Multi Carrier Research Articles

Underwater Acoustic Communication With Multicarrier Binary Frequency Shift Keying

This article describes a novel approach for robust and reliable underwater acoustic communication targeting low data rate applications in very challenging channels. The well-known binary frequency shift keying (BFSK) modulation is extended with multiple pair-wise BFSK subcarriers forming a multicarrier (MC) waveform referred to as MC-BFSK. Time offsets between neighboring subcarriers combined with windowing and guard periods are employed to increase the robustness against Doppler-induced frequency spread/shift and reverberation together with novel methods for synchronization, peak-to-average-power ratio reduction, and soft-value extraction. For the design of the parameters of the waveform, a heuristic approach is utilized. A noncoherent matched filter receiver with spatial diversity is adopted. The MC-BFSK transmission scheme is evaluated by means of computer simulations as well as sea-trial measurements. The obtained results are compared with competing modulation schemes where the proposed MC-BFSK shows better performance in challenging channels. In particular, we are able to decode frames in a sea-trial scenario where the direct path between the transmitter and the receiver is blocked by an island.

Study and analysis of multi carrier modulation techniques – FBMC and OFDM

Modern wireless communication systems such as the 4th Generation (4G) and Long Term Evolution (LTE) are highly attracted to Multicarrier (MC) techniques. OFDM (Orthogonal Frequency Division Multiplexing) and FBMC (Filter Bank Multi-Carrier) transmission schemes are compared in this paper. Analysis of the merits of FBMC and OFDM modulation techniques is based on its Spectral Density, Spectral Efficiency, Peak to Average Power Ratio (PAPR) and Bit Error Rate (BER). FBMC overcomes some of the drawbacks of OFDM. Based on the simulation results, FBMC had low BER, higher PAPR, better Spectral Efficiency and better Spectral Density than OFDM. In comparison with Conventional OFDM, FBMC delivers superior performance.

Single- Versus Multicarrier Terahertz-Band Communications: A Comparative Study

The prospects of utilizing single-carrier (SC) and multi-carrier (MC) waveforms in future terahertz (THz)-band communication systems remain unresolved. On the one hand, the limited multi-path components at high frequencies result in frequency-flat channels that favor low-complexity wideband SC systems. On the other hand, frequency-dependent molecular absorption and transceiver characteristics and the existence of multi-path components in indoor sub-THz systems can still result in frequency-selective channels, favoring off-the-shelf MC schemes such as orthogonal frequency-division multiplexing (OFDM). Variations of SC/MC designs result in different THz spectrum utilization, but spectral efficiency is not the primary concern with substantial available bandwidths; baseband complexity, power efficiency, and hardware impairment constraints are predominant. This paper presents a comprehensive study of SC/MC waveforms for THz communications, utilizing an accurate wideband THz channel model and highlighting the various performance and complexity trade-offs of the candidate schemes. Simulations demonstrate that discrete-Fourier-transform spread orthogonal time-frequency space (DFT-s-OTFS) achieves a lower peak-to-average power ratio (PAPR) than OFDM and OTFS and enhances immunity to THz impairments and Doppler spreads, but at an increased complexity cost. Moreover, DFT-s-OFDM is a promising candidate that increases robustness to THz impairments and phase noise (PHN) at a low PAPR and overall complexity.

A Joint Sonar-Communication System Based on Multicarrier Waveforms

Jointdetection and communication systems demonstrate their unique efficiencies in both spectrum and cost. In this letter, we propose a sonar-communication (SonarCom) system for underwater scenarios based on two multicarrier (MC) waveforms, which are orthogonal frequency division multiplexing (OFDM) and orthogonal chirp division multiplexing (OCDM) waveforms. Different types of waveforms provide flexibilities to deal with various underwater environments. Furthermore, a generalized likelihood ratio test (GLRT) is proposed for detection to deal with multipath channels. Time aliasing techniques are applied to leverage the signal structure. Moreover, a minimum mean square error (MMSE) equalizer is developed for communication to counter frequency-selective fading. Simulation results show that the GLRT detector for the SonarCom system outperforms the existing matched filter (MF). The OCDM scheme maintains better communication performance than the OFDM one.

