Articles de revues : « RF communication systems »

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HALUŠKA, Renát, et Ľuboš OVSENÍK. « EXAMPLE OF SWITCHING HYBRID FSO/RF SYSTEMS ». Acta Electrotechnica et Informatica 20, n^o 4 (21 janvier 2021) : 27–31. http://dx.doi.org/10.15546/aeei-2020-0022.

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This article addresses the issue of optical communication with Free Space Optics (FSO) and its use. The article deals with the design and construction of a monitoring system designed for the collection and processing of data characterizing the nature of conditions along the transmission path of a hybrid FSO system with a radio communication link. Due to the vulnerability of the FSO transmission channel to weather conditions, it is necessary to predict the strength of the received signal and switch to a backup line based on machine learning using decision trees.

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Sorrentino, Roberto, Paola Farinelli, Alessandro Cazzorla et Luca Pelliccia. « RF-MEMS Application to RF Tuneable Circuits ». Advances in Science and Technology 100 (octobre 2016) : 100–108. http://dx.doi.org/10.4028/www.scientific.net/ast.100.100.

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The bursting wireless communication market, including 5G, advanced satellite communication systems and COTM (Communication On The Move) terminals, require ever more sophisticated functions, from multi-band and multi-function operations to electronically steerable and reconfigurable antennas, pushing technological developments towards the use of tunable microwave components and circuits. Reconfigurability allows indeed for reduced complexity and cost of the apparatuses. In this context, RF MEMS (Micro-Electro-Mechanical-Systems) technology has emerged as a very attractive solution to realize both tunable devices (e.g. variable capacitors, inductors and micro-relays), as well as complex circuits (e.g. tunable filters, reconfigurable matching networks and reconfigurable beam forming networks for phased array antennas). High linearity, low loss and high miniaturization are the typical advantages of RF MEMS over conventional technologies. Micromechanical components fabricated via IC-compatible MEMS technologies and capable of low-loss filtering, switching and frequency generation allow for miniaturized wireless front-ends via higher levels of integration. In addition, the inherent high linearity of the MEMS switches enables carrier aggregations without introducing intermodulation distortions. This paper will review the recent advances in the development of the RF MEMS to RF tunable circuits and systems.

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Singhal, Ankita, Nishu Rani, Kritika Sengar, Dolly Sharma, Seema Verma et Tanya Singh. « RF Communication from SISO Systems to MIMO Systems : An Overview ». International Journal of Engineering Trends and Technology 8, n^o 5 (25 février 2014) : 235–39. http://dx.doi.org/10.14445/22315381/ijett-v8p244.

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Raskin, Jean-Pierre. « FinFET and UTBB for RF SOI communication systems ». Solid-State Electronics 125 (novembre 2016) : 73–81. http://dx.doi.org/10.1016/j.sse.2016.07.004.

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Springer, A., et R. Weigel. « RF microelectronics for W-CDMA mobile communication systems ». Electronics & ; Communication Engineering Journal 14, n^o 3 (1 juin 2002) : 92–100. http://dx.doi.org/10.1049/ecej:20020301.

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Young, Darrin J. « Micromachining for rf Communications ». MRS Bulletin 26, n^o 4 (avril 2001) : 331–32. http://dx.doi.org/10.1557/mrs2001.74.

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The increasing demand for wireless communication applications, such as cellular and cordless telephones, wireless data networks, and global positioning systems, motivates a growing interest in building miniature radio transceivers that can support multistandard capabilities. Such transceivers will greatly enhance the convenience and accessibility of various wireless services.

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Zhang, Zhenyu, Anas Chaaban et Lutz Lampe. « Physical layer security in light-fidelity systems ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 378, n^o 2169 (2 mars 2020) : 20190193. http://dx.doi.org/10.1098/rsta.2019.0193.

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Light-fidelity (LiFi) is a light-based wireless communication technology which can complement radio-frequency (RF) communication technologies for indoor applications. Although LiFi signals are spatially more contained than RF signals, the broadcasting nature of LiFi also makes it susceptible to eavesdropping. Therefore, it is important to secure the transmitted data against potential eavesdroppers. In this paper, an overview of the recent developments pertaining to LiFi physical layer security (PLS) is provided, and the main differences between LiFi PLS and RF PLS are explained. LiFi achievable secrecy rates and upper bounds are then investigated under practical channel models and transmission schemes. Beamforming and jamming, which received significant research attention recently as a means to achieve PLS in LiFi, are also investigated under indoor illumination constraints. Finally, future research directions of interest in LiFi PLS are identified and discussed. This article is part of the theme issue ‘Optical wireless communication’.

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Yang, H. Y. D. « Analysis of RF radiation interference on wireless communication systems ». IEEE Antennas and Wireless Propagation Letters 2 (2003) : 126–29. http://dx.doi.org/10.1109/lawp.2003.816634.

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Sreenivasa Reddy, Yeduri, Meenakshi Panda, Ankit Dubey, Abhinav Kumar, Trilochan Panigrahi et Khaled M. Rabie. « Optimisation of indoor hybrid PLC/VLC/RF communication systems ». IET Communications 14, n^o 1 (3 janvier 2020) : 117–26. http://dx.doi.org/10.1049/iet-com.2019.0665.

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Eslami, Ali, Sarma Vangala et Hossein Pishro-Nik. « Hybrid Channel Codes for Efficient FSO/RF Communication Systems ». IEEE Transactions on Communications 58, n^o 10 (octobre 2010) : 2926–38. http://dx.doi.org/10.1109/tcomm.2010.082710.090195.

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Daldal, Nihat, Majid Nour et Kemal Polat. « The Methods toward Improving Communication Performance in Transparent Radio Frequency Signals ». Mathematical Problems in Engineering 2020 (24 avril 2020) : 1–8. http://dx.doi.org/10.1155/2020/7175864.

