High-capacity Connections Research Articles

Synergizing intelligent signal processing with wavelength-division multiplexing for enhanced efficiency and speed in photonic network communications

Abstract The explosive growth of worldwide mobile data traffic seeks innovations in communication technology to cater to the mounting need for rapid connectivity, high-capacity connections. The mainstreaming of 5G technologies for communication is a dramatic step towards meeting the aforementioned goals, with the ability for reshaping IoT (Internet of things), D2D (device-to-Device) communications, and the smart grids. This work conveys an in-depth study of the fundamental innovations that underlie 5G, including full-duplex distribution, huge multiple-input-multiple-output, ultra-dense connections, the phenomenon of beamforming and millimeter-wave approaches. A special emphasis is focused on the integration of photonic technologies, or microwave photonics, which serves as a critical multidisciplinary study topic. Optical fibers, with their tremendous bandwidth and capacity, have been determined as the best medium for backhaul and fronthaul amenities, outpacing conventional copper cables to accommodate tiny cells and next-generation networks. The synergy between optical and wireless access technologies is analyzed with the emphasis on the central role of wavelength-division multiplexing (WDM) for improving network efficiency and speed. The investigation additionally explores the possibility of intelligent signal processing methods combined with WDM to optimize photonic network communications. The mingling of these technologies anticipates producing unrivaled levels of performance, rupturing the path for an additional intelligent, interconnected era.

An Analysis of Cybersecurity Architectures

The 4th Industrial Revolution has increased high-capacity connectivity, new human-machine interactions largely with IoTs and smart devices. This digital revolution offers incredible conveniences such as the ability for users to access volumes of data, governments can address social challenges, connect remote villages in the country, and more. Once secluded systems are now connected and sharing information. This connectedness also poses some inconveniences as well, whenever a device joins the Internet, it becomes publicly discovered. Once these devices are discovered, they become open to cyberattacks. Cybersecurity has become a crucial part of daily life as cyberattacks have increased over time and have become more and more severe. The challenge that cybersecurity consultants find is the difficulty of measuring cybersecurity efforts in organizations. Another challenge could be finding a cybersecurity architecture that is effective and can fit different situations. The main aim of this study was to develop a comprehensive cybersecurity architecture that can be used by cybersecurity consultants when measuring cybersecurity effectiveness. This study conducted an in-depth literature review on current cybersecurity architectures offered by national and international cybersecurity organizations. The identified cybersecurity architectures that have been developed by other organizations were translated, interpreted, compared, and synthesized and a new cybersecurity architecture is proposed. The proposed cybersecurity architecture has the NIST goals as a foundation and the CIA triad at the center. The proposed cybersecurity architecture has domains such as application and Systems security, Information security, Network security, End-point security, Critical Infrastructure security, Mobile security, Storage security, etc. The proposed cybersecurity architecture seeks to assist cybersecurity consultants in answering questions from executives such as: Are we secure? Are security investments delivering value to the business? What is our preparedness for a cyberattack?

Numerical modeling investigation of cross-laminated timber connections consisting of multiple glued-in rods

Glued-in rods are stiff and high-capacity connections that are used in timber structures. Regardless of the many advantages of glued-in rods, research on the glued-in rods in CLT is limited, especially on numerical modeling. This paper provides the numerical modeling principles, validation details, and parametric studies of glued-in rods embedded on the edge of CLT. The numerical modeling was performed on a 3D finite element basis, and the cohesive surface method was used to define the bond lines along the rods. To validate the numerical models, 24 replica experiments were performed and investigated the effect of the rod diameter and of the embedment length on the pull-out strength of rods embedded perpendicular, parallel, and on the boundary of two cross-wised layers. The numerical models were validated according to the maximum load, stiffness, as well as the failure mode of the glued-in rods. The numerical models showed high reliability in simulating the experiments and predicted the strength of the glued-in rods with a maximum of 4% difference. After validation of the numerical models, the parametric study covered the pull-out strength investigation of rods with 20, 24, and 30 mm diameter and anchorage lengths of 250, 350, and 450 mm embedded in the perpendicular, parallel, and on the boundary of cross-wised layers on the edge of 5 and 7 layer CLT panels. The findings showed that increasing the embedment length and rod diameter enhanced the pull-out strength of the glued-in rods, regardless of where the rod was positioned on the CLT's edge. Rods embedded perpendicular to the grain showed the highest pull-out strength, and two rods with 30 mm diameter and 450 mm embedment lengths reached 961 kN pull-out strength. Numerical models showed that for the same diameter and embedment length of two rods embedded on the parallel and on the boundary of two cross-wised layers reached 836 and 738 kN pull-out strength, respectively. Finally, A design equation is provided to determine the pull-out strength of the glued-in rods embedded in CLT based on the shear strength of the bondline.