Multi-carrier switching strategy for high-bandwidth potential balancing control of multilevel inverters

<span lang="EN-US">This paper confers on investigation of a direct torque control (DTC) of induction motor drive by 3 level neutral point clamp (NPC) multilevel inverter. The imbalance problem may deteriorate the electric drive performances which might cause a short circuit condition. Various balancing control strategies were proposed, however, most of them employed complex space vector modulation (SVM) and hysteresis-based controller that generates variable switching frequencies. The proposed method will offer a reliable balancing control strategy with a constant switching frequency, and moreover, it will provide excellent electric drive performances. This research proposed a new multi carrier switching modulation strategy that establish a high-band-width control for neutral point potential in the NPC inverter. Potency of the proposed high-bandwidth potential balancing strategy is validated through the MATLAB/SIMULINK environment.</span>

Switching Sequence Control 31-Level Asymmetric Cascaded of Reduced Switch Count Multilevel Inverter with Multi Carrier Pulse Width Modulation

Various pulse width modulation techniques, including as cascaded multilevel inverters (MLI), diode clamped multilevel inverters, and flying capacitor multilevel inverters, can be used to simply operate common inverters. Due to increased switching losses, current MLIs cannot reach high efficiency. Due to lower losses and THD than standard MLI topologies, the asymmetric cascaded multi-level H-bridge inverter architecture examined in this white paper employs fewer switches and more output voltage levels (Total Harmonic Distortion). The THD is less than the IEEE standard because of the suggested architecture. In this instance, phase difference (PD) multi-carrier PWM techniques are used to control the gate pulses using sinusoidal reference. Each switch receives a different pulse pattern thanks to a method of decimal-to-binary conversion. It is possible to utilise the suggested circuit for applications requiring moderate to high power, and it is quite simple to evaluate. Utilize the MATLAB/SIMULINK environment to simulate time-domain behaviour for the 31-level and 33-level multilevel inverter topologies.

A Joint Filter and Spectrum Shifting Architecture for Low Complexity Flexible UFMC in 5G

The hardware realization of Universal Filtered Multi Carrier (UFMC) architecture has attracted significant attention in fifth generation (5G) and beyond. In addition to the flexibility in fast Fourier transform (FFT)-length, a flexible prototype filter in combination with multiplicative complex spectrum shifting co-efficients is required for realizing flexible UFMC architecture. The existing architectures of UFMC transmitter commonly adopted fixed-size FFT-length, number of subbands, subband size, and filter-length. Moreover, the lack of flexible prototype filter and spectrum localization of filter co-efficients to individual subbands limits the flexible UFMC system design. In this paper, we propose VLSI architecture for a flexible length prototype filter that can generate spectrally shifted filter co-efficients to individual subbands in tune with the changing value of FFT-length, number of subbands, subband size, and filter-length. For 16-bit word size architecture, our proposed design produces filter co-efficients and spectrum shifting co-efficients upto length, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{15}$ </tex-math></inline-formula> . Thus, any desired combination of FFT-length, number of subbands, subband size and filter-length is selected to generate the filter co-efficients for the individual subbands. Moreover, complex multiplication and addition operations are reduced in proposed architecture, quantitatively, about 58.81% reduction in filtering unit is achieved over the state-of-the-art architecture. Finally, hardware implementation output and XILINX post route simulation result matches perfectly with MATLAB simulations.

A Comparative Study of SC and MC Underwater Acoustic Communication Systems

In this study, comparative performance analyzes of single carrier (SC) and multi carrier (MC) underwater acoustic communication (UWAC) schemes are performed in underwater acoustic channel environments. Computer simulation studies are carried out to compare SC and MC UWAC communication systems in multi-path underwater acoustic channel environments based on bit error rate (BER) and mean square error (MSE) accomplishment benchmarks. From the acquired outcomes, it is perceived that the MC-UWAC communication scheme has approximately 3 dB better achievement than the SC-UWAC communication scheme.

