Multicarrier Modulation Scheme Research Articles

THE PERFORMANCE ANALYSIS OF PRECODED SPACE-TIME FREQUENCY MIMO-GFDM OVER RAYLEIGH FADING CHANNELS

The physical layer is implemented in the present communication era with new multicarrier modulation schemes such as Generalized Frequency Division Multiplexing with Multi-Input and Multi-Output (MIMO-GFDM) antenna systems to achieve good spectral efficiency and diversity order. This paper presents precoded Space-Time-Frequency MIMO-GFDM performance analysis to improve the bit error rate performance without increasing transmission power and bandwidth compared to conventional techniques. The proposed system also enhances the diversity order over frequency selective fading channels. In general, we need to perform channel matrix inversion operations at the receiver or channel precoding matrix operations at the transmitter to detect the symbols of MIMO-GFDM systems. This paper's proposed scheme completes the same task without performing channel matrix inversion. Orthogonal transform techniques such as Haar, Harley, Walsh-Hadamard, and Slant transforms are used as precoders at the transmitter for the proposed scheme. The simulation results are validated on the MATLAB working platform. We have compared the bit error rate of the PSTF-MIMO-GFDM system with Space-Time (ST) and Space Frequency (SF) as baseline schemes and different orthogonal transform precoding techniques.

Reduce PAPR in Filtered-CPOFDM using Hybrid Method System

5G multicarrier waveform Filtered Cyclic Prefix Orthogonal Frequency Division Multiplexing (F-CPOFDM) allows for high data speeds and increases in spectrum efficiency. The main drawback of F-CPOFDM is its high peak-to-average power ratio (PAPR), a common element of all multicarrier modulation schemes. In this research is investigate the implementation of a Hybrid strategy to reduce the peak to average power ratio (PAPR) in a F-CPOFDM system and evaluated the impact of employing a Hybrid Technique with Group Codeword Shift (GCS), Median Codeword Shift, Selective Codeword Shift (SCS), and Conventional F-CPOFDM on the reduction of peak to average power ratio (PAPR) in CP-OFDM. The novelty of this research is GCS method integration with WHT Precoding technique for reduce PAPR. Simulation results show that compared to traditional Filtered-CPOFDM, the GCS-WHT method reduces peak PAPR by 59.46 %, while the SCS- method reduces it by 32.43 % and the MCS-WHT method reduces it by 31.53%. Compare to the non-hybrid technique, the GCS only reduce 45.95%, while for SCS and MCS reduce 19.82% and 23.42% respectively. From the results, shows that Hybrid method is better performance compare with non-hybrid method.

On the tensor-based approach to adaptive joint channel estimation/data detection in flexible multicarrier MIMO systems

Multiple-input multiple-output (MIMO) systems employing multicarrier modulation (MCM), including flexible MCM that unifies several MCM schemes, have been well studied recently also in their tensor-based formulation. The latter naturally allows for (semi-)blind joint channel estimation/data detection (JCD), of particular interest in future generation massive MIMO systems, given the uniqueness properties of the tensor decomposition (TD) models. Of course, in the presence of time-varying channels, adaptive JCD needs to be implemented. However, the rich literature on recursive TD has only very little been considered in this context and only for orthogonal frequency division multiplexing (OFDM). In this paper, online TD is adapted to realize adaptive JCD for time-varying flexible MIMO-MCM systems. The common assumptions underlying online TD schemes are revisited on this occasion and shown to be inadequate to cope with fast-fading channels. This is demonstrated via simulation results on two of the most popular MCM systems. The results of this work can serve to motivate further study of online TD to extend its applicability in this and other demanding application contexts.

Progressive Pattern Interleaver with Multi-Carrier Modulation Schemes and Iterative Multi-User Detection in IoT 6G Environments with Multipath Channels.

Sixth-generation (6G) wireless networks demand a more efficient implementation of non-orthogonal multiple access (NOMA) schemes for severe multipath fading environments to serve multiple users. Using non-orthogonal multiple access (NOMA) schemes in IoT 6G networks is a promising solution to allow multiple users to share the same spectral and temporal resource, increasing spectral efficiency and improving the network's capacity. In this work, we have evaluated the performance of a novel progressive pattern interleaver (PPI) employed to distinguish the users in interleaved division multiple access (IDMA) schemes, suggested by 3GPP guidelines as a NOMA scheme, with two multi-carrier modulation schemes known as single-carrier frequency-division multiple access (SC-FDMA) and orthogonal frequency-division multiplexing (OFDM), resulting in SC-FDMA-IDMA and OFDM-IDMA schemes. Both schemes are multi-carrier schemes with orthogonal sub-carriers to deal against inter-symbol interference (ISI) and orthogonal interleavers for the simultaneous access of multiple users. It has been suggested through simulation outcomes that PPI performance is adequate with SC-FDMA-IDMA and OFDM-IDMA schemes in terms of bit error rate (BER) under multipath channel conditions. Moreover, regarding bandwidth requirement and the implementation complexity of the transmitted interleaver structure, PPI is superior to the conventional random interleaver (RI).

