Offset Quadrature Amplitude Modulation 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.

Channel estimation techniques based on intrinsic interference mitigation for FBMC/OQAM systems

Filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) emerges as a noteworthy alternative to orthogonal frequency division multiplexing (OFDM). FBMC/OQAM addresses the limitations of OFDM by utilizing real-valued, even-symmetrical prototype filters with smaller side lobes and faster spectrum decay. This results in lower out-of-band energy and higher spectral efficiency (SE). However, the orthogonality condition of FBMC/OQAM in the real domain introduces an intrinsic interference (II) component that poses challenges for channel estimation (CE). The conventional straightforward OFDM CE techniques cannot be applied directly. To obtain a precise CSI with the FBMC/OQAM system, Kalman filter (KF) is altered and incorporated into the use of AP and coding. The first proposed method, KalCod, employs a data spreading method to diminish the II effect. The simulation results indicate that KalCod has a superior capacity to the other CE methods, while still maintaining a reasonable level of complexity. In the second proposed method, modified Kalman-auxiliary pilot (KAP), an AP is used to eliminate the II at pilot symbols then updating the channel coefficients using modified KF. When used as a CE method for FBMC/OQAM systems, the modified KAP outperforms its competitors in terms of estimation accuracy, simpler implementation, as well as higher throughput and spectral efficiency.

Bi-orthogonality recovery and MIMO transmission for FBMC systems based on non-sinusoidal orthogonal transformation

Filter Bank Multi-Carrier (FBMC) system based on offset Quadrature Amplitude Modulation (offset-QAM) combined with Multiple-Input-Multiple-Output (MIMO) technique faces great challenges. The inherent imaginary interference of FBMC seriously impacts the performance of the Maximum Likelihood (ML) detection technique in MIMO transmission. The application of the Alamouti code is also hindered. In this paper, we present a data-compressed transmission method based on non-sinusoidal orthogonal transformation, which can recover the bi-orthogonality of FBMC and eliminate the imaginary interference. Thereby, the combination of FBMC and MIMO as well as the application of ML technique and Alamouti code are realized. Specifically, we first consider the Walsh transform, which belongs to the non-sinusoidal orthogonal transform, and utilize its property that can reduce the transmission bandwidth to recover the orthogonality of the FBMC in the frequency domain. Secondly, we construct the discrete transmission model of the system and generate the orthogonal compression matrix utilizing the fast Walsh transform. Then, we analyze the multi-frame transmission, calculate the frames interference, and improve the signal-to-interference ratio again by adding guard time slots. Finally, we construct the MIMO transmission model and complete the theoretical analysis. Simulation results show that the proposed scheme has a robust MIMO transmission performance. ML and Alamouti code techniques perform the same as Orthogonal Frequency Division Multiplex in bi-orthogonal FBMC.

A novel piecewise nonlinear companding scaling scheme for FBMC PAPR reduction

The performance of offset quadrature amplitude modulation filter bank multi carrier (OQAM-FBMC) has been noticed to be affected by a high peak-to-average power ratio (PAPR). High PAPR causes the transmit power amplifier to become saturated, improving the bit error rate (BER) and causing out of band (OOB) distortions. In this paper, the PAPR of FBMC systems can be reduced by using shifting and scaling the trigonometric companding technique associated with a reduced BER performance and the power spectral density (PSD) with low OOB distortions. The characteristics of low peak signals are not changed by this companding scheme, while the characteristics of high peak signals are transformed into scaling piecewise nonlinear trigonometric functions. By tuning the parameters the suggested technique maintains the average signal power level unchanged. The theoretical analysis of the proposed scheme is also studied and also compared with the simulation results. The performance of the trigonometric companding scheme is also analysed with the μ-law and A-law existing companding methods and the suggested method obtaining 3 dB and 3.2 dB PAPR improvement respectively. The proposed technique determined to be better in terms of BER performance and spectrum efficiency.

A hybrid approach based on companding and PTS methods for PAPR reduction of 5G waveforms

ABSTRACT As a crucial enabler for the fifth-generation air interface, the filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is being investigated by several researchers. This article suggests using partial transmit sequence (PTS) and companding to create a hybrid peak-to-average power ratio (PAPR) reduction strategy for FBMC/OQAM signals. In the novel PTS Companding scheme, there are several segments to the data block signal, and the overlapping factor determines the number of data blocks in each segment. To obtain the lowest signal power in each segment, we choose the best data block to broadcast and examine the next overlapping data block concurrently. After that, the segment FBMC/OQAM signal peaks are compressed using companding. Based on simulation results and analysis, the proposed hybrid PTS Companding method in FBMC/OQAM systems may reduce PAPR more effectively than conventional PTS and Companding schemes. According to simulation results, the hybrid process can achieve around 5 dB greater PAPR performance than the conventional PTS and companding schemes.