Cyclic behaviour of CLT shear wall hold-down connections using mixed angle self-tapping screws

This paper experimentally examines structural performance of novel cross laminated timber (CLT) hold-down connections consisting of customised steel brackets and self-tapping screws installed with mixed angles relative to loading. The installation of screws at mixed angles combines the high strength and stiffness of inclined screws with the high ductility of 90° screws creating a strong, stiff, and ductile connection. A total of 30 high capacity connection specimens comprising two timber species and five connection configurations are tested under monotonic and cyclic loading. The ratios between inclined screws and 90° screws are investigated in order to optimise the connection seismic performance. Connections consisting of 12× Ø12 mm inclined screws and 12 to 24× Ø12mm / 10 mm 90° screws were found to demonstrate high ultimate strength (470–593 kN), high initial stiffness (212–269 kN/mm) and high ductility (µ=10–20) under cyclic loading. Current strength calculation methods for the connection design are compared to the experimental results and are shown to provide conservative design predictions.

Design and Simulation of Transceiver Antennas in FSO Technology within the 5G Networks

There is an urgent need for high-capacity connection with high data transfer rate in densely populated areas due to the rapid growth of mobile communication technologies and the explosion of data traffic. Multi beam antennas have generated a lot of research interest and have been extensively explored for base station applications due to their ability to boost communication capacity and sustain a high data transfer rate. Multi-beam antennas based on Butler matrices (MABBMs) are also appropriate for base station applications because to their advantages of high gain, simple design, and low profile. This paper's goal is to give a summary of the current MABBMs. The presentation of MABBMs includes its specifications, operating principles, design methodology, and implementation. In the final section, the difficulty of MABBMs for 3G/LTE/5G/B5G base station applications is discussed. The paper is divided into six sections, in the first section an introduction, in the second section base station application standards are presented, the design strategy and operating principles of MABBMs in the third section, and the latest developments in MABBM research for mobile communication systems are addressed in the fourth section, and challenges are presented in fifth Section, and conclusions are presented in the sixth Section.

An optimal algorithm for energy harvesting in optical networks

Optical fiber cables, which make up the majority of the world's telecommunications infrastructure, now carry the vast majority of digital data. However, because to the Internet's exponential expansion and a slew of bandwidth-hungry new services like online gaming, 3D or high-definition television, and cloud computing, this infrastructure will soon run out of capacity. The growing need for faster transmission speeds by clients has led to the development of heterogeneous optical networks. High throughput, portability, and future information interconnects may all be accommodated by such a system. Delivering such high-capacity connections to a mobile client should need heterogeneous optical networks. Different multiple access user technologies have been suggested to meet the needs of a group of future heterogeneous optical network users. In order to address the high energy consumption, poor QoS and low resource utilization in cloud radio access network, this paper proposed a novel algorithm. The main idea is to allocate virtual resources with energy-awareness and hybrid energy supply. Then, the energy arrival and consumption models were established based on different network devices. Simulation results show that the proposed algorithm effectively improved the energy consumption performance and QoS as compared with existing methods.

