Multicarrier Modulation System Research Articles

Comparative Study of THD Characteristics in Different Cascaded H-Bridge Configurations for Multilevel Multicarrier Modulation

This paper presents a comprehensive comparative study investigating the Total Harmonic Distortion (THD) characteristics of various Cascaded H-Bridge (CHB) configurations utilized in Multilevel Multicarrier Modulation (MMCM) systems. The research examines different CHB topologies, focusing on their impact on THD performance in MMCM applications. Through theoretical analysis and simulation, this study evaluates THD levels under varying operating conditions, including different modulation schemes and switching strategies. A discussion on main topologies of multilevel inverter namely H-bridge, NCP(neutral point clamped),NCP- H and flying capacitor is carried out utilizing carrier based PWM methods. Comparison is done on basis of harmonic component, THD and nu of component used by 3, 5 and7 level cascaded H-bridge topology respectively. To support the result a detailed study is carried out using MATLAB Simulink software. Keywords- Multilevel inverter, PWM, THD, NCP, NCP-H.

Papr reduction of FBMC-OQAM signals using Phase Search-PTS and modified discrete fourier transform spreading

In this research, a novel peak-to-average power ratio (PAPR) reduction technique for filter bank multicarrier (FBMC) modulation systems is presented. With multicarrier systems like FBMC, the strategy focuses on the survival of the fittest principle to suit the value of PAPR. The Filter Bank Multicarrier with Offset Quadrature Amplitude Modulation (FBMC-OQAM) has recently captured the attention of numerous academics due to its minimal adjacent channel leakage ratio (CLR). Unfortunately, the issue of increased PAPR measurement has a negative impact on the effectiveness of the FBMC system's energy measurement. In this study, the Phase search-based Partial Transmit Sequence (PS-PTS) approach and Modified Discrete Fourier Transform Spreading (MDFT) are developed for the PAPR reduction of the FBMC-OQAM signals. The increased PAPR measurement is reduced using the PTS and MDFT with osprey optimization method, which may result in a PAPR reduction of roughly 5.1 dB as comparable to the conventional approach.

A NOVEL SCHEME UFMC-DSNT FOR PAPR REDUCTION IN 5G SYSTEMS

The universal filtered multi-carriers (UFMC) waveform is a powerful candidate for multi-carrier modulation (MCM) that is employed in 5G systems. This is thanks to its low bit error rate (BER) and low latency compared to other waveforms, such as generalized frequency division multiplexing (GFDM). The high peak-to-average power ratio (PAPR) is one of the main challenges found in all MCM systems. As the output signal of the UFMC has large peaks, some distortions occur in the signal due to overshoot of the linear region of the high-power amplifier (HAP), which dramatically degrades the BER. Accordingly, it is known from several previous research studies that most proposals to reduce PAPR for the UFMC system have been difficult to implement or have required sending information in parallel to the receiver. For this reason, this paper proposes a new alternative, which is easily implemented and does not require the transmission of secondary information for PAPR reduction. This is done by applying the discrete sliding norm transform (DSNT) technique on the UFMC system, highlighting the proposed DSNT-UFMC scheme. As this previous scheme has not been addressed in any previous research work, it presents, the key contribution of this paper. The simulation results show that the proposed scheme outperforms the conventional one in terms of PAPR reduction, whose improvement reaches 94.6% using the proposed scheme.

Reconfigurable Logic Design of CORDIC Based FFT Architecture for 5G Communications

