Multiple-input Multiple-output (MIMO) Systems

Long Term Evolution (LTE) is the final release of third generation (3G) leading to the fourth generation (4G) network. The demand for a very high speed network connection is the driving force for this mobile network evolution. Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA) are strong multiple access scheme candidates for the downlink and uplink of the LTE and LTE-Advanced Networks with Orthogonal Frequency Division Multiplexing (OFDM) being adopted by third generation partnership project (3GPP) as the standard for modulation technique used in transmission of high data rate in LTE Networks. In this research, a Matlab and Simulink software package were used to model and design an LTE downlink physical layer simulator according to 3GPP specifications. The simulation was carried out for the single downlink, from one eNodeB to User Equipment (UE). The performance of different multi-antenna techniques (transmission modes) was exploited in Diversity scheme and mobility environment with the aim of maximizing LTE performance using Multiple-Input Multiple-Output (MIMO) Optimization. However, the result show that MIMO spatial multiplexing offers the best capacity gains at high SNR and Open Loop Spatial Multiplexing (OLSM) is more robust at high SNR followed by CLSM because of their ability to support high data throughput as well as multi-stream transmission. This research strengthens the belief that performance of different multi-antenna scheme configurations is better than single antenna scheme and that multi-stream transmission will be a practical method for improving the data throughput in LTE Networks than single stream transmission

A miniature Multiple Input Multiple Output (MIMO) Ultrawideband (UWB) antenna with C-band notch is recommended for wireless communications. The radiator is etched on an economical FR4 substrate and is 40 × 21 mm 2 in size. The antenna is comprised of a circularly notched rectangular patch embedded with an ellipse and is fed by a 50-Ω microstrip line. To reduce mutual coupling by <-18 dB throughout the whole operational bandwidth of 2.94-11.61 GHz without employing any coupling device, the two radiators are positioned side-by-side with a separation of 0.03 λ 0 (λ 0 is the wavelength at the lower cutoff frequency of 2.94 GHz). A U-type slit is cut into the patch to produce the band-notch at C-band across 3.63-4.15 GHz. Results from simulation and experiment concludes that the suggested radiator has a wide impedance bandwidth (S 11 <-10 dB) and strong mutual coupling (S 21 <-18 dB) between 2.94 and 11.61 GHz. Except at the notch frequency of 4 GHz, where the gain is-3.21 dBi, the peak gain and peak radiation efficiency are both 4.21 dBi and more than 82%, respectively. The measured envelope correlation coefficient (ECC) of 0.002, peak diversity gain (DG) of 9.999 dB, and mean effective gain (MEG) of less than-3 dB over operating band, along with the omnidirectional characteristics of the radiator, prove its suitability for use in wireless systems.

We present an electromagnetic simulation of a practical mobile terminal with a two-port MIMO antenna on left and right sides of the head. The computed far-field patterns include the effect of head and hand phantoms. We show that the far-field patterns on the two sides are strongly correlated if they are presented in the coordinate system of the phone, but they are completely uncorrelated in the coordinate system of the environment. I.

Resumo: A agricultura familiar camponesa é marcada por conflitos e as inovações da agricultura latifundiária restritivas às necessidades de comunidades assentadas. Entretanto, o desenvolvimento da matriz científica da Agroecologia amplia as possibilidades sociotécnicas. O objetivo geral deste relato é compartilhar a experiência desenvolvida no Assentamento Milton Santos por meio das Tecnologias Sociais (TS). O objetivo específico é apresentar um dispositivo de baixo custo para monitoramento de compostagem caseira. A metodologia seguiu os princípios da Educação Popular com visitas de campo, coleta de dados e validação participativa. Os resultados apontam para um incremento da adubação usual pelo uso do dispositivo, demonstrando como as TS fortalecem redes sociotécnicas essenciais. Este trabalho faz parte do projeto "Agroecologia, tecnologias de produção orgânica em assentamentos rurais e educação popular", fomentado pelo CNPq e desenvolvido no âmbito do Núcleo de Estudos em Agroecologia, Educação e Sociedade

A method to characterize the memory effects in a nonlinear concurrent dual-band transmitter is presented. It is an extension of the conventional two-tone test for power amplifiers to concurrent dual-band transmitters. The output signal of a concurrent dual-band transmitter is affected not only by intermodulation (IM) products but also by cross-modulation (CM) products. In one frequency band, the transmitter is excited by a two-tone signal which frequency separation is swept. In the second band, the transmitter is concurrently excited by another two-tone signal with slightly wider frequency separation. The frequency difference of the two signals is fixed during the frequency sweep. The two-tone test is made at different power levels. The upper and lower third-order IM and CM products are measured. The asymmetry between the upper and lower third-order IM and CM products are measures of the transmitter's memory effects. The measurement results show that the memory effects are more dominant in the third-order IM products than in the CM products. An error analysis and system calibration was performed and measurement results for two different devices are presented.