Adaptive refined random orthogonal matching pursuit algorithm for FBMC/OQAM MIMO framework

The fifth generation of wireless communication is anticipated to provide improved quality of service and enhanced data rates to the end users. One such technology that stands out as a potential transmission scheme for 5G systems is Filter Bank Multicarrier using Offset Quadrature Amplitude Modulation (FBMC/OQAM) with an effective channel estimation technique for improved performance. However, due to the inherent imaginary interference, channel estimation methods relying on preamble structures in FBMC/OQAM systems exhibit sub-optimal performance, particularly within Multiple-Input Multiple-Output (MIMO) setups. For channel estimation schemes based on compressed sensing, the inherent sparsity of wireless channels can be exploited for accurate channel reconstruction and overall performance improvement.We propose a novel compressed sensing based algorithm namely, Adaptive Refined Random Orthogonal Matching Pursuit (ARROMP), for MIMO-FBMC system with Coordinated MultiPoint (CoMP) scheduling. This algorithm adaptively selects a support set by utilizing a double threshold for the minimization of mean squared error and for accurate channel reconstruction. The proposed algorithm's performance is compared with existing Orthogonal Matching Pursuit (OMP) schemes such as random OMP, refined random OMP, and least square-based estimation. The numerical simulations suggest that the proposed adaptive algorithm provides performance improvement in terms of reduced Mean Squared Error (MSE) of channel reconstruction and Bit Error Rate (BER). Moreover, the proposed ARROMP algorithm for MIMO-FBMC is rigorously tested with CoMP scheduling for a cellular network using frequency division duplex mode. The proposed system presents significant improvements in throughput and spectral efficiency for all types of cell users, including cell-edge users. The simulation results validate the improved performance of the proposed algorithm with CoMP scheduling over the existing single-cell system with no coordination.

Equalization methods for Filter Bank Multicarrier OQAM

Filter bank multi-carrier offset-quadrature amplitude modulation (FBMC OQAM) is a hot topic in 5G multi-carrier research. In order to achieve high data rates and reliable wireless communication, receiver channel equalization is required. This is because of the equalizer's excellent spectral efficiency, exceptionally low side-lobe leakage, zero periodic cyclic prefixes (CP), and multiphase filter design. However, a number of degradations, including fading, Doppler shifts, and intermittent symbol interference (ISI), are added to the transmitted data symbols as they traverse the wireless channel, reducing the network's overall quality. To mitigate the negative effects of channel defects, many channel equalization algorithms have been developed for use in modern telecommunications networks. Six different equalizer approaches have been implemented. Using the Pedestrian A and Vehicular B channel in our simulations, we examine how well they function. The system was simulated using MATLAB's Communications Toolbox (an M file). Bit-error-rate (BER) and signal-to-noise ratio (SNR) were used to evaluate the outcomes. The Bit error rate was calculated by checking for differences between the sent and received bit sequences. The best value of the bit error ratio using frequency domain equalization and the time domain equalization 5.4 and 4.7 , respectively.

Combined intra symbol frequency domain averaging channel estimation for polarization division multiplexed coherent optical OFDM/OQAM systems

Intrinsic imaginary interference (IMI) induced by chromatic dispersion (CD) and polarization mode dispersion (PMD) seriously degrades the performance of optical orthogonal frequency division multiplexing offset-quadrature amplitude modulation (O-OFDM/OQAM) systems. Therefore, effective channel estimations are required for such systems to maintain good transmission performance. In the previous publications, both the full loaded (FL) and the half loaded (HL) frequency-domain channel estimation methods for polarization-division-multiplexed (PDM) coherent optical OFDM/OQAM (CO-OFDM/OQAM) systems have been proposed. However, for these frequency-domain methods, the channel frequency-domain responses caused by the correlation of the amplified spontaneous emission (ASE) noise are not considered. In this paper, we systematically discuss the frequency-domain channel transmission model for PDM CO-OFDM/OQAM systems. With the analysis of the correlation of the ASE noise, we propose a combined intra symbol frequency-domain averaging (CISFDA) channel estimation method for PDM OFDM/OQAM systems. Compared with the full-loaded frequency-domain channel estimation (FL-FD) method, the CISFDA method promotes the system robustness against the ASE noise and fiber nonlinear effect significantly. The proposed method is validated by numerical Monte Carlo simulations of the PDM CO-OFDM/OQAM system. Our new algorithm outperforms the FL-FD method in the 36 Gb/s PDM OFDM CO-OFDM/OQAM system, and the transmission distance is improved by 500 km with the bit-error-rate (BER) target at 3.8×10-3.