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In wireless digital communications, amplitude-shift keying (ASK) and frequency-shift keying (FSK) modules are often used and radio frequency (RF), communication synchronization, and noise problems affect the performance very much. In particular, the sending of byte-type data called synchronous and preamble before sending data in intermodule communication increases the sent data and decreases the speed. Also, the microcontroller at the output of the RF receiver module continuously listens to the RF noise and analyzes incoming data, but this increases the processing load of the microcontroller. Moreover, it reduces the speed of performing other operations. In this study, a transparent RF transmitter and receiver have been investigated, and methods for increasing the communication performance of the modules have been proposed and performed. Two of the proposed methods prevented the continuous listening of the microprocessor in the RF receiver structure so that the microprocessor can be used with other processes. In other methods, the compression of the data size was achieved because the transmission of a series of data in RF communication systems was limited to a certain extent. In the last section of the study, since the RF modules have failed to transmit the data due to corruption in the extended data dimensions, the bit carrier control security code has been created for the data series and more healthy communication has been performed.

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Bravo Alvarez, Lisandra, Samuel Montejo-Sánchez, Lien Rodríguez-López, Cesar Azurdia-Meza et Gabriel Saavedra. « A Review of Hybrid VLC/RF Networks : Features, Applications, and Future Directions ». Sensors 23, n^o 17 (30 août 2023) : 7545. http://dx.doi.org/10.3390/s23177545.

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The expectation for communication systems beyond 5G/6G is to provide high reliability, high throughput, low latency, and high energy efficiency services. The integration between systems based on radio frequency (RF) and visible light communication (VLC) promises the design of hybrid systems capable of addressing and largely satisfying these requirements. Hybrid network design enables complementary cooperation without interference between the two technologies, thereby increasing the overall system data rate, improving load balancing, and reducing non-coverage areas. VLC/RF hybrid networks can offer reliable and efficient communication solutions for Internet of Things (IoT) applications such as smart lighting, location-based services, home automation, smart healthcare, and industrial IoT. Therefore, hybrid VLC/RF networks are key technologies for next-generation communication systems. In this paper, a comprehensive state-of-the-art study of hybrid VLC/RF networks is carried out, divided into four areas. First, indoor scenarios are studied considering lighting requirements, hybrid channel models, load balancing, resource allocation, and hybrid network topologies. Second, the characteristics and implementation of these hybrid networks in outdoor scenarios with adverse conditions are analyzed. Third, we address the main applications of hybrid VLC/RF networks in technological, economic, and socio-environmental domains. Finally, we outline the main challenges and future research lines of hybrid VLC/RF networks.

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Cho, Sunghwan, Gaojie Chen, Justin P. Coon et Pei Xiao. « Challenges in Physical Layer Security for Visible Light Communication Systems ». Network 2, n^o 1 (20 janvier 2022) : 53–65. http://dx.doi.org/10.3390/network2010004.

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This article highlights challenges associated with securing visible light communication (VLC) systems by using physical layer security (PLS) techniques. Motivated by the achievements in PLS studies for radio frequency (RF) communication, many PLS techniques for VLC systems were also rigorously investigated by tailoring the RF techniques to the VLC environment. However, careful consideration of the inherent differences between RF and VLC systems is still needed. By disregarding these differences, an eavesdropper could be given an opportunity to wiretap the VLC systems, even when PLS techniques are employed to protect them. Crucially, the fact that it is often not possible to know the number and locations of eavesdroppers in real VLC systems may allow eavesdroppers to devise various cooperative eavesdropping methods. By examining a few examples of the possible eavesdropper threats that can occur in VLC systems, this article offers novel insights into the vulnerabilities of state-of-the-art PLS schemes for VLC systems. Although the focus of the paper is mostly on these weaknesses, some potential solutions are also briefly proposed with a view to stimulating discourse in the community.

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Sinha, Himanshu Kumar, Anand Kumar et Abhishek Saurabh. « Role of RF Propagation in 5g Network ». East African Scholars Journal of Engineering and Computer Sciences 6, n^o 02 (6 mars 2023) : 20–25. http://dx.doi.org/10.36349/easjecs.2023.v06i02.001.

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The performance analysis of various empirical radio propagation models or harvesters used in wireless cellular networks is presented in this paper. In particular, second generation (2G) through fifth generation (5G) cellular networks route loss and cell coverage areas is researched. Planning any wireless communication system requires precise path loss and coverage area forecasting. The Hata model, the Stanford University Interim (SUI) model, and modified SUI models are contrasted in light of the urban terrain. The investigation is carried out at 28 GHz as inspiration for new wave (mm- wave) cellular systems, or for 5G communication. When -75 dBm is used as the desired minimum received power, it is shown that 2G communications (using the Hata model at 900 MHz) has the lowest route loss and thus the widest coverage area. Future mm-wave systems with the smallest coverage area are found to have the highest path loss (at 28 GHz using a modified SUI model).

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Bougas, Ioannis D., Maria S. Papadopoulou, Achilles D. Boursianis, Spyridon Nikolaidis et Sotirios K. Goudos. « Dual-Band Rectifier Circuit Design for IoT Communication in 5G Systems ». Technologies 11, n^o 2 (24 février 2023) : 34. http://dx.doi.org/10.3390/technologies11020034.

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Radio-frequency (RF) energy harvesting (EH) is emerging as a reliable and constantly available free energy source. The primary factor determining whether this energy can be utilized is how efficiently it can be collected. In this work, an RF EH system is presented. More particularly, we designed a dual-band RF to DC rectifier circuit at sub-6 GHz in the 5G bands, able to supply low-power sensors and microcontrollers used in agriculture, the military, or health services. The system operates at 3.5 GHz and 5 GHz in the 5G cellular network’s frequency band FR1. Numerical results reveal that the system provides maximum power conversion efficiency (PCE) equal to 53% when the output load (sensor or microcontroller) is 1.74 kΩ and the input power is 12 dBm.

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Jokic, Ivana, Milos Frantlovic, Zoran Djuric et Miroslav Dukic. « RF MEMS/NEMS resonators for wireless communication systems and adsorption-desorption phase noise ». Facta universitatis - series : Electronics and Energetics 28, n^o 3 (2015) : 345–81. http://dx.doi.org/10.2298/fuee1503345j.