A method to characterize the memory effects in a nonlinear concurrent dual-band transmitter is presented. It is an extension of the conventional two-tone test for power amplifiers to concurrent dual-band transmitters. The output signal of a concurrent dual-band transmitter is affected not only by intermodulation (IM) products but also by cross-modulation (CM) products. In one frequency band, the transmitter is excited by a two-tone signal which frequency separation is swept. In the second band, the transmitter is concurrently excited by another two-tone signal with slightly wider frequency separation. The frequency difference of the two signals is fixed during the frequency sweep. The two-tone test is made at different power levels. The upper and lower third-order IM and CM products are measured. The asymmetry between the upper and lower third-order IM and CM products are measures of the transmitter's memory effects. The measurement results show that the memory effects are more dominant in the third-order IM products than in the CM products. An error analysis and system calibration was performed and measurement results for two different devices are presented.

This paper proposes three novel models for behavioral modeling and digital pre-distortion (DPD) of nonlinear 2 2 multiple-input multiple-output (MIMO) transmitters in the presence of crosstalk. The proposed models are extensions of the singleinput single-output generalized memory polynomial model. Three types of crosstalk effects were studied and characterized as linear, nonlinear, and nonlinear & linear crosstalk. A comparative study was performed with previously published models for the linearization of crosstalk in a nonlinear 2 2 MIMO transmitter. The experiments indicate that, depending on the type of crosstalk, the selection of the correct model in the transmitter is necessary for behavioral modeling and sufficient DPD performance. The effects of coherent and partially noncoherent signal generation on the performance of DPD were also studied. For crosstalk levels of 30 dB, the difference in the normalized mean square error and adjacent channel power ratio was found to be 3-4 dB between coherent and partially noncoherent signal generation.

This paper presents the integration slots and Complementary Split Ring Resonators (CSRRs) in the development of miniaturized, high-gain, dual-band Microstrip Rectangular Patch Antennas (MRPAs) for 5G mobile communication applications. The antennas were designed on a Rogers RT5880 substrate with a thickness of 0.508 mⅿ. Slots and ⅭSRR metamaterial unit cells were integrated into the patch and ground planes, respectively, to achieve size reduction, high gain, and bandwidth enhancement. The design and simulation processes were conducted using ⅭЅΤ Studio Suite 2018. Simulated results of the best-performing antenna showed that integrating CSRRs reduces the MRPA size by approximately 25%, from 330 mm² (16.5 × 20.0 mm²) to 248 mm² (15.5 × 16.0 mm²). The conventional MRPA antenna without slots and CSRRs resonated at 26.59 GHz and 28.0 GHz, offering bandwidths of 0.50 GHz and 0.81 GHz, with corresponding gains of 5.81 dΒ and 9.44 dΒ, respectively. After integrating the slots and CSRRs, the MRPA antenna resonated at 26.75 GHz and 28.0 GHz, with bandwidths increased to 0.52 GHz and 1.10 GHz (enhancements of 4% and 36%), and gains improved to 9.20 dΒ and 11.39 dΒ (enhancements of 58% and 21%), respectively. These enhancements and size reduction make the proposed slotted and CSRR-loaded MRPA antennas suitable for millimeter-wave 5G wireless portable devices.

We propose an adaptive transmission technique for free space optical (FSO) systems, operating in atmospheric turbulence and employing subcarrier phase shift keying (S-PSK) intensity modulation. Exploiting the constant envelope characteristics of S-PSK, the proposed technique offers efficient utilization of the FSO channel capacity by adapting the modulation order of S-PSK, according to the instantaneous state of turbulence induced fading and a pre-defined bit error rate (BER) requirement. Novel expressions for the spectral efficiency and average BER of the proposed adaptive FSO system are presented and performance investigations under various turbulence conditions and target BER requirements are carried out. Numerical results indicate that significant spectral efficiency gains are offered without increasing the transmitted average optical power or sacrificing BER requirements, in moderate-to-strong turbulence conditions. Furthermore, the proposed variable rate transmission technique is applied to multiple input multiple output (MIMO) FSO systems, providing additional improvement in the achieved spectral efficiency as the number of the transmit and/or receive apertures increases.

