Search

We use a dynamic, global computable general equilibrium (CGE) model to capture the economic impacts of internet adoption, modeled through reduced demand in the newsprint and printing and writing paper (pulp and paper) industries. Global newsprint consumption is estimated to fall dramatically by 2030. We rely on estimates from another study that captures the change in global pulp and paper consumption using the global forest products model (GFPM), based on two scenarios: ( i) full per capita internet adoption by 2100 and ( ii) more rapid full internet adoption by 2050. We incorporate reductions in pulpwood consumption into a global multiregional dynamic CGE model to estimate economy-wide impacts in Canadian provinces, the United States, and the rest of the world. Results indicated that the year 2050 internet adoption scenario would result in a reduction in cumulative discounted gross domestic product (GDP) by as much as 17% in some regions of Canada, reduce GDP by 5.8% in the United States, and increase GDP by 3.3% in the rest of the world from 2006 to 2030. These findings highlight the costs of internet adoption, leaving net benefit analysis of adoption to future work. [ABSTRACT FROM AUTHOR]

Multiple-input-multiple-output (MIMO) systems are of interest for meeting the expected demand for higher data rates and lower delays in future wireless packet data systems. In such systems, it is optimal to simultaneously transmit to multiple users compared with a single user in a single-input-single-output system. In addition, multicarrier systems are of interest to combat frequency-selective fading that is experienced over the larger bandwidth that these future broadband systems will use. The use of dirty paper coding further complicates the matter, because the order in which the users are encoded will affect the rates that they can achieve. A well-designed cross-layer scheduling algorithm must take into account the multiple dimensions of this resource-allocation problem and other quality-of-service (QoS) parameters to fully exploit the communications channel. The scheduling problem is often expressed in terms of optimizing some utility function. Unfortunately, the search space for this optimization problem is extremely large, which prohibits an optimal exhaustive search. To this end, we investigate the use of genetic algorithms to reduce the complexity of the scheduling. This paper builds upon prior work that implements scheduling via genetic algorithms in the context of single-carrier systems using zero-forcing beamforming (ZFB). In this paper, we investigate how the genetic algorithm can be adapted to account for the effect of encoding order on the scheduling and how the scheduling can be extended to a multicarrier system. In particular, we investigate the maximum throughput and proportionally fair scheduling criteria. We demonstrate that the performance of the genetic algorithm is near optimal compared with an exhaustive search at a greatly reduced computational complexity. Furthermore, in the case of a multicarrier orthogonal frequency-division multiplexing (OFDM) system, an increase in capacity is shown relative to the single-carrier case. [ABSTRACT FROM AUTHOR]

A simple scheme that achieves the capacity and the reliability function of the wideband Costa dirty-paper channel is proposed. The scheme can be interpreted as an opportunistic version of pulse position modulation (PPM). This interpretation suggests a natural generalization of the scheme which we show to achieve the capacity per unit cost of Gel'fand-Pinsker channels with a zero-cost input letter. [ABSTRACT FROM AUTHOR]

Due to the fact that the quality of the received signal is adversely affected by the beam squint phenomenon, which is especially pertinent to the millimeter wave (mmwave) bands, many studies have been utilised by other researchers to provide light on some of the challenges that come with analysing this type of occurrence. Squint causes several issues, the most important of which are its detrimental effects on gain, line of sight, angle of arrival, progressive phase, usable bandwidth, and fading effect. As a result of these obstacles, the advantages of adopting a high-frequency band such as mmwave in modern wireless communication systems are severely limited. Squint-phenomena-related difficulties, such as decreased channel capacity, increased bit error rate (BER), and lowered quality of services, may have a substantial detrimental impact on channel performance. The squint phenomenon and associated issues become more pressing with the expansion of the frequency spectrum and the deviation of the arrival angle from boresight. The purpose of this article is to provide a comprehensive overview of the relevant literature and to compare and contrast various methods in order to identify the most fruitful lines of inquiry for future research. [ABSTRACT FROM AUTHOR]

This paper investigates an optimization of the conventional relay selection for multirelay environments. In contrast with previously reported selection schemes, where a selected relay accesses the channel in a dedicated cooperative slot, the proposed scheme recovers the bandwidth loss of the half-duplex constraint by allowing two relays to simultaneously access the channels. Based on an appropriate dirty-paper coding (DPC) technique among relays, the proposed scheme enables a relay to establish communication with the destination at the same time that another relay forwards the data from the source. It is proven that the interplay between relay selection and the superposition DPC weight factor provides a tradeoff between relaying and new data performance. Hence, an appropriate codesign of the superposition DPC parameter and opportunistic relay selection can achieve efficient communication for the new data without affecting the relaying performance. The proposed scheme is compared with conventional relaying approaches, and its enhancements are provided through theoretical studies and numerical results. [ABSTRACT FROM AUTHOR]