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During the past two decades a considerable effort has been made to develop radio-frequency (RF) resonators which are fabricated using the micro/nanoelectro-mechanical systems (MEMS/NEMS) technologies, in order to replace conventional large off-chip components in wireless transceivers and other high-speed electronic systems. The first part of the paper presents an overview of RF MEMS and NEMS resonators, including those based on two-dimensional crystals (e.g. graphene). The frequency tuning in MEMS/NEMS resonators is then analyzed. Improvements that would be necessary in order for MEMS/NEMS resonators to meet the requirements of wireless systems are also discussed. The analysis of noise of RF MEMS/NEMS resonators and oscillators is especially important in modern wireless communication systems due to increasingly stringent requirements regarding the acceptable noise level in every next generation. The second part of the paper presents the analysis of adsorption-desorption (AD) noise in RF MEMS/NEMS resonators, which becomes pronounced with the decrease of components' dimensions, and is not sufficiently elaborated in the existing literature about such components. Finally, a theoretical model of phase noise in RF MEMS/NEMS oscillators will be presented, with a special emphasize on the influence of the resonator AD noise on the oscillator phase noise.

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Zhang, Caozheng, Libo Zheng, Jinghao Yu, Pengfei Ye et Yi Liu. « A low insertion loss RF switch using a 130 nm SOI process ». Journal of Physics : Conference Series 2384, n^o 1 (1 décembre 2022) : 012008. http://dx.doi.org/10.1088/1742-6596/2384/1/012008.

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Abstract To realize a better radio frequency (RF) communication system, the RF switch, as an important module, is used to cooperate with other devices to form an RF front end for optimizing communication performances. This paper designs a single-pole multi-throw (SPMT) RF switch, which exhibits a low insertion loss of 0.57 dB at 1.9 GHz under the voltage of 2.2 to 4.7 V. The RF switch is fabricated using a 130 nm silicon-on-insulator (SOI) complementary metal-oxide-semiconductor (CMOS) process. It can be used in multi-frequency and multi-mode applications such as 4G/5G. The proposed RF switch has competitive performance and can be combined with other modules to achieve better wireless communication and promote the development of ultra-wideband and multi-mode wireless communication systems.

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Singer, Andrew C., Gizem Tabak et Michael L. Oelze. « High data rate ultrasonic communications ». Journal of the Acoustical Society of America 151, n^o 4 (avril 2022) : A244. http://dx.doi.org/10.1121/10.0011201.

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Ultrasonic signals have been used in biomedical applications since at least the 1940s. Underwater acoustic signals have been used in the subsea industry for ranging since the early 1900s and for SONAR imaging and communication in the decades that followed. Since the development of subsea communication systems in the 1940s, increasingly sophisticated means have be developed for transmitting information acoustically through the highly variable ocean environment. State-of-the-art acoustic communication systems leverage ultrasonic transducers to achieve data transmission rates that mirror radio-frequency (RF)-based WiFi systems on land. The increasing use of wireless implanted medical devices (IMDs) have increased interest in through-tissue communications. Restrictions on the available bandwidth and transmit signal power limit the data rates of RF-based IMDs. In this talk, we give an overview of video-capable ultrasonic wireless communication between IMDs and external devices. We emphasize the potential of such a system for improving video capsule endoscopy and describe the challenges of through-tissue acoustic communication. Building on experience with subsea-communication systems, we discuss methods to cope with attenuation, dispersion, reflection, and nonlinear propagation. Some of our recent experiments performed ex vivo with soft tissue samples and in vivo with anesthetized animal subjects will be discussed.

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Gueye, Ibrahima, Ibra Dioum, Idy Diop, K. Wane Keita, Papis Ndiaye, Moussa Diallo et Sidi Mohamed Farssi. « Performance of Hybrid RF/FSO Cooperative Systems Based on Quasicyclic LDPC Codes and Space-Coupled LDPC Codes ». Wireless Communications and Mobile Computing 2020 (30 décembre 2020) : 1–15. http://dx.doi.org/10.1155/2020/8814588.

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Free space optical (FSO) communication systems provide wireless line of sight connectivity in the unlicensed spectrum, and wireless optical communication achieves higher data rates compared to their radio frequency (RF) counterparts. FSO systems are particularly attractive for last mile access problem by bridging fiber optic backbone connectivity to RF access networks. To cope with this practical deployment scenario, there has been increasing attention to the so-called dual-hop (RF/FSO) systems where RF transmission is used at a hop followed by FSO transmission to another. In this article, we study the performance of cooperative transmission systems using a mixed RF-FSO DF (decode and forward) relay using error-correcting codes including QC-LDPC codes at the relay level. The FSO link is modeled by the gamma-gamma distribution, and the RF link is modeled by the Additive White Gaussian Noise (AWGN) model. Another innovation in this article is the use of cooperative systems using a mixed FSO/RF DF relay using quasicyclic low-density parity check (QC-LDPC) codes at the relay level. We also use the space-coupled low-density parity check (SC-LDPC) codes on the same scheme to show its importance in cooperative optical transmission but also in hybrid RF/FSO transmission. The latter will be compared with QC-LDPC codes. The use of mixed RF/FSO cooperative transmission systems can improve the reliability and transmission of information in networks. The results demonstrate an improvement in the performance of the cooperative RF/FSO DF system based on QC-LDPC and SC-LDPC codes compared to RF/FSO systems without the use of codes, but also to the DF systems proposed in the existing literature.

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Roy, Amlan Jyoti, Bhargavjyoti Sharma, Avinab Das, Sajid-ul Haque et Dr Runumi Sarma. « Long Range RF- Text based Communication System ». International Journal for Research in Applied Science and Engineering Technology 11, n^o 8 (31 août 2023) : 747–50. http://dx.doi.org/10.22214/ijraset.2023.55242.

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Abstract: With the growth of the Internet of Things (IoT) and other wireless applications in recent years the need for long-range and low-power communication systems has increased. This issue can be resolved by application of LoRa (Long Range) technology, which offers a long-range, low-power, and dependable communication system. LoRa is a wireless modulation technique derived from Chirp Spread Spectrum (CSS) technology. It encodes information on radio waves using chirp pulses in a way similar to the communication principles used naturally by dolphins and bats. LoRa modulated transmission is robust against disturbances and can be received across large distances. In this paper a study on long-range RF text-based communication utilizing LoRa module is presented

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Liu, Jiahao, Jihong Yu, Xiaoming Chen, Rongrong Zhang, Shuai Wang et Jianping An. « Covert Communication in Ambient Backscatter Systems With Uncontrollable RF Source ». IEEE Transactions on Communications 70, n^o 3 (mars 2022) : 1971–83. http://dx.doi.org/10.1109/tcomm.2022.3144447.