The growing popularity of direct current (DC) power sources, energy storage systems, and DC loads has recently shifted the focus away from alternating current (AC) microgrids and towards DC-only systems. However, smart and energy-efficient building integration and effective microgrid administration are prerequisites. Direct current microgrids, which include solar modules as their principal power source, an energy storage device (battery), and an essential DC load, may have their energy consumption managed with the help of our study. Within the microgrid (MG) architecture, the DC-DC boost converter enables the PV module to operate in many modes, one of which is Maximum Power Point Tracking (MPPT). In order to link the battery and supercapacitor to the DC bus, the system also makes use of a DC-DC bidirectional converter. By restricting the charging/discharging currents and state of charge (SoC) of the batteries and supercapacitors, the proposed control approach seeks to manage power flow within the microgrid while considering their lifespan. This method simplifies and improves upon previous approaches to DC load supply by doing away with complicated energy management or maximum power point tracking methods. We conceived and simulated the DC microgrid under investigation thanks to Matlab/Simulink. We fulfil the load demand while maintaining system stability and performance. We provide a presentation and discussion of findings from controller design, analysis, and simulation validation for several operating modes.

For the purpose of target localization, Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) radar has been proposed. OFDM technique has been adopted in order to a simultaneous transmission and reception of a set of multiple narrowband orthogonal signals at orthogonal frequencies. Although multi-carrier systems such as OFDM support high data rate applications, they do not only require linear amplification but also they complicate the power amplifiers design and increase power consumption. This is because of high peak-to-average power ratio (PAPR). In this work, a new proposition has been made based on the Pulse Width Modulation (PWM) to enhance the MIMO-OFDM radar systems' performance. In order to check the proposed systems performance and its validity, a numerical analysis and a MATLAB simulation have been conducted. Nevertheless of the system characteristics and under same bandwidth occupancy and system's specifications, the simulation results show that this work can reduce the PAPR values clearly and show capable results over the ones in the literature.

We analyze the outage probability for the orthogonal space-time block code based multiple-input multiple-output (MIMO) relay networks, composed of one source, one relay, and a single destination. The relay forwards the decoded and interleaved information sequence even though the information part may contain error(s), according to the lossy forward strategy. In spatially independent MIMO channels, we find that the diversity order of the relay network can be interpreted and formulated by the well-known max-flow min-cut theorem. Moreover, we extend the analysis to the case of spatially correlated MIMO channels. Approximated explicit expressions for the outage probabilities are obtained in high signal-to-noise ratio regime.

This paper investigates iterative frequency domain technieques for the reception of spatially multiplexed single carrier signals transmitted over frequency-selective multiple input multiple output (MIMO) channels. The investigated equalizers are based on the softcancellation (SC) and minimum mean square error (MMSE) filtering technique for turbo-coded single carrier point-to-point MIMO systems. We consider two different transmit antenna separation techniques in the frequency domain: (1) antenna-by-antenna (AA) and (2) joint over antenna techniques (JA). (1) aims to separate signals in different layers by MMSE filtering antenna-by-antenna, whereas (2) aims to detect the composite signal comprised of the signals transmitted from the multiple antennas. In (2) the composite received signal is decomposed by using the spatial maximum aposteriori probability (MAP) algorithm. We evaluate performances in terms of frame error rate (FER) and troughput in pointto-point MIMO frequency-selective fading channels. Impacts of spatial correlation on performance of the two detectors are also investigated in this paper.

The knowledge of the variability of a received signal at distant points to the Base Station (BS) is key for reliable and efficient radio signal transmissions. In consequence, developing a robust Path Loss Model (PLM) for determining the Path Loss (PL) between a High Altitude Platform Station (HAPS) and the User Equipment (UE) on the ground is crucial in positioning the HAPS. This paper presents a HAPS PLM for Ede environment. The PLM was developed based on some demographic data of the Ede land area. The parameters employed in the development of the PLM were buildings plots width, inter-building spacing, maximum building height, carrier frequency, HAPS altitude, PL exponent and elevation angles ranging from 10 0 to 90 0. The developed PLM was simulated for Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios at 2 GHz and 20 GHz. The PL values for Ede were compared with the PL values for Arlington (a suburban environment). For the LOS scenario, the same average PL value was obtained for both Ede and Arlington environments. However, for the

In this paper, resilient transmission in a multicell multiple-input multiple-output (MIMO) interference wiretap channel model is studied. Each base station (BS) transmits confidential messages to its intended legitimate user with multiple antennas, in the presence of eavesdroppers that can overhear the transmission. We study the problem of finding the optimal transmit covariance matrices at the BSs to maximize the secrecy sum rate, which is typically non-convex and intractable to obtain the global optimal solution. A distributed iterative optimization algorithm based on a novel decomposition framework across all users is proposed. The decomposition framework preserves the convexity of the objective function and linearizes the non-convex part. At each iteration, the BSs simultaneously solve a sequence of problems that are decoupled convex approximations of the original secrecy sum-rate function. Moreover, the complexity of the algorithm is analyzed. Numerical results are presented to validate the effectiveness of the proposed distributed algorithm.

