites, which only needed to succeed in aggregate. Iridium also used "culture" as a tool which "aimed to respect the local (whether inhering in an individual, an institution, or a geographic region)" while assuming that "it could be harmonized with the global (as conceived by the venture)" (p. 4). In fact, Iridium hired cultural anthropologists and futurists who predicted that the "Iridium Revolution" would have a beneficial impact on cultures around the world, advancing individual entrepreneurship, women's rights, sexual freedom, and more. In the mid-1990s, major media outlets such as Wired magazine publicized Iridium in similarly glowing terms. [End Page 928] Yet in 1999, Iridium filed for bankruptcy. Despite some rhetoric about uplifting citizens of the developing world, the service was largely marketed to well-heeled business travelers who did not need "global" telecommunications, but rather mobile telecommunications in the major cities that served as hubs of global commerce. By the 1990s, networks based on terrestrial cellular towers could serve these needs with more compact phones, better reliability, and lower costs than a satellite-based network. Additionally, Iridium depended upon partnerships with "gateways" in nations around the world; these were tasked with obtaining regulatory permission to operate Iridium, and then selling the service to companies that would then enroll individual subscribers. But many gateways did not share Western business values or priorities, and faced constraints not anticipated by Iridium; ultimately, they did not generate a sufficient number of customers. The tensions between Iridium's global multinational ambitions and local political and cultural realities played a significant role in the project's demise. Iridium's greatest asset, a globe-spanning satellite constellation, was nonetheless rescued from a fiery fate of de-orbiting and incinerating as the satellites plunged towards the earth. The U.S. military stepped in to encourage a group of investors to buy the satellites, forming Iridium Satellite Corporation. The Defense Information Systems Agency then promptly awarded the new corporation a contract. Iridium was ultimately used for communications in the Iraq and Afghanistan wars. Collins' account of Iridium is well-researched and written. It brings together and builds upon multiple themes in the history of technology, including digital utopianism, "systems" thinking, business history, and...

An Ultra-Low-Power 4.7mA-Rx 22.4mA-Tx Transceiver Circuit in 65-nm CMOS for M2M Satellite Communications

As of today, the machine-to-machine and Internet of Things (IoT) markets have significantly benefited from the deployment of diverse and efficient terrestrial low-power wide area networks (LPWAN) thanks to technologies such as SIGFOX UNB, LoRa, or NB-IoT. To further increase the coverage of such networks to remote areas, a satellite-based network with close interconnection to a terrestrial one is required. In this brief, we show the feasibility of a satellite link based on system and technological concepts similar to those used for LPWAN. We additionally prove the possibility of integrating the terminal transceiver in a single CMOS IC with power consumption and cost of the same order of magnitude as the terrestrial one. To this end, a complete L-band transceiver has been implemented. The transmitter modulates 400 symbols/s QPSK signals at as high as +12 dBm output power for 22.4 mA consumption under 3.3 V. The receiver consumes 4.7 mA while detecting the presence of low Earth orbit satellite pilots and demodulating the 20 ksymbols/s QPSK signal with −112 dBm sensitivity. The baseband processing handles up to 40 kHz Doppler shift and +/ − 440 Hz/s Doppler drift. The IC is processed in 65-nm CMOS technology from Taiwan Semiconductor Manufacturing Company Limited.

A Cost-Effective Ship Safety Data Transfer in Coastal Areas

ABSTRACT Yang, H., 2018. A Cost-Effective Ship Safety Data Transfer in Coastal Area.. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1206–1210. Coconut Creek (Florida), ISSN 0749-0208. Recent advances in information and communications technology (ICT) have improved ship safety management. Ships can be monitored and controlled remotely using ship-to-ship and ship-to-shore communications technologies. These methods entail the sharing of vessel status information to prevent ship-related accidents and increase safety. In coastal areas, most ships transmit and receive data via wireless communications networks based on radio frequency (RF), long-term evolution (LTE), satellite, and other technologies. RF-based and LTE-based networks can be utilized when the communications are within the range of dozens of kilometers. On the other hand, satellite-based networks cove...

Resource-Considerate Data Routing Through Satellite Networks

In many envisaged satellite-based networks, such as constellations or federations, there often exists a desire to reduce data latency, increase delivered data volume, or simply exploit unused resources. A strategy is presented that achieves efficient routing of data, in a store-carry-forward fashion, through satellite networks that exhibit delay- and disruption-tolerant network characteristics. This network-layer protocol, termed Spae, exploits information about the schedule of future contacts between network nodes, because satellite motion is deterministic, along with the capacity of these contacts to route data in such a way as to avoid significant overcommitment of data along a resource-limited journey. Results from simulations of a federated satellite system indicate consistent benefit in terms of network performance over other, less-sophisticated, conventional methods, and comparable performance to a packet-optimal, full-knowledge approach.