Low-complexity GFDM transmission scheme for low earth orbit satellite communications

As a promising multi-carrier modulation scheme, Generalized Frequency Division Multiplexing (GFDM) has certain advantages in low earth orbit satellite communications. However, the cost of GFDM to obtain these advantages is the self-interference caused by non-orthogonality and the increase of computational complexity. This paper proposes two low-complexity transceiver schemes for GFDM based on matrix sparsity. Firstly, the paper summarizes two GFDM modulation structures, referred to as structure types I and II, based on modulation data. Next, the modulation matrix in both structures is divided into sub-matrices, and the modulation sub-matrix is made sparse by leveraging the properties of the Fourier transform, so as to reduce the complexity of the transmitter. Similarly, by performing sparse processing on the received matrix and converting it into a block diagonal matrix form, the complexity of the receiver can be effectively reduced. The computational costs of our proposed schemes are analyzed in detail and compared with the existing solutions that are known to have the lowest complexity. The simulation results demonstrate that the two proposed schemes can provide satisfactory low-complexity performance depending on the time–frequency structure.

Analysis of Filtered Multicarrier Modulation Techniques Using Different Windows for 5G and Beyond Wireless Systems

In contemporary wireless communication systems, multicarrier modulation schemes have become widely adopted over single-carrier techniques due to their improved capacity to address challenges posed by multipath fading channels, leading to enhanced spectral efficiency. Orthogonal frequency division multiplexing (OFDM), a prevalent multicarrier scheme in 4G, is favored for its ease of implementation, interference resilience, and high data rate provision. But it falls short of meeting the requirements for 5G and beyond due to limitations such as out-of-band (OOB) emissions and cyclic prefixes. This paper introduces the filter bank multicarrier (FBMC) and universal filtered multicarrier (UFMC) with quadrature amplitude modulation (QAM) and phase shift keying (PSK) waveforms through Additive White Gaussian Noise channel (AWGN), Rayleigh fading channel and Rician channel. The objective of this paper is to enhance the performance of UFMC with reduced complexity through the new filtering approach for achieving optimal outcomes. The proposed scheme, incorporating Tukey filtering technique, demonstrates superior performance in reducing peak-to-average power ratio (PAPR) and improving bit error ratio (BER) compared to the original UFMC signal without necessitating additional power increments. Specifically, the UFMC system with Tukey filtering achieves a notable net gain of 5 dB. Simulation results demonstrate that utilizing various filter types in FBMC and UFMC systems, combined with QAM modulation, significantly reduces OOB emissions compared to conventional systems. In aspect to BER, Tukey window showed almost 10−6 at 15 dB SNR in UFMC which is better than FBMC.

A New Asymmetric H-6 Structured Multilevel Inverter with Reduced Power Components

Multilevel inverters play a key role in improving the power quality for industrial, domestic, and renewable energy sectors due to sinusoidal output voltage through small voltage steps, lesser THD (total harmonic distortion), and EMI (electromagnetic interference). There are several variants in MLI structures to generate a stepped voltage with their own operating characteristics, which flaws in switching devices with gate drivers, current conducting switches varied with varied voltage levels, and switches with different abilities in blocking voltagesto overcome increases in implementation costs and restrict its usage in high-power applications. Therefore, this article paves a solution for the above problem, which orients a new structure for asymmetric operation to propel large voltage levels with small values of switches in parallel with conventional topologies. The subtlety of the proposed topology is governed by a multicarrier pulse width modulation scheme, and ten different voltage magnitude algorithms are developed and compared foreffectiveness.Hitherto, many existing MLI topologies with reduced power switches have beendeveloped; among these, the H6 structure attempts to curtail the reduced conduction path. The operation of the suggested topology is confirmed in a Matlab/Simulink environment, and real-time performance is investigated using a laboratory prototype to accord the simulated results.

