Broadband Communication

Wireless communications technologies play an essential role to support the Public Protection and Disaster Relief (PPDR) operational needs. The current Private/Professional Mobile Radio (PMR) technologies used for PPDR communications offer a rich set of voice-centric services but have very limited data transmission capabilities, which are unable to handle the increasing PPDR community demand for a wider range of data-centric services. Though some efforts have been devoted to upgrade PMR technologies with better data transfer capabilities, the progression towards an enhanced mobile broadband PMR standardized solution still lags behind the achievements made in the commercial wireless industry, which recently culminated in Long-Term Evolution (LTE) technology. Because of this contrasting progress, the adoption of commercial mainstream LTE technology to satisfy the PPDR community's data communication needs is gaining momentum and offers significant opportunities to create and exploit the synergies between the commercial and PPDR domains, which have remained almost entirely separate to date. In this context, this paper first discusses the suitability of LTE and related technologies for mobile broadband PPDR service provisioning. Next, it presents the argument that the most plausible future scenarios to deliver the increasingly dataintensive applications demanded by the PPDR agencies are expected to rely on the use of both dedicated and commercial LTE-based mobile networks. From this basis, the paper proposes a system architecture solution for PPDR service provisioning that enables PPDR service access through dedicated and commercial networks in a secure and interoperable manner and ensures proper allocation of the networks' capacity to PPDR applications through the dynamic management of prioritization policies. In addition, the spectrum-related issues that are central to the proposed PPDR service provisioning solution are addressed, and a solution based on the joint exploitation of dedicated and shared spectra is proposed.

This research paper utilizes a systematic literature review methodology, drawing from the Scopus database and VOSViewer analysis, to investigate the current landscape of 6G telecommunications research and its potential implications. Our findings indicate that 6G technology is poised to revolutionize wireless communication, with significant ramifications for key sectors such as autonomous vehicles, transportation, and manufacturing, ushering in an era of unprecedented connectivity and operational efficiency. A notable trend is the growing interest among researchers in critical technical aspects, including bandwidth, latency, signal processing, spectrum management, spectral efficiency, Intelligent Reflecting Surfaces (IRS), meta-communication, and beamforming. Geographically, China and the United States lead in 6G research, reflecting a global competition to harness its transformative potential. Most researchers driving innovation in this field have engineering and computer science backgrounds. We anticipate the widespread deployment of 6G technology by 2030, with ongoing research efforts focusing on diverse implementation techniques across industries. Expected advancements encompass Machine-to-Machine (M2M) communication, Massive Multiple Input Multiple Output (mMIMO) systems, IRS utilization, novel waveform technologies, meta-communication, Orthogonal Time Frequency Space (OTFS) modulation, Generalized Frequency Division Multiplexing (GFDM), and the integration of Low-Density Parity-Check (LDPC) codes, all poised to enhance network speed and reduce latency significantly. Furthermore, the Metaverse is expected to experience exponential growth, driven by the capabilities of the 6G network. This paper contributes original insights to the burgeoning field of 6G telecommunications, offering a comprehensive overview of its current status and potential implications across various domains, particularly in management.

This paper describes the advantages that the introduction of photonic integration technologies can bring to the development of photonic-enabled wireless communications systems operating in the millimeter wave frequency range. We present two approaches for the development of dual wavelength sources for heterodyne-based millimeter wave generation realized using active/passive photonic integration technology. One approach integrates monolithically two distributed feedback semiconductor lasers along with semiconductor optical amplifiers, wavelength combiners, electro-optic modulators and broad bandwidth photodiodes. The other uses a generic photonic integration platform, developing narrow linewidth dual wavelength lasers based on arrayed waveguide gratings. Moreover, data transmission over a wireless link at a carrier wave frequency above 100 GHz is presented, in which the two lasers are free-running, and the modulation is directly applied to the single photonic chip without the requirement of any additional component.