Motivated by the current demand for improvements in transmission rate and energy efficiency of random wireless cellular networks, we investigate the theoretical model of random cognitive radio network in Rayleigh-lognormal fading environment. In such a network, we derive an analytical expression for the connection probability, transmission rate, and energy efficiency of a secondary network in a single-tier downlink scenario, considering the probabilities of unoccupied channel selection and of successful transmission, where source-destination pairs are randomly located according to Poisson point processes. Moreover, we approach the problem of optimization of transmission rate and energy efficiency using a required connection probability constraint to improve the system performance. Our numerical results indicate that there exists an optimal combination of transmission power and secondary transmitter density where transmission rate and energy efficiency are maximized.

Intelligent Reflecting Surface-IRS or Reconfigurable intelligent surface-RIS is a transmission technology that can enhance the performance of wireless communication systems by reflecting electromagnetic signals in a specific direction. The question is which RIS-aided scheme is the most appropriate for a given wireless communication scenario, considering performance factors such as energy efficiency and transmit power. In the literature, two oriented RIS-aided schemes are usually determined: The Exhaustive RIS-Aided (ERA) scheme and the Opportunistic RIS-Aided (ORA) scheme. Both schemes have been considered for evaluating the performance of wireless communication. This paper presents a methodology and analysis of RIS technology for wireless communication systems. It presents a mathematical model to optimize the reflected signal's phase shift and evaluates the system's performance using numerical simulations. Moreover, it proposes two algorithms for implementing the ERA and ORA schemes. It analyzes the ERA and ORA methods transmit power schemes to determine their energy efficiency. The analysis of the experimental investigations shows that the ORA scheme has sophisticated transmit power values and attains maximum energy efficiency by using less energy compared to the ERA scheme. ORA is superior to ERA in terms of energy and efficiency.

There are considered problems of turbocode using in special telecommunication systems in the article. There are showed basic principles of turbocode building and they characteristics.Рассмотрены вопросы применения турбокодов в специальных телекоммуникационных системах. Указаны основные принципы построения турбокодов и их характеристики

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Изобретение относится к области инерциальной навигации, гироскопических измерений и автоматического управления, а именно — к способам фазовой синхронизации между гироскопами, входящими в состав рой-систем или распределённых мультиагентных инерциальных комплексов. Более конкретно, изобретение относится к способам согласования фазовых состояний гироскопических модулей на основе пространственно-интерференционного взаимодействия физических полей, что позволяет обеспечить коллективную ориентацию, устойчивое управление и согласованное движение в рое без централизованного управляющего устройства.
Настоящее изобретение может быть применено в беспилотной авиации, автономных подводных аппаратах, робототехнических системах, системах космической ориентации, мобильных распределённых сенсорных платформах, а также в перспективных навигационно-вычислительных комплексах, основанных на фазовом согласовании между отдельными физическими узлами. Способ может быть реализован как на основе оптических или акустических фазовых трактов, так и в электромагнитном ближнем поле, что обеспечивает широкую область применения при минимальной зависимости от внешней инфраструктуры.

This paper of Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System overviewed the Current issues regarding the WiMAX System of today. The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. We Can Say that In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The Paper is explaining the major contents regarding the the bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, paper propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simul...

Resumo: A Caatinga, bioma predominante do semiárido nordestino, com suas peculiaridades climáticas, apresenta uma alta diversidade florística. No entanto, o desmatamento devido às atividades relacionadas ao extrativismo e agropecuária vem ganhando dimensões preocupantes, comprometendo o equilíbrio ambiental. Diante disso, destacam-se os Sistemas Agroflorestais como um instrumento para recuperação de áreas degradadas. Notadamente nos SAF's se pratica os princípios da agroecologia. Neste sentido, este trabalho, objetivou listar por meio de levantamento bibliográfico, espécies vegetais com potencias usos para implantação de SAF's na caatinga, resultando em 102 espécies vegetais, identificadas em melíferas, madeireiras, alimentícios, fibra, forrageira, oleaginosas, ornamental, medicinal, e fixação de nitrogênio.

