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242 articles for “Multi-frequency”
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Performance Analysis of OFDM System Using Non-conventional Transform and Non-conventional Mapping Schemes over Rayleigh Channel
Abstract: ABSTRACT High data rate wireless transmission is required to meet the rapidly increasing demands for mobile communications. Fast Fourier transform (FFT)-OFDM has drawn much attention due to its simple implementation and robustness against frequency-selective fading channels. Recently, the advantages of the discrete cosine transform (DCT)-based OFDM have come to the light. In this paper, performance of the conventional FFT-OFDM system is compared with non-conventional DCT-OFDM in terms of bit error …
Published in Journal of Communication Engineering & Systems · Vol. 2, Issue 1, 2012 · pp. 13–20 Read article
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Machine Learning-Based Channel Estimation in 5G, Beyond-5G, and 6G Networks: Recent Advances and Future Directions
Abstract: Accurate channel estimation is one of the most fundamental challenges in modern wireless communication systems. In fifth- generation (5G) New Radio (NR) and emerging sixth-generation (6G) networks, precise knowledge of the wireless channel is essential for achieving reliable data transmission, high spectral efficiency, and low Bit Error Rate (BER). Conventional estimation techniques such as Least Squares (LS) and Minimum Mean Square Error (MMSE) rely on mathematical channel models and predefined …
Published in Journal of Telecommunication, Switching Systems and Networks · Vol. 13, Issue 2, 2026 Read article
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Review And Analysis of Application of Conductive Polymer Composites in Power-Efficient RF Circuits For 5G PAPR Reduction
Abstract: The need for low power RF circuits has gained more importance in the background of fifth-generation (5G) wireless communication systems, since the inherent PAPR characteristic of 5G signals—especially when using orthogonal frequency division multiplexing (OFDM) based techniques—becomes high. This high PAPR limits the efficiency of RF power amplifiers, increases power consumption, and induces thermal management challenges. In this context, conductive polymer composites (CPCs), based on advanced polymer matrices integrated with …
Published in Journal of Polymer & Composites · Vol. 13, Issue 3, 2025 · pp. 111–125 Read article
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Improvement of BER in Wavelet Transform-based OFDM System with Kalman Filter
Abstract: AbstractWe know that bandwidth is the most precious commodity in all communication systems such as 2G, 3G and 4G. Each service provider is now searching how to accommodate a large number of users within a limited allocated bandwidth, In order to increase the data rate of wireless medium with higher performance, orthogonal frequency division multiplexing (OFDM) is chosen. In this paper, the bit error rate analysis (BER) of discrete wavelet …
Published in Journal of Communication Engineering & Systems · Vol. 4, Issue 1, 2014 · pp. 21–28 Read article
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PAPR Reduction using Selective Mapping Method for OFDM Communication Systems
Abstract: AbstractSelective mapping method (SLM) is one of the most important techniques used for peak-to-average power ratio (PAPR) reduction of orthogonal frequency division multiplexing (OFDM) communication system. It is simple in implementation, gives distortionless transmission and reduces PAPR significantly. Mathematical modelling and Matlab simulation have been carried out to analyse its performances. At of CCDF, PAPR values for OFDM signal without applying any reduction technique is 11.5, 11.8, 12.1, 12.4 and …
Published in Journal of Communication Engineering & Systems · Vol. 5, Issue 3, 2015 · pp. 50–57 Read article
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Performance Analysis of DWT Based OFDM System using SRRC Filter in Mobile Wimax over Fading Environment
Abstract: AbstractWavelets amid its capability to provide simultaneous information in both time and frequency domain, along with minimization of interference and improved bandwidth efficiency, is considered broadly as an efficient approach to replace fast Fourier transform (FFT) in the conventional orthogonal frequency division multiplexing (OFDM) systems. Efficient filter pulses are employed spectrally in such systems in order to mitigate the effect of inter-symbol interference (ISI) as well as satisfy the bandwidth …
Published in Journal of Communication Engineering & Systems · Vol. 7, Issue 1, 2017 · pp. 1–10 Read article
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A Review on Energy Efficiency Challenges and Techniques for EE in 5G Network
