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Optical wireless communication (OWC) stands out as one of the most promising technologies in the sixth-generation (6G) mobile networks. The establishment of high-quality optical links between transmitters and receivers plays a crucial role in OWC performances. Here, by a compact beam splitter composed of a metasurface and a fiber array, we proposed a wide-angle (~120°) OWC optical link scheme that can parallelly support up to 144 communication users. Utilizing high-speed optical module sources and wavelength division multiplexing technique, we demonstrated each user can achieve a communication speed of 200 Gbps which enables the entire system to support ultra-high communication capacity exceeding 28 Tbps. Furthermore, utilizing the metasurface polarization multiplexing, we implemented a full range wide-angle OWC without blind area nor crosstalk among users. Our OWC scheme simultaneously possesses the advantages of high-speed, wide communication area and multi-user parallel communications, paving the way for revolutionary high-performance OWC in the future. In this work, the authors present a metasurface-based wide-angle beam splitter designed for future applications in optical wireless communication. By leveraging the metasurface polarization multiplexing and wavelength division multiplexing properties, they achieved a high-performance optical wireless communication system, possessing a Tbps communication rate, more than 120° coverage range, and up to 144 users parallel communication capabilities. [ABSTRACT FROM AUTHOR]

Cyclic interleaved frequency division multiplexing (CIFDM) stands out as a promising solution for enhancing diversity reception over frequency-selective channels. Within the CIFDM framework, cyclic interleaving at the transmitter, followed by multipath detection at the receiver, collaboratively contributes to performance improvement. A recent advancement in this domain is the introduction of CIFDM-successive interference cancellation (CIFDM-SIC) (Anuthirsha and Stuwart in ETRI J, 1--11, 2024), a multipath multistage detection method. However, CIFDM-SIC leaves room for improvement, as it only partially mitigates multipath interference resulting from the semi-orthogonality of codes in CIFDM. To address this limitation, our current approach introduces a CIFDM-decorrelative successive interference cancellation (CIFDM-dSIC) method. In the proposed CIFDM-dSIC, a decorrelation process is employed to effectively eliminate non-orthogonal interference components arising from the cross-correlation of codes in the SIC output stages. Specifically, after the completion of the entire SIC operation, interference at each output stage, except the last one, is eliminated through path-specific decorrelation of the effective spreading codes. We have conducted a comprehensive evaluation of the performance of CIFDM-dSIC under various scenarios, comparing it with both existing CIFDM and traditional interleaved frequency division multiplexing methods. Simulation results unequivocally establish the dominance of the proposed CIFDM-dSIC, affirming its reliability in terms of bit error rate and diversity reception. [ABSTRACT FROM AUTHOR]

The anti-sorting transmission is one of the primary RF stealth signals, as well as radio frequency (RF) stealth is one of the greatest significant study areas in radar stealth technology. This study first examines the anti-sorting signal's design basis. Next, it is suggested to use a quadratic stochastic appropriate algorithm on the cosine exponent. Furthermore, utilizing the suggested nonlinear chaotic mapping, a more unpredictable wide-interval PRI signals is created while taking the sorting individual's allowable limits into account. Finally, evaluations of intricacy, equilibrium, and unpredictability confirm the effectiveness of the suggested chaotic mapping. The transmitter capacity for anti-sorting is then modeled. The outcomes demonstrate the intended signal's strong anti-sorting capabilities. [ABSTRACT FROM AUTHOR]

Inter-satellite optical wireless communication (IsOWC) is frequently utilized for fast data transmission between various far away satellites in free space. Thousands of users are connected via broad-area applications that use network topologies with many frequencies per optical fiber and a range of transmission rates and capacities. Multiple frequencies being transmitted simultaneously on a fiber having a nanometer range (1300–1600) that is a powerful feature of an optical communications link. When coupled with optical amplifiers, the WDM idea creates communication lines that provide rapid user-to-user communication throughout national borders. A well-known drawback of free space optics (FSO) or Inter-Satellite Link (ISL) is degradation in optical signal power, in addition to its appealing advantages. The traditional system is improved in order to solve this issue. Using the optisystem-15 simulator, we analyzed the IsOWC link's capability for fast data transfer based on subjective factors including received power, Q-factor and BER. 16-channels multiplexed with modulation technique transmitters to the system are explained by the projected model. The link has been used at various data rates, distances, and external Match-Zehnder modulation. Applied a series hybrid optical amplifier of erbium-doped fiber amplifier (EDFA) and a laser amplifier that exists prior to and after the OWC line with the given parameters. Different OWC ranges with a loop control of 3 loops that made total link length 1600 km, and searching different data rates to show their impact on system efficiency, which showed a great enhancement in results that are crucial to the current inter-satellite OWC link. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligence surface (RIS) consists of a large number of low-cost passive reflecting elements has attracted significant attention from communication communities, which is mainly due to its ability to substantially improve the communication performance. In light of this, we develop a three-dimensional geometry-based multiple-input multiple-output propagation model in this article, which is mainly suitable for describing the high-speed railway communications assisted by RIS in macrocell environments, such as train-to-train scenarios. In such propagation model, the waves emitted from the mobile transmitter experience non line of sight propagation links before reaching the mobile receiver, as well as the RIS propagation links before reaching the receiver. We compute the expressions of the RIS-assisted high-speed railway channel propagation properties, for example, spatial-time cross-correlation functions, between different propagation links. Then, we study the temporal autocorrelation functions of the propagation links in the provided propagation model for distinct movement time instants. Analysis shows that the communication performance can be enhanced by rising the number and the size of RIS reflecting elements, and it is validated by numerical simulation results. [ABSTRACT FROM AUTHOR]

A quantum conference key agreement (QCKA) protocol based on differential-phase-shift quantum key distribution is presented, which provides a common secret key for secure communication between more than two parties. In the proposed protocol, one party simultaneously broadcasts a weak coherent pulse train with {0, π} phases to multiple parties that measure the phase differences between adjacent pulses using a delay interferometer followed by photon detectors, and the transmitter and receivers share secret key bits from the coincident counts in the receivers. The system setup and operation are simpler than those of conventional QCKA schemes that use a multipartite quantum entanglement state. The key creation performance is evaluated by considering the eavesdropping probability. The results indicate that the proposed scheme offers better performance than the conventional entanglement-based QCKA system. [ABSTRACT FROM AUTHOR]

To enhance the information security in multiple input multiple output (MIMO) wireless communication systems, nonlinear transmission is studied in this paper by pushing the power amplifier (PA) at the transmitter to operate in the nonlinear region, even near to the saturate point. Linearization reception technique is then adopted at the legal user's receiver to remove the distortion caused by the nonlinear PA, so that the distortion-free signal can be drawn, and correct demodulation and decoding could be achieved. While for the eavesdroppers, the information required to complete the nonlinear reception could hardly be obtained, since the critical training sequence is designed to be invisible to the eavesdropping users, so the security transmission between the legitimate users can be obtained. Then, the security capacity by nonlinear transmission is analyzed in the MIMO–OFDM systems, where the signal to distortion plus noise ratio is derived, and the upper approximation is also presented. Numerical simulations are carried out to verify the effectiveness of the proposed scheme with practical reception algorithm, and it is shown that obvious security capacity can be acquired with both memory and memoryless PAs. [ABSTRACT FROM AUTHOR]