This paper proposes and demonstrates experimentally the application of optical polarization-multiplexed radioover-fiber wireless backhauling of fully standard 3GPP carrieraggregated multiple-input multiple-output (MIMO) signals. The experimental work demonstrates successful long-reach optical transmission of 3GPP carrier-aggregated LTE-Advanced (LTE-A) signals using 2×2 MIMO spatial diversity. The suitability of MIMO provision using radio-over-fiber optical links is demonstrated over different E-UTRA frequency division duplex frequency bands. The performance of electrical carrier aggregation is evaluated in different configurations comprising one, three and five LTE-A component carriers of 10 and 20 MHz bandwidth each. The experimental results demonstrate successful 2×2 MIMO radioover-fiber polarization-multiplexed transmission of five LTE-A carriers over 25 km, three LTE-A carriers over 75 km and an LTE-A carrier over 100 km of standard single mode fiber to provide pervasive MIMO wireless service to a large number of users.

A compact self-isolated Multi Input Multi Output (MIMO) antenna array is presented for 5G mobile phone devices. The proposed antenna system is operating at the 3.5 GHz band (3400-3600 MHz) and consists of eight antenna elements placed along two side edges of a mobile device, which meets the current trend requirements of full-screen smartphone devices. Each antenna element is divided into two parts, a front part and back part. The front part consists of an I-shaped feeding line and a modified Hilbert fractal monopole antenna, whereas the back part is an L-shaped element shorted to the system ground by a 0.5 mm short stub. A desirable compactness can be obtained by utilizing the Hilbert space-filling property where the antenna element's overall planar size printed on the side-edge frame is just (9.57 mm × 5.99 mm). The proposed MIMO antenna system has been simulated, analyzed, fabricated and tested. Based on the selfisolated property, good isolation (better than 15 dB) is attained without employing additional decoupling elements and/or isolation techniques, which increases system complexity and reduces the antenna efficiency. The scattering parameters, antenna efficiencies, antenna gains, and antenna radiation characteristics are investigated to assess the proposed antenna performance. For evaluating the proposed antenna array system performance, the Envelope Correlation Coefficients (ECCs), Mean Effective Gains (MEGs) and channel capacity are calculated. Desirable antenna and MIMO performances are evaluated to confirm the suitability of the proposed MIMO antenna system for 5G mobile terminals.

The use, as diversity antennas, of electromagnetic cavities with radiated slots etched on their faces is discussed. From this kind of geometries, many antenna configurations can be designed in order to provide uncorrelated signals. As an example, a three-port antenna which combines polarization and radiation pattern diversities is presented. The structure operates in the 5 GHz band and exhibits a coupling between input ports less than -30 dB in measurement. Envelope correlations between radiation patterns of each port are less than 0.035 which makes this structure well-suited for antenna diversity systems.

The next paper brings the development of an improve implementation of Activity-based costing using Wireless Mesh Networks with MIMO channels. The study of the efficiency of this implementation in MIMO channels, is simulated with Space-Time Block Coding with convolutional codification and BPSK modulation, to show that this way of manages costing and the correct exploitation of wireless technologies in communications, generate new value to enterprises. Also the monetary differences of the costs, the impact of the use of better channels are presented.

The study search to understand the production process of agroecological farming family in District Pains, Santa Maria, RS. Then, we sought to understand the importance of family farming as a way of valuing community in social, economic and environmental. Furthermore, we tried to meet the changes in agricultural practices District Pains, highlighting alternative farming practices and sustainable benefits to the local community. The paper presents a qualitative approach where they were used as instruments of research interviews that have been applied to social subjects involved.

Controlling pressurized water reactors (PWRs) is a challenging task due to their inherent nonlinearity, modeling uncertainties, time-varying parameters, and multi-input multi-output (MIMO) nature. These factors require advanced control strategies to maintain safe and efficient operations. This paper focuses on the nonlinear controller design for PWRs, where external disturbances and system uncertainties are the primary challenges. To enhance the control performance of PWRs, the authors propose an integrated approach using Model Predictive Control (MPC) and Second Order Linear Active Disturbance Rejection Control (SOLADRC). MPC is utilized to optimize the reactor core by predicting the dynamic behavior of the system and proactively adjusting the control inputs. SOLADRC is employed to provide robust regulation of key operating parameters, such as reactor power, coolant temperature, and pressure, in the presence of both known and unknown disturbances. Comprehensive simulations and analysis demonstrate the effectiveness of the integrated MPC-SOLADRC approach in improving the PWR's operational efficiency, flexibility, and safety margins. The results show that the combined MPC and SOLADRC strategy outperforms traditional control methods in terms of set point tracking, disturbance rejection, and constraint handling. This work contributes to the advancement of control optimization techniques for MIMO systems, paving the way for enhanced safety, reliability, and economic performance of PWR.

Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is one of the most attractive candidates for fourth generation (4G) mobile radio communication. It effectively combats the multipath fading channel and improves the bandwidth efficiency. At the same time, it also increases system capacity so as to provide a reliable transmission. However, the main drawback of MIMO-OFDM system is high peak-to-average power ratio (PAPR) for large number of sub-carriers, which result in many restrictions for practical applications. Coding, phase rotation and clipping are among many PAPR reduction schemes that have been proposed to overcome this problem. In this paper, we mainly investigate the PAPR reduction performance with two different PAPR reduction methods: partial transmit sequence (PTS) and selective mapping (SLM). These two methods are sub-entities of phase rotation scheme. We propose an algorithm, Sub-Optimal algorithm that shows better PAPR reduction compared to the existing algorithms. Results are verified using MATLAB software.

OFDM is a subset of frequency division multiplexing in which a single channel utilizes multiple subcarriers on adjacent frequencies. In addition the sub-carriers in an OFDM system are overlapping to maximize spectral efficiency. That means OFDM is multi-carrier communication technique which is used in both wired and wireless communication. OFDM is the time domain signal which is a sum of several sinusoids and these sinusoids makes Peak to Average Power Ratio (PAPR).PAPR is major drawback of OFDM. There are several PAPR reduction techniques but, pre-coding is an efficient method for PAPR reduction. This paper represents a new pre-coding technique-Walsh Hadamard Transform (WHT). The obtained results show that WHT is attractive solution to PAPR problems of OFDM signals.

In this paper, a novel approach is proposed for the orthogonal frequency-division multiplexing (OFDM) SAR imaging, where a sufficient cyclic prefix (CP) is added to each OFDM pulse. As the key in a wireless communications system, the sufficient CP insertion converts an inter symbol interference (ISI) channel from multi paths into multiple ISI-free sub channels. Analogously, it provides an inter-range-cell interference (IRCI)-free (high range resolution) SAR image in a SAR system. In the past secondand third-generation wireless communications, the existing linear-frequencymodulated (or step frequency) and random noise synthetic aperture radar (SAR) systems are corresponds to the frequency-hopping and direct-sequence spread spectrum systems. The sufficient CP insertion along with our newly proposed SAR imaging algorithm, particularly for the OFDM signals differentiates all the existing studies in the literature on OFDM radar signal processing. Simulation results are presented to illus...

This paper presented a planar printed multiple-inputmultiple-output (MIMO) antenna with a dimension of 100 x 45 mm 2 . It composed of two crescent shaped radiators placed symmetrically with respect to the ground plane. Neutralization line applied to suppress mutual coupling. The proposed antenna examined both theoretically and experimentally, which achieves an impedance bandwidth of 18.67% (over 2.04-2.46 GHz) with a reflection coefficient < -10 dB and mutual coupling minimization of < -20 dB. An evaluation of MIMO antennas is presented, with analysis of correlation coefficient, total active reflection coefficient (TARC) and capacity loss. These characteristics indicate that the proposed antenna suitable for some wireless applications.

Future wireless networks are expected to face several issues, but cooperative non-orthogonal multiple access (C-NOMA) is a promising technology that could help solve them by providing unprecedented levels of connection and system capacity. In this regard, the influence of the power location coefficient (PLC) for remote users adopting multiple-input-multiple-output (MIMO) and massive MIMO has been explored to provide effective performance. The goal of this study is to design fifth-generation (5G) downlink (DL) NOMA power domain (PD) networks with a variety of distances and PLCs for remote users and then to compare their outage probability (OP) performance versus signal to noise ratio (SNR). As a novel approach to improving OP performance rate and mitigating the influence of the PLC for remote users, DL C-NOMA is combined with 16×16, 32×23, and 64×64 MIMO and 128×128, 256×256, and 512×512 massive MIMO. The results were obtained that the 64×64 MIMO improves the OP for the remote user b...