There are numerous goals in next-generation cellular networks (5G), which is expected to be available soon. They want to increase data rates, reduce end-to-end latencies, and improve end-user service quality. Modern networks need to change because there has been a significant rise in the number of base stations required to meet these needs and put the operators’ low-cost constraints to the test. Because it can withstand interference from other wireless networks, and Adaptive Complex Multicarrier Modulation (ACMM) system is being looked at as a possible choice for the 5th Generation (5G) of wireless networks. Many arithmetic units need to be used on the hardware side of multicarrier systems to do the pulse-shaping filters and inverse FFT. The main goal of this study is to adapt complex multicarrier modulation (ACMM) for baseband transmission with low complexity and the ability to change it. We found that this is the first reconfigurable architecture that lets you choose how many subcarriers a subband has while still having the same amount of hardware resources as before. Also, under the new design with a single selection line, it selects from a set of filters. The baseband modulating signal is evaluated and tested using a Field-Programmable Gate Array (FPGA) device. This device is available from a commercial source. New technology outperforms current technology in terms of computational complexity, simple design, and ease of implementation. Additionally, it has a higher power spectrum density, spectral efficiency, a lower bit error rate, and a higher peak to average power ratio than existing technology.

Per-Wavelet Equalization for Discrete Wavelet Transform Based Multi-Carrier Modulation Systems

The Discrete Wavelet Transform (DWT) has gained attention in the area of Multi-Carrier Modulation (MCM) because it can overcome some well known limitations of Discrete Fourier Transform (DFT) based MCM systems. Its improved spectral containment removes the need for a cyclic prefix, be it that appropriate equalization then has to be added as the cyclic convolution property no longer holds. Most DWT based MCM systems in the literature use Time-domain EQualizers (TEQs) to mitigate the channel distortion. In this paper, a Per-Wavelet EQualizer (PWEQ) is proposed which directly maximizes the Signal-to-Interference-plus-Noise Ratio (SINR) per symbol and is applicable to any wavelet family. The proposed PWEQ provides a performance upper bound for the TEQs for DWT based MCM systems. The computational complexity of the PWEQ is reduced by modifying the Filter Bank (FB) structure of the DWT. Simulations are performed to compare the PWEQ performance against the TEQs for DWT based MCM systems and the similar Per-Tone EQualizer (PTEQ) for DFT based MCM systems. The simulations are performed using measured Asymmetric Digital Subscriber Line (ADSL) and G.fast channels with Fejér-Korovkin (FK) wavelets. The proposed PWEQ increases the SINR on the received symbols compared to the TEQs at the cost of an increased computational complexity.

OFDM System Design for Measured Ultrasonic Underwater Channels.

In this paper, we present the development of a multicarrier modulation system of low complexity for broadband underwater acoustic communications (UAC), whose frequency band is located in the ultrasonic range, specifically between 32 kHz and 128 kHz. Underwater acoustic channels are recognized among the most hostile communication channels due to their strong time and frequency selectivity and, hence, the design of high-performance systems is a challenge that is difficult to resolve at the present time with state-of-art technology. The aim of the proposed system is to reach a reasonable bit rate, between 40 and 50 Kbps, over these channels that allows, for instance, the transmission of video signals of limited quality. We describe an orthogonal frequency division multiplexing (OFDM) modem prototype with a parameter setting and design specifically adapted to the channel nature. For this purpose, actual measurements carried out at the Mediterranean sea, on shallow waters, have been used to evaluate the system performance and to optimize the design. A discussion on several modulations and OFDM configurations is presented that leads to the selection of differential and non-differential quadri-phase shift keying (QPSK) as good candidates depending on synchronization capabilities.

Performance improvement on spectral efficiency and peak to avearge power reduction for 5G system

<span>Filter bank multicarrier with offset quadrature amplitude modulation (FMBC/OQAM) system which can offer higher data rate 1 Gbps and improved bandwidth efficiency because of not require of cyclic prefix (CP) to avoid interference from the adjacent channels compared to fourth generation (4G) orthogonal frequency division multiplexing (OFDM) and other wireless systems. Because of these advantages FBMC/OQAM are used in fifth generation (5G) technology. In this FBMC/OQAM system, bandwidth capacity will be further increased by using multiple input multiple output (MIMO) channel. But in our proposed scheme we can use hyper–MIMO channel, in which at base station (BS) more number of transmitting antennas are used that for the improve the spectral efficiency performance better than traditional MIMO channel. But the most important drawback of hyper MIMO FBMC/OQAM is the higher peak to average-power ratio (PAPR) that degrade overall system performance in 5G. In 4G technology, to reduce PAPR a number of techniques are used. In our proposed system we can use mu-law non-linear companding technique and precoding discrete cosine transform (DCT) to reduce PAPR value for multicarrier modulation system compare to other systems.</span>