Abstract: AbstractThis paper includes the survey of Energy Efficiency challenges and need in 5G network and D2D technique to improve energy efficiency without comprising the user experience. Improving the energy efficiency is important part while designing a network. The cellular systems must be energy efficient, especially in mobile communication which has made the battery constraint a major issue. This has motivated optimization of energy for the use of mobile devices. Mobile …
Published in Journal of Microwave Engineering and Technologies · Vol. 7, Issue 2, 2020 · pp. 21–29 Read article
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Comparison of Symmetrical and Asymmetrical Cascaded H-Bridge Inverter with Single DC Source
Abstract: This paper presents the comparison of traditional cascaded H-bridge inverter with isolated DC sources (symmetrical arrangement) and the proposed cascaded H-bridge inverter with single DC source (asymmetrical arrangement). Also, fundamental switching strategy is used to generate the control pulses. A conventional cascaded H-bridge (CHB) inverter requires ‘n’ numbers of DC sources for 2n + 1 levels. Without requiring transformers, the scheme proposed here allows the use of a single DC …
Published in Journal of Power Electronics and Power Systems · Vol. 2, Issue 1, 2012 · pp. 8–17 Read article
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27- Level High Frequency Transformer Based- MLI for Integration of Renewable Energy
Abstract: This research proposes a unique high-frequency transformer (HFT)-based multilevel inverter(MLI) with 27 levels can be constructed with a single DCpower supply and twenty switching devices. The proposedMLI topology comprises three medium frequency isolationtransformers, each with a different rated voltage. Since thetransformers used in MLI operate at high frequencies, thesuggested system has a smaller volume and weight. Acascaded H-bridge (CHB) connects each transformer'sprimary windings, and the secondary windings areconnected in series …
Published in Journal of Power Electronics and Power Systems · Vol. 13, Issue 2, 2023 · pp. 1–11 Read article
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Behaviour of Tri-Directional Advanced Composite Beam Using Finite Element Method
Abstract: The present work shows the modal analysis of tri-directional advanced composite beams using the finite element method. The mechanical parameters of the beam are supposed to vary in the direction of beam length (x), width (y), and thickness (h). In this work material parameters are assumed to vary according to the exponential rule of functionally graded material. To authenticate the accuracy of the present work, the result with a particular …
Published in Journal of Polymer & Composites · Vol. 13, Issue 1, 2025 · pp. 610–620 Read article
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Estimation of Semi-Blind Channel for Two-Way Relay by Using CRB: Pilot-based and Random Pilot-based
Abstract: The main purpose of semi-blind channel estimation scheme is for frequency-selective channel estimation, for multi-input and multi-output (MIMO) on relay networks, for using high bandwidth efficient use of spectrum. This scheme motivate to the low complexity of system to allow exchange information users to users by using an intermediate relay node. Because of superposition of signals at the relay node, section receiving signal at the user terminals is affected by …
Published in Current Trends in Signal Processing · Vol. 7, Issue 2, 2017 · pp. 22–31 Read article
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Diffusion-Based Enhancement of Low-SNR Time- Frequency Signals
Abstract: Traditional enhancing techniques are useless in low signal-to-noise ratio (LSNR) situations because noise drastically interferes with communication signals. Based on an enhanced DiffBIR model, this paper suggests a dual-stage signal improvement approach that combines diffusion with deep learning. By combining the Inception module for multi-scale feature extraction with the Pixel Fusion Attention (PFA) module for significant region highlighting, the model improves signal recovery in the time- frequency domain. Experiments show …
Published in Current Trends in Signal Processing · Vol. 16, Issue 2, 2026 · pp. 15–27 Read article
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Low-Power Reconfigurable Digital Filter Design Using FPGA for IoT Edge Devices
Abstract: The rapid evolution of the Internet of Things (IoT) has led to an exponential increase in the deployment of edge devices that continuously process real-time sensor data under strict power, latency, and computational constraints. Digital filtering remains a critical operation in these devices, supporting tasks such as noise removal, data conditioning, and feature extraction for intelligent decision-making. However, conventional filter implementations on microcontrollers or fixed digital signal processors often struggle …
Published in International Journal of VLSI Circuit Design & Technology · Vol. 3, Issue 2, 2025 · pp. 23–34 Read article