A wideband Rayleigh fading channel is considered with causal channel state information (CSI) at the transmitter and no receiver CSI. A simple orthogonal code with energy detection rule at the receiver (similar to pulse position modulation in IEEE Trans. Inf. Theory, vol. 46, no. 4, Apr. 2000 and IEEE Trans. Inf. Theory, vol. 52 no. 5, May 2006) is shown to achieve the capacity of this channel in the wideband limit. This strategy transmits energy only when the channel gain exceeds a threshold, hence only needs causal transmitter CSI. In the wideband limit, this capacity without any receiver CSI is the same as the capacity with full receiver CSI, which is proportional to the logarithm of the bandwidth. Similar threshold-based pulse position modulation is shown to achieve the capacity per unit cost of the dirty-tape channel (dirty paper channel with causal transmitter CSI and no receiver CSI), which equals its capacity per unit cost with full receiver CSI. Then, a general discrete channel with i.i.d. states is considered. Each input has an associated cost and a zero cost input “0” exists. The channel state is assumed to be known at the transmitter in a causal manner. Capacity per unit cost is found for this channel and a simple orthogonal code is shown to achieve this capacity. Later, a novel orthogonal coding scheme is proposed for the case of causal transmitter CSI and a condition for equivalence of capacity per unit cost for causal and noncausal transmitter CSI is derived. [ABSTRACT FROM PUBLISHER]

Torsional oscillations greatly affect performance and. determine the bandwidth (BW) and damping of speed loops. Backlash due to gear reducers can also contribute to the triggering of oscillations, especially when the drive runs at very low load torque. This paper presents a detailed evaluation of these effects in typical electromechanical drive trains applied to paper machine sections. The cases evaluated consider torsional oscillations in two-mass and three-mass systems, and the effect of shaft diameter and length on the resonant frequencies of three typical paper machine sections. Time-domain response plots are evaluated to show the effect of speed response overshoot, reducer backlash, and step or ramp speed commands. Based on these results, mechanical design guidelines are given for the most significant drive train components in order to minimize torsional oscillations of the speed-controlled drive system. [ABSTRACT FROM AUTHOR]

The steady improvements in the networking infrastructure and ever increasing broadband penetration has fueled the resurgence of voice-over-IP (VoIP). One of the important contributors to this growth has also been the development and wide acceptance of the session initiation protocol (SIP). However, the current usage of SIP requires a per-application deployment (each application using its own SIP stack). In addition to shared port number problems, this leads to a narrow development of SIP based services, even though SIP, as a protocol, offers incredible opportunities for enabling various applications simultaneously. In this paper, we propose SPLAT—a unified SIP platform, consisting of a client-side SIP service and supporting network infrastructure blocks, that provide unified mechanisms to execute generic SIP functions through an exported higher level API. Applications can leverage the API and ready-made building blocks for creating richer interfaces without significant and often repeated development effort, e.g. a conferencing server coupled with a gaming server can provide context-aware audio conferencing between occupants of a particular game room. Importantly, the SPLAT framework is available to all applications including the ones not inherently based on SIP and thus presents a great opportunity for enhancing such applications. The SIP service API is designed to be extensible and provides novel higher level functional primitives like ad hoc conferencing and seamless transition of sessions. In addition, it also exports a low level interface for specialized applications that need direct access to SIP call flows. Another feature of the service is that it allows a user to plug-in an end device (softphone, IP phone, PSTN phone) of his/her choice on a per-session basis. We demonstrate the richness of the API by describing prototypes for enhancing various applications as well as new converged applications. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A microstrip line on very thin membrane substrate (0.05 mm) is slot-coupled through a thick air substrate (12.7 mm) to excite an L-band radiating patch element. A breadboard unit achieved a relatively wide bandwidth of 100 MHz (8%). Very narrow coupling slot is used with aspect ratio of 160 (conventional slot aspect ratio is between 10 to 30). This new feed design makes the thin-membrane or inflatable array antenna technology more practical. It reduces the number of thin-membrane layers required for a dual-pol wide-band inflatable array from three layers in a previous design to two layers. In addition, this technology allows the thin-membrane array antenna elements to be readily integrated with thin-membrane-mounted transmit/receive (T/R) modules. Calculation shows that, without the patch, the micros trip line and slot combination can also radiate as a paper-thin (0.05 mm) radiator at the L-band frequencies. [ABSTRACT FROM AUTHOR]

We propose an effective method for the detection and identification of dangerous substances by using the broadband THz pulse. This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously. By analyzing the time-dependent spectrum of the THz pulse transmitted through or reflected from a substance, we follow the average response spectrum dynamics. Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface. For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria. Restrictions of usually used detection and identification methods, based on a comparison between the absorption frequencies of a substance under analysis and a standard substance, are demonstrated using a physical experiment with paper napkins. [ABSTRACT FROM AUTHOR]