UltraStar: A Lightweight Simulator of Ultra-Dense LEO Satellite Constellation Networking for 6G

The mega-constellation network has gained significant attention recently due to its great potential in providing ubiquitous and high-capacity connectivity in sixth-generation (6G) wireless communication systems. However, the high dynamics of network topology and large scale of mega-constellation pose new challenges to the constellation simulation and performance evaluation. In this paper, we introduce UltraStar, a lightweight network simulator, which aims to facilitate the complicated simulation for the emerging mega-constellation of unprecedented scale. Particularly, a systematic and extensible architecture is proposed, where the joint requirement for network simulation, quantitative evaluation, data statistics and visualization is fully considered. For characterizing the network, we make lightweight abstractions of physical entities and models, which contain basic representatives of networking nodes, structures and protocol stacks. Then, to consider the high dynamics of Walker constellations, we give a two-stage topology maintenance method for constellation initialization and orbit prediction. Further, based on the discrete event simulation (DES) theory, a new set of discrete events is specifically designed for basic network processes, so as to maintain network state changes over time. Finally, taking the first-generation Starlink of 11 927 low earth orbit (LEO) satellites as an example, we use UltraStar to fully evaluate its network performance for different deployment stages, such as characteristics of constellation topology, performance of end-to-end service and effects of network-wide traffic interaction. The simulation results not only demonstrate its superior performance, but also verify the effectiveness of UltraStar.

Formation of Hot Spots in Coated Conductors During Static and Dynamic DC Loading

High voltage DC transport at long distances represents an opportunity for wider use of superconductors. In particular, the second generation of high temperature superconductor tapes produced in form of coated conductors (CC) offers a unique solution for protecting a high-capacity connection against fault currents. In the resistive superconducting fault current limiter (R-SFCL), the CC tape would emerge as a substantial resistance in case of overcoming its critical current, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_c</i> . Non-uniformity of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_c</i> along the CC length is a common issue requiring attention. Because of highly nonlinear current/voltage dependence, the spot with critical current <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_cmin</i> < <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_c</i> could transform into the hot spot with rapid rise of local temperature. Due to its small dimension, it would not create an observable voltage at the device terminals, thus may escape attention of a quench detection system. We have investigated the mechanism of hot spot creation at the DC currents between <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_cmin</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_c</i> , and the analytical formulas have been derived predicting the limits of stable operation. Now we extend the analysis to the case of the limitation event, when for a fraction of second the current exceeds also the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_c</i> . It is desirable that the temperature rise happens along all the conductor length, leading to a quick reduction of transported DC. Numerical modelling has been utilized to analyze such an event, and a simplified analytical model has been developed to predict the range of currents causing the formation of hot spots.

Disaggregation and cloudification of metropolitan area networks: enabling technologies and impact on architecture, cost, and power consumption [Invited

The deployment of the new 5G system and ultra-broadband access networks, on one side, and the advent of network disaggregation and cloudification paradigms, on the other, are producing disruptive changes in metropolitan area networks (MANs). The new central offices will be more like small data centers than traditional Telco-type central offices. The presence of general-purpose servers, in partial or total replacement of specialized equipment or cards, and also hosting new functions and services, significantly changes the way the central office is organized and how the equipment internetworks. After having defined a reference architecture named cloudified-MAN, the paper briefly introduces the enabling technologies that include information technology (IT) systems, packet switches, and optical equipment. A disaggregated model is applied to all layers and systems. In the optics field, special insight on high data rate (up to 1.6 Tb/s) transceiver technology developed by the TERIPHIC project is provided as an example of low-cost and low-power technology. Through a quantitative techno-economic case study on a realistic network scenario aimed at short-term and medium-term time horizons, the paper provides indications on what could be the impact of the new architecture on costs and energy consumption. The main outcome of the study is that the IT and optical parts are those with the highest fractions of overall cost, and specifically for the optics, the cost of wavelength division multiplexing transceivers increases significantly in the medium term due to the demand for high-capacity connections ( &gt; 400 G b / s ), while the line system cost (reconfigurable optical add-drop multiplexer) decreases in percentage. Another significant result is that in terms of energy consumption, the IT component has been found to be the dominant one (70%–75% of the total), followed by packet devices (about 20%–25%) and optical systems, the latter with significantly lower percentage values (less than 5%) in all cases analyzed.