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Circuit Topologies, Operation, Control Schemes and Modulation Techniques of Modular Multilevel Inverter
Abstract: The Modular Multilevel Converter (MMC) is one of the developing topology. MMC has several attractive features such as a modular structure, transformer-less operation, easily scalable in terms of voltage and current, low expense for redundancy and fault tolerant operation and excellent output waveforms quality. Due to these attractive features industry and researcher increased the interest in this converter. This interest results in the development of new power topologies, modulation strategies …
Published in Journal of Power Electronics and Power Systems · Vol. 7, Issue 1, 2017 · pp. 28–40 Read article
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Frequency Regulation in Two Area System with PSO Driven PID Technique
Abstract: Now a modern days power system structures gives a major advantages in applications at the time, losses are also produced. To get the stable operation of this structured power system need balancing between total generation with total load demand and system losses. Rising and falling load demand throws off the real and reactive power balances. As a result, the system frequency and tie line interchange power deviate from their pre-programmed …
Published in Journal of Power Electronics and Power Systems · Vol. 12, Issue 2, 2022 · pp. 8–20 Read article
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Design a Rectangular Spiral Microstrip Multi-band Antenna
Abstract: This paper presents a rectangular spiral microstrip antenna operate in multi-band between the frequency ranges of 0.5–5.0 GHz. The proposed rectangular spiral microstrip antenna will be light weight, flexible, slim and compact unit compare with current antenna used in these bands. The paper also presents the detail steps of designing the rectangular spiral microstrip antenna and at different iteration level. This paper is also present how to increase no of …
Published in Journal of Electronic Design Technology · Vol. 3, Issue 1-3, 2012 · pp. 15–23 Read article
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An Update on HIV-2 Infection
Abstract: Human immunodeficiency virus type 2 (HIV–2) infection is an important cause of disease in a number of regions of the world. But the knowledge about this infection is sparse. Prevalence data on HIV-2 is heterogeneous. HIV-2 has a lower infectivity than HIV-1 which can be related to the lower RNA levels in this virus. The rate of progression to Acquired Immunodeficiency Syndrome (AIDS) in HIV-2-infected patients is highly variable making …
Published in Research and Reviews: A Journal of Microbiology and Virology · Vol. 8, Issue 2, 2018 · pp. 34–42 Read article
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Analysis of Fractal based Nested Geometries Built on Design Configurations
Abstract: AbstractFractal antenna based on the nested geometries are proposed and designed in this letter. The paper depicts the design optimization of the nested geometries for multi-rate characteristics. The antenna is fed by waveguide port. The design is obtained at the center frequency 3.5 GHz. Moreover the effect various nested elements have been observed in the geometry. The modification in geometry is introduced using pentagonal elements of the patch. The enhancement …
Published in Journal of Communication Engineering & Systems · Vol. 4, Issue 3, 2014 · pp. 9–17 Read article
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Reduce Harmonic Distortion using Pseudorandom PWM Technique
Abstract: Due to harmonic content in the voltage and current wave forms in the power electronic devices working at high frequencies cause mechanical vibrations, acoustic noise, and EMI interference makes the workers uncomfortable. Proposed work deals with a new and effective technique to possess low acoustic noise and mechanical vibration when lower switching frequency is chosen. Pseudo random pulse width modulation the new established technique is used to eliminate this undesirable …
Published in Journal of Microcontroller Engineering and Applications · Vol. 3, Issue 2, 2016 · pp. 8–13 Read article
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Design and Performance Analysis of Multi-Standard CMOS LNA Using Switched Capacitor and MIM Capacitor in 180nm Technology
Abstract: Low noise amplifier (LNA) is terribly important block in designing broadband receivers for wireless broadband communications. Being the primary active element in receiver chain it creates larger demand for LNAs that are smaller, consume less power, and provide sufficient gain, low noise and high compact design. The projected LNA is extremely integrated with low noise figure having wide calibration range with improved RF power handling system and acquires less space …
Published in Journal of VLSI Design Tools and Technology · Vol. 5, Issue 3, 2015 · pp. 37–44 Read article