Purpose: In Sri Lanka, the Radio Frequency Spectrum (RF spectrum) has traditionally been overseen managed and regulated by the government regulatory body(s), mainly accommodating the administrative RF spectrum management regime. This approach entails allocating and assigning RF spectrum to licensed operators solely through administrative means, with the regulatory authority having sole control and rights over it. However, in line with global trends, in recent years, many countries have begun to transition towards market-based approaches to RF spectrum management from legacy administrative regime, aiming to improve efficiency, promote innovation, and foster competition in the telecommunications sector. Currently, the regulatory landscape in Sri Lanka is also exploring the transition towards a market-oriented spectrum management regime. In this context, this legal research article critically analyses the viability and appropriateness of the transition from administrative RF spectrum management to market-based RF spectrum management in Sri Lanka in a regulatory context, highlighting various dimensions to be considered while migrating. Design/methodology/approach: In this research paper, the authors have considered the regulatory aspects of the transition from an administrative to a marked-based approach for the RF spectrum in Sri Lanka. Hence, the authors shall be carrying out a legal research using the doctrinal research methodology, which is commonly used in legal research. This research article considers John A. Posner’s law and economic theory and John Lock’s property rights theory as the theoretical foundation. Further, this research paper uses qualitative research methodology. By using the said methodological approach, the authors analyse the current administrative RF spectrum management regime in Sri Lanka comparing it with global trends towards market-based approach and thereby evaluate the primary objectives behind the transition, the current RF spectrum framework, and the anticipated challenges that they would encounter with the transition. Findings: The analysis revels that RF spectrum management in Sri Lanka under the administrative system is restrictive and hinders innovation and competition, compared to a more liberalized market-based approach. A market-based approach, characterized by auctions, in primary markets and spectrum sharing, trading, and leasing in secondary markets identified as a potential solution to these limitations. However, the study also highlights several challenges, including the need for regulatory reform, capacity building, and the development of a robust legal framework to support the transition. Originality: This paper contributes to the existing body of knowledge by providing a detailed analysis of the potential shift in RF spectrum management practices within Sri Lanka, in the regulatory context, a subject area that has not been extensively explored in the local context. It offers a comparative perspective with international practices and provides actionable recommendations tailored to Sri Lankan conditions. Implications: The findings suggest that transitioning to a market-based RF spectrum management regime could significantly improve the efficiency and dynamism of Sri Lanka's telecommunications sector. However, careful planning and implementation are crucial to address potential challenges and ensure that the transition supports long-term goals of innovation and competition. The recommendations aim to guide policymakers in developing a framework that balances market efficiency with regulatory oversight. [ABSTRACT FROM AUTHOR]

Recently, broadband optical access networks were being deployed worldwide to deliver large bandwidth to end users. Currently, the operators have been mainly deploying time-division multiplexing (TDM) passive optical networks (PON) in their networks. As bandwidth demand continues to increase, the industry further selected several next generation optical access (NGA) options to upgrade from current TDM-PON architectures. Besides increasing bandwidth requirement, current TDM-PONs suffers from limited reach and split-ratio. To further reduce the capital and operational expenditure requirements of current TDM-PON, NGA architectures must consolidate the number of central office sites. Long-reach optical access (LROA) architectures are promising solutions that employ optical amplifiers to increase optical budget to support longer reach and higher split-ratio in the distribution network. As more end users are supported over shared physical medium in LROA, access network security is of greater importance. The first part of this article reviews important LROA architectures and their enabling technologies. Moreover, few works in current literature address security weaknesses in LROA. The second part of this article reviews these security weaknesses as well as monitoring and control techniques employed in current TDM-PONs. In addition, a novel class of quasi-passive and reconfigurable devices is presented that addresses aforementioned security weaknesses and is suitable for LROA. [ABSTRACT FROM AUTHOR]

We report on the temperature dependence of ozone absorption cross-sections measured in our laboratory in the spectral range 213–1100nm with a spectral resolution of 0.02–0.24nm (Full Width Half Maximum, FWHM) in the atmospherically relevant temperature range from 193 to 293K. The temperature dependence of ozone absorption cross-sections was established using measurements at eleven temperatures. The methodology of the absolute broadband measurements, experimental procedures and spectra processing were described in our companion paper together with the associated error budget. In this paper, we report in detail on our data below room temperature and compare them with literature data using direct comparisons as well as the standard approach using a quadratic polynomial in temperature fitted to the cross-section data. [ABSTRACT FROM AUTHOR]

In this paper we discuss the methodology of taking broadband relative and absolute measurements of ozone cross-sections including uncertainty budget, experimental setups, and methods for data analysis. We report on new ozone absorption cross-section measurements in the solar spectral region using a combination of Fourier transform and echelle spectrometers. The new cross-sections cover the spectral range 213– 1100nm at a spectral resolution of 0.02–0.06nm in the UV-vis and 0.12–0.24nm in the IR at eleven temperatures from 193 to 293K in steps of 10 K. The absolute accuracy is better than three percent for most parts of the spectral region and wavelength calibration accuracy is better than 0.005 nm. The new room temperature cross-sections data are compared in detail with previously available literature data. The temperature dependence of our cross-sections is described in a companion paper. [ABSTRACT FROM AUTHOR]

Wideband spectrum sensing with a high-speed analog-digital converter (ADC) presents a challenge for practical systems. The Nyquist folding receiver (NYFR) is a promising scheme for achieving cost-effective real-time spectrum sensing, which is subject to the complexity of processing the modulated outputs. In this case, a multipath NYFR architecture with a step-sampling rate for the different paths is proposed. The different numbers of digital channels for each path are designed based on the Chinese remainder theorem (CRT). Then, the detectable frequency range is divided into multiple frequency grids, and the Nyquist zone (NZ) of the input can be obtained by sensing these grids. Thus, high-precision parameter estimation is performed by utilizing the NYFR characteristics. Compared with the existing methods, the scheme proposed in this paper overcomes the challenge of NZ estimation, information damage, many computations, low accuracy, and high false alarm probability. Comparative simulation experiments verify the effectiveness of the proposed architecture in this paper. [ABSTRACT FROM AUTHOR]