A Fair SINR Performance Comparison of FBMC/OQAM and FBMC/QAM Multicarrier Communication Systems in the Discrete-Time Framework

In the last couple of decades, multicarrier modulations have witnessed a considerable interest in wireless communication networks due to their ability to fight against multipath fading and offer multiple access with flexible resource sharing. One of the well known multicarrier modulation systems is filter-bank multi-carrier with an offset quadrature amplitude modulation (FBMC/OQAM), which was proposed as a powerful solution during the standardization of 5G. In this paper, we derive a closed-form expression of the signal to interference plus noise ratio (SINR) for FBMC/OQAM systems in the discrete-time context, for arbitrary wide sense stationary uncorrelated scattering (WSSUS) channels as well as transmitter (Tx) and receiver (Rx) waveforms. We quantify the potential gains in SINR brought by FBMC/OQAM, which exclusively operates on critical lattice density, with respect to FBMC/QAM, which have the flexibility to operate on critical or non-critical lattice densities. For completeness, we compare the performance of FBMC/OQAM in the discrete-time context, sweeping the discrete space of waveforms supports, with that of FBMC/OQAM in the continuous-time context, using the Hermite functions, and show how they perform similarly. Simulation results prove that FBMC/OQAM optimization algorithm, performing with the ping-pong optimized pulse shaping (POPS) paradigm, converges rapidly to excellent SINR values, even with small supports durations, in discrete-time context, which is equivalent to a reduced number of Hermite functions, in the continuous-time context.

Design and performance analysis of modern communications systems based on Multicarrier compression technique

This paper shows how to enhance the bandwidth and bit error rate (BER) performance of modern communications system in multicarrier modulation systems by including a compression technique in frequency dimensional after multicarrier modulation. The proposed system design for multi-carrier systems was implemented using a standard system based on Fast Fourier Transform (FFT). This proposed idea of the multicarrier modulation system done by adding the Discrete Wavelet Transform (DWT) as compression stage to multicarrier coefficients. This operation will be done by sending the approximation coefficients of DWT and discard the details coefficients. The details coefficients in receiver side will compensate with zeros in IDWT stage. The simulation results were examined using additive white Gaussian noise (AWGN), flat Rayleigh fading and selective fading channels showing that the proposed additional compression scheme after DWT can double the data rate and reduce the bit error rate (BER).

Влияние нестационарных помех в анализе информационных моделей с модуляцией с одной и несколькими несущими

The aim of the study is to try to analyze the most common mechanisms of impulse noise impact on data transmitted in the symbols of single-carrier and multi-carrier modulation systems. The paper solves the problem of a qualitative analysis of the destructive effect of impulse noise on the possibility of restoring symbols of digital modulation systems operating on the basis of a copper cable infrastructure. The performed analysis uses induction as research methods, which allows extending isolated special cases of symbol distortion to the generalized procedures for degrading the transmitted information quality; an analogy involving the consideration of similar mechanisms for modifying data in a stream of modulated signals with one carrier and multiple ones. The novelty of the findings obtained consists in generalizing the process of decoding errors due to noise bursts to the systems with one carrier and several ones, as well as in differentiating the influence of the noise pulse duration and power on the transmitted symbols. As the main findings of the work, we can note the identification of the impact ambiguity of impulse noise on the transmission systems of digital subscriber lines, expressed in the necessity to take into account while analyzing both the parameters of the noise itself and the type of modulation, and the energy and time relationships between the useful signal and noise. Thus, the work shows that the destructiveness degree of the impulse noise impact on the transmission system of a digital subscriber line is determined by several characteristics that should be taken into account when developing mechanisms for the protection against interference, or, conversely, to justify the inappropriateness of their use.