A Comparative Performance Evaluations of SC and MC VLC Systems in Underwater Environments

In this study, comparative performance analyzes of single carrier (SC) and multi carrier (MC) visible light communication (VLC) schemes in underwater optical channel environments are performed. Computer simulation studies are carried out to compare SC and MC VLC communication systems in underwater optical LOS and N-LOS channel environments based on bit error rate (BER) success benchmark. From the acquired outcomes, it is perceived that SC-VLC communication system has approximately 8 dB better performance than MC-VLC communication system in both channel environments.

Game Theory-Based Power Allocation Strategy for NOMA in 5G Cooperative Beamforming

Non-orthogonal multiple access (NOMA) is a Fifth Generation (5G) technique that allows many users to simultaneously access the same time–frequency separating channels via successive interference cancellation (SIC) receiver. Cooperative NOMA (CNOMA) is an effective tool to prevent performance degradation of far users by allocating minimal power to users with good channel conditions. In this paper, we proposed a fair power and channel allocation scheme based on the Nash bargaining solution (NBS) game solution in full-duplex, cooperative beamforming (BF) for multicarrier (MC) NOMA. The proposed NBS scheme assigns optimal power and channel allocation according to channel conditions while maintaining a fair rate amongst cooperative users. NBS provides a fair and optimum approach for maximizing the total rate of CNOMA. The signal-to-leakage (SLR) ratio precoding technique is considered as a design performance criterion for beamforming vector towards achieving power domain CNOMA players. Simulation results show that at BER = $${10}^{-5}$$ , the NBS power allocation (proposed scheme) improved by 2 dB in terms of Signal-to-Noise Ratio (SNR), compared with the non-cooperative scheme, and 3 dB compared with the multiple-input multiple-output NOMA (MIMO-NOMA). Both improvements were as a result of interference reduction and information sharing in the network. In terms of fairness, the proposed NBS scheme shown a high level of fairness at 0.8401, compared to the other similar approaches in the literature.

Overlay dynamic spectrum sharing in cognitive radio for 4G and 5G using FBMC

Dynamic spectrum sharing allows the 4G-LTE and 5G-NR to use the same frequency spectrum band for communication and the spectrum allocator allocates the spectrum to the users based on their demands. In this paper we have analyzed existing OFDM (orthogonal Frequency division multiplexing) Technique in the physical layer for the spectrum sharing and proposed a FBMC (Filter Bank Multi Carrier) technique with Long duration Pulse Shaping filter and designed a Sequence Based Spectrum Allocator for designing a high spectral efficient network. Results were validated based on the parameters like Secondary User Score and Primary User Satisfaction Ratio and Secondary user throughput for overlay spectrum sharing mode in cognitive radio.

Performance Analysis of OFDM, FBMC and UFMC Modulation Schemes for 5G Mobile Communication MIMO systems

The rapid development in the field of Internet and mobile communication systems has demanded the technology of the 5th generation communication mimo systems to develop rapidly over the past few years. The name given to the next generation of wireless communication is 5G. Till now 4G provided the speed upto few mbps but the main drawback lies in reproducing the real time applications. In this scenario, 5th generation systems come into picture. 5g modulation schemes are developed exclusively for the Internet, video, voice, and data services. The ODFM has few disadvantages high peak power to average power ratio resulting in requirement of the high-power amplifiers. So, to overcome this problem, 5g modulation schemes Filter bank multi carrier systems and universal filter multicarrier systems are used. As we go higher the frequency range, there is an issue of frequency selectivity and thus by using the mimo techniques the problem of frequency selectivity can be solved. In this paper, we have compared the performance analysis of the Orthogonal frequency division multiplexing (OFDM) mimo system, Filter bank multicarrier (FBMC) mimo systems and Universal filter multicarrier (UFMC) mimo systems with respect to Bit error rate, power spectral density, data rate and issue of spectral confinement which is observed in FBMC and UFMC is resolved and thus reducing the complexity of the 5g system.