The impedance expansion method (IEM), which has been previously proposed by the authors of this paper, is a circuit modeling technique for electrically very small devices. This paper describes a circuit modeling procedure that utilizes the IEM and eigenmode analysis for a wireless power transfer system. First, a multimode circuit model that can represent the higher order resonances in a broadband frequency range is presented. Subsequently, a single-mode circuit model—consisting only of passive elements—that can represent both the radiated and conduction loss powers at approximately its operating frequency band is presented. [ABSTRACT FROM AUTHOR]

Many emerging applications, such as factory automation, electric power distribution, and intelligent transportation systems, require multicast Ultra-Reliable Low-Latency Communications (mURLLC). Since 3GPP Release 17, 5G systems natively support multicast functionality, including multicast Hybrid Automatic Repeat Request and various feedback schemes. Although these features can be promising for mURLLC, the specifications and existing studies fall short in offering guidance on their efficient usage. This paper presents the first comprehensive system-level evaluation of mURLLC, leveraging insights from 3GPP specifications. It points out (i) how mURLLC differs from traditional multicast broadband wireless communications, and (ii) which approaches to provide mURLLC require changing the paradigm compared with the existing solutions. Finally, the paper provides recommendations on how to satisfy strict mURLLC requirements efficiently, i.e., with low channel resource consumption, which increases the capacity of 5G systems for mURLLC. Simulation results show that proper configuration of multicast mechanisms and the corresponding algorithms for mURLLC traffic can reduce resource consumption up to three times compared to the baseline solutions proposed for broadband multicast traffic, which significantly increases the system capacity. [ABSTRACT FROM AUTHOR]

In today's scenario, wireless communication is turning into a decisive and leading backbone to access the worldwide network. Therefore, the usage of mobile phones and broadband is rising staggeringly. To satisfy their expulsive needs, it demands increment in data rates while providing higher bandwidth and utilizing optical fiber in wireless communication, and this becomes a worldwide analysis area. Radio over fiber (RoF) system is taken into account as best solution to fulfill these needs. In RoF system, the radio frequency signal operated at millimeter wave (30–300 GHz) is centralized and processed at control station (CS) and also, the CS upconverts this electrical signal to optical domain. By employing optical fiber link, this signal reaches to base station (BS). Then, the received optical signal converts back to electrical domain at the respective BS. Now BS radiates the electrical signal to corresponding mobile station (MS) in commission with the millimeter wave frequency bands. This RoF system is providing massive bandwidth, facilitating large mobility for RF frequency signals, small loss, fast and cost effective setup, wonderful security, and unlicensed spectrum etc. The RoF system introduces microcells structure for BS cells to boost the frequency reuse and needed capacity. It has benefits in terms of ability to fulfill increasing bandwidth demands to cut back the power consumption and the dimensions of the handset devices. This paper firstly explains the overview of existing wireless mobile communication and broadband systems and then, targets the review of RoF system which will become energy efficient system for next generation mobile communication and future broadband systems. This paper also includes the performance degradation and evaluation parameters. Finally, this paper presents the various research opportunities for its implementation zone. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method for generating broadband orbital angular momentum (OAM) beams utilizing the two neighboring ports of the uniform circular array (UCA) excited with a phase difference of (2(π + δ)l)/N. This approach differs from current arrays used to generate an OAM beam with a phase difference of 2πl/N. We establish that the UCA can produce OAM beams covering 83% (7-17 GHz) of the bandwidth. The array antenna consists of three Vivaldi elements with a phase difference between adjacent ports, capable of generating OAM beams of mode 2 when being fed with equal amplitude and phase. In contrast to current OAM antenna arrays that require complex phase-shifting networks for feeding, our proposed antenna array offers simplicity in its feeding mechanism. Furthermore, the UCA-based Vivaldi antenna presents a novel approach for generating wideband OAM beams and holds significant potential for applications in broadband communication. [ABSTRACT FROM AUTHOR]

Communication systems are greatly hampered by many disruptive noises in powerline communication systems (PLC), which come with strong interference, resulting in the malfunction of PLC systems. Hence, there is a need to model noise and its effect on communication systems. This paper presents noise modelling and mitigation techniques for indoor broadband powerline communication systems. To model the PLC noise, frequency domain measurements employing the GSP‐930 spectrum analyser were carried out to determine the noise frequency response in the frequency range of 1–30 MHz. The results obtained were plotted. While the analytical model for the noise model is presented, furthermore, noise mitigation techniques for multiple input multiple output PLC (MIMO‐PLC) systems in the form of spatial modulation PLC systems have been proposed. The SM‐PLC system employs the indices of the individual transmit lines to increase the data rate, as opposed to the traditional MIMO‐PLC systems, where the symbol to be transmitted is transmitted by duplicating the symbol across all lines. The proposed system uses the maximum likelihood (ML) detector at the receiver to obtain estimates of the transmitted symbols. The simulation results of the SM‐PLC system are compared with the already existing MIMO‐PLC system and show a significant improvement of ≈6 dB and 5.2 dB in signal‐to‐noise ratio (SNR) at a bit error rate of 10(−5) for spectral efficiencies of 4 bits per channel use (bpcu) and 6 bpcu, respectively. On comparison of the SM‐PLC system having a combination of additive white Gaussian noise and impulse noise at the receiver, the SM‐PLC system outperformed the traditional MIMO‐PLC by 3.5 and 3.8 dB in SNR for 4 and 6 bpcu, respectively. [ABSTRACT FROM AUTHOR]