This paper addresses the routing problem in packet switching free-space optical (FSO) mesh networks. FSO mesh networks are emerging as broadband communication networks because of their high bandwidth (up to Gbps), low cost, and easy installation. Physical layer topology design of degree-constrained FSO mesh networks has been studied in a recent communication [1]. In this paper, we propose four different routing algorithms, and evaluate their performances through simulations for a number of FSO mesh networks with different topologies and nodal degrees. The performance parameter against which we evaluate these algorithms is the mean end-to-end delay. Our proposed least cost path (LCP) routing algorithm, which is based on minimizing the end-to-end delay, is considered as the bench mark. The performance of each of other three proposed algorithms is evaluated against the bench mark. Our proposed minimum hop count with load-balancing (MHLB) routing algorithm is based on the number of hops between the source and the destination node to route the traffic. Simulations show that the MHLB routing algorithm performs best in most cases compared with the other two. It results in minimum average delay and least blocked traffic.

One of the hot topics in the communication world is to realize a network able to offer a combination of services complying with different requirements in every place of the world, thus achieving the concept of "entertainment everywhere". In such a context a key role is played by aeronautical world that seems to be one of the last remaining islands in which broadband communications are not available. The present paper aims at studying resource management for a CDMA-based return link via satellite to provide passengers with new generation services. We focus on the connection admission control problem for QoS guarantees, analyzing in particular, the effective bandwidth concept over CDMA discussing its applicability to a multi-service packet switched network. Two admission control algorithms are then derived, based on the effective bandwidth concept for the circuit switched-like services and on a moving average window and linear predictor model for packet switched services. Finally, the performance over aeronautical broadband communication system is evaluated.

Multiple-input multiple-output (MIMO) communication technology has proved itself as a widely used technology nowadays. MIMO can be generally referred to as a communication channel which has multiple numbers of transmitters and receivers of antenna which directly affects the communication's performance. These days MIMO communication technologies are used in various technologies such as long-term evolution (LTE) and Wi-Fi. In this article, we discuss the different terminologies related to the MIMO communication systems such as its narrowband model characteristics, MIMO channel capacity and decomposition of the channel, various types of its diversity gain based methodologies & also its space-time modulation and coding techniques. This paper provides a brief summary of various multiple-input multiple-output technologies emphasizing its various characteristics.

Rad opisuje razvoj i karakteristike radiorelejnog uređaja RP8-24. Uređaj je razvijen krajem 60-ih godina 20. stoljeća u Radioindustriji Zagreb (RIZ) uz suradnju sa Zavodom za visokofrekventnu tehniku zagrebačkog Elektrotehničkog fakulteta (ETF). Uređaj RP8-24 bio je suvremen telekomunikacijski uređaj za prijenos 24 PCM kanala radijskim putem i po svojoj je izvedbi bio usporediv ili čak bolji od sličnih uređaja u Europi i svijetu u to vrijeme. S obzirom da je proizvodnja uređaja odavno ugašena političkom odlukom, a postojeći uređaji su otpisani i uništeni te da projektna i proizvodna dokumentacija postoji tek u fragmentima u privatnim zbirkama i pismohranama, ovaj rad je pokušaj očuvanja sjećanja na dostignuće hrvatskih inženjera koje je moglo biti uspješno i na svjetskoj razini.

Two new bit-swap commands are introduced by this contribution: An Express-Swap command for reliable and very fast implementation of swapping and a Bit-Swap Confirmation command for low-complexity implementation of absolutely reliable swapping. ________________________________________________________________________ NOTICE This contribution has been prepared to assist Standards Committee T1-Telecommunications. This document is offered to the Committee as a basis for discussion and is not a binding on any of the companies listed as authors. The requirements are subject to change after further study. The authors specifically reserve the right to add to, amend, or withdraw the statements contained herein.

This paper presents a performance analysis of several representative dual-radio relay network (DRRN) topologies. In our architecture, both access and backhaul links are constructed using IEEE802.11n radio interfaces operating in 2.4GHz band. We first investigate the effects of multihop and star relay configurations on aggregated client throughput performance. Then we study how Received Signal Strength Indicator (RSSI) or received signal power may impact on DRRN's network coverage and capacity performance. The insights gained from this study will provide a good reference for on how to design and deploy DRRN.

The paper describes a unified methodology which takes into account the advantages and disadvantages of different Power Line Communication (PLC) technologies suitable for Smart Metering deployment. The methodology should provide a detailed evaluation of PLC technologies based on a clear definition of the different parameters and their measurement. Based on this methodology, we should be able to provide a comparison of the selected technologies and the methodology should also provide data for the design of a telecommunication infrastructure for Smart Metering/Smart Grids. In this paper and based on this methodology, we also present the performance tests carried out in laboratory environment on low voltage and in on-field conditions on medium voltage.