RETRACTED ARTICLE: A comprehensive survey 5G wireless communication systems: open issues, research challenges, channel estimation, multi carrier modulation and 5G applications

RETRACTED ARTICLE: A comprehensive survey 5G wireless communication systems: open issues, research challenges, channel estimation, multi carrier modulation and 5G applications

Signal Processing of Filter Bank Multi Carrier for 5G

The spectrum efficiency in fourth-generation (4G) i.e. orthogonal frequency division multiplxing (OFDM) systems has become a major problem at this time due to the increasing need for communication bandwidth. This efficiency is reduced due to the high out-of-band emission (OoBE) that exist. As one of the candidates that still has the potential to be used in the fifth generation (5G) signal modulation method, this paper aims to make observations by out of band emission simulation on a multi carrier filter bank (FBMC). This paper illustrated facets of the 5G with FBMC modulation scheme. To illustrate it, 24 sub-carriers were simulated with each sub-carrier spaced 15 kHz, later the power spectral density of the FBMC signal is plotted. The MATLAB simulation results with the 256-QAM order indicated that FBMC is more advantageous than OFDM because it offers higher spectral efficiency with a difference of 130 dBW/Hz. In other words, this system offers low out of band emission. Previously, an illustration of the FBMC prototype was also shown.

Filter Bank Multi Carrier Signal System for Frequency Selective Channels

Filter Bank Multicarrier (FBMC) frameworks are a subclass of multicarrier (MC) frameworks. The essential guideline, separating spectrum into many thin sub channels, may not be new, MC frameworks have seen wide appropriation. These days, multicarrier regulation frameworks dependent on the discrete Fourier transforms are usually used to transmit over recurrence particular channels subject to forceful noise aggravations. In any case, these handsets experience the ill effects of poor sub channel spectral control, that is, the measure of inter channel impedance isn't unimportant. It very well may be indicated that the framework execution reduces when it is dependent upon an unsettling influence with a large portion of its energy focused on a narrow frequency band. This Paper aims that identify the Filter Bank Multi Carrier (FBMC) performance. The MIMO system combined with the FBMC then identifies the over Frequency Selective Channel (FSC). Here the analysis for FSC, Flat fading model FBMC and system with MMSE equalization. The Prototype filters are analyzing the system performance characteristics. The Power Spectral Density (PSD) of the MIMO FBMC system for the given spectrum. The proposed systems are best to compare all existing technique and we measure the spectral efficiency of the system.

Power Quality Improvement in Modular Multilevel Inverter Using for Different Multicarrier PWM

Pulse width modulation (PWM) is a powerful technique employed in analog circuit convert with a microprocessor based digital output. Besides, Pseudo Random Multi Carrier (PRMC) involves in two random PWM strategies to minimize the harmonic order for 9- level cascaded multilevel H-bridge (CHB) inverter and 9-level Modular Multilevel inverter are introduced. The design mainly focuses on the (Pulse Width Modulation) PWM method, in which two nearest voltage levels are approached in estimated output voltage prediction based on the Partial swarm optimization (PSO) algorithm, and it conveys a random variation in the pulse position of output by Pseudo Random Multi Carrier- Pulse Width Modulation (PRMC-PWM). The CHB and the Modular inverters generate low distortion output by using PMRC. The simulation and prototype circuit are developed for the nine level output using sixteen switches and ten with Resistive-Inductive (R-L) load variation condition. The power quality is improved in CHB and Modular inverter (MoI) with minimized harmonics in various modulation index (MI) as varied from 0.1 up to 0.8. The circuit is designed by using a Field Programmable Gate Array (FPGA), Implementing a PSO algorithm for both CHB, and MoI are proposed. The comparisons of results are verified with lower order harmonics and find the best switching angle across the MLI switches. Modular inverter furthermore investigates with PRMC, Random Nearest level (RNL) modulation scheme are presented, and the proposed circuit is along with the respective degree of the output voltage were synthesized in non-linear load by the development of reactive power across a motor load.

