Multicarrier Modulation Technique Research Articles

A Novel 4 × 1 MISO-VLC System with FBMC-OQAM Downlink Signals

A novel visible-light communication (VLC) system with 4 × 1 multi-input–single-output (MISO) channels is designed. In the system, the filter bank multicarrier (FBMC) and offset quadrature amplitude modulation (OQAM) techniques are used to generate downlink signals. The principles and implementation methods are proposed and analyzed, and the light intensity and received light power distribution of four LED emitters are discussed. The results demonstrate that it not only satisfies the requirements of indoor information access but also provides daily lighting. The used FBMC-OQAM signals exhibit better reception performance than orthogonal frequency division multiplexing (OFDM) signals. The system used has a lower bit error rate (BER) and larger access bandwidth compared to a 1 × 1 single-input–single-output (SISO) system. It has the potential for application advantages in future indoor VLC system applications.

Capacity and Reliability of Ionosphere Communication Channel Based on Multi-Carrier Modulation Technique and LUF-MUF Variation

Capacity and Reliability of Ionosphere Communication Channel Based on Multi-Carrier Modulation Technique and LUF-MUF Variation

PAPR analysis in OTFS using the centre phase sequence matrix based PTS method

Orthogonal time–frequency space (OTFS) is a multicarrier modulation technique for high-speed data transfer in wireless communications. In an OTFS system, many subcarriers are used to send the modulated symbols. This makes OTFS signals have a high peak-to-average power ratio (PAPR). We suggest a partial transmit sequence (PTS) approach based on the Centre Phase Sequence Matrix (CPSM) to lower the high PAPR. Furthermore, the suggested method effectively searches for the best possible combination of phase rotation factors to reduce computing complexity. We examine the outcomes regarding bit error rate (BER), power spectral density (PSD), and PAPR to validate the competing transforms in the OTFS system. Along with non-orthogonal multiple access (NOMA), filter bank multi-carrier (FBMC), universal filter multi-carrier (UFMC), and orthogonal frequency division multiplexing (OFDM), the PAPR, BER, and PSD performance of OTFS were also compared. According to the data, the suggested PTS + CPSM reduces PAPR more effectively than the current PTS. It is also mentioned that by increasing the number of sub-blocks (s = 2 and 4), the suggested PTS + CPSM can achieve an even better PAPR rate. According to the experimental results, the suggested approach has dramatically decreased the PAPR while maintaining the BER and PSD performance with the least amount of computational complexity.

Modified Error Function Companding for reduction of PAPR in GFDM signals

Generalized Frequency Division Multiplexing (GFDM) is a multicarrier modulation technique, nevertheless, it provides high peak to average power ratio (PAPR) which affects the power amplifier (PA) efficiency. In this work, the modified error function companding is proposed for reducing PAPR in GFDM signals. The power scaling parameter (η) and companding parameter (a) are used to reduce the peak power. The average power is not altered in the proposed method, so there is no need to adjust the dynamic gain of PA. The theoretical expressions for the transform gain, achievable PAPR reduction and closed form expression of attenuation factor are derived. Moreover, the transform gain, attenuation factor, power spectral density, PAPR and bit error rate (BER) performance of the proposed method is analysed for different values of companding parameter. The results ensure that the proposed mEFC method at a=1 provides significant PAPR reduction than existing companding methods.

Seven‐level single‐source switched capacitor inverter with triple boosting capability and high reliability

SummaryA single‐source switched capacitor multilevel inverter (SCMLI) topology utilizing only 10 switches and 1 diode with the capability of generating seven output voltage levels and a triple voltage boosting factor is proposed in this paper. The converter has capacitors that are self‐balanced and do not require any additional circuitry. The multicarrier sinusoidal pulse width modulation (PWM) technique is used to generate various switching signals for the 10 switches. Moreover, the reliability analysis using the Markov model has been carried out to assess the lifespan of power electronic components used in the proposed converter. The converter's performance is analyzed when an open circuit fault occurs in one or multiple switches. Power loss and efficiency in the converter are calculated by PLECS software using thermal modeling. The efficiency of SCMLI was found to be 97.6% for a 300 W load. The inverter working is verified by building a 500 W prototype in the lab. The experimental results in steady‐state and dynamic conditions agree with the theoretical and simulation analysis.