Subcarrier Filtering For Spectrally Efficient Multicarrier Modulation Schemes and Its Impact on PAPR: A Unified Approach

Subcarrier Filtering For Spectrally Efficient Multicarrier Modulation Schemes and Its Impact on PAPR: A Unified Approach

SIMULASI SKEMA UNIVERSAL FILTERED MULTI-CARRIER (UFMC) PADA SISTEM KOMUNIKASI DIGITAL

Universal Filtered Multi-Carrier (UFMC) is a multi-carrier modulation scheme that is an alternative to the Orthogonal Frequency Division Multiplexing (OFDM) scheme currently used in 4G communication systems and wireless local area networks (WLAN). The weakness of OFDM lies in the high peak-to-average power ratio (PAPR) value and out-of-band (OOB) emission which can cause interference between carriers. UFMC is one of the schemes used to overcome the weaknesses of OFDM. This research aims to study the performance of UFMC for data transmission on AWGN channel with 256-QAM, 1024-QAM, and 4096-QAM modulation. In addition, 256-point, 512-point, and 1024-point FFTs were also used to see the effect on the achievable bit error rate (BER) and PAPR value. The simulation results show that for all simulated FFT sizes and QAM values, 256-QAM produces the lowest BER value. Using a 1024-point FFT, a BER of 10-3 can be achieved with an SNR of 20 dB. The lowest PAPR value obtained in the simulation is 7.1891 dB.

Visible Light Communications: A Survey on Recent High-Capacity Demonstrations and Digital Modulation Techniques

In order to deal with the increasing number of mobile devices and with their demand for Internet services, particularly social media platforms, streaming video, and online gaming, Radio-Frequency (RF) wireless networks have been pushed to their capacity limits. In addition to this, 80% of the total data traffic is carried out by users inside buildings. Therefore, new technologies have started to be considered for indoor wireless communications. Visible Light Communications (VLC) can provide both illumination and communications, appearing as an alternative or complement to RF wireless networks. VLC offers high bandwidth and immunity to interference from electromagnetic sources. This manuscript reviews recent high-capacity VLC demonstrations. The main focus of this work is to present digital-signal-processing techniques used in VLC systems. Different modulation formats are analyzed, which can be divided into two large groups, namely single-carrier and multi-carrier modulation schemes. Finally, some recently proposed capacity-achieving strategies are presented. We discuss how to implement these techniques and how they will be useful for the continued development of VLC systems.

Highly Sensitive SPAD-Based Receiver for Dimming Control in LiFi Networks

Visible light communication (VLC) is an emerging mode of wireless communication that supports both illumination and communication. One essential function of VLC systems is the dimming control, which requires a sensitive receiver for low-light conditions. The use of an array of single-photon avalanche diodes (SPADs) is one promising approach to enhancing receivers’ sensitivity in a VLC system. However, because of the non-linear effects brought on by the SPAD dead time, an increase in the brightness of the light might degrade its performance. In this paper, an adaptive SPAD receiver is proposed for VLC systems to ensure reliable operation under various dimming levels. In the proposed receiver, a variable optical attenuator (VOA) is used to adaptively control the SPAD’s incident photon rate according to the instantaneous received optical power so that SPAD operates in its optimal conditions. The application of the proposed receiver in systems with various modulation schemes is investigated. When binary on–off keying (OOK) modulation is employed due to its good power efficiency, two dimming control methods of the IEEE 802.15.7 standard based on analogue and digital dimming are considered. We also investigate the application of the proposed receiver in the spectral efficient VLC systems with multi-carrier modulation schemes, i.e., direct current (DCO) and asymmetrically clipped optical (ACO) orthogonal frequency division multiplexing (OFDM). Through extensive numerical results, it is demonstrated that the suggested adaptive receiver outperforms the conventional PIN PD and SPAD array receivers in terms of bit error rate (BER) and achievable data rate.

Performance Comparison of FBMC-OQAM and CP-OFDM Using AWGN Channel

The 5G NR network planning covers the types of use scenarios and applications that include Enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communications (URLLC), and Massive Machine Type Communications (MTC). Regarding multicarrier modulation schemes, Orthogonal Frequency Division Multiplexing (OFDM) has become the most popular choice in previous technology, so OFDM is a strong candidate for its 5G NR technology application. However, OFDM has disadvantages such as higher PAPR and decreased bandwidth efficiency due to the addition of CP. These weaknesses can be overcome by the FBMC modulation scheme with Offset Quadrature Amplitude Modulation (OQAM) as a more efficient CP replacement for its implementation in 5G NR. This study analyzed the development of OQAM in Filter Bank multicarrier (FBMC) and compared it with using Cyclic Prefix (CP) based on OFDM using the AWGN channel. The first step of this research is to present an overview of the modulation scheme used. Next, compare the performance of FBMC-OQAM and CP-OFDM by analyzing several Bit Error Rate (BER) simulation results against the SNR value when both systems use the same simulation parameters. Based on the test results of each BER, both methods have different values, almost 2 dB for the same BER results. It indicates that the FBMC-OQAM system reached the BER value of 10-4 at SNR 15 dB. The CP-OFDM system, meanwhile, was able to achieve a BER value of 10-4 at SNR 17 dB. These results indicate that the FBMC-OQAM system is superior to CP-OFDM based on the BER values.