A Novel Concatenated LWT and WHT Based UFMC Waveform Design for the Next Generation Wireless Communication Systems

A novel concatenated Lifting Wavelet Transform (LWT) and Walsh Hadamard Transform (WHT) with Universal Filtered Multi Carrier (UFMC) waveform is suggested as an alternative to Orthogonal Frequency Division Multiplexing (OFDM) waveform for the next generation wireless telecommunication systems in this paper. The suggested waveform is composed of LWT and WHT with UFMC waveform. Both the elimination the disadvantages of OFDM and the improvement the achievement of UFMC waveform, from the fifth generation waveform candidates, has been aimed with the suggested waveform. In order to verify the performance of the suggested waveform and compare with the traditional OFDM, UFMC, and LWT‐UFMC waveform computer simulation studies are performed in additive white Gaussian noise and flat Rayleigh fading channel environments. The acquired computer simulation results exhibit that the achievement of the suggested waveform has better than the achievement of the traditional OFDM, UFMC, and LWT‐UFMC waveform. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

PAPR Reduction for FBMC Systems with Ant Bee Colony Optimization

Multi carrier systems are most prevalent modern wireless communication systems which are employed for high data rate transmission. At present, FBMC (Filter bank multi carrier) with OQAM (Offset-QAM) has drawing attention for many researchers to implement new physical layers and wireless protocols. As in the case of multi carrier system, this FBMC also suffers from high PAPR, so this paper presents a PAPR reduction approach with ant bee colony (ABC) optimization. ABC algorithm functionality is similar to honey mining where the labor is shared for nectar source and hence find out the optimal solution. Experimental results shows that the proposed approach could able to attain considerable improvement in decreasing the PAPR whencompared against the conventional FBMC and SLM (selective mapping method) based FBMC approaches.

Signal Properties under Multi-Carrier Chaos–Shift Keying

In recent years, increased demand for high-quality multimedia services requires increasing the wireless communications application data rates and be more reliable and secure. To meet this request, the researches related to Multi-Carrier (MC) transmission technologies have made considerable efforts in recent years because multi-carrier techniques can improve the data transmission rates. In this research, an overall study on performing Multi-Carrier Chaos Shift keying by using a technique Orthogonal Frequency Division Multiplexing (OFDM) is presented. A multi-carrier system simulation is designed because of the limited speed provided by Chaos Shift keying (CSK) due to the spreading factor. To increase security in this system; the chaotic sequence was generated by proposed to modify on one of the well-known chaos generators that is a tent map. The performance test and the security analysis were carried out using the Bit Error Rate (BER), Mean Squared Error (MSE), correlation test; the chaotic characteristics of the chaos generators sequences using are tested the Lyapunov Exponent. Results have showed the proposed tent map the autocorrelation is like a delta function, so that it appears as a noise that is difficult to discern the information carried by signal, it is much more sensitive to change the initial state and control parameters, where the proposed tent map provides better chaotic properties for encryption such as greater Lyapunov exponent, compared with well-known chaos maps (Logistic map1, Tent map, Quadratic map), it provides a lower Bit Error Rate (BER) performance than a tent map. In addition, the proposed method to multi-carrier CSK system with various Spreading Factors (SF) values outperforms the CSK system in improving the data transmission rate.

Bit Error Rate Performance of Multi Carrier System Utilising QPSK and OQPSK with Guard Interval.(Dept.E)

Bit Error Rate Performance of Multi Carrier System Utilising QPSK and OQPSK with Guard Interval.(Dept.E)