Deep learning based asymmetrical autoencoder for PAPR reduction of CP-OFDM systems

Adoption of Orthogonal Frequency Division Multiplexing (OFDM) in 5th Generation New Radio (5G NR) as a multicarrier modulation technique allows high data rate transmission with lower complexity. However, problem such as peak to average power ratio (PAPR) has decreased the transmitter efficiency. Recently, several attempts have been made to reduce the high PAPR in OFDM utilizing deep learning (DL) based on autoencoder architecture. However, the proposed autoencoder using symmetrical autoencoder (SAE) is followed by high computational complexity at both transmitter and receiver as well as BER performance degradation. Since 5G NR focuses on massive 5G internet of things eco-system, a flexible carrier spacing is used to support diverse spectrum bands which is afterward named as Cyclic Prefix OFDM (CP-OFDM). In this study, we aimed to contribute to this growing area of research by exploring the potential of our proposed asymmetrical autoencoder (AAE) to reduce high PAPR in the CP-OFDM system. Four AAE models have been developed in this study and the performance of the models were evaluated based on comprehensive conditions such as data training at different corruption levels, cyclic prefix length, upsampling factors and loss function levels. The investigation of AAE in 5G CP-OFDM system has shown superior performance using a 5×1 AAE model that can reduce a substantial amount of PAPR, BER degradation and computational complexity compared to conventional SAE. This study lays the groundwork for future research into the asymmetrical approach of autoencoder especially in 5G and beyond networks.

Performance enhancement and PAPR reduction for MIMO based QAM-FBMC systems.

Filter Bank Multi-Carrier (FBMC) is attracting significant interest as a multi-carrier modulation (MCM) approach for future communication systems. It offers numerous advantages in contrast to Orthogonal Frequency Division Multiplexing (OFDM). Nonetheless, similar to many other MCM techniques, FBMC encounters a significant challenge with a high Peak-to-Average Power Ratio (PAPR). Additionally, incorporating Multiple-Input and Multiple-Output (MIMO) into FBMC presents heightened difficulties due to the presence of complex interference and increased computational complexity. In this paper, we first study the performance analysis of MIMO based Quadrature Amplitude Modulation (QAM)-FBMC systems considering the system complexity and interference. To enhance coverage effectively using beamforming with multiple antennas, it is essential to reduce PAPR to minimize the input backoff (IBO) required by nonlinear power amplifiers. Therefore, we propose new PAPR reduction method for MIMO based QAM-FBMC systems leveraging the null space within the MIMO channel using clipping and filtering (CF) technique. The PAPR reduction signals generated in this process are then mapped to the null space of the overall MIMO channel for each frequency block. Through computer simulations using a nonlinear power amplifier model, we illustrate that the proposed method substantially enhances both PAPR and throughput of MIMO based FBMC systems compared to conventional methods.

PAPR reduction in CP-OFDM (5G) using hybrid technique

The Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) is a 5G multicarrier waveform that offers great data speeds and improvements in spectrum utilisation. The primary CP-OFDM’s weakness is its excessive peak-to-average power ratio (PAPR), which is a characteristic of all multicarrier modulation techniques. We study the application of a hybrid technique approach how to lower the peak to average power ratio (PAPR) in a CP-OFDM system. We also evaluated the outcomes of peak to average power ratio (PAPR) decrease in CP-OFDM, utilising a hybrid technique with Group Codeword Shift (GCS), Median Codeword Shift, Selective Codeword Shift (SCS), and Conventional CP-OFDM. When compared to the non-hybrid technique, the simulation results indicate that the hybrid approach is superior in reducing the peak PAPR by more than 65 percent.