DWPT vs OFDM Under a Noisy Industrial Channel

In the industrial world, a trend towards connected, robotic and intelligent factories is in constant development to face competition from countries with low production costs. The industrial revolution ‘Industry 4.0’ is considerably reducing the boundaries between the physical and digital worlds. This has given rise to interconnected factories in which people, machines and products interact with each other using smart sensors. Commonly referred to as Industrial Internet of Thing (IIoT). Except that, it requires adapted communication systems for the industrial environment. Such a propagation environment is known by its complexity that should be considered in order to propose a robust and reliable communicating system. In this paper, a performance evaluation between a pulse-modulated Discrete Wavelet Packet Transform (DWPT) system and an Orthogonal Frequency Division Multiplexing (OFDM) multicarrier modulation system over a noisy industrial channel will be presented. Thus, allowing not only to provide an alternative to conventional high-rate industrial wireless communication systems but also to know the limits of both techniques

PAPR reduction using OQAM for spectrum sensing

PurposeThe tremendous growth of wireless applications and the demand for high data rate, the spectrum utilization improvement has been the most crucial challenges for wireless communication. Adapting cognitive radio with orthogonal frequency division multiplexing or offset quadrature amplitude modulation (OFDM/OQAM) improves the spectrum and energy efficiencies.Design/methodology/approachThus, it overcomes the spectral leakage problem at the transmitter side and leads to less interference from secondary user (SUs) to primary user (PUs) and between the SUs in cognitive radio technology. The benefit of exploiting pulse shape filtering in the OFDM/OQAM is to not only eliminate the requirement of the guard bands but also reduce the out of band energy transmission, which also improves the spectral isolation from the neighboring systems. But the high peak to average power ratio (PAPR) phenomenon is a common issue in the majority of the multicarrier modulation systems and thus OFDM/OQAM is no exception in this case.FindingsTherefore, this paper aims to examine the effect of integrating the Walsh–Hadamard Transform (WHT) on the power spectral density and investigates the problem of PAPR in the WHT/OQAM system.Originality/valueThus, it overcomes the spectral leakage problem at the transmitter side and leads to less interference from SUs to PUs and between the SUs in cognitive radio technology. The benefit of exploiting pulse shape filtering in the OFDM/OQAM is to not only eliminate the requirement of the guard bands but also reduce the out of band energy transmission, which also improves the spectral isolation from the neighboring systems. But the high PAPR phenomenon is a common issue in the majority of the multicarrier modulation systems thus OFDM/OQAM is no exception in this case.

Exploring the effect of LED nonlinearity on the performance of layered ACO-OFDM.

Visible light communication (VLC) depends on light emitting diodes (LEDs) for data transmission. This is one of the strengths of VLC motivated by high optical efficiency and low cost. However, LEDs impose nonlinear effects on the transmitted signal and limit overall system performance, especially in the case of multicarrier modulation systems. This paper extends to the layered asymmetrically clipped optical, orthogonal frequency division multiplexing (LACO-OFDM) and investigates the impact of LED nonlinearity on system performance. The effect of the second-order nonlinear distortion in addition to the clipping noise is presented and analyzed at different power values assuming different strengths of nonlinearity. With a variable number of layers, the system performance is explored considering a nonlinear LED model. Finally, the impact of nonlinearity is investigated in the case of ACO-OFDM for the sake of comparison, bearing in mind that ACO-OFDM represents the first layer of LACO-OFDM.

Design and Performance Evaluation of Lattice Daubechies Wavelet Filter Banks for Less Complex Cognitive Transceivers

Wavelet Packet Based Multicarrier Modulation (WPMCM) system uses usually a prototype filter bank multicarrier. The Daubechies-D10 filter bank (D10FB) is the basic framework of multicarrier modulation (MCM) transceiver system. In this paper, Lattice structures of exact Daubechies-D10 wavelet filter are adopted to design a prototybe filter bank realized for a proposed structure of WPMCM transceiver system. Magnitude and phase responses of the exact Daubechies-D10 LPF and the proposed structure are compared. They are nearly the same in the passband with improved roll-off characteristics of the magnitude response of the proposed. Whilefrom the results, it appears that the proposed WPMCM structure possess low speed of operation, less complexity and less power consumption.It is also noticed from SNR comparison, that the performance evaluation of the proposed WPMCM transceiver system is a moderate between other two previously issued structures.