A CODEC, fabricated in 3.3-V CMOS, provides the low-voltage transmitter and receiver interfaces between the modem digital signal-processing engine and the high-voltage hybrid circuitry for either the central office or the remote terminal ends of the subscriber loop, configurable by metal mask option. Extensive use of digital interpolation filters in the transmitter, decimation filters in the receiver, and oversampled data converters minimize the complexity of analog filters. On-chip filtering and 14-bit data converters support echo-canceling modems without requiring external filters. With additional external filters, frequency-division duplexing is also supported. The die area is 67.5 mm 2. The power dissipation in the central office and remote terminal are 600 and 760 mW, respectively.

We are currently in the midst of a revolution in communications that promises to provide ubiquitous access to multimedia communication services. In order to succeed, this revolution demands seamless, easy-to-use, high quality interfaces to support broadband communication between people and machines. In this paper we argue that spoken language interfaces (SLIs) are essential to making this vision a reality. We discuss potential applications of SLIs, the technologies underlying them, the principles we have developed for designing them, and key areas for future research in both spoken language processing and human computer interfaces.

We are currently in the midst of a revolution in communications that promises to provide ubiquitous access to multimedia communication services. In order to succeed, this revolution demands seamless, easy-to-use, high quality interfaces to support broadband communication between people and machines. In this paper we argue that spoken language interfaces (SLIs) are essential to making this vision a reality. We discuss potential applications of SLIs, the technologies underlying them, the principles we have developed for designing them, and key areas for future research in both spoken language processing and human computer interfaces.

This paper presents a MATLAB ® toolbox for the time-domain simulation and high-level sizing of pipeline analog-to-digital converters. SIMULINK ® C-coded S-functions are used to describe the behavioral models of all building blocks, including their main circuit errors. This approach significantly speeds up system-level simulations while keeping high accuracy − verified with HSPICE − and interoperability of different subcircuit models. Moreover, their combined use with an efficient optimizer makes the proposed toolbox a valuable CAD tool for the high-level design of broadband communication analog front-ends. As a case study, an embedded 0.13µm CMOS 12bit@80MS/s A/D interface for a PLC chipset is designed to show the capabilities of the presented tool. †1

The framework of Long term evolutionadvanced (LTE-A) presents a carrier aggregation (CA) approach to increase the client throughput of component carriers (CC) using the aggregation method. Earlier researchers didn't consider error probability and factors related to delay concerning carrier aggregation in radio resource allocation with the works of the downlink. Subsequently, past techniques can't give the best quality with regards to service contrasted with LTE-A norm. In this research, we consider the radio asset the board issue with line delay by magnifying into it's the head, likelihood in parcel misfortune, the postpone edge in various kinds of information. Concerning this, few limitations will be forced after particulars of the LTE-A framework. Henceforth, a modified technique has been proposed, in this method to boost the throughput of the overall system and reduce the computation complexity. Broad reenactments are done from more notable strategies to confirm the general exhibition of the proposed strategy. The outcome got shows that the proposed strategy beats the past techniques in the estimation of normal client throughput, normal cell throughput, decency file, and phantom productivity.

In the framework of ESA's ARTES-5 program the Institute of Applied Systems Technology (Joanneum Research) in cooperation with the Department of Communications and Wave Propagation has developed a novel meshed satellite communications system which is optimised for Internet tra c and applications (L*IP-Local Network Interconnection via Satellite Systems Using the IP Protocol Suite). Both symmetrical and asymmetrical connections are supported. Bandwidth on demand and guaranteed quality of service are key features of the system. A novel multi-frequency TDMA access scheme utilises e cient methods of IP encapsulation. In contrast to other solutions it avoids legacy transport network techniques. While the DVB-RCS standard is based on ATM or MPEG transport cells, the solution of the L*IP system uses variable-length cells which reduces the overhead signiÿcantly. A exible and programmable platform based on Linux machines was chosen to allow the easy implementation and adaptation to di erent standards. This o ers the possibility to apply the system not only to satellite communications, but provides seamless integration with terrestrial ÿxed broadcast wireless access systems. The platform is also an ideal test-bed for a variety of interactive broadband communications systems. The paper describes the system architecture and the key features of the system.