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Liao, Zhaohui, Liang Yang, Jianchao Chen, Hong-Chuan Yang et Mohamed-Slim Alouini. « Physical Layer Security For Dual-Hop VLC/RF Communication Systems ». IEEE Communications Letters 22, n^o 12 (décembre 2018) : 2603–6. http://dx.doi.org/10.1109/lcomm.2018.2873725.

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Letertre, Thierry, Vikass Monebhurrun et Zeno Toffano. « Accurate measurement of RF exposure from emerging wireless communication systems ». IOP Conference Series : Materials Science and Engineering 44 (23 avril 2013) : 012015. http://dx.doi.org/10.1088/1757-899x/44/1/012015.

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Xie, Lianghui, Osama Elnahas, Qinglin Zhao et Zhi Quan. « Data-Driven RF Transmit Power Calibration for Wireless Communication Systems ». IEEE Wireless Communications Letters 9, n^o 5 (mai 2020) : 721–25. http://dx.doi.org/10.1109/lwc.2020.2967213.

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Chunming Liu, Heng Xiao, Qiang Wu et Fu Li. « Spectrum design of RF power amplifier for wireless communication systems ». IEEE Transactions on Consumer Electronics 48, n^o 1 (février 2002) : 72–80. http://dx.doi.org/10.1109/tce.2002.1010094.

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Getu, Tilahun M., Wessam Ajib et Rene Landry. « Power-Based Broadband RF Interference Detector for Wireless Communication Systems ». IEEE Wireless Communications Letters 7, n^o 6 (décembre 2018) : 1002–5. http://dx.doi.org/10.1109/lwc.2018.2845373.

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Narayanan, Ram, Kyle Gallagher, Gregory Mazzaro, Anthony Martone et Kelly Sherbondy. « Hardware Design of a High Dynamic Range Radio Frequency (RF) Harmonic Measurement System ». Instruments 2, n^o 3 (19 août 2018) : 16. http://dx.doi.org/10.3390/instruments2030016.

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Radio frequency (RF) circuit elements that are traditionally considered to be linear frequently exhibit nonlinear properties that affect the intended operation of many other RF systems. Devices such as RF connectors, antennas, attenuators, resistors, and dissimilar metal junctions generate nonlinear distortion that degrades primary RF system performance. The communications industry is greatly affected by these unintended and unexpected nonlinear distortions. The high transmit power and tight channel spacing of the communication channel makes communications very susceptible to nonlinear distortion. To minimize nonlinear distortion in RF systems, specialized circuits are required to measure the low level nonlinear distortions created from traditionally linear devices, i.e., connectors, cables, antennas, etc. Measuring the low-level nonlinear distortion is a difficult problem. The measurement system requires the use of high power probe signals and the capability to measure very weak nonlinear distortions. Measuring the weak nonlinear distortion becomes increasingly difficult in the presence of higher power probe signals, as the high power probe signal generates distortion products in the measurement system. This paper describes a circuit design architecture that achieves 175 dB of dynamic range which can be used to measure low level harmonic distortion from various passive RF circuit elements.

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Sarma, Ch Amarnatha, Syed Inthiyaz et B. T. P. Madhav. « Design and Assessment of Bio-Inspired Antennas for Mobile Communication Systems ». International Journal of Electrical and Electronics Research 11, n^o 1 (30 mars 2023) : 176–84. http://dx.doi.org/10.37391/ijeer.110125.

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RF front-end system in the mobile communication system consists of an antenna, filter, and amplifier section. Now a day, there is a need to reduce the size of this RF front-end system. Here the challenge is the reduction in the size of the RF front end without degrading the performance. One way to reduce the size is by reducing the size or area of the antenna. This work proposes and simulates three Bio-inspired microstrip (BIMS) antenna designs. They are flower, Butterfly, and leaf shapes presented based on the perturbation method, Gielis super formula, and modified polar transformation models, respectively. These BIMS antennas were printed on fiberglass laminate (FR4) as substrate with a dielectric constant of εr = 4.4 and a loss tangent of 0.02. The simulation results cover parameters of the antenna, such as reflection coefficients (S11), surface current density (Jsurf), and radiation patterns. They offer a maximum gain of 14 dBi, 8 dBi, and 4dBi, respectively, and their results are compared with other works. These antennas are less in size, so they occupy less area compared to conventional rectangular or circular patch antenna, which radiates in L and S bands at different frequency ranges.

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Allegro, Gabriele, Alessio Fascista et Angelo Coluccia. « Acoustic Dual-Function Communication and Echo-Location in Inaudible Band ». Sensors 22, n^o 3 (8 février 2022) : 1284. http://dx.doi.org/10.3390/s22031284.

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Acoustic communications are experiencing renewed interest as alternative solutions to traditional RF communications, not only in RF-denied environments (such as underwater) but also in areas where the electromagnetic (EM) spectrum is heavily shared among several wireless systems. By introducing additional dedicated channels, independent from the EM ones, acoustic systems can be used to ensure the continuity of some critical services such as communication, localization, detection, and sensing. In this paper, we design and implement a novel acoustic system that uses only low-cost off-the-shelf hardware and the transmission of a single, suitably designed signal in the inaudible band (18–22 kHz) to perform integrated sensing (ranging) and communication. The experimental testbed consists of a common home speaker transmitting acoustic signals to a smartphone, which receives them through the integrated microphone, and of an additional receiver exploiting the same signals to estimate distance information from a physical obstacle in the environment. The performance of the proposed dual-function system in terms of noise, data rate, and accuracy in distance estimation is experimentally evaluated in a real operational environment.