From Circuit Theory to Modeling, Large Networks and VLSI Design

This paper presents a historical review of author's early works influenced by the Circuits and Systems Group at UC Berkeley of which Prof. Ernest S. Kuh was a core member. They range from modeling of nonlinear devices and systems, in particular memristors, design optimization of satellite-based private communication networks to CMOS VLSI design and layout.

Magnetic Resonance Imaging Research in Sub-Saharan Africa: Challenges and Satellite-Based Networking Implementation

As part of an NIH-funded study of malaria pathogenesis, a magnetic resonance (MR) imaging research facility was established in Blantyre, Malaŵi to enhance the clinical characterization of pediatric patients with cerebral malaria through application of neurological MR methods. The research program requires daily transmission of MR studies to Michigan State University (MSU) for clinical research interpretation and quantitative post-processing. An intercontinental satellite-based network was implemented for transmission of MR image data in Digital Imaging and Communications in Medicine (DICOM) format, research data collection, project communications, and remote systems administration. Satellite Internet service costs limited the bandwidth to symmetrical 384 kbit/s. DICOM routers deployed at both the Malaŵi MRI facility and MSU manage the end-to-end encrypted compressed data transmission. Network performance between DICOM routers was measured while transmitting both mixed clinical MR studies and synthetic studies. Effective network latency averaged 715 ms. Within a mix of clinical MR studies, the average transmission time for a 256 × 256 image was ~2.25 and ~6.25 s for a 512 × 512 image. Using synthetic studies of 1,000 duplicate images, the interquartile range for 256 × 256 images was [2.30, 2.36] s and [5.94, 6.05] s for 512 × 512 images. Transmission of clinical MRI studies between the DICOM routers averaged 9.35 images per minute, representing an effective channel utilization of ~137% of the 384-kbit/s satellite service as computed using uncompressed image file sizes (including the effects of image compression, protocol overhead, channel latency, etc.). Power unreliability was the primary cause of interrupted operations in the first year, including an outage exceeding 10 days.

On using satellite-based networks for capacity building and education for all: A case study of Rajiv Gandhi project for EduSat-supported elementary education

One of the serious problems associated with Indian school education has been high dropout rate. The reasons are many and varied but the major constraints are: non-availability of adequate number of competent and trained teachers in most of the schools and separate room for each class. To overcome such problems and increase equitable access to all, it was considered prudent to use capabilities of satellite based teaching-learning. This network was also to be used for capacity building of in-service teachers. So an indigenously built, dedicated satellite for education-educational satellite (EduSat)-was launched on September 20, 2004, which supports one national hub and five regional hubs. This paper discusses the case study of Rajiv Gandhi project for EduSat-supported elementary education (RGPEEE) project for imparting value added education and professional development of in-service teachers. The project was implemented by Indira Gandhi National Open University (IGNOU). More than 862 schools in four Hindi speaking states chosen on the basis of physical contiguity were networked through 850 ROTs and 12 SITs. In the first phase (pilot), the project focused mainly on Sidhi district, inhabited mainly (90%) by tribal population and one of the most educationally less-developed districts of Madhya Pradesh. Through ten orientation programmes, 868 teachers and functionaries associated with the project were oriented at different levels to familiarize them in imparting instruction through EduSat and their role and responsibility in facilitating child learning. They were also trained in developing content for tele-teaching; development of knowledge repositories as effective and sustainable sources of courseware. Feedback studies undertaken to judge the effectiveness of EduSat reveal that it is being well received and making steady progress towards improvement in attendance and academic achievement of children and creation of better learning- environment in schools. Key words: Information and communication technologies (ICTs), educational satellite (EduSat), Indian national satellite (INSAT), receive only terminals (ROTs), satellite interactive terminals (SITs), education for all/univeralisation of elementary education-Sarva Shiksha Abhiyan (SSA)

Performance Analysis of TCP-AFC for Satellite-based Networks

Satellite has been identified as a potential candidate to meet the explosive Internet demand and to evolve the global Internet services. With a view to combat channel errors predominant in satellite based networks, TCP with Adaptive Flow Control and Delayed Fast Recovery (TCP-AFC) has been designed to identify a random loss with the help of selective acknowledgments. TCPAFC has demonstrated significant performance enhancement in error prone environments through simulations and experiments on an active emulated network. In order to substantiate the improvement, we investigate the performance of TCP-AFC in a real environment consisting of a Ku band satellite link, which is more susceptible to atmospheric conditions. This paper focuses on evaluation of TCP-AFC in real life situations having appreciable channel noise and delay. Results of the extensive experiments conducted on a test bed consisting of a symmetric GEO satellite link for different channel conditions, data volume, data type and data traffic are presented in this paper. Analysis of the results reconfirms the compatibility of TCP-AFC in a heterogeneous network besides the performance improvement over a dedicated satellite link .