Telecommunications profoundly impacts all major aspects of our everyday life. As a consequence, student instruction typically includes a series of specialized courses, each addressing a distinct telecommunication area, separating wireless from fixed (optical) communications. This creates the problem of knowledge fragmentation, hindering the student's perception of the topic since, at the service level, the applications and services offered to the users seem "virtually" independent from the underlying infrastructure. In this paper, to address this problem, we designed, analyzed, and implemented a 6 h course module on the five generations of wireless and fixed networks, which was presented as an integral part of the undergraduate course "Broadband Communications", which was offered at the Dept. of Electrical and Electronic Engineering, School of Pedagogical and Technological Education (ASPETE), Athens, Greece. The main targets of this module are the following. Firstly, it aims to familiarize students with the fixed generations taxonomy, defined by the ETSI Industry Specification Group (ISG) F5G. This taxonomy serves as a foundation for understanding the evolution of telecommunications technologies. Secondly, the module seeks to integrate the acquired knowledge of the students in their previous telecommunication-related courses. During their curriculum, this knowledge was divided into two separate parts: wireless and fixed (optical). By coupling these two areas, students can develop a deeper understanding of the field. Lastly, the module aims to explore cutting-edge technologies and advancements in the telecommunications industry. In this way, it prepares students to enter the professional world during the fifth-generation era. Additionally, it provides them with valuable insights into the ongoing research and development in the field of 6G. Overall, this module serves as a comprehensive platform for students to enhance their understanding of telecommunications, from the foundational concepts to the latest advancements. To evaluate the impact of this module, the students were asked to fill out a questionnaire that included seven questions upon module completion. This questionnaire was completed successfully by 32 students in the previous academic year and by 16 students in this academic year. Moreover, a 20-question multiple choice quiz was offered to the students, allowing us to probe more into the typical errors and misconceptions about the topic. [ABSTRACT FROM AUTHOR]

An elliptically tapered slot antenna (TSA) with high and relatively-flat gain is proposed in this paper. Its measured 10-dB impedance bandwidth is 2.65–12.90 GHz which covers the frequency range of ultra-wideband (UWB). Meanwhile, on the lower band of UWB (3 to 5 GHz), the measured antenna gain varies within 9.25 to 10.25 dBi. Furthermore, differing from many TSAs, the ground plane is just a simple rectangular structure but not a tapering shape. [ABSTRACT FROM AUTHOR]

Broadband solar and terrestrial irradiance measurements of high temporal resolution are needed to study inhomogeneous clouds or surfaces and to derive vertical profiles of heating/cooling rates at cloud top. An effcient method to enhance the temporal resolution of slow-response measurements of broadband irradiance using pyranometer or pyrgeometer is introduced. It is based on the deconvolution theorem of Fourier transform to restore amplitude and phase shift of high frequent fluctuations. It is shown that the quality of reconstruction depends on the instrument noise, the pyrgeometer response time and the frequency of the oscillations. The method is tested in laboratory measurements for synthetic time series including a boxcar function and periodic oscillations using a CGR-4 pyrgeometer with response time of 3 s. The originally slow-response pyrgeometer data were reconstructed to higher resolution and compared to the predefined synthetic time series. The reconstruction of the time series worked up to oscillations of 0.5 Hz frequency and 2Wm-2 amplitude if the sampling frequency of the data acquisition is 16 kHz or higher. For oscillations faster than 2 Hz the instrument noise exceeded the reduced amplitude of the oscillations in the measurements and the reconstruction failed. The method was applied to airborne measurements of upward terrestrial irradiance from the VERDI (Vertical Distribution of Ice in Arctic Clouds) field campaign. Pyrge20 ometer data above open leads in sea ice and a broken cloud field were reconstructed and compared to KT19 infrared thermometer data. The reconstruction of amplitude and phase shift of the deconvoluted data improved the agreement with the KT19 data. Cloud top temperatures were improved by up to 1 K above broken clouds while an underestimation of 2.5Wm-2 was found for the upward irradiance over small leads when using the slow-response data. The limitations of the method with respect to instrument noise and digitalization of measurements by the data acquisition are discussed. [ABSTRACT FROM AUTHOR]

Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross-sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross-sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye).We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross-sections over the 360-420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with literature values for this spectral region. The refractive index determined for nigrosin is 1.78(±0.03)+0.19(±0.08)i at 360nm and 1.53(±0.03)+0.21(±0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71(±0.02)+0.07(±0.06)i at 360nm and 1.66(±0.02)+0.06(±0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction crosssection, and complex refractive index as a function of wavelength. [ABSTRACT FROM AUTHOR]

A call for papers on Next Generation Networks (NGN) is presented.