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Puntsri, Kidsanapong. « Improvement of RF-Pilot Based Phase Noise Compensation in CO-OFDM Communication Systems ». ECTI Transactions on Electrical Engineering, Electronics, and Communications 13, n^o 2 (3 avril 2015) : 58–64. http://dx.doi.org/10.37936/ecti-eec.2015132.171033.

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This paper presents an improvement of random phase noise (RPN) compensation under chromatic dispersion (CD) by a modified two stages RF-pilot-based. The first stage is similar to the conventional RF-pilot-based method and the second stage is called the fine RPN compensation. The second stage is used for minimizing the random rotation phasor by employing a RF-pilot window. The performance of RPN mitigation is evaluated by a numerical simulation method. At the forward error correction (FEC) limit, a sum laser linewidth tolerance of ~3.1 MHz can be achieved for the 256-quadrature amplitude modulation (QAM) and ~10 MHz for 64-QAM. For CD mitigation, the linear and cubic spline interpolation methods are investigated. The simulation results show that the cubic spline interpolation method provides a significant bit error rate performance improvement.

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Salvi, Sanket, et Geetha Vasantha. « An Optical Camera Communication Using Novel Hybrid Frequency Shift and Pulse Width Modulation Technique for Li-Fi ». Computation 10, n^o 7 (30 juin 2022) : 110. http://dx.doi.org/10.3390/computation10070110.

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With an increase in network-connected devices, the existing Radio Frequency (RF) spectrum is getting highly saturated. Non-RF-based communication systems have recently garnered attention as they can be considered an alternative to RF-based systems for some applications. The availability of efficient and low-cost electronic components like Light Emitting Diode (LED), photodiode, and cameras have been pivotal in building communications systems using visible light. High-speed communication using visible light can be achieved with customized hardware and software. Visible Light Communication (VLC) uses various properties of light to encode digital data, which is then modulated and transmitted over a short distance to the receiver. Photodiodes are inexpensive and provide low complexity implementation, but their adoption requires modifying existing devices to house dedicated sensors. On the other hand, in Optical Camera Communication (OCC), existing camera-based receivers are used to extract encoded data using properties of light like color, blink frequency, intensity, and polarity. In this paper, a novel OCC technique to achieve improved robustness using a Hybrid Frequency Shift Pulse Width Modulation (HFSPDM) is proposed, implemented, and evaluated. The performance of the proposed technique is compared for a short distance with On-Off Keying (OOK) and Binary Frequency Shift-OOK (BFSOOK) due to similar computational requirements. It was observed that the proposed technique used a 17% lesser number of frames than BFSOOK and provided 8% better BER than OOK under a test environment. It also supports longer distance communication than OOK as it is less sensitive to external noise.

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Márton, Michal, Ľuboš Ovseník, Ján Turán, Michal Špes et Jakub Urbanský. « Design of Helix Antenna for 9.2GHz in FEKO for FSO/RF Hybrid System Focused on Height of Helix ». Carpathian Journal of Electronic and Computer Engineering 11, n^o 2 (1 décembre 2018) : 3–7. http://dx.doi.org/10.2478/cjece-2018-0010.

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Abstract Nowadays we are living in the ages of expansion of communication. The young generation depends on the online communications with other. Each of the devices is purposed to communication. Cloud data storage systems are available only with stable connection. Requirements are growing up to date. The answer on these requirements: the high speed of transmission, high level of security and wide bandwidth are optical communication systems. This system offers comparable features as optical system with physical optical fibers. But it has one big drawback. It is sensitivity to weather changes. We have to make backup link for case of outages. One part of design FSO/RF system in our case contains selection of appropriate type of RF antenna. We are looking for appropriate candidate. This paper is focused on analysis of helix antenna operating in non-licensed frequency range on 9.2GHz. The point of this paper is the examination of the impact of the height of helix designed antenna.

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Hu, Shengbo, Jinrong Mo, Tingting Yan et Yanfeng Shi. « Power Control for Passive QAM Multisensor Backscatter Communication Systems ». Journal of Sensors 2017 (2017) : 1–9. http://dx.doi.org/10.1155/2017/4319709.

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To achieve good quality of service level such as throughput, power control is of great importance to passive quadrature amplitude modulation (QAM) multisensor backscatter communication systems. First, we established the RF energy harvesting model and gave the energy condition. In order to minimize the interference of subcarriers and increase the spectral efficiency, then, the colocated passive QAM backscatter communication signal model is presented and the nonlinear optimization problems of power control are solved for passive QAM backscatter communication systems. Solutions include maximum and minimum access interval, the maximum and minimum duty cycle, and the minimal RF-harvested energy under the energy condition for node operating. Using the solutions above, the maximum throughput of passive QAM backscatter communication systems is analyzed and numerical calculation is made finally. Numerical calculation shows that the maximal throughput decreases with the consumed power and the number of sensors, and the maximum throughput is decreased quickly with the increase of the number of sensors. Especially, for a given consumed power of sensor, it can be seen that the throughput decreases with the duty cycle and the number of sensors has little effect on the throughput.

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Xu, Longteng, Kun Zhu, Ran Wang et Shimin Gong. « Performance Analysis of RF-Powered Cognitive Radio Networks with Integrated Ambient Backscatter Communications ». Wireless Communications and Mobile Computing 2018 (2018) : 1–16. http://dx.doi.org/10.1155/2018/8509693.

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Integrating ambient backscatter communications into RF-powered cognitive radio networks has been shown to be a promising method for achieving energy and spectrum efficient communications, which is very attractive for low-power or no-power communications. In such scenarios, a secondary user (SU) can operate in either transmission mode or backscatter mode. Specifically, an SU can directly transmit data if sufficient energy has been harvested (i.e., transmission mode). Or an SU can backscatter ambient signals to transmit data (i.e., backscatter mode). In this paper, we investigate the performance of such systems. Specifically, channel inversion power control and an energy store-and-reuse mechanism for secondary users are adopted for efficient use of harvested energy. We apply stochastic geometry to analyze coverage probability and achievable rates for both primary and secondary users considering both communication modes. Analytical tractable expressions are obtained. Extensive simulations are performed and the numerical results show the validity of our analysis. Furthermore, the results indicate that the performance of secondary systems can be improved with the integration of both communication modes with only limited impact on the performance of primary systems.