PAPR, Spectral Efficiency, BER and SNR Analysis of OFDM: A Novel Partial Transmit Sequence-Particle Swarm Optimization Technique

Orthogonal frequency division multiplexing (OFDM) is a widely used multicarrier modulation (MCM) technique in the field of wireless communications, specifically designed to facilitate high-speed data transmission. The use of several subcarriers inside an OFDM system for the transmission of modulated symbols results in the generation of OFDM signals with a significant peak-to-average power ratio (PAPR). In this study, we propose a novel approach for mitigating the high PAPR in wireless communication systems (WCS). Our method utilizes a partial transmit sequence (PTS) strategy, which is enhanced by using an adaptive particle swarm optimization (PSO) algorithm. In this study, we present a description of an OFDM system employing the standard PTS technique in conjunction with PSO. To mitigate computational complexity, the suggested methodology efficiently explores the optimal amalgamation of phase rotation components. Experimental findings demonstrate that the computational complexity and PAPR have been greatly minimized by the suggested method.

Reduce PAPR In Filtered-CPOFDM using Modified SCS Method System

Filtered Cyclic Prefix Orthogonal Frequency Division Multiplexing (F-CPOFDM) is a 5G multicarrier waveform that enables high data rates and spectrum efficiency improvements. The primary drawback of F-CPOFDM is that it has a high peak to average power ratio (PAPR), which is a characteristic of all multicarrier modulation techniques. This paper shows the study of the application on Group Codeword Shift (GCS) approach to reduce the peak to average power ratio (PAPR) in a Filtered- CPOFDM system in this article. Additionally, this paper also compared the results of peak to average power ratio (PAPR) reduction with low complexity in Filtered-CPOFDM using a Group Codeword Shift (GCS) approach, Selective Codeword Shift (SCS), and Conventional CPOFDM. The simulation results indicate that the Group Codeword Shift (GCS) approach reduces peak PAPR by 45.95 percent when compared to conventional Filtered-CPOFDM, 26.13 percent when compared to the Selective Codeword Shift (SCS) method and 22.53 percent when compared to the Median Codeword Shift (MCS) method.

Passive array micro-magnetic stimulation device based on multi-carrier wireless flexible control for magnetic neuromodulation.

Objective.The passive micro-magnetic stimulation (µMS) devices typically consist of an external transmitting coil and a single internal micro-coil, which enables a point-to-point energy supply from the external coil to the internal coil and the realization of magnetic neuromodulation via wireless energy transmission. The internal array of micro coils can achieve multi-target stimulation without movement, which improves the focus and effectiveness of magnetic stimulations. However, achieving a free selection of an appropriate external coil to deliver energy to a particular internal array of micro-coils for multiple stimulation targets has been challenging. To address this challenge, this study uses a multi-carrier modulation technique to transmit the energy of the external coil.Approach.In this study, a theoretical model of a multi-carrier resonant compensation network for the arrayµMS is established based on the principle of magnetically coupled resonance. The resonant frequency coupling parameter corresponding to each micro-coil of the arrayµMS is determined, and the magnetic field interference between the external coil and its non-resonant micro-coils is eliminated. Therefore, an effective magnetic stimulation threshold for a micro-coil corresponding to the target is determined, and wireless free control of the internal micro-coil array is achieved by using an external transmitting coil.Main results.The passiveµMS array model is designed using a multi-carrier wireless modulation method, and its synergistic modulation of the magnetic stimulation of synaptic plasticity long-term potentiation in multiple hippocampal regions is investigated using hippocampal isolated brain slices.Significance.The results presented in this study could provide theoretical and experimental bases for implantable micro-magnetic device-targeted therapy, introducing an efficient method for diagnosis and treatment of neurological diseases and providing innovative ideas for in-depth application of micro-magnetic stimulation in the neuroscience field.

PAPR Reduction in Cyclic Prefix OFDM (5G) System using Group Codeword Shifting Technique

Cyclic Prefix Orthogonal Frequency Division Multiplexing (CPOFDM) is a 5G multicarrier waveform that enables high data rates and spectrum efficiency improvements. The primary drawback of CPOFDM is that it has a high peak to average power ratio (PAPR), which is a characteristic of all multicarrier modulation techniques. We study the application of a Group Codeword Shift (GCS) approach to reduce the peak to average power ratio (PAPR) in a CPOFDM system in this article. Additionally, we compared the results of peak to average power ratio (PAPR) reduction with low complexity in CPOFDM using a Group Codeword Shift (GCS) approach, Selective Codeword Shift (SCS), Median Codeword and Conventional CPOFDM.