Neurosurgical content for mobile devices

Moore’s law is long-term trend in the history of computing hardware. It basically says that the number of transistors that can be placed inexpensively on an integrated circuit roughly doubles every 2 years.[2] Although the exact time frame varies in several documents, the description originates from 1965 and is still valid today. Modern computers have tremendous processing power, but at the same time they are a fraction of the size compared to their predecessors of 20-30 years ago. Modern computing hardware shows an increasing trend toward mobility, while offering high resolution color displays, multimedia capacities, and integrated network connectivity (phone, internet, GPS, Bluetooth). The latter is particularly important for developing countries, where cable networks are rare. Satellite-based wireless networks for phone and Internet are expected to become the primary choice for connectivity, and mobile devices can serve as a cost-effective hardware solution. To have users benefit from all features on mobile devices, content needs to be optimized for smaller screens and limited keyboard input. This is also important for scientific and clinical applications. Mobile applications are used differently from desktop applications. They should allow users to perform some common tasks in a quick and efficient manner. Of course, the nature of these tasks depends on the nature of the application. For Surgical Neurology International (SNI), we wanted a web application that offers you quick access to the pillars of our website: the articles, the posts and the forum. It is also important that you are able to qucikly and easily access our multimedia and social network updates.

Maximizing delay-constrained throughput in multi-channel DS-CDMA ALOHA networks through power diversity and successive decoding

We study multi-channel ALOHA networks (e.g., satellite-based networks) for online transaction processing, striving to maximize attainable throughput while meeting a deadline with near certainty. This captures the service provider's fixed costs and per-transaction revenue, the user's delay consciousness and ALOHA's probabilistic nature. Specifically, we consider CDMA channels and successive-decoding receivers. Interestingly, judicious use of power diversity is shown to be extremely effective: with a single transmission, capacity is doubled relative to that with power equalization. With the deadline permitting as few as one or two retransmission attempts upon failure, the probability of not meeting it can be virtually diminished (10?5 and 10?8, respectively) while approaching the throughput attainable without delay constraints. This also holds for limited mean transmission power. Thus, the effect of power diversity in conjunction with CDMA depends strongly on the type of receiver and on the exact performance measure, and the proposed approach is worth considering for next-generation systems.

Selected eHealth Applications in Cyprus from the Training Perspective

In this paper a review of selected eHealth applications in Cyprus is presented linked with their success or failure based on their training activities. The eHealth systems presented and their training activities include an update of the health information system (HIS) in the public hospitals, a medical system for emergency telemedicine (AMBULANCE and EMERGENCY-112 projects), a home monitoring system for cancer patients (DITIS), a satellite-based network in healthcare applications (EMISPHER and HEALTHWARE projects), and the training activities of the Cyprus Society of Medical Informatics. Different methodologies for training were used ranging from classical approaches like train the trainers, using demo cases followed by personal training, group training, and workshops, to more recent methodologies based on eLearning sessions including teleconsultations. The training was carried out successfully in all cases. However, not all eHealth systems were put into practice successfully, mainly for reasons not related to training. It is anticipated that this paper will promote the importance of these applications and their training activities as well as help in the spin off of others thus enabling the offering of a better service to the citizen.

Application of Generalized approach to Datum Transformation between Local Classical and Satellite-based Geodetic Networks

The major problem with transforming from a classical to a satellite-based network is the typically low and heterogeneous accuracy of the classical network coordinates, especially in the height component. The accuracies and the statistical correlations between the point coordinates are expressed in the variance-covariance matrix (VCV). There is a great advantage if this prior information is included in the transformation model, together with the VCV matrix of the satellite-based network. An analysis of the northern part of the geodetic network of the State of Israel was conducted, using real data coming from both classical and satellite-based networks. The detailed investigation of the VCV matrix of the northern part of the G1 network, the satellite geodetic geodynamic network, and the M points from the classical network, confirmed the suitability of the so-called "Generalized Approach" to datum transformation.