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.

5G NR fiber-FSO-wireless systems with dual-polarization and single-carrier optical modulation schemes (invited)

A fifth-generation (5G) new radio (NR) fiber-free-space-optical (FSO)-wireless system with dual-polarization and single”–carrier optical modulation schemes is proposed and realized for the first time. Compared with the single-polarization scheme, adopting the dual-polarization scheme is attractive because it can significantly enhance the transmission capacity of the system. Compared with the multi-carrier optical modulation scheme, using single-carrier optical modulation is attractive because it can effectually suppress the dispersion-induced limitations caused by fiber transmission and distortions produced by beating from multiple optical carries. Through 40-km single-mode fiber, 500-m FSO, and 4-m/3-m/2-m/1-m/0.5-m 5G wireless cascaded-medium, 5G NR millimeter-wave (MMW) and sub-THz signals are transmitted with low bit error rates (<3.8 × 10−3 forward error correction limit) and clear constellations in x- and y-polarizations. This newly-built 5G NR fiber-FSO-wireless system shows promise to enable 5G NR evolution toward MMW and sub-THz bands, which has a substantial impact on the convergence of fiber optics, optical wireless, and 5G wireless communications.

Joint radar communication system design based on filter bank multicarrier modulation scheme

Since orthogonal frequency division multiplexing (OFDM) signals are sensitive to Doppler shift, OFDM signals with cyclic prefix (CP) not only reduce the communication rate but also result in symmetric pseudo peaks in the ambiguity function of the radar, which eventually lead to the degradation of the performance of the joint radar communication system (JRCS). In this study, a novel JRCS is proposed based on the filter bank multicarrier (FBMC) waveform for the inverse synthetic aperture radar (ISAR) imaging and communication system. On the one hand, FBMC waveforms are capable of low orthogonality between subcarriers, which can counter Doppler and multipath effects. On the other hand, FBMC waveforms do not require CP, so the false targets can be avoided and spectral efficiency can be improved. The influence of multipath effect and Doppler shift on FBMC waveform in an integrated system is analysed in detail, and a Doppler compensation algorithm suitable for FBMC-integrated waveform is proposed. The phase error caused by target motion can be iteratively compensated to obtain a well-focussed ISAR image. Finally, considering the ISAR image entropy after motion compensation as the evaluation metric, extensive simulation experiments verify the noise robustness and effectiveness of the proposed algorithm. Compared with the conventional OFDM and CP-OFDM schemes, the simulation verifies that the proposed waveform design and processing method has better performance in the ISAR imaging and communication integrated system.

Low-latency and High-Reliability FBMC Modulation scheme using Optimized Filter design for enabling NextG Real-time Smart Healthcare Applications.

This paper presents a prototype filter design using the orthant optimization technique to assist a filter bank multicarrier (FBMC) modulation scheme of a NextG smart e-healthcare network framework. Low latency and very high reliability are one of the main requirements of a real-time e-healthcare system. In recent times, FBMC modulation has gotten more attention due to its spectral efficiency. The characteristics of a filter bank are determined by t’s, prototype filter. A prototype filter cannot be designed to achieve an arbitrary time localization (for low latency) and frequency localization (spectral efficiency), as time and frequency spreading are conflicting goals. Hence, an optimum design needed to be achieved. In this paper, a constraint for perfect or nearly perfect reconstruction is formulated for prototype filter design and an orthant-based enriched sparse ℓ1-optimization method is applied to achieve the optimum performance in terms of higher availability of subcarrier spacing for the given requirement of signal-to-interference ratio. Larger subcarrier spacing ensures lower latency and better performance in real-time applications. The proposed FBMC system, based on an optimum design of the prototype filter, also supports a higher data rate as compared to traditional FBMC and OFDM systems, which is another requirement of real-time communication. In this paper, the solution for the different technical issues of physical layer design is provided. The presented modulation scheme through the proposed prototype filter-based FBMC can suppress the side lobe energy of the constituted filters up to large extent without compromising the recovery of the signal at the receiver end. The proposed system provides very high spectral efficiency; it can sacrifice large guard band frequencies to increase the subcarrier spacing to provide low-latency communication to support the real-time e-healthcare network.