The article focuses on a study that aims at analyzing the impact of atmospheric propagation and the radiometer characteristics on the scanning radiometer measurements. In the study, a forward radiative transfer model is used to measure the biases caused in different frequency bands in various microwave radiometer characteristics, like receiver bandwidth and antenna beam width. It shows higher impact of antenna beam width as compared to receiver bandwidth.

In this paper, we give a list of ATM related papers. This is not a complete list. Rather, it represents the bulk of the references in this ever-growing area. For easier use of this reference list, we have classified the papers into the following six categories: general, source characterization, switching, congestion control, routing, and transport. [ABSTRACT FROM AUTHOR]

The article discusses the evolution stages of the UWB antenna and the parametric analysis of the UWB notch antenna. This collection of research papers explores various aspects of antenna design and high-speed wireless communication, delving into the forefront of technology for modern telecommunications. The fabricated and tested MIMO antenna shows UWB response and good isolation between the antenna elements, making it suitable for UWB MIMO applications. [Extracted from the article]

This paper presents the design of a broadband and high-power amplifier with bounded performance technique (BPT). Like the real frequency technique (RFT) or the simplified RFT (SRFT), BPT achieves broadband performance via matching at some in-band discrete real frequencies. It solves some design issues that are not addressed in the RFT and the SRFT. Among them are the inclusion of the design specifications in the device selection and design process and the possible degradation of operation metrics that are not optimized. BPT also avoids complicated analytic mathematics by using circuit prototypes. In this paper, we show the design of an amplifier with BPT. It has a 3-dB compression power of at least 100 W and a drain efficiency of at least 50% over the band 1–2.8 GHz or 94.7% fractional bandwidth. We also show the design of the same amplifier with the traditional SRFT and compare its expected performance with that designed with BPT. [ABSTRACT FROM AUTHOR]

This paper proposes a wideband and low direct-coupling tapered slot antenna (TSA) using electromagnetic bandgap (EBG) structure. We name this antenna the EBG-TSA. In some near field imaging systems including ground penetrating radars, a number of TSAs are arranged into an array with very small spacing in order to realize high-resolution imaging without synthetic aperture processing. Then, the direct coupling among TSA elements is nonnegligible and harmful. In this paper, we show that the EBG structure is effective in reducing the direct coupling with its stopband, which prevents an electromagnetic wave from propagating in a specific frequency band. Our EBG-TSA reduces its direct coupling by 3 dB or more in a wide band. We also find that the tapered EBG structure area assists the radiation by guiding the fin current flow two-dimensionally along the tapered slot so that the boresight gain increases. The EBG structure contributes to both the direct coupling reduction and the boresight gain enhancement. [ABSTRACT FROM AUTHOR]

With the development of wireless technology, signals propagating in space are easy to mix, so blind detection of communication signals has become a very practical and challenging problem. In this paper, we propose a blind detection method for broadband signals based on a weighted bi-directional feature pyramid network (BiFPN). The method can quickly perform detection and automatic modulation identification (AMC) on time-domain aliased signals in broadband data. Firstly, the method performs a time-frequency analysis on the received signals and extracts the normalized time-frequency images and the corresponding labels by short-time Fourier transform (STFT). Secondly, we build a target detection model based on YOLOv5 for time-domain mixed signals in broadband data and learn the features of the time-frequency distribution image dataset of broadband signals, which achieves the purpose of training the model. The main improvements of the algorithm are as follows: (1) a weighted bi-directional feature pyramid network is used to achieve a simple and fast multi-scale feature fusion approach to improve the detection probability; (2) the Efficient-Intersection over Union (EIOU) loss function is introduced to achieve high accuracy signal detection in a low Signal-Noise Ratio (SNR) environment. Finally, the time-frequency images are detected by an improved deep network model to complete the blind detection of time-domain mixed signals. The simulation results show that the method can effectively detect the continuous and burst signals in the broadband communication signal data and identify their modulation types. [ABSTRACT FROM AUTHOR]

This paper considers propagation of low-frequency broadband pulses in shallow water. It focuses on across-slope propagation in wedge-shaped oceanic waveguides and on single hydrophone receiving configurations. In a low-frequency shallow-water context, propagation is dispersive and usually described by modal theory. However, in the presence of a tilted bottom, propagation is also affected by 3-D effects (horizontal refractions). The paper shows that time-frequency analysis is a suitable tool to illustrate and understand 3-D propagation. It illustrates the pertinence of the time-frequency analysis of 3-D signal by proposing an algorithm to estimate the seabed slope using a single receiver. The method is benchmarked on numerical simulations, and successfully applied on small-scale experimental data. [ABSTRACT FROM PUBLISHER]