The deployment of power line communication (PLC) has gained tremendous attention in recent times because of the dawn of the internet, the increasing need for fast connectivity, and it does not require any new wiring installations which significantly reduces the deployment costs. Power lines are originally designed to transmit power from the suppliers to the customers at low frequency (50 Hz or 60 Hz). They are used to improve communication infrastructure, therefore making them useful as a communication channel. This paper presents an investigation of the use of the existing power grid line as a medium for Broadband communication by using orthogonal frequency division multiplexing (OFDM) technology at the transceiver. The transmitter performs coding of data signals to keep it from fading and radiation. In order to repair signals attenuated and affected by noise during transmission over the power line, the decoupling and OFDM receiver performs filtering and decoding, respectively. In the OFDM transmitter, quadrature phase-shift keying (QPSK) modulation as well as the OFDM receiver QPSK demodulation are used to create a set of data symbols and to predict the probability of errors. An error of 0.036 dB was obtained, which is in the allowable range of signals with good quality to be transmitted to the customers. The Coupling circuit is used as the heart of the system design and is used to insert the modulated signals from the transmitter to the power line. It is also used to extract the signals from the receiver, and to protect the circuit from medium and low voltage and low-frequency signals (less than or equal to 32 kV and 50 Hz). [ABSTRACT FROM AUTHOR]

In this work, the performance of layered transmission with optimum decoding order and multiuser diversity is analyzed in a K-user downlink network. The transmitter is equipped with two antennas whereas every user has r ( r ≥ 2 ) antennas. In each training period, the transmitter opportunistically schedules a single user based on a set of scalar feedback (FB) values sent back from the users. Investigating on what should be fed back, three distinct FB strategies are studied and an exact joint distribution expression is derived in each case for the evaluation of the average outage probability. Analytical results are obtained without disregarding the impact of error propagation and broadly differ from the former approximated analyses. It is shown that one of the inspected strategies clearly outperforms the others and can achieve full multiuser diversity gain of K. We show that by just a scalar FB from the users to the transmitter, which can easily be quantized in accordance with the desired accuracy, a significant power gain can be accomplished at the transmitter as compared to a single-user scenario. For the mathematical analysis, we rely on the fact that all orderings are equiprobable under independent and identical fading. To that end, we obtain the joint distribution of the ordered gains from the joint distribution of the unordered gains. [ABSTRACT FROM AUTHOR]

This article introduces a uniform theory of diffraction–physical optics (UTD–PO) formulation for analyzing radiowave multiple diffraction emanating from trees and buildings in green urban areas, considering illumination from a low transmitter and assuming spherical-wave incidence. Based on Babinet's principle, this solution models buildings as rectangular sections and accounts for the influence of tree crowns (assuming these rise above the average rooftop height) by incorporating appropriate attenuation factors/phasors into the diffraction phenomena of buildings. The validation of the formulation is achieved through measurements made at the 39 GHz 6G mmWave frequency on a scale model of a green urban environment comprising bonsai trees and bricks. The main advantage of the proposed solution is that the calculations only include single diffractions due to recursion, circumventing the need to use higher-order diffraction terms in the diffraction coefficients, thus reducing the computation time and power. Our results may be beneficial for the design of mobile communication systems, including 6G networks, situated in green urban areas and with transmission source positioned lower than the surrounding infrastructure. [ABSTRACT FROM AUTHOR]

In this study, we use a time-varying parameter vector autoregression in conjunction with the extended joint connectedness approach (TVPVAR-EJC) to examine the interrelationships among five variables, namely digitalization measured by the number of individuals using the Internet (% of the population), mobile cellular subscriptions (per 100 people), human capital index, CO2 emissions, and GDP, from 1996 to 2019 in Vietnam. Net total directional connectedness of digitalization and other variables suggests that it consistently acts as a net shock transmitter, whereas human capital was found to be a net receiver of corresponding shocks from 1997 to 2019. The emission of CO2 was a net critical receiver in 1998 but remained as a net transmitter for the rest of the period. Pairwise connectedness reveals that digitalization appeared as a net shock transmitter in connection with the human capital index and GDP. In the relationship with human capital, digitalization's role was critical. [ABSTRACT FROM AUTHOR]

High-speed GaN-based lasers play a pivotal role in visible light communication (VLC) systems; however, the causes of the limited modulation response of our fabricated laser diode (LD) are not fully understood. Accordingly, we constructed an equivalent circuit model for both the LD and its packaging. This model enabled us to analyze the series resistance and parallel capacitance of the LD at different injection currents. Experiments and simulations were performed to investigate the intrinsic responses of the LD. The series resistance and parallel capacitance are responsible for S21 roll-off at low frequencies. Determination of the packaging design parameters on the modulation response of a transistor outline (TO)-can packaged LD was investigated which is important to achieve the impedance match in the future. The value of each discrete component was determined by fitting the scattering parameters of the equivalent circuit model to the packaged LD. Reducing the series resistance and parallel capacitance improved the modulation response. Our study firstly illustrates the design and manufacture of violet-blue-green laser transmitters with a large modulation bandwidth for ultra-high-speed VLC from the point of the impedance influence. [ABSTRACT FROM AUTHOR]

The rapid evolution of passive optical network (PON) technologies has been driven by the necessity to accommodate 5th-generation system requirements. This research introduces a PON wavelength division multiplexing-based optical transmitter that is improved in both fiber link and bit rate. The transmitter is designed to connect many clients to a single-mode optical fiber. The optical transmitter under consideration is designed to provide an optimum data rate up to 20 Gbps per user. The data is modulated using a 2-bit per symbol Quadrature Phase Shift Keying (QPSK), and an M-array pulse coder. The R.F. signal is optically modulated during the optical system stage using a Mach–Zehnder external modulator supplied with an optical carrier generated by a vertical cavity surface emitting laser (VCSEL). Two PON configurations are devised in this context: initially, 16 VCSELs spanning 193.1–194.6 THz with a 10 GHz separation are utilized to modulate 16 data sources with 16 MZM. In contrast, in the second configuration, to reduce input laser power and system complexity, 16 data consumers share a single 193.1 THz VCSEL. Simulations of the performance measurements were conducted by Optisystem 19 for both configurations. The initial system configuration permits 20 Gbps transmission to 120 km with a Q-factor of at least 6. The power penalty of this configuration was reduced from − 970 to − 930 dB. The second configuration guarantees the dependability of data transmission over a distance of 100 km. The maximal Q-factors for the first and second configurations are 12 and 10, respectively, at a distance of 20 km. It has been established that the ideal input bias current for a VCSEL is 2 mA. The effects of the quadrature phase shift keying modulation QPSK is clearly appeared, as the current results are surpassed the peer publications regarding the utmost achievable fiber link length, Q-factor and supported data rate. [ABSTRACT FROM AUTHOR]