Performance Investigations and PAPR Reduction Analysis Using Very Efficient and Optimized Amended SLM Algorithm for Wireless Communication OFDM System

The orthogonal frequency division multiplexing (OFDM) is the most encouraging multi-carrier modulation system chosen for the high data rates but the objective is to resolve intrinsic common issue of peak to average power ratio (PAPR). The projected algorithm is illustrated in this research study which is established upon selected mapping (SLM) with pseudo-random sequence under time domain μ law companding of signal. Besides the significant competitive characteristics of conventional SLM algorithm (ConvenSLM-Algo) (Mestdagh et al. in Electron Lett 32(22):2056–2057, 1996. https://doi.org/10.1049/el:19961384 ), it undergoes the tedious complexity in generation of phase sequence and for the recovery of sequence, side information is mandatory. The key concern, thus, to eliminate the tedious problem of designing of phase sequence along with the aim of reducing the fluctuation of signal with high PAPR. Henceforth, in the projected algorithm (Projected-Algo) a noteworthy strategy has been investigated and followed for the designing of phase sequence which is very easy and for the recovery of information at receiver, side information of index of column of phase sequences can be used because of straightforwardness in its establishment. Hence, we demonstrate the effective overall excellent performance of Projected-Algo along with analysis and also comparative study of Projected-Algo outperforms the conventional OFDM system (unchanged), ConvenSLM-Algo [16], SLM with new pseudo random phase sequences (ModSLM-Algo) given in literature (Ali et al. in Canadian conference on electrical and computer engineering, 2018. https://doi.org/10.1109/CCECE.2018.8447835 ).

MIMO-OFDM/OCDM low-complexity equalization under a doubly dispersive channel in wireless sensor networks

In this article, three novel systems for wireless sensor networks based on Alamouti decoding were investigated and then compared, which are Alamouti space–time block coding multiple-input single-output/multiple-input multiple-output multicarrier modulation (MCM) system, extended orthogonal space–time block coding multiple-input single-output MCM system, and multiple-input multiple-output system. Moreover, the proposed work is applied over multiple-input multiple-output systems rather than the conventional single-antenna orthogonal chirp division multiplexing systems, based on the discrete fractional cosine transform orthogonal chirp division multiplexing system to mitigate the effect of frequency-selective and time-varying channels, using low-complexity equalizers, specifically by ignoring the intercarrier interference coming from faraway subcarriers and using the LSMR iteration algorithm to decrease the equalization complexity, mainly with long orthogonal chirp division multiplexing symbols, such as the TV symbols. The block diagrams for the proposed systems are provided to simplify the theoretical analysis by making it easier to follow. Simulation results confirm that the proposed multiple-input multiple-output and multiple-input single-output orthogonal chirp division multiplexing systems outperform the conventional multiple-input multiple-output and multiple-input single-output orthogonal frequency division multiplexing systems. Finally, the results show that orthogonal chirp division multiplexing exhibited a better channel energy behavior than classical orthogonal frequency division multiplexing, thus improving the system performance and allowing the system to decrease the equalization complexity.