Àííîòàöèÿ.  ñòàòüå ïðåäñòàâëåíà øèðîêîïîëîñíàÿ ïðÿìîóãîëüíàÿ äèýëåêòðè÷åñêàÿ ðåçîíàíñíàÿ àíòåííà DRA (dielectric resonator antenna) â ôîðìå êîâðà Ñåðïèíñêîãî, ðàáîòàþùàÿ â X-äèàïàçîíå, êîòîðàÿ õàðàêòåðèçóåòñÿ ìîäåëüþ äèýëåêòðè÷åñêîãî âîëíîâîäà DWM (dielectric waveguide model). Äëÿ ñíèaeåíèÿ ñòîèìîñòè DRA â êà÷åñòâå ìàòåðèàëà èñïîëüçîâàí äåøåâûé òåôëîí. Ðåçóëüòàòû ìîäåëèðîâàíèÿ ïðîâåðåíû ñ ïîìîùüþ ðåàëèçîâàííîãî ïðîòîòèïà.  ñòàòüå îáû÷íàÿ ïðÿìîóãîëüíàÿ DRA ñðàâíèâàåòñÿ ñ ïðÿìîóãîëüíûìè DRA â ôîðìå ôðàêòàëà ïåðâîé è âòîðîé èòåðàöèé. Îáñóaeäàåòñÿ ìåòîäîëîãèÿ ïðîåêòèðîâàíèÿ àíòåííû è åå ðåçîíàíñíûå è ðàäèàöèîííûå õàðàêòåðèñòèêè. Îáîñíîâàííîñòü ïîëó÷åííûõ ðåçóëüòàòîâ ïîäòâåðaeäàåòñÿ áëèçêèì ñîâïàäåíèåì ýêñïåðèìåíòàëüíûõ è ìîäåëèðîâàííûõ ðåçóëüòàòîâ. Èçìåðåíèÿ íà ïðîòîòèïå ïîêàçàëè øèðèíó ïîëîñû ïðîïóñêàíèÿ 48%, îïðåäåëÿåìóþ ïî ïîëíîìó âõîäíîìó ñîïðîòèâëåíèþ. Ïðè ýòîì îíà îõâàòûâàåò âñþ ïîëîñó ÷àñòîò Õ-ñ ïîäîáíîé äèàãðàììîé íàïðàâëåííîñòè âî âñåé ïîëîñå è óñèëåíèåì 7,5 äÁè â äèàïàçîíå 9,0-11,5 ÃÃö.

Microstrip patch antennas (MPAs) are widely used in wireless communication systems due to their low cost, compact profile, and ease of fabrication. However, their limited gain and narrow bandwidth often restrict their applications. With fіfth-generation (5G) networks demanding compact, high-gain, and wide bandwidth antennas, this work presеnts dual-band Mіcrostrip Rectangular Patch Antеnnas featuring LI-shaped and middle slots, specifically designed to enhance gaіn and bandwіdth for 5G mobilе communication applications. Inserting slots into a unified rectangular patch antenna led to significant gain and bandwidth enhancements, effectively meeting the demands of 5G Systems. The study utilizes the Computer Studio Suite (CST) for simulation, optimizing slot dimensions to achieve the best performance. The newly designed patch antennas were thoroughly evaluated and compared with previous microstrip patch array antenna designs targeting the 26 GHz and 28 GHz frequency bands. The proposed antennas exhibited substant

WiMAX OFDM-based systems are characterized by their ability to provide high data rate with low BER (bit error rate) at low SNR (signal to noise ratio). In this paper, we demonstrate the performance of the system under real fading IEEE standardized channels; originally known as the Stanford University Interim (SUI) channels for broadband wireless access. The six channel models characterize most possible environmental fading effects. They define three terrain channel types; soft fading environment (SUI 1 and SUI 2), intermediate fading environment (SUI 3 and SUI 4) and harsh fading environment (SUI 5 and SUI 6). Each fading environment is thus characterized by two channels representing the possible extremes so that the actual fading channel falls in between. All mandatory WiMAX parameters such as BPSK, 16-QAM, Reed Solomon encoding, to name a few, were used in the simulation of the system and their results in terms of BER versus SNR plots were analyzed. Our focus is on optional parame...

By coupling a fractal loop resonator onto the back of a loaded‐fractal loop monopole and a shorted loop, a new triple‐band USB dongle antenna has been achieved and presented. The proposed antenna supports WiFi (2.4–2.5 GHz and 5.15–5.875 GHz) and WiMAX (3.4–3.6 GHz) applications. The proposed triple‐band planar antenna consists of a loaded‐fractal loop monopole for the 2.4 GHz band, a shorted loop for the 5.5 GHz band, and a coupled fractal loop resonator for 3.5 GHz band. The antenna has a small size of 10 × 42 × 0.8 mm3, which is suitable for USB dongle. Good return loss and omnidirectional radiation pattern characteristics have been obtained in the all three bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:863–866, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27421

The image transmission over wireless channel is already explored by many researchers. Due to eye perception for only low frequency component the de-noising technique may be add at receiver end of the wireless device. In this paper WiMAX system are used for image transmission and fuzzy de-noising method is used for improving the performance. PSNR and RMSE are taken as two parameters for comparing the performance. The MIMO technique is also used here with the 2 x 1 antenna system for BER performance improvement. A clear improvement using denoising technique is found and described in this paper.