Achieving three-dimensional (3D) omnidirectional wireless power transfer (OWPT) without any active control is challenging. This paper proposes a square polyhedron transmitter (SPTx) based on the reverse current of parallel coil, which can create a 3D omnidirectional magnetic field. To minimize the counteracting of the reverse magnetic field, each coil is equipped with magnetic shielding material. The coils of SPTx are connected in series and excited by a single power supply without any current amplitude or phase control circuits. The performance of SPTx system is validated with different receivers (Rx) by experiments. In the experiment with dual Rxs, the maximum transmission efficiency is 79.6% with an efficiency stability rate of 49%. In addition, the output power does not affect the efficiency, and more Rxs will increase transmission efficiency. [ABSTRACT FROM AUTHOR]

Physical layer (PHY) authentication methods provide spatial security by exploiting the unique channel between two users. In recent years, many studies focused on substituting traditional threshold-based detection mechanisms with machine/deep learning classifiers to solve the threshold selection problem and obtain better detection accuracy. However, these studies assume that receivers have access to spoofer's channel information at the training of the classifier, which is unrealistic for real-time scenarios. In this study, we propose a PHY-authentication architecture for wireless multiple access channels (W-MACs) that removes this assumption and works without any prior information about the spoofer. The proposed method is designed for multi-user systems and is suitable for any classifier model or communication protocol. The feasibility and the performance of the proposed method are investigated via computer simulations and compared with a benchmark model. The results proved the feasibility of the proposed method as it can detect spoofers successfully without requiring spoofers' channel information. [ABSTRACT FROM AUTHOR]

Millimeter wave massive multiple-input and multiple-output (MIMO) systems support several antennas at the receiver and transmitter sides to serve several users in a communication system. Due to its several antennas, the system cost is very high and faces challenges such as blockage, path loss, and interference. To solve the above interference problem, beamforming technology and LMS Kalman filter-based Hybrid Precoding are used in millimeter wave massive MIMO system by directing the signal in the desired direction and to get a reduced bit error rate. Therefore, proposed hybrid precoding aims to leverage the advantages of both digital and analog beamforming while significantly reducing the number of RF chains compared to the number of antennas, all while maintaining the benefits of spatial multiplexing. This paper compares the performance of various precoding techniques, including Analog-only Beamsteering, Zero Forcing (ZF), Minimum Mean Square Error (MMSE), Kalman, Minimum Square Error Fully digital (MSE Fully digital), and Proposed Least Mean Squares (LMS) Kalman Hybrid Precoding, using performance metric parameters such as spectral efficiency, energy efficiency, bit error rate, and Information rate. The LMS Kalman Hybrid Precoding improved the spectral efficiency by almost 6.228 bps/Hz at 10 dB with ten channel paths concerning the Analog-only Beamsteering and almost 3.748, 2.974, 2.758, and 0.399 bps/Hz for the Zero Forcing (ZF) Hybrid Precoding, MMSE, Kalman, and MSE Fully Digital Hybrid Precoding techniques, respectively, which shows the superiority of the Proposed Least Mean Squares (LMS) Kalman Hybrid Precoding. [ABSTRACT FROM AUTHOR]

This study investigates volatility spillovers and network connectedness among four cryptocurrencies (Bitcoin, Ethereum, Tether, and BNB coin), four energy companies (Exxon Mobil, Chevron, ConocoPhillips, and Nextera Energy), and four mega-technology companies (Apple, Microsoft, Alphabet, and Amazon) in the US. We analyze data for the period November 15, 2017–October 28, 2022 using methodologies in Diebold and Yilmaz (Int J Forecast 28(1):57–66, 2012) and Baruník and Křehlík (J Financ Economet 16(2):271–296 2018). Our analysis shows the COVID-19 pandemic amplified volatility spillovers, thereby intensifying the impact of financial contagion between markets. This finding indicates the impact of the pandemic on the US economy heightened risk transmission across markets. Moreover, we show that Bitcoin, Ethereum, Chevron, ConocoPhilips, Apple, and Microsoft are net volatility transmitters, while Tether, BNB, Exxon Mobil, Nextera Energy, Alphabet, and Amazon are net receivers Our results suggest that short-term volatility spillovers outweigh medium- and long-term spillovers, and that investors should be more concerned about short-term repercussions because they do not have enough time to act quickly to protect themselves from market risks when the US market is affected. Furthermore, in contrast to short-term dynamics, longer term patterns display superior hedging efficiency. The net-pairwise directional spillovers show that Alphabet and Amazon are the highest shock transmitters to other companies. The findings in this study have implications for both investors and policymakers. [ABSTRACT FROM AUTHOR]

This study examines the time-varying asymmetric interlinkages between nine US sectoral returns from January 2020 to January 2023. To this end, we used the time-varying parameter vector autoregression (TVP-VAR) asymmetric connectedness approach of Adekoya et al. (Resour Policy 77:102728, 2022a, Resour Policy 78:102877, 2022b) and analyzed the time-varying transmitting/receiving roles of sectors, considering the positive and negative impacts of the spillovers. We further estimate negative spillovers networks at two burst times (the declaration of the COVID-19 pandemic by the World Health Organization on 11 March 2020 and the start of Russian-Ukrainian war on 24 February 2022, respectively). Moreover, we performed a portfolio back-testing analysis to determine the time-varying portfolio allocations and hedging the effectiveness of different portfolio construction techniques. Our results reveal that (i) the sectoral return series are strongly interconnected, and negative spillovers dominate the study period; (ii) US sectoral returns are more sensitive to negative shocks, particularly during the burst times; (iii) the overall, positive, and negative connectedness indices reached their maximums on March 16, 2020; (iv) the industry sector is the largest transmitter/recipient of return shocks on average; and (v) the minimum correlation and connectedness portfolio approaches robustly capture asymmetries. Our findings provide suggestions for investors, portfolio managers, and policymakers regarding optimal portfolio strategies and risk supervision. [ABSTRACT FROM AUTHOR]

Wireless Network-on-Chip (WNoC) incorporating on-chipantennas has emerged as a promising alternative to overcome the communication bottleneck due to high frequency operation, propagation delay, crosstalk delay, noise and need for repeaters inwired interconnects in chip-multiprocessors (CMPs). Recent advancements in nano materials, such as graphene have enabled the development of novel plasmonic graphene devices, which intrinsically operate in THz band. This ultra-low power andcompact graphene-based nano-antennas (GNA) establishes ultra-high bandwidth THz-on-chip wireless links for intra/inter-chip communication. In this article, we design and simulate a novel fork-shaped planarplasmonic nano-patch antenna using grapheneon SiO2/Si substrate that can be integrated into transceivers working at THz frequencies operating from 0.5 THz to 2.6 THz. By simulation at THz band, proposed antenna performance as a wireless inter/intra-chip link is investigated by numericallyobtaining itssignal transmission coefficient characteristics between the two on-chip antennas, acting as transmitter and receiver or vice-verse for short-range THz communication among wireless NoC based multi-core processors integrated on same substrate. Theresults are obtained by placing the antennas in broadside orientation, that can communicate with intra-chip transmission coefficients ranging from − 20 dB to − 60 dB while sustaining bandwidths upto 0.13–0.2 THz. Further, the effect of transmission and radiation performance of proposed antennas with increase in distance dlink is studied along with reconfigurable nature of graphene with varying chemical potentials from 0.1 eV − 0.5 eV. Proposed antenna has obtained maximum gain and radiation efficiency of 3.89 dB and 58% at 1.83 THz when chemical potential of 0.1 eV is applied. This concept can broadly be applied to future systems as it can be directly integrated into transceivers as graphene is compatible with CMOS processes.Fabrication process steps of proposed on-chip antenna and its feasibility as a real device in chip environment isalso discussed. [ABSTRACT FROM AUTHOR]