A novel PAPR reduction algorithm for DCO-OFDM/OQAM system in underwater VLC

In the underwater visible light communication (VLC), the photon propagation scattering effect is obvious and the multipath effect is enhanced as the link distance increases. This paper uses orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) of filter bank multicarrier technology (FBMC), which is based on time frequency localization (TFL) filter, to overcome inter symbol interference (ISI) and inter carrier interference (ICI). Since light-emitting diode (LED) modulation needs positive modulation signal, we use the direct current (DC) bias to add on OFDM/OQAM signal so that the signal is positive. But, as the OFDM/OQAM is also multicarrier modulation system, the instantaneous fluctuation of OFDM/OQAM signal is bigger than single carrier modulation system and the nonlinear distortion is very serious. Therefore, this paper puts forward the modified overlapped selective mapping (M-OSLM) suppression algorithm to restrain the peak to average power ratio (PAPR), and optimizes the range of data symbol which affects on current data symbol by taking the characteristic of filter bank into consideration so that decrease PAPR. Thus, the instantaneous volatility of OFDM/OQAM signals is reduced in order to select the appropriate DC bias and reduce the clipping distortion. The simulation results show that compared with DC-biased cyclic prefix optical OFDM (DCO-CP-OFDM), DC-biased optical OFDM/OQAM (DCO-OFDM/OQAM) has a better overcoming ability on ISI of underwater wireless optical scattered channel. Meanwhile, the performance of PAPR reduction is greatly improved by M-OSLM algorithm. The signal-to-noise ratio (SNR) is improved by 3 dB averagely compared to DCO-CP-OFDM at the same bit error rate (BER).

Performance of IDWPT/DWPT compared with OFDM under an Industrial Channel

Abstract In the industrial world, a trend towards connected, robotic and intelligent factories is on the rise to face competition from countries with low production costs. The industrial revolution ‘Industry 4.0’ is considerably reducing the boundaries between the physical and digital worlds. This has given rise to interconnected factories in which people, machines and products interact with each other using smart sensors. This paper presents a comparison between a pulse-modulated Discrete Wavelet Packet Transform (DWPT) system and an Orthogonal Frequency Division Multiplexing (OFDM) multicarrier modulation system in a noisy industrial propagation environment. This to provide an alternative to conventional high-rate wireless communication systems using an Industrial Internet of Thing (IIoT).

Compensation of Phase Noise and IQ Imbalance in Multi-Carrier Systems

Compensation for the impacts of phase noise (PN) and in-phase and quadrature (IQ) imbalance on cyclic-prefix (CP) based multi-carrier modulation systems in the presence of imperfect channel estimation is considered in this paper. A unified two-stage algorithm is proposed. In the first stage, IQ imbalance parameters and channel impulse response are estimated based on the transmission of a preamble which is designed in such a way that the estimation of IQ imbalance does not require any knowledge about the channel and PN. Given the estimates from the first stage, the impacts of IQ imbalance and PN are subsequently compensated in the second stage based on the transmission of pilot symbols. The proposed algorithm is further extended to a MIMO system that employs a diversity technique. Simulation results are presented for a wide range of PN and IQ imbalance scenarios to corroborate the effectiveness of the proposed algorithm.

Hybrid Zadoff‐Chu and multilateral piecewise exponential companding transform–based PAPR reduction technique in OFDM systems

SummaryThe orthogonal frequency‐division multiplexing (OFDM) is a multicarrier modulation system that is used to transmit the large volume of data to the receiver. Reducing the peak‐to‐average power ratio (PAPR) in OFDM system is one of the demanding and crucial task in recent days. For this reason, various precoding and companding mechanisms are developed in the traditional works, but it remains with the limitations of increased complexity, reduced performance, and nonlinear distortion. The reduction of PAPR is achieved by minimizing the companding distortion with the enhancement of the bit error rate (BER) performance significantly. Then, in order to avoid clipping in OFDM, a multilateral piecewise exponential companding transform (MPECT) method has been utilized rather than using piecewise exponential companding transform (PEC) where PAPR is getting reduced. The OFDM is very sensitive to synchronizing error. To overcome this sensitivity, employ the Zadoff‐Chu sequence to carrier frequency offsets. Zadoff‐Chu matrix transform (ZCMT) has numerous merits among the other ODFM systems such as the improvement in the performance of the channels that are fading away and provides an ideal periodic autocorrelation and a constant magnitude periodic cross correlation. Both of these techniques provide improvement in the ODFM systems. To get more efficiency, this paper aims to develop a hybrid technique by integrating the ZCMT and MPECT techniques for reducing the PAPR in OFDM systems. Further, convolutional encoding is applied for better BER and PAPR. The simulation results of the proposed ZCMT‐MPECT technique are evaluated and compared with the conventional OFDM and other precoding methods.