The image transmission over wireless channel is already explored by many researchers. Due to eye perception for only low frequency component the de-noising technique may be add at receiver end of the wireless device. In this paper WiMAX system are used for image transmission and fuzzy de-noising method is used for improving the performance. PSNR and RMSE are taken as two parameters for comparing the performance. The MIMO technique is also used here with the 2 x 1 antenna system for BER performance improvement. A clear improvement using denoising technique is found and described in this paper.

This paper reports a design of 2×1 multiple input multiple output (MIMO)
structure of antenna with 23×45 mm2 dimension. Each element in the MIMO
antenna is a quarter wave transformer fed microstrip patch antenna. To
lessen the effect of coupling, a rectangular parasitic decoupler is positioned
between the two elements. Results report that antenna resonates at 6 GHz,
coupling is reduced by 14 dB using parasitic decoupler S12 and S21
obtained with parasitic decoupler are same which -33.06 dB. The diversity
gain (DG) is 9.99 dB, which is nearly close to 10 dB, and the envelope
correlation coefficient (ECC) is less than 0.00034. These values reflect the
good diversity performance. Measured findings match those from the
simulation. As we confront the delicate environment, the proposed antenna
is suited for number of wireless applications, including 802.11, 802.16
standards of IEEE.

This paper presents a simplified Multiple-Input Multiple-Output (MIMO) antenna tailored for dual-band applications, featuring a co-planar waveguide (CPW) fed configuration that integrates ultra-wideband (UWB) and narrowband capabilities. The single element design employs a circular patch with a central rectangular bar and circular slot, achieving impedance bandwidths from 3.96-9.89 GHz and 12.09-18.16 GHz, with a peak gain of 3.83 dBi. In MIMO configuration, a parasitic element effectively reduces mutual coupling, achieving mutual coupling less than-20 dB, while orthogonal element placement enhances the polarization diversity, crucial for the multipath environments. The antenna's compact size (18.5 mm × 46.8 mm) facilitates integration into various platforms, delivering a peak gain of 4.77 dBi at 7.65 GHz, low envelope correlation coefficients (ECC < 0.001), and high diversity gain (approximately 10 dB). Comparative analysis highlights the design's competitive advantages in bandwidth, isolation, gain, and efficiency, addressing miniaturization and coupling challenges, and making it a robust solution for next-generation wireless systems.

The characterization of the global maximum of energy efficiency (EE) problems in wireless networks is a challenging problem due to its nonconvex nature in interference channels. The aim of this work is to develop a new and general framework to achieve globally optimal power control solutions. First, the hidden monotonic structure of the most common EE maximization problems is exploited jointly with fractional programming theory to obtain globally optimal solutions with exponential complexity in the number of network links. To overcome this issue, we also propose a framework to compute suboptimal power control strategies characterized by affordable complexity. This is achieved by merging fractional programming and sequential optimization. The proposed monotonic framework is used to shed light on the ultimate performance of wireless networks in terms of EE and also to benchmark the performance of the lower-complexity framework based on sequential programming. Numerical evidence is provided to show that the sequential fractional programming achieves global optimality.

La importancia del comportamiento dinamico de los procesos quimicos ha conducido a plantear nuevas estructuras de control que permitan mejorar el desempeno del proceso. En el presente trabajo se empleo una estructura de control DMC (Control de Matriz Dinamica), en un sistema de intercambiador de calor de tubo y coraza con dos variables de entrada y dos variables de salida. Para la sintonizacion del sistema se utilizo el modelo propuesto por J. Cooper et al. (1998), y se analizo el comportamiento de la planta ante respuestas escalon.

-Les turbo codes produits (TCP) sont décodés par un algorithme qui utilise deux paramètres alpha et beta, évoluant avec le nombre de décodages et fixés expérimentalement. L'influence de ces paramètres sur les performances des turbo codes produits est primordiale. Pour des raisons pratiques, ces coefficients sont optimisés seulement pour un code particulier. En les adaptant aux circonstances du décodage, c'est-à-dire en tenant compte du code, de la modulation, du canal de transmission, le décodeur itératif des codes produits gagne en portabilité et en performances.