PAPR and BER Analysis in FBMC/OQAM System with Pulse Shaping Filters and Various PAPR Minimization Methods

Filter Bank Multicarrier with Offset Quadrature Amplitude Modulation(FBMC/OQAM) system design based on frequency sampling prototype filter takes into account the low frequency utilization of Orthogonal Frequency Division Multiplexing(OFDM) caused by adding Cyclic Prefix(CP). The CP decreases spectral efficiency and increases Peak to Average Power Ratio(PAPR). FBMC is an OFDM enhancement. In this paper to reduce the PAPR, we explained companding methods. We have proposed an FBMC that makes use of prototype pulse shaping filters which can be adjusted to meet system requirements in order to defeat these limitations. Due to its significant effect on the performance of FBMC-OQAM, choosing the right filter is crucial. Different prototype filters are used to investigate the performance of the FBMC-OQAM in this paper. Using the validated system, it was found that frequency utilization is more and good out-band suppression as well as an excellent application value in 5G technology. By using ?-law companding method, FBMC/OQAM provides better performance. It produces low PAPR, low out of band(OoB), high BER performance, less computational complexity and high spectral efficiency as compared to other methods.

Filter bank multi-carrier based offset ternary phase shift keying(FBMC/OTPSK)

Filter bank multi-carrier (FBMC) is a popular researched technique for wireless communications that offers several advantages over traditional orthogonal frequency-division multiplexing (OFDM) systems. In this paper, we propose a FBMC system using offset Triangle phase shift keying (TPSK) modulation (FBMC/OTPSK), analyze its bit error rate (BER) performance via additive white Gaussian noise (AWGN) channel, and compare it to that of conventional FBMC using offset quadrature amplitude modulation (FBMC/OQAM) system. Simulation results show that the proposed FBMC/OTPSK system considerably improves BER performance over FBMC/OQAM system. Additionally, we explore the impact of using ternary convolutional coding (TCC) with TPSK and binary convolutional coding (BCC) with QAM. The presented TPSK modulation encoded by TCC offers better error rate performance and minimum amplitude fluctuation compared to QAM encoded by BCC; therefore, TCC-coded OTPSK is proposed to be used with FBMC instead of BCC-coded OQAM to benefit from its lower error rates without bandwidth expansion, as well increase information carried by symbol, hence increases throughput.

Multilayered optical orthogonal frequency division multiplexing with offset quadrature amplitude modulation for visible light communication systems

Multilayered optical orthogonal frequency division multiplexing with offset quadrature amplitude modulation for visible light communication systems

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 Pilot-Aided Timing Recovery Algorithm With High Tolerance to Impairments for OQAM-Based Digital Multi-Band Systems

Timing recovery (TR) plays an important role in the digital signal processing (DSP) of coherent receivers. In TR, timing error (TE) is extracted by the timing recovery algorithm (TRA) and fed back to adjust the clock sampling phase. However, widely-used Gardner and Godard TRAs are sensitive to spectral roll-off factor and differential group delay (DGD), and more importantly, are inapplicable to the offset quadrature amplitude modulation (OQAM) system. In this paper, we propose a novel pilot-aided TRA for the OQAM-based digital multi-band (OQAM-DMB) system, which is robust to different impairments including rotation of state of polarization (RSOP), DGD, spectral roll-off, residual chromatic dispersion (rCD), residual carrier frequency offset (RFO), and laser linewidth. 1.12-Tbit/s simulations and 320-Gbit/s experiments show that OQAM-DMB based on the proposed algorithm works properly for all spectral roll-off factors and exhibits excellent tolerance against DGD, RSOP, rCD, RFO, and laser linewidth, and outperforms QAM-DMB using conventional TRAs. The digital phase-lock loop can be locked for the clock frequency offset within ±80 ppm and all initial sampling phase offsets. Although investigated in OQAM-DMB, the proposed algorithm is also applicable to conventional QAM-DMB.