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Saber, Mohammad Javad, et Siavash Rajabi. « On Secrecy Performance of Millimeter-Wave RF-Assisted FSO Communication Systems ». IEEE Systems Journal 15, n^o 3 (septembre 2021) : 3781–88. http://dx.doi.org/10.1109/jsyst.2021.3065885.

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Yang, Liang, Wang Guo et Imran Shafique Ansari. « Mixed Dual-Hop FSO-RF Communication Systems Through Reconfigurable Intelligent Surface ». IEEE Communications Letters 24, n^o 7 (juillet 2020) : 1558–62. http://dx.doi.org/10.1109/lcomm.2020.2986002.

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Abadi, Mojtaba Mansour, Zabih Ghassemlooy, Stanislav Zvanovec, David Smith, Manav R. Bhatnagar et Yongle Wu. « Dual Purpose Antenna for Hybrid Free Space Optics/RF Communication Systems ». Journal of Lightwave Technology 34, n^o 14 (15 juillet 2016) : 3432–39. http://dx.doi.org/10.1109/jlt.2016.2571846.

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Argudo, Allyffazzkkamn, et Ghislaine Nasibu. « Cyber-Physical Attack Using High Power RF in Havana, Cuba ». International Conference on Cyber Warfare and Security 18, n^o 1 (28 février 2023) : 7–18. http://dx.doi.org/10.34190/iccws.18.1.961.

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Abstract: Global communications have relied heavily on fiber-optic cables. Satellite communications have become the norm for areas that are not highly populated or easily reached by conventional wires. The availability and use of satellite communications systems have had a limited market; with this limitation, the need for open development of each vendor's software never gained traction. This led to weaknesses not being discovered until a flaw was made public in a systems breach that affected the end users. Wireless communications that rely on microwaves lead to the use of malware to provide an override to normal operations of the equipment. As the issue of Stuxnet would allow for the override of the safety settings of satellite terminals, the malware could even be deployed remotely through a system update. The weaponization of such systems is now a point of concern. Previous studies have shown that naval satellite communications systems can be a weapon by removing the software power limitations McKay, R. W 2021 [15]. As satellite systems on ships can be larger due to being fixed, transmission power generation may be more significant. This study considers the land-based mobile systems deployed against any target and quickly dismantled and removed. Can land-based mobile satellite communication systems affected by Stuxnet or manually altered yield the same power output, and at what range will it affect human tissue? This is believed to be the case with the ongoing investigation. The survey results showed that mobile equipment could be dangerous to human tissue at distances easily achieved by mobile terminals, especially if the target is a fixed location like a building with large glass windows that R.F. power can penetrate easily

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Márton, Michal, Ľuboš Ovseník, Ján Turán et Michal Špes. « Design of Pyramidal Horn Antenna for 2.45GHz in FEKO for Application in Experimental FSO/RF Hybrid System ». Carpathian Journal of Electronic and Computer Engineering 11, n^o 1 (1 septembre 2018) : 7–10. http://dx.doi.org/10.2478/cjece-2018-0002.

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Abstract Communication technologies are growing for day to day because demand on data sharing is unstoppable. Users require availability of approach to network at all time. Implementation of smart technologies allows communication of all type of devices. Capacity of data flow have to grow. Video formats HD or 4K require transmit on high data speed. Based on the demands many types of different communication systems which are suitable for these speeds were designed. One of these systems is FSO (Free Space Optics). FSO system is based on transmission of optical beams which carry the information. This system allow high data speed comparable with standard optical fiber in range to 10km. One of drawbacks of this system is LOS (Light of Sight) between communication points. The other drawback is sensitivity to weather changes. Optical beams interfere with water particles and cause attenuation on transmission path. The solution is in implementation using hybrid FSO/RF system which combines optical communication system with RF (Radio Frequency) backup link. We realized FSO communication link on Technical University of Košice. Our research is focused on design of appropriate type of antenna for our RF backup link. Our results in this area were published.

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Pokhodzey, Larisa V., et Yurij P. Paltsev. « Critical analysis of Russian and foreign hygienic regulations of electromagnetic fields (EMF) created by modern wireless communication and communication systems ». Russian Journal of Occupational Health and Industrial Ecology 63, n^o 6 (12 juin 2023) : 397–405. http://dx.doi.org/10.31089/1026-9428-2023-63-6-397-405.

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The authors present a critical analysis of domestic SanPiNs, international recommendations (ICNIRP 2020, EU Council Recommendation 1999/519/EC, EU Directive 2013/35/EC, IEEE Std C95.1-2019) and national standards of the USA, England, Germany, France, China, Italy and Switzerland establishing hygienic regulations for radio frequency band EMF RF created by modern wireless communication and communications systems. It is shown that the RF EMF remote controls in the workplace and for the population, installed in the Russian Federation, are generally the most stringent compared to foreign recommendations, due to different methodological approaches to the hygienic rationing of the factor. In the Russian Federation, hygienic standards of EMF are developed on the basis of comprehensive hygienic, clinical-physiological, epidemiological and chronic experimental studies of bioeffects of non-thermal levels. Most foreign countries use international recommendations as national EMF standards, the basis for determining the threshold level of EMF is the thermal effect. In order to solve the issues of harmonization of hygienic standards of RF EMF, it is necessary to conduct in-depth scientific research to study the features of their biological action and impact on human health. It should be taken into account that the EMFs created by modern wireless communication systems, according to their multi-frequency characteristics, modulation modes, intensity and time parameters, the nature and methods of exposure to workers and the population, differ significantly from EMFs for which there are already existing hygienic standards. Ethics. This study did not require the conclusion of the Ethics Committee.

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Hashimoto, Ken Ya, Hideki Hirano, Shuji Tanaka et Masayoshi Esashi. « Functional RF Devices Powered by MEMS Technologies ». Advances in Science and Technology 81 (septembre 2012) : 75–83. http://dx.doi.org/10.4028/www.scientific.net/ast.81.75.