A scheme for the compensation of chromatic dispersion in Radio over Fiber systems with enhanced performance is proposed and demonstrated. The system implements a cascade of an Ideal Dispersion Compensation Filter and a tanh apodized, linearly chirped Fiber Bragg Grating for mitigating the degradation caused by chromatic dispersion. The analysis probes variations in transmission distance and channel spacing while investigating vital performance parameters like the Q factor and Bit Error Rate. Two-channel spacings of 100 GHz and 50 GHz, transmission distances ranging between 70 and 120 km and effective refractive index of the apodized and linearly chirped FBG extending between 1.3 and 1.5 are considered for the study. The analysis also covers the analysis of optical signal to noise ratio as the fiber length is varied. Additionally, the system performance is evaluated when the transmitted power of the continuous wave Laser in the transmitter segment is altered. The simulation results demonstrate that the system provides acceptable Q factor and BER values even at a transmission distance of 120 km. The comparative analysis with the formerly published results validates the performance enhancement achieved by the proposed system. [ABSTRACT FROM AUTHOR]

The electromagnetic detection method is the main method of marine oil and gas resource exploration, and the marine electromagnetic transmitter is the key equipment of marine electromagnetic detection systems. At present, the power factor of the controllable source circuit of the electromagnetic transmitter is low, energy cannot be fed back, and the capacitance of the filter capacitor is large, which results in a large volume of the electromagnetic transmitter and high maintenance costs. Thus, a cascaded H-bridge controllable source circuit combined with active power decoupling technology is introduced in this paper. First, the topological structure and working principle of the controllable source circuit of the electromagnetic transmitter are analyzed, and an improvement plan is proposed for the existing problems of the controllable source circuit. Second, the working principle of the improved controllable source circuit is analyzed, and the advantages of the improved scheme are expounded. Then a control strategy based on linear active disturbance rejection control (ADRC) is proposed, and a linear ADRC controller is designed. Simulation results show that the improved controllable source circuit reduces the capacitance value, improves the power factor, reduces the volume of the underwater towing body, and reduces the maintenance cost of the system. The proposed control strategy makes the DC voltage have better anti-disturbance performance, and improves the reliability of the electromagnetic transmitter in deep sea exploration. [ABSTRACT FROM AUTHOR]

In the context of clean energy and green cryptocurrency development, the relationship between energy and cryptocurrency markets deserves further exploration. This study employs a quantile time-frequency connectedness approach to measure the dynamic connectedness and volatility propagation mechanisms between oil, clean energy, green cryptocurrency (GC), and non-green cryptocurrency (NGC) markets. Our findings suggest that, at median and low volatility levels, the oil and clean energy markets act as net receivers, taking on volatility spillovers from cryptocurrency markets. However, at high volatility levels, oil and clean energy markets transform into net transmitters. Most NGCs are volatility transmitters, while most GCs are volatility receivers in the median and extremely high volatility cases. We also observe that the total connectedness index (TCI) is heterogeneous over time and dependent on economic events. At median and low volatility levels, the short-run TCI makes the primary contribution. On the other hand, for high volatility levels, where short-term TCI does not have an absolute advantage, long-term TCI plays a greater role in many periods. Additionally, there is asymmetry in the TCI (including long-term and short-term TCI) at the quantile level. In the median and extreme scenarios, the COVID-19 has caused different levels of shock on oil, clean energy, GC, and NGC markets connectedness. [ABSTRACT FROM AUTHOR]

Fixed Point-to-Point microwave wireless systems with high spectral efficiency are needed to meet the pervasive and increasing demand for capacity in back-haul networks of mobile radio systems. In this context, spatially multiplexed LoS-MIMO (Line-of-Sight Multiple Input Multiple Output) systems have been studied for about twenty years, particularly in the millimeter wave frequency bands (above 15 GHz). However, their deployment in real networks has been really limited, to the authors' knowledge. This has been due to several factors, i.e. the practical possibility of using extremely high-level modulation formats (nowadays up to 8192-QAM), the joint use of co-channel dual polarization, and the availability of wider channel bands in the new high frequency ranges (e.g. E-Band). In addition, a crucial reason has been the difficulty of installing multiple antennas spaced apart in order to maximize the MIMO spatial multiplexing so providing the maximum capacity gain. This optimal antenna separation, even for the classical MIMO M × N with M = 2 antennas at the receiver and N = 2 antennas at the transmitter, can be several meters, e.g. 5.71 m at 23 GHz on a 5 km link. In this article, we analyze the performance of LoS-MIMO systems where antenna separation is highly sub-optimal, for limiting the array size, and a satisfactory performance is made possible by the exploitation of specific bit loading and power allocation strategies and the setting of the working region of the RF transmitter power amplifiers to operate at a given Signal-to-Inter Modulation Distortion Ratio (SIMDR). The result is an overview of the advantages and drawbacks of compact LoS-MIMO from a wider perspective than in the existing literature, including fundamental aspects for the practical implementation of these systems. Performance is discussed in many cases of interest and compared with the state of the art SISO (Single Input Single Output) system. [ABSTRACT FROM AUTHOR]

Empirical evidence suggests that marine animals perceive and orient to local distortions in the earth's natural magnetic field. Magnetic fields (MFs) generated by electrified underwater cables may produce similar local distortions in the earth's main field. Concern exists that these distortions may impact migration movements of MF-sensitive animals. The Trans Bay Cable (TBC) is a ± 200-kV, 400-megawatt, 85-km high-voltage direct current transmission line buried through San Francisco Bay (37° 56′ 8.81″ N, 122° 27′ 0.19″ W). Detections of adult green sturgeon implanted with acoustic transmitters were used from six cross-bay receiver arrays from 2006 to 2015 to investigate how inbound and outbound migration movements through lower portions of their route to/from upstream breeding grounds are related to the TBC's energization status (off/on) and other local environmental variables. Here, we assess how these variables impacted transit success, misdirection from the migration route, transit times, and migration path locations within stretches between the Bay's mouth and the start of the Sacramento River. Overall, there was varied evidence for any effect on migration behavior associated with cable status (off/on). A higher percentage of inbound fish successfully transited after the cable was energized, but this effect was nonsignificant in models including temperature. Outbound fish took longer to transit after cable energization. Inbound and outbound migration path locations were not significantly influenced by cable energization, but results suggest a potential subtle relationship between energization and both inbound and outbound paths. Overall, additional migration-based studies are needed to investigate the impact of anthropogenic cables on marine species. [ABSTRACT FROM AUTHOR]