Experimental investigations of glued-in rod connections in CLT

The widespread availability of cross-laminated timber (CLT) provides opportunities to extend the use of wood structures beyond low-rise residential construction. Glued-in rods (GiR) are an interesting technical solution for numerous timber structural applications, amongst them, the not yet exploited potential in conjunction with CLT. This paper summarises experimental investigation on the performance of GiR in CLT. Two 5-ply CLT panel thicknesses (139 and 175 mm), two steel rod diameters (dR = 12.7 and 19.1 mm), and five anchorage lengths (la = 6dR, 10dR, 12dR, 14dR and 18dR) were considered in applications parallel and perpendicular to the CLT major strength axis. A total of 220 uni-axial quasi-static monotonic tension tests were conducted. The results, assessed in terms of load-carrying capacity (ranging from 14 kN to 154 kN) and failure modes (plug-shear failure and lamination tear-out), demonstrated the impact of the connection’s geometric design parameters and that steel rods glued into CLT offer an alternative high capacity connection. The results will serve as the benchmark for subsequent numerical modelling, including the determination of joint capacity.

Non-Terrestrial Networks in the 6G Era: Challenges and Opportunities

Many organizations recognize non-terrestrial networks (NTNs) as a key component to provide cost-effective and high-capacity connectivity in future 6th generation (6G) wireless networks. Despite this premise, there are still many questions to be answered for proper network design, including those associated to latency and coverage constraints. In this paper, after reviewing research activities on NTNs, we present the characteristics and enabling technologies of NTNs in the 6G landscape and shed light on the challenges in the field that are still open for future research. As a case study, we evaluate the performance of an NTN scenario in which aerial/space vehicles use millimeter wave (mmWave) frequencies to provide access connectivity to on-the-ground mobile terminals as a function of different networking configurations.

Delivering Gigabit Capacities to Passenger Trains: Tales from an Operator on the Road to 5G

Delivering reliable and high-capacity Internet connectivity to high-speed train users is a challenge. Modern railway cars act as Faraday cages and a typical train consist comprises several hundreds of users moving at high velocity. Furthermore, with the global availability of fourth generation (4G) Long Term Evolution (LTE), user expectations have dramatically increased: it is expected to be online anytime and anywhere. Demand for mobile high-capacity is being driven by video and music streaming services, for lower latency and higher availability by gaming, and for more reliability and even uplink capacity by mission critical applications. Finally, the life-cycle of the railway industry is much longer than for telecommunications, which makes supporting 5G challenging. In this paper, we survey the challenges associated with delivering high-capacity connectivity to train users, describe potential options, and highlight how a leading western European operator is tackling these challenges and preparing for 5G and beyond.

Cost-Optimal Deployment of a C-RAN With Hybrid Fiber/FSO Fronthaul

Centralized radio access network (C-RAN) has been considered as an architectural solution able to reduce capital and operational expenditure in dense 5G cellular networks while allowing better network performance. The C-RAN approach decouples baseband units from antenna sites and places them in selected locations, connected by the so-called fronthaul links. These links require expensive high-capacity connections, thus calling for cost-efficient deployment. This paper presents a hybrid fronthaul solution for C-RAN based on both optical fibers and free-space optics (FSO) to enhance fronthaul flexibility and minimize deployment costs. Two design strategies based on integer linear programming are proposed for both greenfield and brownfield deployments. The first strategy is referred to as joint planning (JP) and is based on the joint minimization of the number of deployed remote radio heads (RRHs) and the cost of the hybrid fiber/FSO fronthaul. The second strategy is based on two-step disjoint planning (DP) that first identifies a cost-optimal RRH placement and then finds the corresponding minimum cost deployment for the fronthaul links. Results obtained with JP and DP are compared in dense urban area scenarios (i.e., with characteristics similar to festivals or concerts), highlighting the advantage of the JP approach compared to DP, both in terms of costs and an enhanced flexibility during the network design process.