Stručni članak Sažetak: Veliki rast i razvoj računalnih mreža te razmjena velike količine podataka naglašava potrebu za korištenjem kvalitetnih mrežnih protokola. Temeljni zadatak modernih mrežnih protokola je osiguravanje sigurne i pouzdane komunikacije između računala i procesa, sprečavanje neželjenog pristupa informacijama te pronalaženje optimalnog (najkraćeg) puta kroz mrežu. Osnovni cilj izrade ovog rada je usporedba i prikaz mogućnosti korištenja Distance Vector i Link State protokola usmjeravanja. U radu je ukratko prikazan razvoj protokola usmjeravanja te je napravljena njihova podjela i analiza mogućnosti primjene. Detaljno su opisani Belmann-Fordov, DUAL (Diffusing Update ALgorithm) i Dijkstrin algoritam pronalaženja najkraćeg puta u mreži, koji su osnova za kreiranje kvalitetnih tablica usmjeravanja. Prikazan je postupak povezivanja nekoliko lokalnih mreža i konfiguriranje usmjernika različitim protokolima usmjeravanja. Usporedbom brzine konvergencije tablica usmjeravanja u realnom okruženju provjerene su mogućnosti primjene Distance Vector i Link State protokola u manjim i srednje velikim mrežama.

key distribution (QKD) has shown the potential for the production of cryptographic key for ultra-secure communications. The performance of any QKD system is ultimately limited by the signal to noise ratio on the single-photon channel, and over most useful communications links the resulting in key rates are impractical for performing continuous one-time-pad encryption of today's broadband communications. We have adapted clock and data recovery techniques from modern telecommunications practice to increase the repetition rate of a free-space QKD system by roughly 2 orders of magnitude over previous demonstrations. We have also designed the system to operate in the H-α Fraunhofer window at 656.28 nm, where the solar background is reduced by roughly 7 dB. To achieve high repetition rates this system takes advantage of silicon single-photon avalanche photodiodes with < 50 ps timing resolution and high detection efficiency in the visible region. This free-space QKD system is designed to operate at a repetition rate of 2.5 GHz. We have identified scalable solutions for delivering sustained one-time-pad encryption at 10 Mbps, thus making it possible to integrate quantum cryptography with first-generation Ethernet protocols.

Worldwide Interoperability for Microwave Access or better known as WiMAX is a technology based on IEEE 802.16 standard with guaranteed QoS which provides high speed data rates. In this paper, we analyze the performance of VoIP over the commercial WiMAX networks through traffic measurements. The measurements focused on two QoS elements, jitter and latency that greatly affect the quality of the network. These parameters were measured using JPerf software and the values were compared with the Standard Quality Management scale by ITU-T P.862. A comparison between VoIP in WiMAX and broadband 3G are also included.

With the deployment of high speed train (HST) systems increasing worldwide and their popularity with travelers growing, providing broadband wireless communications (BWC) in HSTs is becoming crucial. In this paper, a tutorial is presented on recent research into BWC provision for HSTs. The basic HST BWC network architecture is described. Two potential cellular architectures, microcells and distributed antenna systems (DASs) based cells, are introduced. In particular, the DAS is discussed in conjunction with radio over fiber (RoF) technology for BWC for HSTs. The technical challenges in providing DAS-based BWC for HSTs, such as handoff and RoF are discussed and outlined. Index Terms-Microcells, distributed antenna systems, handoff, high speed train, mobile communications, radio over fiber.

This paper presents a fast and reliable method for precise orientation (attitude) determination for a moving vehicle. The method uses the carrier phase measurements of GPS receivers. To solve the so called integer ambiguity problem the additional accelerometer and magnetometer is used. These sensors should be calibrated, the calibration method is also presented. The attitude determination method is tested in real circumstances, during a real flight with a sailplane. Based on the results further corrections are initiated which results more precise measurements.

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.