We investigate the response bandwidth of a superheterodyne Rydberg receiver at a room-temperature vapor cell, and present an architecture of multi-channel lasers excitation to increase the response bandwidth and keep sensitivity, simultaneously. Two microwave fields, denoted as a local oscillator (LO) E LO and a signal field E SIG , couple two Rydberg states transition of | 52 D 5 / 2 〉 → | 53 P 3 / 2 〉 . In the presence of the LO field, the frequency difference between two fields can be read out as an intermediate frequency (IF) signal using Rydberg electromagnetically induced transparency (EIT) spectroscopy. The bandwidth of the Rydberg receiver is obtained by measuring the output power of IF signal versus the frequency difference between two fields. The bandwidth dependence on the Rabi frequency of excitation lasers is presented, which shows the bandwidth decrease with the probe Rabi frequency, while it is quadratic dependence on the coupling Rabi frequency. Meanwhile, we investigate the effect of probe laser waist on the bandwidth, showing that the bandwidth is inversely proportional to the laser waist. We achieve a maximum response bandwidth of the receiver about 6.8 MHz. Finally, we design an architecture of multi-channel lasers excitation for increasing the response and keeping the sensitivity, simultaneously. Our work has the potential to extend the applications of Rydberg atoms in communications. [ABSTRACT FROM AUTHOR]

To address the rising demand for high-speed wireless data links, communication systems operating at frequencies beyond 100 GHz are being targeted. A key enabling technology in the development of these wireless systems is the phased antenna array. Yet, the design and implementation of such steerable antenna arrays at frequencies over 100 GHz comes with a multitude of challenges. In particular, the cointegration of active electronics at each antenna element poses a major hurdle due to the inherent space constraints in the array. This article proposes a novel scalable concept for opto-electronic phased antenna arrays operating at 140 GHz. It details the system architecture of a transmitter that enables the implementation of large scale, wideband, 2D steerable phased antenna arrays and presents the design and measurement of a compact SiGe power amplifier (PA) chip to be used as one of its key building blocks. The amplifier achieves a gain of 20 dB at 135 GHz, features a P 1 d B of 14.6 dBm and can support data rates up to 45 Gbps in a limited footprint of only 540μm × 550μm. This makes it one of the fastest, most powerful D-band power amplifiers in literature with a footprint compatible with λ 2 -spaced phased array integration. [ABSTRACT FROM AUTHOR]

Equipping Galileo satellites with a VLBI transmitter (VT) will allow to observe satellites next to quasars with Very Long Baseline Interferometry (VLBI) radio telescopes. This concept will facilitate the direct estimation of the satellite orbits in the celestial reference frame. Moreover, these observations along with usual Galileo observations can be used to transfer the space tie between the VT and the antenna on the Galileo satellite to the Earth surface realizing the frame tie at the geodetic site with VLBI radio telescope and Galileo antenna. In this study, we assess the accuracy of that frame tie by simulating the estimation of station coordinates from VLBI observations to Galileo satellites next to quasars. We find that at least two or three satellites need to be equipped with a VT with the best results if all satellites with a VT are placed in the same plane. Concerning the ratio between satellite and quasar observations within a schedule, the results suggest that the optimal ratio is around 30% to 40% satellite observations out of the total number of observations in order to have enough observations for the estimation of the station coordinates but still enough quasar observations to ensure a sufficient sky-coverage for the estimation of troposphere parameters. The best scenario with two satellites yields repeatabilities for the east and north components between 7.5 and 10 mm, and for the up component between 9.5 and 12 mm. In case there is a third satellite with a VLBI transmitter in the same plane, the repeatabilities are reduced by up to 2 mm for the horizontal components and up to 3 to 4 mm for the up component. Rotating the schedules over the constellation repeat cycle of Galileo of 10 days reveals that there are differences between the individual days, but there are no days with a significantly worse precision of the estimated station coordinates. [ABSTRACT FROM AUTHOR]

This paper studies overlay-based cognitive radio networks (ObCRNs) where transmission from a licensed transmitter (LT) to a licensed receiver (LR) is supported by an unlicensed transmitter (UT) who has its own communication to an unlicensed receiver (UR). To improve power efficiency of UT and diversity gain at UR and LR, UT operates in direct transmission (DT) or amplify-and-forward (AF) mode or decode-and-forward (DF) mode, and UR and LR combine signals with selection combining (SC) and maximum ratio combining (MRC) from LT and UT. Explicit outage probability expressions for ObCRNs with MRC/SC and DT/AF/DF are proposed to promptly rate its performance. Numerous results reveal the efficacy of the proposed solution and its flexibly-controlled performance. [ABSTRACT FROM AUTHOR]

A new method for capacity and spectral efficiency increases is a full-duplex communication, where sending and receiving are done simultaneously. Hence, severe interference leaked from the transmitter to the receiver, which can disrupt the system's operation completely. For interference reduction, the transceiver tries to estimate the interfering symbols to remove their effects. A typical method is to use the Hammerstein model. In this method, nonlinear power amplifier (PA) and multipath channel are modeled with a successive nonlinear system and a finite impulse response filter. Then, the model parameters are adjusted, and interference symbols are estimated from the transmitted symbols. In the Hammerstein method, the interference symbols are estimated directly from the transmitted symbols. But practically, the transmitted symbols first pass through the pulse-shaping filter and become a signal. Then, this signal passes through the nonlinear PA and communication channel. Finally, the received signal is filtered by the matched filter (MF) at the receiver and converted to the symbols again. In this procedure, the amplifier and the communication channel affect the transmitted signal directly and distort transmitted symbols indirectly. Therefore, in the practical situation, when we consider the transmitter's pulse-shaping filter and the receiver's MF, the estimated symbols with the Hammerstein method are erroneous. To solve this problem, a new MF at the receiver is proposed and adjusted according to the interfering signal. We have shown that this method is far better than the Hammerstein method. [ABSTRACT FROM AUTHOR]

Home ranges of free-living mammals have typically been studied via radio-tracking to understand how individuals use their environment. Recently, GPS collars have become popular in large mammals. However, GPS collars are rarely used in small mammals, as they are too heavy, especially when needing coating to protect against gnawing. Here we test the efficiency of mini-GPS collars to measure range estimates compared to the use of radio-collars in a small rodent of 100 g body mass. We equipped 20 bush Karoo rats with mini-GPS loggers and thereafter with radio-transmitters to determine ranges. We validated the accuracy of the mini-GPS loggers by comparing them with the fixes from a handheld GPS and found both to be similar. We estimated range sizes using both traditional methods of Kernel and minimum convex polygon estimates as well as modern methods from movement ecology taking the location error of the mini-GPS into account. Using modern methods led to smaller range estimates, but results were in so far consistent that daily ranges for bush Karoo rats determined using mini-GPS were much larger than home range estimates from radio tracking. Using radio-tracking enabled us to establish the central shelter, while the mini-GPS revealed areas where rats had been observed foraging. We found a distinct location error and therefore suggest using modern approaches from movement ecology which can take this error into account. In sum, mini-GPS revealed more accurate estimates of the ranges than radio-tracking in a small rodent of 100 g body mass. [ABSTRACT FROM AUTHOR]