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This paper discusses use of MEMS technologies in radio frequency (RF) frontend. First, configuration of RF front-end in current wireless communication systems is surveyed, and research trends of the flexible RF front-end and software defined radio (SDR) are discussed. Second, various RF tunable filters are introduced, and we discuss how high performances are expected by the use of tunable RF surface and bulk acoustic wave (SAW/BAW) filters provided that above mentioned key technologies are developed. Finally, our attempts for realization of tunable RF SAW/BAW filters are introduced.

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Javed, Sana, Louey Issaoui, Seonghyeon Cho et Hyunchae Chun. « Utilization of LED Grow Lights for Optical Wireless Communication-Based RF-Free Smart-Farming System ». Sensors 21, n^o 20 (14 octobre 2021) : 6833. http://dx.doi.org/10.3390/s21206833.

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Indoor smart-farming based on artificial grow lights has gained attention in the past few years. In modern agricultural technology, the growth status is generally monitored and controlled by radio-frequency communication networks. However, it is reported that the radio frequency (RF) could negatively impact the growth rate and the health condition of the vegetables. This work proposes an energy-efficient solution replacing or augmenting the current RF system by utilizing light-emitting diodes (LEDs) as the grow lights and adopting visible light communications and optical camera communication for the smart-farming systems. In particular, in the proposed system, communication data is modulated via a 24% additional green grow LED light that is also known to be beneficial for the growth of the vegetables. Optical cameras capture the modulated green light reflected from the vegetables for the uplink connection. A combination of white ceiling LEDs and photodetectors provides the downlink, enabling an RF-free communication network as a whole. In the proposed architecture, the smart-farming units are modularized, leading to flexible mobility. Following theoretical analysis and simulations, a proof-of-concept demonstration presents the feasibility of the proposed architecture by successfully demonstrating the maximum data rates of 840 b/s (uplink) and 20 Mb/s (downlink).

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Muhammad, Surajo, Jun Jiat Tiang, Sew Kin Wong, Ali H. Rambe, Ismahayati Adam, Amor Smida, Mohamed Ibrahim Waly, Amjad Iqbal, Adamu Saidu Abubakar et Mohd Najib Mohd Yasin. « Harvesting Systems for RF Energy : Trends, Challenges, Techniques, and Tradeoffs ». Electronics 11, n^o 6 (20 mars 2022) : 959. http://dx.doi.org/10.3390/electronics11060959.

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The RFEH design challenges can be broadly classified into overall radio frequency direct current (RF-to-DC) power conversion efficiency (PCE), form factor, operational bandwidth (BW), and compactness. A detailed overview of the essential components of an RFEH system is presented in this paper. Various design approaches have been proposed for the realization of compact RFEH circuits that contribute immensely to mm-wave rectenna design. Effective mechanisms for configuring the rectenna modules based on the recommended spectrums for the RFEH system were also outlined. This study featured a conceptual viewpoint on design tradeoffs, which were accompanied by profound EH solutions perspectives for wireless power communications. The work covers some challenges attributed to 5G EH in mm-wave rectenna: from a controlled source of communication signals to distributed ambient EH and system level design. Conversely, the primary targets of this work are to: (I) examine a wide range of ambient RF sources and their performance with various antennae and RF-rectifier layouts; (II) propose unique rectenna design techniques suitable for current trends in wireless technology; (III) explore numerous approaches for enhancing the rectenna or RF-rectifier efficiency in a low-power ambient environment; and (IV) present the findings of a comprehensive review of the exemplary research that has been investigated. These are aimed toward addressing the autonomous system’s energy challenges. Therefore, with the careful management of the reported designs, the rectenna systems described in this study would influence the upcoming advancement of the low-power RFEH module.

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Samir, Ahmed, Mohamed Elsayed, Ahmad A. Aziz El-Banna, Imran Shafique Ansari, Khaled Rabie et Basem M. ElHalawany. « Performance Analysis of Dual-Hop Hybrid RF-UOWC NOMA Systems ». Sensors 22, n^o 12 (15 juin 2022) : 4521. http://dx.doi.org/10.3390/s22124521.

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The hybrid combination between underwater optical wireless communication (UOWC) and radio frequency (RF) is a vital demand for enabling communication through the air–water boundary. On the other hand, non-orthogonal multiple access (NOMA) is a key technology for enhancing system performance in terms of spectral efficiency. In this paper, we propose a downlink NOMA-based dual-hop hybrid RF-UOWC with decode and forward (DF) relaying. The UOWC channels are characterized by exponential-generalized Gamma (EGG) fading, while the RF channel is characterized by Rayleigh fading. Exact closed-form expressions of outage probabilities and approximated closed-form expressions of ergodic capacities are derived, for each NOMA individual user and the overall system as well, under the practical assumption of imperfect successive interference cancellation (SIC). These expressions are then verified via Monte-Carlo simulation for various underwater scenarios. To gain more insight into the system performance, we analyzed the asymptotic outage probabilities and the diversity order. Moreover, we formulated and solved a power allocation optimization problem to obtain an outage-optimal performance. For the sake of comparison and to highlight the achievable gain, the system performance is compared against a benchmark orthogonal multiple access (OMA)-based system.

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Maity, Santigopal, Madutha Santosh Kumar, Chaitali Koley, Debashish Pal et Ayan Kumar Bandyopadhyay. « Design of the Radio Frequency Section of a Ka-Band Multiple Beam Ladder-Type Extended Interaction Klystron ». Electronics 11, n^o 22 (17 novembre 2022) : 3781. http://dx.doi.org/10.3390/electronics11223781.

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Ka-band frequencies are becoming increasingly popular due to their application potential in high-data-rate wireless communications relevant to 5G applications, satellite link establishment, etc. High-power amplifiers in this frequency band, offering several tens of watts of output RF power, are one of the main enabling components of these communication systems. This article reports the design studies and analysis of the radio frequency (RF) section of a multiple beam-extended interaction klystron (MB-EIK). The proposed multiple beam RF section with a ladder-type EIK structure offers several crucial features, such as a low-voltage operation, moderate operational bandwidth, and high output power. Starting from the design of the intermediate cavities, the input and output sections and the overall RF section are presented. The proposed RF section supports the operation at 28.5 GHz center frequency with about a 500 MHz 3 dB bandwidth employing four electron beams with a 4 kV DC accelerating field.