This paper investigates the design of power and spectrally efficient coded modulations based on Amplitude Phase Shift Keying (APSK) modulation with application to satellite broadband communications. APSK represents an attractive modulation format for digital transmission over nonlinear satellite channels due to its power and spectral efficiency combined with its inherent robustness against nonlinear distortion. For these reasons APSK has been very recently introduced in the new standard for satellite Digital Video Broadcasting named DVB-S2 [1]. Assuming an ideal rectangular transmission pulse, for which no nonlinear inter-symbol interference is present and perfect pre-compensation of the nonlinearity, we optimize the APSK constellation. In addition to the minimum distance criterion, we introduce a new optimization based on channel capacity; this new method generates an optimum constellation for each spectral efficiency. To achieve power efficiency jointly with low bit error rate (BER) floor we adopt a powerful binary serially concatenated turbo-code coupled with optimal APSK modulations through bit-interleaved coded modulation. We derive tight approximations on the maximumlikelihood decoding error probability, and results are compared with computer simulations. In Ref. [2], the current analysis is complemented with the effects related to satellite nonlinear distortion effects with a band-limited transmission pulse and including demodulator timing,

Among the different classes of mobile users, public transportation and especially fast trains represent an extremely interesting market, also taking into account that the spatial limitations and the aesthetic constraints are less strict than for the private car market. On the other hand, the railroad environment features some peculiar fading events that have to he carefully taken into account in the system design phase. In this context, the FIFTH (Fast Internet for Fast Train Hosts) project, co-funded by the European Commission, has the main goal to provide satellite based communication services to the passengers traveling onboard high speed trains, namely digital TV and internet access 111.

Some mathematical models for supporting the development of semi/ fully automated air traffic control systems are discussed. Particularly, the flow control problem is approached as a constrained optimization problem on a multicommodity network. The proposed mathematical model, by means of a suitable time discretization, is initially changed into a "static" one. Then a multicommodity algorithm, based on the resource directive decomposition method, is used for the actual computation of the optimal flow in the network. The method is evaluated from the point of view of its practical implementation and its capability to take into account the peculiar aspects of the problem. An application, relative to the Rome air traffic control region, is discussed.

The communication between network nodes within different protocol domains is often regarded simply as a black box with unknown configuration conditions in the path. We address network heterogeneity using a white box approach and focus on its interconnection processes. To achieve this purpose, a Performance Analysis Framework (PAF) is proposed which is composed of the formalization of the latter using process algebra (PA) and the corresponding teletraffic performance models. In this contribution, we target the IEEE 802.16 and IEEE 802.11 protocols. For the teletraffic models, we extend previous models for such scenario with the inclusion of the following protocol operational parameters (metrics): bit error rate (BER), packet error ratio (PER), and packet length (pl). From the framework teletraffic models, the optimal packet length (OPL), end to end throughput, delay, and packet loss are obtained. The PAF outperforms previous modeling solutions in terms of delay and throughput relative to NS3 simulation results.

Worldwide Interoperability for Microwave Access or better known as WiMAX is a technology based on IEEE 802.16 standard with guaranteed QoS which provides high speed data rates. In this paper, we analyze the performance of VoIP over the commercial WiMAX networks through traffic measurements. The measurements focused on two QoS elements, jitter and latency that greatly affect the quality of the network. These parameters were measured using JPerf software and the values were compared with the Standard Quality Management scale by ITU-T P.862. A comparison between VoIP in WiMAX and broadband 3G are also included.

IEEE 802.16 is considered today as the most promising technology, to provide extension of wireless broadband communications into metropolitan environments. One of the main design challenges in 802.16 is the introduction of an efficient traffic scheduler that handles resource allocation in the wireless interface. This paper proposes such a scheduler, referred to as the "Frame Registry Tree Scheduler", that aims at providing differentiated treatment to data connections, based on their QoS characteristics. The scheduler uses a tree structure in order to prepare time frame creation and reduce processing needs at the beginning of each time frame. Simulation results show that the proposed scheduler can attain considerable improvement in terms of throughput and packet losses.

This paper presents an efficient method for updating echo canceller (EC) coefficients in ADSL transceivers during transmission that removes the dependency of updates on the far end signal. The new method improves on the frequency domain EC architecture by Ho, Cioffi, and Bingham in that it converges faster, improves the stability to perturbation, and is not prone to bias from pilot tones. The new EC updating system architecture is presented for both the central office and remote terminal systems and is fully compliant with the ITU-T G.DMT standard.