The selection of a suitable method for tagging fish with transmitters is essential to ensure the feasibility of telemetry studies. Here, using a micro-acoustic transmitter, we examined the effects of tagging methods such as external attachment and surgical implantation on tag retention, and growth and survival of hatchery-reared spotted halibut at the release size (ca. 8–10 cm in total length). Fish with surgical implantation showed higher survival and retention rates than those with external attachments. However, the tagging methods did not influence the growth of the tagged fish. These findings indicated that surgical implantation of acoustic transmitters can be applied to small-sized spotted halibut. Overall, the findings can enhance the study about post-release movement of hatchery-reared fish at the release size to manage and conserve flatfish stocks. [ABSTRACT FROM AUTHOR]

In this paper, an array multi-transmitter multi-mode wireless power transfer system is proposed. The system realizes the joint modulation of three transmitter coil working modes of single transmitter coil, dual transmittercoil and four transmitter coils in the wireless power transfer system through PI closed-loop control, which can realize the stable output of WPT system in three different transmitter coil work modes. It effectively compensates for the shortcomings of the single working mode of a single transmitter coil and the limited range of effective working areas, and improves the robustness of the wireless power transfer system. [ABSTRACT FROM AUTHOR]

We present a 3-D ultrasound imaging system utilizing a light-based ultrasound transmitter. The system achieves high spatial resolution through a plain surface coated with a thin layer of carbon nanotubes (CNTs), which is optically scanned by a pulsed laser. The transmitter is fabricated by depositing a CNT-polydimethylsiloxane composite onto a glass substrate using techniques such as dip coating, dropping, and spin coating. The transmission characteristics are dependent on the laser beam width and CNT layer thickness, with the spin-coated layer demonstrating a center frequency of 9.08 MHz and bandwidth of 12.65 MHz. The imaging system boasts an axial resolution of 200 μm and lateral resolution of 190 μm. 3-D imaging was successfully performed on a chicken heart with a penetration depth up to 30 mm, providing a potential replacement for complex high voltage pulser circuits with a simple and manufacturable optical ultrasound transmitter. [ABSTRACT FROM AUTHOR]

Distributed wireless network devices are mostly battery-powered. Transmitting a message on distributed wireless networks uses more energy than receiving one, which in turn uses more energy than internal computations. Therefore, in this paper, we study the problem of randomized leader election in synchronous distributed single-hop networks with a special focus on the energy complexity. We provide algorithmic solutions to the implicit version of leader election problem where non-leader nodes need not be aware of the identity of the leader. Because the size of a message impacts the energy consumption, we highlight that the solutions we propose consume very little energy: each device is allowed to send a single one-bit message only once and listen to the network during two time slots at most. We first consider four well-studied variants of the radio network (RN) model depending on the transmission and reception abilities of the participating devices: RNstrongCD: both transmitters and listeners can detect collision, RNsenderCD: only transmitters can detect collision, RNCD: only listeners can detect collision, RNnoCD: no device can detect collision. Next, we study the beeping network model. The time and energy complexities of all our algorithms are deterministic and they succeed in electing a unique leader with high probability even under the restriction that each node can only send once a single one-bit signal. When the nodes are aware of the total number n of the participants, our algorithm elects a leader in O (log n) rounds. When n is not known beforehand but an upper bound u on n with log u = Θ (log n) is known by all participating nodes, we design a randomized algorithm with O (log 2 n) time complexity for the RN models. For beeping networks, our algorithm has O (n ε) time complexity ( 0 < ε < 1 ). The parameter ε can be tuned to increase the probability of success of the algorithms. [ABSTRACT FROM AUTHOR]

Adaptive analog beamforming is a key technology to enable spatial control of millimeter-wave wireless signals radiated from phased array antennas (PAAs) which is essential to maximize the capacity of future mobile networks and to ensure efficient usage of scarce spectrum. Intermediate frequency-over-fiber (IFoF), on the other hand, is a promising technology for the millimeter-wave (mm-wave) mobile fronthaul due to its low complexity, high optical spectral efficiency, and low latency. The combination of IFoF and PAA is key to implement mm-wave mobile communications in a scalable, centralized, efficient, and reliable manner. This work presents, for the first time to the best of the authors' knowledge, an extensive outdoor measurement campaign where an experimental IFoF mm-wave wireless setup is evaluated by using PAAs with adaptive beamforming on the transmitter and receiver sides. The configuration of the experimental setup is according to 5G standards, transmitting signals wirelessly at 27 GHz central frequency in the n258 band. The employed PAAs are composed of 8-by-8 patch antenna arrays, allowing beam steering in the azimuth and elevation angles. Furthermore, different end-user locations, antenna configurations, and wireless scenarios are tested in the outdoor experiment, showing excellent EVM performance and achieving 64-QAM transmission over up to 165.5 m at up to 1.88 Gbit/s. The experimental results enable optimization of the experimental setup for different scenarios and prove the system's reliability in different wireless conditions. In addition, the results of this work prove the viability and potential of IFoF combined with PAA to be part of the future 5G/6G structure. [ABSTRACT FROM AUTHOR]

Metasurfaces have promising potential to revolutionize a variety of photonic and electronic device technologies. However, metasurfaces that can simultaneously and independently control all electromagnetics (EM) waves' properties, including amplitude, phase, frequency, polarization, and momentum, with high integrability and programmability, are challenging and have not been successfully attempted. Here, we propose and demonstrate a microwave universal metasurface antenna (UMA) capable of dynamically, simultaneously, independently, and precisely manipulating all the constitutive properties of EM waves in a software-defined manner. Our UMA further facilitates the spatial- and time-varying wave properties, leading to more complicated waveform generation, beamforming, and direct information manipulations. In particular, the UMA can directly generate the modulated waveforms carrying digital information that can fundamentally simplify the architecture of information transmitter systems. The proposed UMA with unparalleled EM wave and information manipulation capabilities will spark a surge of applications from next-generation wireless systems, cognitive sensing, and imaging to quantum optics and quantum information science. The authors show a universal metasurface antenna capable of simultaneously and independently controlling all five fundamental properties of electromagnetic waves, including amplitude, phase, frequency, polarization, and momentum. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the role of asprosin in the regulation and mechanisms of oxygen transport in the blood and the gas transmitter system in men with different body mass index. The indicators of lipid and carbohydrate metabolism, as well as the oxygen transport function of the blood and the concentration of gas transmitters, nitrogen monoxide and hydrogen sulfide in it, were determined. A higher concentration of asprosin was found in individuals with an increased body mass index and grade I obesity. With an increased content of asprosin, there is a decrease in the main indicators of blood oxygenation and an increase in the affinity of hemoglobin for oxygen. An increase in the concentration of nitrogen monoxide and a decrease in hydrogen sulfide were revealed at a high content of asprosin, which may be important for the formation of the mechanisms of oxygen transport in the blood. [ABSTRACT FROM AUTHOR]