This paper derives the maximum achievable sum-rate and presents the optimal encoding/decoding framework for rate-diverse wireless network coding (RD-WNC) over broadband channels consisting of multiple parallel subchannels. RD-WNC applies to a communication scenario in which a base station wants to deliver two different messages with different rates to two users. The base station combines the two separate messages into one network-coded message and broadcasts the network-coded message to both users. Each user then extracts its desired message from the network-coded message by subtracting from it the other message, which we assume to be side information available to the user. Deriving the maximum achievable sum-rate for RD-WNC is challenging when the channel consists of multiple parallel subchannels with different channel coefficients (e.g., the subcarrier channels of OFDM systems), since apart from the rate allocation between the two users, optimal power allocation among multiple subchannels needs to be identified. The first contribution of this paper is a new “mountain-leveling” power allocation algorithm to achieve the maximum sum-rate. With the resulting power allocation, we can then achieve the corresponding optimal sum-rate by having a separate encoding/decoding mechanism for each subchannels, but doing so is cumbersome and complex when the number of subchannels is large. The second contribution of this paper is a practical encoding/decoding framework using only one encoder-decoder mechanism for all subchannels without sacrificing sum-rate optimality. We provide numerical results to corroborate our theoretical findings and to demonstrate the benefits of our encoding/decoding framework. [ABSTRACT FROM AUTHOR]

Heterogeneous Internet of Things (IoT) applications generate a diversity of novelty applications and services in next-generation networks (NGN), which is essential to guarantee end-to-end (E2E) communication resources for both control plane (CP) and data plane (DP). Likewise, the heterogeneous 5th generation (5G) communication applications, including Mobile Broadband Communications (MBBC), massive Machine-Type Commutation (mMTC), and ultra-reliable low latency communications (URLLC), obligate to perform intelligent Quality-of-Service (QoS) Class Identifier (QCI), while the CP entities will be suffered from the complicated massive HIOT applications. Moreover, the existing management and orchestration (MANO) models are inappropriate for resource utilization and allocation in large-scale and complicated network environments. To cope with the issues mentioned above, this paper presents an adopted software-defined mobile edge computing (SDMEC) with a lightweight machine learning (ML) algorithm, namely support vector machine (SVM), to enable intelligent MANO for real-time and resource-constraints IoT applications which require lightweight computation models. Furthermore, the SVM algorithm plays an essential role in performing QCI classification. Moreover, the software-defined networking (SDN) controller allocates and configures priority resources according to the SVM classification outcomes. Thus, the complementary of SVM and SDMEC conducts intelligent resource MANO for massive QCI environments and meets the perspectives of mission-critical communication with resource constraint applications. Based on the E2E experimentation metrics, the proposed scheme shows remarkable outperformance in key performance indicator (KPI) QoS, including communication reliability, latency, and communication throughput over the various powerful reference methods. [ABSTRACT FROM AUTHOR]

In this paper, a quad-mode endfire planar phased antenna array with wide scan angle and 1.2 mm clearance is proposed for 5G mobile terminals. The proposed antenna can obtain over 8 GHz of impedance bandwidth. In this paper, it is suggested to efficiently combine a multimode array element with different radiation patterns for each mode into a phased antenna array. In the array, similar and wide embedded radiation patterns are obtained for the all four modes. Furthermore, a coaxial to differential stripline transition is designed in this paper. The differential feeding structure is very compact and utilizes only MMPX connector and vias. The total scan pattern and coverage efficiency of the measured and simulated phased array antenna are calculated in the range from 25 to 33 GHz, and good agreement between measured and simulated results is observed. The mean coverage efficiency along the frequency range is very similar, but minor difference in variance of coverage efficiency is observed in the measurements. The coverage efficiency of around 50% for the threshold gain of 5 dBi is achieved in the chosen frequency range. [ABSTRACT FROM AUTHOR]

E-health is being adapted in modern hospitals as a significant addition to the existing healthcare services. To this end, modern hospitals urgently require a mobile, high-capacity, secure, and cost-effective communication infrastructure. In this paper, we explore potential applications of a hybrid broadband power line communication (PLC) and Wi-Fi in an indoor hospital scenario. It utilizes the existing power line cables and Wi-Fi plug-and-play devices for indoor broadband communication. Broadband power line (BPL) adaptors with Wi-Fi outputs are used to build an access network in hospitals, particularly in areas where the wireless router signal is poor. The Tenda PH10 AV1,000 AC Wi-Fi power line adapter is a set of BPL adapters that offer operational bandwidth of up to 1,000 Mbps. These adapters are based on the HomePlug AV2 protocol and can provide a data rate up to 200 Mbps on the physical layer. An experiment using the PLC Wi-Fi kit is carried out to show that a Wi-Fi and PLC hybrid network is the best candidate to provide wide range of practical applications in a hospital including, but not limited to, telemedicine, electronic medical records, early-stage disease diagnosis, health management, real-time monitoring, and remote surgeries. [ABSTRACT FROM AUTHOR]