Optical wireless or Free Space Optics (FSO) has received considerable attention as an alternative to existing Radio Frequency (RF) communication system. This is due to the growing demand for wireless broadband communications and congestion on bandwidth of RF spectrum. In optical wireless application, the performance of the receiver is significantly determines the overall performance of optical wireless link. Receiver is required to have large aperture. Accordingly, the detector is required to have a large detection area which produces high photodetector capacitance and limits the receiver bandwidth. In this paper, the front-end optical receiver designs especially for wireless application have been focused where a fundamental requirement is the achievement of wide dynamic range and broad bandwidth. Through a review on reported works, the bootstrapping technique is found effectively reduces the photodetector capacitance associated with the large area photodetector. Consequently, the overall bandwidth of the system can be improved.

Satellites are well suited for broadband communications. In this paper we consider the special features of satellite systems, some of the broadband applications that are well-suited for satellites and some of the technologies which make possible broadband satellite communications, as well as the research programs that led to their development. We describe how such technologies, and other factors, have contributed to the evolution of broadband satellite systems, and discuss some of the challenges in establishing such systems. We finish by offering some concluding remarks on the role of satellites for broadband access.

A modification to the Asymmetrically-Clipped Optical Orthogonal Frequency-Division Multiplexing (ACO-OFDM) technique is proposed through unipolar encoding. A performance analysis of the Bit Error Rate (BER) is developed and Monte Carlo simulations are carried out to verify the analysis. Results are compared to that of the corresponding ACO-OFDM system under the same bit energy and transmission rate; an improvement of 1 dB is obtained at a BER of 10-4. In addition, the performance of the proposed system in the presence of atmospheric turbulence is investigated using single-input multiple-output (SIMO) configuration and its performance under that environment is compared to that of ACO-OFDM. Energy improvements of 4 dB and 2.2 dB are obtained at a BER of 10-4 for SIMO systems of 1 and 2 photodetectors at the receiver for the case of strong turbulence, respectively.

Commonly used technique to realize broadband microstrip antenna is by cutting the slots at an appropriate position inside the patch. The slot introduces a mode near the fundamental mode of the patch and yields broadband response. The bandwidth of an E-shaped microstrip antenna is further increased by cutting the pair of rectangular slots on one of its edge. This increase in bandwidth is due to another mode introduced by additional pair of slots. In this paper, modal variations, for this modified E-shaped antenna are studied. It has been observed that the slot affects the resonance frequency of higher order mode, which along with modes of E-shaped patch, realize higher bandwidth. Also the broadband proximity fed variation of modified E-shaped antenna in 950 MHz frequency range is proposed. This antenna gives a larger BW of 47% with broadside radiation pattern with a peak gain of approximately 10 dBi.

key distribution (QKD) has shown the potential for the production of cryptographic key for ultra-secure communications. The performance of any QKD system is ultimately limited by the signal to noise ratio on the single-photon channel, and over most useful communications links the resulting in key rates are impractical for performing continuous one-time-pad encryption of today's broadband communications. We have adapted clock and data recovery techniques from modern telecommunications practice to increase the repetition rate of a free-space QKD system by roughly 2 orders of magnitude over previous demonstrations. We have also designed the system to operate in the H-α Fraunhofer window at 656.28 nm, where the solar background is reduced by roughly 7 dB. To achieve high repetition rates this system takes advantage of silicon single-photon avalanche photodiodes with < 50 ps timing resolution and high detection efficiency in the visible region. This free-space QKD system is designed to operate at a repetition rate of 2.5 GHz. We have identified scalable solutions for delivering sustained one-time-pad encryption at 10 Mbps, thus making it possible to integrate quantum cryptography with first-generation Ethernet protocols.

In visible light communication (VLC) systems based on light emitting diodes (LEDs), the nonlinearity of LEDs often leads to a high bit error rate (BER), which limits the system's performance. While artificial neural networks (ANNs) have been used as predistorters to mitigate LED nonlinearity, their effectiveness is hampered by overfitting. This paper proposes an adaptive predistorter based on amplitude time-delay twin support vector regression (ATD-TSVR) to address the nonlinearity of LEDs in orthogonal frequency division multiplexing (OFDM)-based VLC systems. The authors demonstrate through experiments that LED nonlinearity is the primary source of signal distortion in nonlinear VLC systems. Simulation results show that the proposed ATD-TSVR predistorter achieves superior BER, Inputs/Outputs curves, power spectral density (PSD), and constellation plots in an 80Mbit/s OFDM nonlinear VLC system. Meanwhile, as compared to the traditional SVR approach, the CPU training time of ATD-TSVR can be reduced by more than four times. The adaptive pre-distortion method herein is generally applicable to broadband VLC systems and also proves the application prospect and effectiveness of TSVR in VLC system.