Information encryption technique has broad applications in individual privacy, military confidentiality, and national security, but traditional electronic encryption approaches are increasingly unable to satisfy the demands of strong safety and large bandwidth of high-speed data transmission over network. Optical encryption technology could be more flexible and effective in parallel programming and multiple degree-of-freedom data transmitting application. Here, we show a dual-layer optical encryption fluorescent polymer waveguide chip based on optical pulse-code modulation technique. Fluorescent oligomers were doped into epoxy cross-linking SU-8 polymer as a gain medium. Through modifying both the external pumping wavelength and operating frequency of the pulse-code modulation, the sender could ensure the transmission of vital information is secure. If the plaintext transmission is eavesdropped, the external pumping light will be switched, and the receiver will get warning commands of ciphertext information in the standby network. This technique is suitable for high-integration and high-scalability optical information encryption communications. Data security of internet is increasingly more demanding in the current era, yet the traditional electronic approach is limited in speed and efficiency. Here, the authors proposed a dual-layer optical encryption fluorescent polymer waveguide chip based on optical pulse-code modulation to mitigate the limitations. [ABSTRACT FROM AUTHOR]

Inductive power transfer (IPT) technology is a promising solution for charging the electric vehicles (EVs) by enabling an EV to charge its energy storage system (battery) without any connecting wires through magnetic coupling. This paper proposes a new receiver design named Hollow Solenoid receiver that is compatible with the standard double-D transmitter defined by the SAE J2954 standard. A deep design analysis for the proposed Hollow Solenoid receiver is presented to define the optimum design parameters for coil (inductances, number of turns, dimensions, wires, etc.) and ferrite core (dimensions, number, arrangement, etc.). Several WPT3 (11.1kVA) solenoid receiver (SR) designs were presented and analyzed based on efficiency, weight, size, volume, and cost. The performance of the proposed SR was compared with the global Double-D receiver (DDR) presented by the SAE J2954 standard under different lateral and rotational alignment and loading conditions considering coupling factor, transmission power and efficiency, and stray electromagnetic fields (EMFs). The entire IPT system including coils, compensation network, power converters, controls, and battery load was modeled and analyzed for both SR and DDR coils. The results reveal that the proposed SR is compatible with the global DD transmitter at different alignment and loading conditions and is able to transmit the desired power (11 kW) at an efficiency > 85%. Hollow SR design shows the highest efficiency and lowest size, weight, and cost compared to DDR and other designs. [ABSTRACT FROM AUTHOR]

The antenna is essential for anyone who wishes to communicate with others in remote regions. The antenna acts as a transducer that converts electromagnetic into electric power and vice versa. Based on the mode of application, different types of antennas are used. One of the most used antenna types is MIMO, which stands for multiple-input and multiple outputs. In wireless MIMO, multiple antenna elements are connected on both the receiver and transmitter sides. The reviewed antennas are printed on various substrates, and simulation is carried out in the HFSS tool. Optimized MIMO antenna algorithms are implemented in the MATLAB tool. Optimization algorithms such as the Hybrid Jaya-grey wolf optimization algorithm (J-GWO), Particle swarm optimization algorithm (PSO), Quasi-newton optimization algorithm (QNO), Salp swarm optimization algorithm (SSO), Moth-flame optimization algorithm (MFO), Ant colony optimization algorithm (ACO), Social spider optimization algorithm (SSO), Sealion optimization algorithm (SLO), Genetic algorithm optimization (GA) and hybrid Differential evolution based naked mole-rat optimization algorithm (HDN), Invasive weed optimization algorithm (IWO) and Teaching–learning optimization algorithm (TLBO) are reviewed from various literature. Many recent research works are analyzed to provide an efficient idea for the researchers to implement new optimization techniques in future. [ABSTRACT FROM AUTHOR]

The article analyses the effectiveness of a chaotic communication scheme based on synchronization of hyperbolic chaos generators used as a receiver and a transmitter. It is shown that useful information nonlinearly mixed into the transmitter signal can be detected by the receiver if the receiver has stable synchronization with the transmitted signal. Research, aimed to confirm the hypothesis that robustness, strong chaoticity and noise-like wideband spectrum of this type of oscillators provide reliability and stability of transmission, has been carried out. This study also shows the effect of noise and frequency distortion of the signal in a communication channel on the quality of information detection. [ABSTRACT FROM AUTHOR]

Continuous-variable quantum key distribution (CV-QKD) provides a theoretical unconditionally secure solution to distribute symmetric keys among users in a communication network. However, the practical devices used to implement these systems are intrinsically imperfect, and, as a result, open the door to eavesdropper attacks. In this work, we study the impact of transmitter stage imperfections on the performance and security of a Discrete Modulated (DM) CV-QKD system using M-symbol Quadrature Amplitude Modulation (M-QAM) and Amplitude and Phase Shift Keying (M-APSK) coupled with Probabilistic Constellation Shaping (PCS). Assuming two different modulation stage topologies, we first deform the constellations and then evaluate the secure key rate achievable with the deformed constellation. The presented results show that, due to the erroneously estimated channel parameters, non-monitored imbalances greatly reduce the system's performance, with situations where Bob and Alice estimate that no secure bits can be obtained while the real value of the key rate is still positive. Our results show the importance of monitoring these constellation imbalances and show that the optimal constellation may vary depending on the degree of device imperfection. [ABSTRACT FROM AUTHOR]

In this paper, we study a cognitive radio wireless-powered communication network with an integrated intelligent reconfigurable surfaces system. Actually, massive connectivity and limited energy are the primary challenges to implementing ultra-reliable and low-latency services, as it is extremely difficult to maintain the quality of service and manage the connection of a huge number of users to small cells. So, this paper investigates the application of NOMA-based simultaneous wireless information and power transfer (SWIPT) for massive mobile systems in which the underlay spectrum sharing network is designed to mitigate the interlayer interference such that interference with the primary network is kept less than a predefined level. Problem modeling takes into account residual hardware impairments and channel estimation errors under practical conditions. The communications between the servers and users of NOMA-based small cells are accomplished via an interference-limited multihop connection through intermediate relays. Based on the partial relay selection (PRS) protocol, an optimal relay is selected from K relays to transmit the received signal to multiple user equipment, namely, the far users (FU) and the near users (NU). In addition, to maximize the system total throughput, we formulate the transmitter (Tx)-relay-receiver (Rx) matching problem, which is a mixed-integer nonlinear programming (MINLP) problem. To address this nondeterministic polynomial-time NP-hard problem, we applied a gradient algorithm to obtain a stable matching. The impact of the transmission power, the number of Tx/Rx pairs, and the number of intermediate relays on the sum rate are investigated. Based on the simulation results, the hardware failure parameter has a negative impact on system performance, whereas the channel estimation index is always advantageous to outage probability (OP). Also, the analysis of the energy efficiency and key performance indicators proves that the proposed approach outperforms other similar schemes from the power saving and QoS assurance perspectives. [ABSTRACT FROM AUTHOR]