Future 6G networks are envisioned to support very heterogeneous and extreme applications (known as verticals). Some examples are further-enhanced mobile broadband communications, where bitrates could go above one terabit per second, or extremely reliable and low-latency communications, whose end-to-end delay must be below one hundred microseconds. To achieve that ultra-high Quality-of-Service, 6G networks are commonly provided with redundant resources and intelligent management mechanisms to ensure that all devices get the expected performance. But this approach is not feasible or scalable for all verticals. Specifically, in 6G scenarios, mobile devices are expected to have speeds greater than 500 kilometers per hour, and device density will exceed ten million devices per square kilometer. In those verticals, resources cannot be redundant as, because of such a huge number of devices, Quality-of-Service requirements are pushing the effective performance of technologies at physical level. And, on the other hand, high-speed mobility prevents intelligent mechanisms to be useful, as devices move around and evolve faster than the usual convergence time of those intelligent solutions. New technologies are needed to fill this unexplored gap. Therefore, in this paper we propose a choreographed Quality-of-Service management solution, where 6G base stations predict the evolution of verticals at real-time, and run a lightweight distributed optimization algorithm in advance, so they can manage the resource consumption and ensure all devices get the required Quality-of-Service. Prediction mechanism includes mobility models (Markov, Bayesian, etc.) and models for time-variant communication channels. Besides, a traffic prediction solution is also considered to explore the achieved Quality-of-Service in advance. The optimization algorithm calculates an efficient resource distribution according to the predicted future vertical situation, so devices achieve the expected Quality-of-Service according to the proposed traffic models. An experimental validation based on simulation tools is also provided. Results show that the proposed approach reduces up to 12% of the network resource consumption for a given Quality-of-Service. [ABSTRACT FROM AUTHOR]

Electronic activities are realized on the Internet due to the growth of the Internet. As conference organization is getting more popular, we proposed an electronic virtual conference system (EVCS) to handle all activities of real-world conferences. The EVCS includes a virtual conference management system (VCMS) and a mobile conferencing system (MCS). Video conferencing is a trend of future communications. With the improvement of broadband network technologies, video conferencing becomes possible in the global society. It is feasible to use video conferencing technologies to organize future international conferences. As such, transportation and accommodation costs are saved. This paper proposed a total solution toward virtual conferencing. We use a mobile server/storage pre-broadcasting technique, as well as a communication network optimization algorithm, which is based on a graph computation mechanism. The system also relies on a network bandwidth reservation facility as well as a multicasting control function. With the assistance of the virtual conference management system, the system is able to support virtual conferencing in the future academic society. [ABSTRACT FROM AUTHOR]

Wireless networks have recently required the development of a backbone system with high bandwidth capacity and optical fiber transmission over long distances as well. Therefore, coherent optical technology provides broadband communications with advanced modulation techniques to meet the requirements of wireless networks, such as the fifth-generation 5G system. In this paper, the Dual Polarization-M-Quadrature Amplitude Modulation (DP-M-QAM) levels have been integrated with the Dense Wavelength Division Multiplexing (DWDM) technique. The system focuses on high data transmission over long-haul optical fiber with digital signal processing (DSP) treatment in the receiving section. The transmission of 100 Gbits/s, × 16 channels has been achieved using Single Mode Fiber (SMF) over lengths from 80 to 320 km, and channel spacing up to 100 GHz. The DP-M-QAM modulation levels based on coherent DWDM simulation were evaluated using the Optical Signal-to-Noise Ratio (OSNR) parameter. The performance of the proposed model is evaluated and analysed in terms of different results of Bit Error Rate (BER) and Error Vector Magnitude (EVM). Compared to already existing solutions, our system demonstrates the best compromise in terms of the number of channels, the long transmission distance of up to 300 km and also minimum BER, which makes it an efficient solution. The proposed transmission provides a DSP subsystem to support a broader range of DP-MQAM modulation formats for high-speed wireless communication networks. [ABSTRACT FROM AUTHOR]

The XXXI Electrical and Electronic Engineering Conference (XXXI JIEE-2023) is an annual event organized by the Faculty of Electrical and Electronic Engineering at the Escuela Politécnica Nacional in Quito, Ecuador. The conference aims to disseminate graduation projects, research advancements, and academic papers in the field. It provides an opportunity for knowledge exchange, professional connections, and staying updated on the latest technologies. The conference included international keynote speakers, technical paper presentations, student works, and tutorials on various topics such as reconfigurable antennas, power grid monitoring, and energy storage technologies. The XXXI JIEE-2023 focused on addressing challenges in smart grids, power systems, renewable energy, automation, robotics, power electronics, and signal processing, among others. The conference aimed to contribute to the sustainable development of the energy, telecommunications, and production sectors in Ecuador while promoting a lower environmental impact. The conference proceedings underwent a single-blind peer review process, with an acceptance rate of 82.75%. [Extracted from the article]

This paper presents the system design, calibration, and example measurements of a novel ultra-wideband, low-cost, real-time channel sounder. The channel sounder operates in the frequency range from 3 to 18 GHz with a 15-GHz bandwidth thus providing a Fourier delay resolution of 66.7 ps. It sequentially measures overlapping sub-bands of 1-GHz bandwidth to cover the whole frequency range. By using a waveform generator and a digitizer with relatively lower sample rates, the design significantly lowers the cost compared with sampling the whole band simultaneously. With the transmitting power of 40 dBm, the maximum measurable path loss is 132 dB without accounting for possible antenna gains. In this paper, we also describe the calibration procedure along with the method to stitch sub-bands into a combined channel response across 15 GHz of bandwidth. The channel sounder performance is compared with a vector network analyzer (VNA) measurements acquired in the same static channels. In contrast to VNAs, however, our channel sounder can measure the whole band in 6 ms and can, thus, operate in dynamic environments with coherence time more than 6 ms. Additionally, we present sample results from a measurement campaign performed in an indoor corridor investigating the delay spreads statistics over the range of 3–18 GHz. [ABSTRACT FROM AUTHOR]