Has Europe missed the endgame of telecommunications policy?

The European Electronic Communications Code (EECC) is a major milestone in the EU's telecommunications policy. But is it such a step forward and are the technical and market developments such that the EECC is the endgame? An endgame would mean that sustainable competition is reached in all telecommunications markets. The current paper argues that the EECC's new policy goal of investment in very high capacity connectivity could actually lead to policies that end in sustainable infrastructure competition. The EECC's policies, however, are not courageous enough to reach this goal. This lack of courage also characterizes the EU's gatekeeper policies on call terminations and net neutrality. In both these areas an endgame with sustainable competition is possible.

Performance Investigation and Design of Pile-to-Pile Cap Connections Subject to Uplift

Substructure bridge components are designed to resist gravitational forces such as dead load and vehicular live load, as well as lateral forces including wind, vehicular braking, and centrifugal force effects. Significant lateral forces can create “uplift” conditions on some portions of the foundation. A review of current design techniques regarding uplift in the pile-to-pile cap connection indicates a lack of uniformity in the design process across state agencies stemming from minimal research performed in this area. In addition, approved uplift anchors for use in the field have not been tested. In order to close this gap, twenty-one full-scale steel H-pile specimens were fabricated and tested in Iowa State University’s Structural Engineering Laboratory to test the capacity of the pile-to-pile cap connection under static tensile loading. Specimens were cast both with and without anchorage and with 12” and 24” embedment depths in order to understand the behavior of the connection and to determine a suitable anchorage detail and design approach for uplift cases. Findings revealed that: (i) capacity of bare piles is generally underestimated and could be more frequently considered for uplift design; (ii) concrete cracking leads to a loss of bond in these types of connections; and (iii) positive anchorage or embedment that extends above the lower rebar mat of the footing is necessary to develop a high capacity connection.

Hybrid OFDM RoF-Based WDM-PON/MMW Backhaul Architecture For Heterogeneous Wireless Networks

In this paper, a hybrid backhaul architecture, which is based on wavelength-division multiplexing passive optical networks (WDM-PON) and millimeter-wave (MMW) communications, is proposed to deliver orthogonal frequency-division multiplexing (OFDM) signals in heterogeneous wireless networks. MMW radio-over-fiber (RoF) technique, which combines the advantages of the both optical fiber and wireless communications, is used to simplify the base stations and provide flexibility long reach and high capacity connections. The feasibility of the proposed hybrid backhaul architecture is investigated via the bit-error rate (BER) performance of a downlink under the impacts of fiber nonlinear, wireless fading and noise components including clipping noise, amplifier noise and photodetector noise. The numerical results obtained from this study help to determine the optimum system parameters such as the optical launched power, modulation index, and amplifier gain so as to minimize the link’s BER.

On Measuring the Geographic Diversity of Internet Routes

Route diversity in networks is elemental for establishing reliable, high-capacity connections with appropriate security between endpoints. As for the Internet, route diversity has already been studied at both the autonomous system and router level topologies by means of graph theoretical disjoint paths. In this article we complement these approaches by proposing a method for measuring the diversity of Internet paths in a geographical sense. By leveraging the recent developments in IP geolocation we show how to map the paths discovered by traceroute into geographically equivalent classes. This allows us to identify the geographical footprints of the major transmission paths between end-hosts, and building on our observations, we propose a quantitative measure for geographical diversity of Internet routes between any two hosts.