An overshoot generated in the optical fiber communication system's transmitter may degrade bit error ratio performance and even damage the device. This overshoot is caused by the output capacitance of driver, the parasitic inductance of bonding wire, and vertical-cavity surface-emitting laser (VCSEL). This paper introduces a 25Gb/s VCSEL driver using a current-mode pre-equalization technique to suppress overshoot. The driver is designed in 0.13 μ m SiGe BiCMOS technology. The post-simulation results show that the pre-equalization technique applied to the driver can suppress the overshoot in the VCSEL output waveform. The measurement results show that the VCSEL driver can output an electrical eye diagram to suppress the overshoot. The core area of the VCSEL driver chip is 0.305 mm × 1.207 mm, including driver circuit, delay circuit, bandgap reference circuit, and digital-to-analog converter. [ABSTRACT FROM AUTHOR]

In this research, we study the interference cancellation capabilities of receivers and transmitters in multiple-input-multiple-output (MIMO) systems using theoretical calculations and numerical simulations in Quadriga. We study so-called Reduced Channel Zero-Forcing (RCZF) class of precoding as well as Minimum MSE Interference Rejection Combiner (MMSE-IRC) and QR Maximum Likelihood Detection (QR-MLD) receivers. The precodings from the RCZF class are widely used in practice and include for example Zero-Forcing (ZF) and Eigen Zero-Forcing (EZF) precodings. Our theoretical and experimental results confirm that MMSE-IRC and QR-MLD receivers in combination with the RCZF precoding provide complete interference suppression asymptotically. The major findings and the calculation results far as the RCZF class of precoding as well as the MMSE-IRC and QR-MLD receivers' performance concerned, which is a subject of the paper. [ABSTRACT FROM AUTHOR]

In this article, we compute the Secrecy Outage Probability (SOP) and the Probability of Strictly Positive Secrecy Capacity (SPSC) for Cognitive Radio Networks with Adaptive Transmit Power and energy harvesting using multiple antennas. The secondary source harvests power using multiple antennas using node A signal. Node A is a node transmitting Radio Frequency signals. Then, it adapts its power to generate interference at primary receiver P R less than T. Our analysis takes into consideration the interference between primary and secondary nodes. In fact, the Signal to Interference plus Noise Ratio is analyzed at the secondary destination in the presence of interference from the primary transmitter. We derive the SOP and SPSC when the secondary source and destination have multiple antennas. The transmission is made from the best antenna of the secondary source to the best receiving antenna at the secondary destination. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiple access (OFDMA) is a multi-carrier, multiple access (MA) technique, which is widely adopted in contemporary wireless standards. Single carrier-frequency division multiple access (SC-FDMA) is a modified version of OFDMA which employs single carrier transmission by pre-coding the data symbols using discrete Fourier transform (DFT). However, these systems are highly vulnerable to the adverse effects arising in the channel, carrier frequency offset (CFO) and in-phase/quadrature phase (I/Q) imbalances. In the uplink communication scenario, the signal received at base station is the superposition of signals from all the active users. Even though the adverse effects caused by the communication channel and CFOs are addressed in the related literature extensively, the effect of I/Q-imbalances at the transmitter and the receiver is rarely considered. The effect of I/Q-imbalances will make the equalization process at the base station more complex. It is because the overall effective channel with radio impairments must be included in the system modelling. Hence the receiver processing should contain the equalization for effect of the channel, CFOs and I/Q imbalances. In this paper, we propose a novel technique based on the oblique projection (OP) technique for equalizing the channel, radio imbalances and synchronization errors caused by both transmitter (TX) and receiver (RX) for OFDMA/SC-FDMA uplink systems. We also propose an equalization technique with reduced computational complexity to overcome the adverse effects caused by I/Q imbalances and CFOs. The results of the simulation studies illustrate that the proposed techniques can compensate all the above-mentioned effects and they offer very good performance under both TX and RX I/Q imbalances. [ABSTRACT FROM AUTHOR]

On-line performance monitoring of RF integrated circuits throughout their operating lifetime is a promising way to enhance their reliability. This paper explores the feasibility of adapting the indirect test strategy to implement on-line RF performance monitoring. After stating the principle of the proposed solution, we consider the fundamental requirements necessary to adapt the indirect test strategy. Finally, a proof of concept is established through a practical case of study by monitoring the power level delivered by the RF transmitter of a wireless microcontroller: hardware measurement results demonstrate the potential of this approach. [ABSTRACT FROM AUTHOR]

It is extremely important to accurately measure the liquid level as a process variable of a storage tank used by any plant. The transmitted electrical signal from a liquid level transducer or any other transducer to a remote indicator or controller may sometimes suffer from the measurement error due to its contamination with noise signal. This may be easily avoided by using modern optical fiber communication technique wherein we see the production of optical signal from the transducer output and its noise free communication through fiber-optic cable. In thie present paper, an opto-electronic liquid level transmission technique has been proposed for liquid which is conducting in nature and generally, collected in a storage tank. The electronic part of the transmitter unit consists of a modified capacitive transducer with a signal conditioner unit which produces an electrical DC output voltage which is linearly related with the level of the conducting liquid in the storage tank. This DC voltage is transformed into an optical signal with the help of Mach–Zehnder Interferometer (MZI) based electro- optic converter. Generated Optical signal may be dispatched to any location which is remote in nature by using fiber optic cable. Thus, various types of measurement error observed in the conventional capacitive level transmitter are minimized by using the proposed system. In the preset paper, a prototype model of the proposed system has been designed and developed to test its functionality. A good linear characteristic of the normalized optical output in support of the derived equations is observed. [ABSTRACT FROM AUTHOR]

In recent years, Multiple Input–Multiple Output (MIMO) has been used to expand data transfer for ensuring consistency. The transmitter and receiver use several antennas and they can achieve high spectral characteristics. The numbers of users and antennas increase rapidly questions the stability and reliability of the system. When MIMO is deployed, the complexity of the system increases and it becomes a major problem in many detection systems. When more and more number of receiver and senders pre-require an increased number of hardware components and a part it further increases the system's complexity and design. It is important to develop sophisticated components to improve compliance with many standards without compromising the Bit Error Rate (BER) performance of the components. The proposed work introduces a New Hybrid MIMO Detector (NHMD), which provides the solution for the complicated design procedure. The core concentration of this work is to minimize the complexity (Hardware) of the system by applying simplest design approach. This Hybrid system with a minimalistic detection approach helps in improve the BER: (Bit Error Rate) of the framework without compromising the overall performance of the system. This proposed method is designed on the Modified Optimal Differential Evolution (MODE) algorithm which is used to apt the best detector by deploying the objectives of this work. In addition, this method uses parallel processing to reduce the amount of arithmetic logic. The proposed NHMD method is implemented for cylindrical devices belonging to different FPGA families with different antenna configurations (2 × 2, 4 × 4). The proposed NHMD method provides superior quality by combining multiple detectors. The simulation results confirm that the NHMD method uses low equipment as well as low power consumption and provides high efficiency without affecting BER performance. [ABSTRACT FROM AUTHOR]