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Majeed, Ammar A., et Ismail Hburi. « Energy-Efficient Optimization of mm-Wave Communication Using a Novel Approach of Beamspace MIMO-NOMA ». Wasit Journal of Engineering Sciences 10, n^o 2 (1 août 2022) : 223–39. http://dx.doi.org/10.31185/ejuow.vol10.iss2.287.

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The new concept of Beamspace Multiple Input Multiple Output system (BS-MIMO) was developed to address the issue of reduced Energy Efficiency (EE) of the traditional MIMO in millimeter-Wave (mm-Wave) wireless communication systems by decreases the large number of radio frequency chains (RF-chains) while maintaining the same number of antennas in those systems. On the other hand, a fewer RF-Chains leads to a smaller number of users that the system can serve as a result of the number of users that can be served must be equal to/or less than the RF-chains’ number. To overcome the above issue, the BS-MIMO is proposed to be integrated with Non-Orthogonal Multiple-Access (NOMA) scheme to produce the novel approach of BS-MIMO-NOMA. As a result, the novel scheme is capable of serving a group of users with correlated channels via a single RF-chain. In this paper, we will address the issue of EE of the above-mentioned communication systems. Specifically, we propose and develop an iterative algorithm with a low complexity that achieves near-perfect performance. The proposed scheme, named MSE-DPA (for Mean-Square-Error-Based Dynamic Power Allocation Algorithm), is checked to ensure this validity of Figure-of-Merit. The simulation results indicate that the EE is approximately 85% greater than that of traditional (fully-digital) MIMO systems for a certain fair system and environment scenario.

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Wu, Yan, Gang Li et Dejin Kong. « Performance Analysis of Relay-Aided Hybrid FSO/RF Cooperation Communication System over the Generalized Turbulence Channels with Pointing Errors and Nakagami-m Fading Channels ». Sensors 23, n^o 13 (6 juillet 2023) : 6191. http://dx.doi.org/10.3390/s23136191.

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To improve the performance of fee-space optical communication systems, this paper analyzes the performance of a relay-aided hybrid fee-space optical (FSO)/radio frequency (RF) cooperation system based on a selective combination and decoding forward transmission scheme. In this system, the FSO sub-link experienced Málaga turbulence with pointing errors and the RF sub-link suffered Nakagami-m fading. Firstly, the probability density function (PDF) and cumulative distribution function (CDF) of the end-to-end output signal-to-noise ratio (SNR) of the relay-aided hybrid FSO/RF system are derived. Then, using the extended generalized bivariate Meijer’s G-function (EGBMGF) and the approximate analytical formula of the generalized Gauss–Laguerre integral, mathematical expressions of the end-to-end average bit error rate (ABER) and outage probability of the relay-aided hybrid FSO/RF system with different subcarrier intensity modulation and different detection schemes are derived. Through a simulation analysis of the system, the results show that compared with the other three modulation technologies, the hybrid FSO/RF direct link and relay-aided hybrid FSO/RF system with coherent binary phase shift keying (CBPSK) modulation have the best bit error performance. Compared with direct detection, the hybrid direct link and relay-aided hybrid system with coherent detection can significantly improve the communication performance. Increasing the RF fading parameter m can further improve the bit error and outage performance of the hybrid direct link and relay-aided hybrid system; the hybrid direct link can significantly mitigate the degradation of communication performance in the FSO system caused by pointing errors, and the relay-aided hybrid system can further improve the communication performance; under weak turbulence conditions, the impact of pointing errors on the performance of the relay-aided hybrid system can even be ignored. The greater the total number of paths in the relay-aided hybrid system, the better the communication performance of the system; however, the more hops, the worse the performance of the system. The outage probability of the hybrid direct link and relay-aided hybrid system are very sensitive to the decision threshold, and the larger the decision threshold, the worse the outage performance. The transmission distance of different hybrid direct links has little impact on the performance of hybrid direct links and relay-aided hybrid systems. Improving the signal-to-noise ratio of RF sub-links significantly improves the performance of hybrid direct links and relay-aided hybrid systems.

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Venkatalakshmi, B., et K. Radhika. « Design of Solid Mounted Components Using Bulk Acoustic Wave Technology for Communication ». Advanced Materials Research 433-440 (janvier 2012) : 7579–82. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.7579.

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Low power and portable systems working at high frequency are becoming a significant force in the communication industry. SAW filters have been used in wireless communication systems since the early days of mobile phones. But applications at the higher handset frequencies run up against the capability of conventional SAW structures. Bulk Acoustic Wave (BAW) Technology, a relatively recent addition to this portfolio follows MEMS principle to design high performance microwave components for RF communication. Simulation of the Bulk Acoustic Resonator using Butterworth Van Dyke Model (BVD) Model and design of Ladder Filter with the designed resonator in the RF design platform Agilent ADS (Advanced Design System) have been presented. The simulated results confirm the tuning of operating frequency of designed BAW device at 2.4 GHz.

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HIKITA, MITSUTAKA. « SAW ANTENNA DUPLEXERS FOR MOBILE COMMUNICATION ». International Journal of High Speed Electronics and Systems 10, n^o 03 (septembre 2000) : 793–824. http://dx.doi.org/10.1142/s0129156400000647.

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Mobile communications systems such as cellular radios have recently become very widespread and important to both business and personal users. A key component in the radio transceiver is an antenna duplexer, which makes it possible to use a single antenna to transmit and receive RF signals simultaneously. In this chapter, block diagrams of radio transceivers are shown and the frequency characteristics required for duplexers are discussed with regard to the system requirements. Procedures for designing duplexers using SAW-resonator-coupled filters and experimental results relevant to several systems are presented. Non-linear characteristics of the duplexers are also discussed.

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Pedro, J. C., et N. B. Carvalho. « A novel nonlinear distortion characterisation standard for RF and microwave communication systems ». Engineering Science & ; Education Journal 10, n^o 3 (1 juin 2001) : 113–19. http://dx.doi.org/10.1049/esej:20010306.

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