Business Data Services: Crucial Link and Market Power Choke Point in the Digital Communications Network

Business Data Services (BDS) have been growing at almost 15% per year for a decade and a half, driven by the fact that high capacity, high quality, always on connections are vital to a wide range of businesses and economic activities. Affected services include not only communications – mobile, broadband and video – but all forms of high capacity connection for hospitals, ubiquitous networks like ATMs, and the evolving in the Internet of Things. The point at which the ocean of data coursing through the digital network becomes a stream directed to each individual consumer is the new chokepoint in the communications network. This paper uses a traditional antitrust approach embedded in the structure-conduct-performance paradigm to describe the industrial organization of the digital communications sector. It argues that the inherent economic conditions in communications markets combined with a long period of lax antitrust enforcement and weak regulation to allow the emergence of a “Tight Oligopoly on Steroids” in which BDS plays a central role. High concentration is a problem, but the problem is magnified by several other characteristics that are well recognized in the antitrust literature. The same four firms constitute the tight oligopoly across four communications product markets, meaning that the number of firms needed to engage in parallel and reciprocal conduct is very small. Their history prior to the Telecommunications Act of 1996 and their pattern of expansion since have resulted in geographic separation of home (fortress) territories, technological specialization, and product segmentation. This enables them to dampen rivalry. The paper documents the severe and unique problem in the BDS market through three sets of data -- the evidentiary record compiled in the FCC’s decade long Special Access proceeding, the FCC’s reading of that data in a Final Rule and FNPRM, and a unique data set from New York that sheds light on the BDS market in the largest state served by Verizon that fills gaps in the record. The data shows that the BDS market is not only one of the most concentrated markets in the entire digital communications sector (with CR4 values close to 100% and HHI indices in the range of 6000 to 7000), but also that it is rife with the abuse of market power. Analysis of price, cost and profit shows that market power is being exercised to yield excess prices that produce profits that are not merely “supranormal,” but persistent and astronomical. Analysis of contracting, bundling, and other qualitative conduct indicates that market power is being exercised along both horizontal and vertical dimensions. The paper concludes with a brief critique of the fundamental flaws in the recent FCC Flip-Flop order that sweeps 20 years of abuse under the rug and ensures the abuses will continue because it is based on the same theory of potential competition that has failed for the past two decades. The radical theory of potential competition adopted by the FCC bears a striking resemblance to an earlier discredited theory of hypothetical competition (perfect contestability) that did a great deal of policy harm before rigorous empirical analysis proved it was inapplicable to the real world. In this case, the FCC has the empirical record before it, but failed to read that record in a reasonable manner. The FCC’s declaration that it is time for and new start, is correct, but this analysis shows that by ignoring the empirical record, disregarding well-established analytic models and violating legally mandated administrative procedures the FCC has headed in the wrong direction.

Pre-equalization technique enabling 70 Gbit/s photonic-wireless link at 60 GHz.

In this paper, we demonstrate a 70 Gbit/s photonic-based wireless link at 60 GHz using a single RF carrier and a single polarization. This high capacity is achieved by using 32QAM modulation with a symbol rate of 14 GBd. We show a novel pre-equalization technique that enables usage of such very high bandwidths at 60 GHz. Our work indicates that the consumer oriented 60 GHz band could be a viable alternative to more expensive E-band or sub-THz links for high capacity photonic wireless transmission, mobile backhauling and last-mile high-capacity connections.

The service overlay network design problem for interactive internet applications

Consider a private network of geographically dispersed computers with fast and high capacity connections, and an Internet application session, such as a massive multiplayer online game, with a server and a set of clients. We refer to the former as a service overlay network (SON), and assume that it could be connected to the Internet. The problem is to decide how to configure and utilize the SON in support of this application, such that the clients׳ speed of communication with the server is within given communication performance requirements.We provide an Integer Programming formulation of this problem, and prove that it is NP-Hard. In an attempt to solve the problem within strict computational time requirements of actual applications, we develop a solution framework based on partitioning and enumerating the solution space into smaller subproblems, one or more of which contains an optimal solution. In this framework, we develop and test an optimal seeking exact, and a fast polynomial time heuristic algorithm with success. The exact algorithm sets optimally solvable sizes of the subject problem, whereas the heuristic algorithm sets the size of solvable instances in a real application.