Performance Analysis of GFDM System in 5G Cellular Networks

Orthogonal Frequency Division Multiplexing (OFDM) is employed in the current 4G cellular technologies. Because of its resistance to multipath propagation channels, OFDM is a popular multicarrier modulation technique. Although OFDM is one of the effective approaches for a 4G network, out-of-band radiation, inter-symbol interference (ISI), and inter-carrier interference make this method unsuitable for 5G. (ICI). A new approach or next-generation cellular network, i.e., very high data rate, low latency, greater throughput, more device connectivity, and improved device-to-device communication, should be used to deliver effective and dependable communication. The system introduces generalized frequency division multiplexing (GFDM). In GFDM, a single cyclic prefix is utilized throughout the frame and an adjustable pulse-shaping filter can be used to monitor the transmitted signal’s out-of-band emission. Using this ISI, the multipath channel can be controlled. In the proposed system, with large signal constellations, higher-order modulation schemes, and advanced receiver structure, a very high data rate can be achieved. By using various iterative receiver structures the performance of the GFDM system in 5G cellular networks can be analyzed.

An Efficacious Modulation Gambit Using Fewer Switches in a Multilevel Inverter

Since multicarrier based modulation techniques are simple to implement and can be used to control inverters at any level, they are frequently employed in modern multilevel inverters in high or medium power applications. When considering the many multi-carrier modulation techniques available, level-shifted pulse-width modulation (LSPWM) is often chosen for its superior harmonic performance. However, this traditional LSPWM method is not suitable for controlling newly proposed reduced switch count (RSC) MLI topologies. The research work in this paper seeks to elucidate the reasons why conventional LSPWM is ineffective in controlling RSC MLI topologies, and proposes a generalized LSPWM system based on logical expressions. The proposed method can be utilized with symmetrical and asymmetrical RSC MLIs, and can be extended to an arbitrary number of levels. The merit of the proposed method for controlling any RSC configuration with satisfactory line-voltage THD (≈1.8%) performance (identical to conventional LSPWM) was evaluated using multiple 13-level asymmetrical RSC-MLI topologies. A MATLAB model was developed and then subjected to simulation and real-world testing to prove the effectiveness of the proposed modulation strategy.

BER and PSD Improvement of FBMC with Higher Order QAM Using Hermite Filter for 5G Wireless Communication and beyond

Nowadays, multicarrier modulation schemes are being widely used in wireless communication system than single-carrier modulation techniques. Single-carrier modulation schemes are less capable of dealing with multipath fading channels than multicarrier modulation schemes, which results in lower spectral efficiency. Multicarrier modulation schemes have the ability to overcome multipath fading channels. Multicarrier modulation technique currently used in 4G technology in many countries is OFDM and it is easy for implementation, immune to interference, and provide fast data rate. However, the rising users demand on wireless communication resulted in need for further advancement of wireless communication system. The present OFDM transmission does not fulfill the requirements of 5G wireless communication system and beyond due to major limitations such as out of band emission and usage of cyclic prefix. To overcome the challenges of OFDM, different modulation schemes like Filter Bank Multicarrier with Offset-QAM, Filter Bank Multicarrier with QAM, Universal Filter Multicarrier, Filtered-OFDM, and Weighted Overlap and Added-OFDM are proposed. In this study, the Filter Bank Multicarrier with QAM using Hermite prototype filter is proposed to overcome drawbacks of OFDM and all other proposed waveforms. The performances of each multicarrier technique are analyzed based on power spectral density and bit error rate. Simulation result shows that the power spectral density of FBMC with QAM using Hermite filter resulted in 4.7 dB reduction of out of band emission compared to FBMC with QAM using PHYDYAS filter. The bit error rate is also reduced for Vehicular A, Vehicular B, Pedestrian A, and Pedestrian B channel models.

Li-Fi concept in terms of modulation techniques

Li-Fi (light fidelity) is a bidirectional wireless system that transmits data via LED or infrared light. Li-Fi technology only needs a light source with a chip to transmit an internet signal through light waves. The system has a receiver to pick up light signals and transmitter to send light signals back to the lamp using infrared light. The technology has high data rate as well as high spectral efficiency and also robust against inter symbol interference. Different forms of OFDM (a multicarrier modulation technique) are being used for Li-fi scheme. This paper reflects the theoretical study of various modulation techniques of Li-fi technology.