Rolling Shutter OFDM Scheme for Optical Camera Communication Considering Mobility Environment Based on Deep Learning

This paper presents a rolling shutter orthogonal frequency-division multiplexing (RS-OFDM) optical camera communication higher rate longer range proposed in IEEE 802.15.7a Task Group (TG7a) using an image sensor as a receiver. OFDM is a digital multi-carrier modulation scheme deployed for broadband wireless communication to resolve the inter-symbol interference (ISI) effect caused by the multipath channel. In optical wireless communication systems, OFDM was applied widely for indoor applications: internet of things, e-health, vehicular, and localization systems. The mobility scenario is a big problem for OWC systems, which reduces the system performance due to the optical channel variation in the processing time. In addition to that, signal detection should be considered in the mobility environment to improve the signal-to-noise ratio of OWC systems. In this paper, we proposed the convolution neural network (CNN) for LED detection in the RS-OFDM system, considering the mobility effect. In addition to that, the deep neural network was applied to detect the start of OFDM frame instead of conventional technology (Van De Beek algorithm). By applying our approach, the RS-OFDM system can achieve long communication (18 m distance) with a low error rate in the 2 m/s velocity environment.

An Enhanced Z-Source Switched MLI Capacitor for Integrated Micro-Grid with Advanced Switching Pattern Scheme

In this paper, the Enhanced Z-Source Switched Capacitor Multi-Level Inverter (EZSC-MLI) is presented, which can generate a greater number of levels and magnitude in output. The proposed MLI has greater recognition due to its low harmonic profile, fewer switching components, compact size, low switch stress, isolated DC supply, high efficiency, and low cost. A high voltage boost factor is achieved by using the Z-Source. The Switched Capacitor module is used for charging all the capacitors to equal voltage magnitude based on a self-balanced scheme. The proposed topology for grid integration requires dual control loops, a primary voltage control loop, and a secondary current control loop. The performance of the proposed 7-level topology for grid integrated systems is verified with multi-carrier advanced modulation schemes and by simulations carried out in Matlab/Simulink.

Frequency Domain Detection and Precoding for Massive MIMO With Single Carrier Modulation

Single carrier modulation (SCM) schemes are attractive for uplink (UL) transmissions due to improved power efficiency at the user equipment (UE) transmitter compared with multi-carrier modulation schemes. In a massive MIMO scenario with SCM, the UL detection must mitigate the effects of inter-symbol interference and multi-user interference. This processing is effectively performed in the frequency domain (FD) using a minimum mean squared error (MMSE) detector when the transmission is framed with a cyclic prefix. This paper analyzes an MMSE-based detector compatible with distributed processing in a time-division duplex (TDD) system. The matrix inverses computed for the UL detection are then reused to perform multi-user precoding for the downlink (DL). We find that this scheme yields tremendous savings in computational complexity compared to commonly used zero-forcing (ZF) precoding without sacrificing any performance. Since MMSE processing introduces a bias to the estimates, we derive the scalar coefficients necessary to cancel the MMSE bias. The impact of channel estimation errors is analyzed for both the UL and DL cases in conjunction with a power-efficient approach to SCM channel estimation. Moreover, extensive simulations are performed to confirm our theoretical findings.

An Improved Conventional Diode-Clamped Multilevel Inverter Using Non-Zero Triangular- Based Unipolar Modulation Scheme

This paper presents an improved conventional diode-clamped multilevel inverter using non-zero triangular-based unipolar modulation scheme. The proposed scheme is meant to reduce the number of carrier waves, minimize the circuits of modulation scheme and obtain stabilized output voltage waveforms. Non-zero triangular-based unipolar modulation scheme is actualized by using two zero-free triangular wave carriers and two modulating sinewaves for line-to- line five level output voltage waveforms in single phase full bridge diode-clamped multilevel inverter unlike conventional multicarrier sinusoidal pulse width modulation that uses four triangular waves and one modulating sinewave for the same inverter type. The proposed system also used microcontroller in the combinational of its wave signals in order to generate the appropriate triggering signals for switching the power semiconductor switches. The proposed system has the following features: (i) It produces two distinct triggering trains (W1 and W2) meant to reduce the low and high harmonics unlike conventional modulation techniques (ii) All its carrier waves operate in continuous current mode which makes it unique from other multicarrier and other related modulation schemes (iii) it has low component counts. The proposed scheme on the conventional diode-clamped inverter produced the following results: voltage and current with total harmonic distortions of 0.4547%, stabilized 400V output voltage and 20A output current, probability results at each level of voltage and current occurrences are 0.10, 0.25, 0.25, 0.75 and 0.90; power output of 80kW, low component counts of modulation circuit scheme and experimental prototype.