Bandwidth enhancement of a rectangular microstrip antenna using a T-shaped microstrip feed is explored in this paper. A 2:1 VSWR impedance bandwidth of 23% is achieved by employing this technique. The far-field patterns are stable across the pass band. The proposed antenna can be used conveniently in broadband communications.

This work describes the development of a monitoring system for vessels from the Marine Technology Unit (UTM) of the Spanish Research Council (CSIC) and draws on the graph capabilities and the potential access to remote data that is offered by Google Earth and the new satellite data transmission capabilities installed on-board. Performance analysis is carried out at several critical points of the system, in terms of data processing and networking, showing that, with minor variations in implementation, this system can be adopted to monitor a greater number of mobile units while at the same time remain sufficiently flexible to be used as a didactic teaching tool for schools and universities. This development is a product of a more ambitious acquisition project that deals with the modeling and acquisition of oceanographic data led by a working group at the UTM and the Universitat Politècnica de Catalunya.

The paper presents the realization of the system for consumption monitoring and the system for power quality control in the hall 4 of the company GRUNER Serbian d.o.o. in Vlasotince, Serbia. The motivation for the establishment of the mentioned systems are machine failures within the warranty period for which the machine suppliers refuse to recognize the warranty, due to poor voltage conditions and frequent power sags within the industrial plant. Power quality problems are caused by external influences coming from the power supply network. For these reasons, a system of power network analysers was designed and implemented by the company Conseko d.o.o., Belgrade. This system monitors and records all relevant parameters of power quality (voltages, currents, active and reactive power, power factor, harmonic content, THD, etc.) in key parts of the hall 4 (molding, air conditioning, tool room, dining room, laboratory, etc.). In addition to this, the monitoring system provides complete insight into consumption and distribution of consumption at a given time interval, which represents an exceptional convenience for optimal distribution of internal consumption and financial calculation of power consumption of each subsystem, which directly affects to the economic profit. The Cloud subsystem is also installed in the system, so that all relevant parameters can be monitored in real time via a remote computer or through an application on a mobile phone.

TV white spaces refer to the allocated but locally unused TV spectrum and can be used by unlicensed devices as secondary users. Thanks to their lower frequencies (e.g., 54-698 MHz in the US), communication over the TV spectrum has excellent propagation characteristics over long distances and through obstacles. These characteristics along with their wide availability make the TV white spaces a great choice and alternative to many existing wireless technologies, especially the ones that need long range and high bandwidth communication. In the last decade, there have been numerous efforts from academia, industries, and standards bodies for exploiting the potentials of the TV white spaces for several applications including wireless broadband Internet access. Their characteristics and features also hold potentials for many new applications including sensing and monitoring, Internet of Things, wireless control, smart utility, location-based services, and transportation and logistics. In this paper, we perform a retrospective review and comparative study of existing work on networking in the TV white spaces. Additionally, we discuss the associated research challenges such as dealing with the interference between primary and secondary TV spectrum users, TV white space temporal and spatial variations and fragmentation, antenna design, mobility, and security. We also describe the future research directions to handle the above challenges. To the best of our knowledge, this is the first comprehensive survey on the literature of TV white space networking research.

Rad opisuje razvoj i karakteristike radiorelejnog uređaja RP8-24. Uređaj je razvijen krajem 60-ih godina 20. stoljeća u Radioindustriji Zagreb (RIZ) uz suradnju sa Zavodom za visokofrekventnu tehniku zagrebačkog Elektrotehničkog fakulteta (ETF). Uređaj RP8-24 bio je suvremen telekomunikacijski uređaj za prijenos 24 PCM kanala radijskim putem i po svojoj je izvedbi bio usporediv ili čak bolji od sličnih uređaja u Europi i svijetu u to vrijeme. S obzirom da je proizvodnja uređaja odavno ugašena političkom odlukom, a postojeći uređaji su otpisani i uništeni te da projektna i proizvodna dokumentacija postoji tek u fragmentima u privatnim zbirkama i pismohranama, ovaj rad je pokušaj očuvanja sjećanja na dostignuće hrvatskih inženjera koje je moglo biti uspješno i na svjetskoj razini.