Multi-Level Inverter Fed Induction Motors Based on Simplified and Efficient Modulation Techniques

Speed control of three phase and single phase induction motors represents a very important issue in residential and industrial applications. This paper presents a voltage to frequency speed control of both single phase and three phase induction motors derived by multi-level inverters (MLIs). 15-level and 31-level multi-level inverters are considered. Both MLIs are operated by applying two proposed simplified and efficient modulation techniques in addition to the application of conventional multicarrier sinusoidal pulse width modulation technique MC-SPWM. The proposed modulation techniques overcome several difficulties related to MC-SPWM. The scaler voltage to frequency control method operates very well during starting along with step changes in motor speeds. Simulation results verify the high performance of the proposed modulation techniques when controlling both induction motors based on 15-level and 31-level MLIs.

Modified [formula omitted]-law Root Companding for PAPR reduction in GFDM signals

Generalized Frequency Division Multiplexing (GFDM) is a multicarrier modulation technique and able to meet the requirements of next generation wireless systems. But it exhibits high peak to average power ratio (PAPR), which degrades the efficiency of the power amplifier (PA). In this work, modified Root Companding and modified μ-law Root Companding are proposed to reduce PAPR in GFDM signals. The existing methods alter the average power due to expansion of small signals, whereas the proposed method keeps the average power as constant by adjusting both small and large signals. Therefore, the adjustment of dynamic gain in PA is not required. Transform gain and achievable PAPR reduction of the proposed methods are compared by varying companding metrics such as companding root R and companding parameter μ. Also, bit error rate (BER) performance is analysed over AWGN channel and the value of R, μ is chosen such that companding distortion is small. The theoretical PAPR distribution of the proposed methods are derived and validated with Monte-Carlo simulations. The BER performance over multipath fading channel is also analysed. Further, the BER, PAPR and power spectral density performance of the proposed methods are compared with conventional OFDM, GFDM and existing PAPR reduction methods. The computational complexity is also analysed.

Analysis of Multi Carrier Modulation techniques for 5G Physical Layer Communications

The more enchanting Multicarrier Communication (MCM) techniques like Fifth Generation (5G), Long Term Evolution (LTE) and Fourth Generation (4G) are the enhancing techniques that contribute the progress of wireless communication systems. The most effective way to save resources in 5G is to make efficient use of all existing discontinuous spectrums, which maximizes Spectrum Efficiency (SE). A valid comparison of many 5G MCM techniques is made in this work, namely Universal Filter Multi Carrier (UFMC), Filter Bank Multi Carrier (FBMC) and Orthogonal Frequency Division Modulation (OFDM). Various Key Performance Indicators (KPI) such as Bit Error Ratio (BER), Signal to Interference Ratio (SIR), Power Spectral Density (PSD) and ratio between Peak Power and Average Power, Throughput, and Spectral Efficiency (SE) are evaluated and compared under various realistic channels. UFMC Modulation technique is compatible with existing channel estimation and detection techniques and further improves SE. The SE of FBMC has been improved by 2% with Hermite filter when compared to PHYSDAS, RRC prototype filters. It has been observed that FBMC offered better SIR, Throughput, also a complex design of filter reduced BER and PAPR.

Low and High Frequency Control Strategy for Asymmetrically Switched Cascaded Multilevel Inverter

This paper proposes low and high frequency control techniques for asymmetrically switched cascaded multilevel inverters (MLI). Initially, Low frequency-based switching angle calculation methods are proposed for the suggested topology. Then high frequency-based Multi-carrier pulse width modulation (MCPWM) techniques are used to control the switching states of multilevel inverters for asymmetrical sources. The proposed multilevel inverter is a reduced switch topology with a modular version realized. From the modular version of the topology, three asymmetrically switched (7, 13 & 21) levels are simulated by MATLAB/Simulink environment and comparisons among themselves are also considered according to method of switching techniques and power quality, i.e. total harmonic distortion (THD). The designed inverters are recommended for photovoltaic power generation as they are suitable to integrate separate DC power sources. The inverters are designed and simulated with a proper simulation environment and experimentally verified through hardware in loop (HIL) using OPAL-RT (OP-5600) testbed.