A Novel PAPR Reduction in Filter Bank Multi-Carrier (FBMC) with Offset Quadrature Amplitude Modulation (OQAM) Based VLC Systems

The peak to average power ratio (PAPR) is one of the major problem with multicarrier-based systems. Due to its improved spectral efficiency and decreased PAPR, Filter Bank Multicarrier (FBMC) has recently become an effective alternative to the orthogonal multiplexing division (OFDM). For filter bank multicarrier communication/offset quadrature amplitude modulation-Visible light communication (FBMC/OQAM-VLC) systems is proposed a PAPR reduction technique. The suggested approach overlaps the proposed FBMC/OQAM-based VLC data signal with the existing signals. Non-redundant signals and data signals do not overlap in the frequency domain because data signals are scattered on odd subcarriers whereas built signals use even subcarriers. To reduce the effects of large-amplitude signal reduction, the suggested technique converts negative signals into positive signals rather than clipping them off as in conventional FBMC-based VLC systems. The PAPR reduction and bit error rate (BER) are realized using a scaling factor in the transformed signals. Complementary cumulative distribution function(CCDF) and BER are used to calculate the performance of the proposed approach. The presented study found that FBMC/OQAM-VLC systems to achieve a good trade-off between PAPR reduction and BER.

Multi-antennas PAPR Reduction for FBMC/OQAM System

Background: The filter bank multicarrier (FBMC) with offset quadrature amplitude modulation (OQAM) is a promising future generation of wireless systems. However, like multicarrier modulations (MCM), FBMC/OQAM has a high peak-to-average power ratio (PAPR), which allows the FBMC/OQAM signal to pass through the nonlinear region of the high-power amplifier (HPA) in the time domain and causes in-band and out of band (OOB) distortion. Methods: In this paper, a new method to overcome this problem called multi-antennas PAPR (MAP) reduction is proposed. It consists of using I antennas in transmission and reception to transmit I FBMC/OQAM sub-signals with low PAPR. The complementary cumulative distribution function (CCDF), the bit error rate (BER), and the energy efficiency are used to evaluate the method's performance. Results: The simulation results showed that the new technique can reduce the PAPR of the original signal by more than half, achieve BER comparable to that of the original signal without HPA, and when the input back-off (IBO) equals 3dB, the error vector magnitude (EVM) result can be reduced from 19% to 7%. Conclusion: The PAPR, BER, and EVM of MAP technique are much better than the original system.

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.

A Lattice-Reduction-Aided Sphere Decoder for Underwater Acoustic FBMC/OQAM Communications

Because of the inherent interference, it is difficult for filter-bank multi-carrier (FBMC) with the offset-quadrature amplitude modulation (OQAM) systems to achieve high-performance symbol detection, especially over the underwater acoustic (UWA) channels. This letter explores a novel receiver approach to solve this problem by establishing a unified transmission matrix (UTM) model and proposing a lattice-reduction-aided sphere decoder (LRA-SD). The simulation and sea trial results indicate that in the UWA FBMC/OQAM communication systems, the UTM-based LRA-SD outperforms the linear detectors and is more computationally efficient than the maximum likelihood (ML) detector.

Continuous unconstrained PSO‐PTS strategy to maximize HPA energy efficiency for FBMC‐OQAM systems

AbstractIn filter bank multi‐carrier (FBMC) with offset quadrature amplitude modulation (OQAM) systems, the major limitation of FBMC‐OQAM signaling is the high peak‐to‐average power ratio (PAPR). High PAPR results in increased hardware complexity and is also prone to non‐linear effects of high‐power amplifiers (HPA). The existing HPA energy‐efficient optimization strategies are constrained severely by the scarcity and heterogeneity of signal distribution in the degree of freedom. This paper theorizes the optimal FBMC‐OQAM signal distribution, which has a global and steady feature and evaluates the maximal HPA efficiency‐suited multi‐carrier modulation (MCM) signal. This paper first proposes that the Binary Particle Swarm Optimization based Partial Transmit Sequence (BPSO‐PTS) with the Input‐Back Off Modulation Error Ratio (IBO‐MER) scheme traces the signal distribution for maximal HPA efficiency to save supply‐side energy. This paper further proposes Continuous‐Unconstrained Particle Swarm Optimization based PTS(CUPSO‐PTS) with IBO‐MER to obtain the theoretical boundaries and drastically accelerate convergence in the continuous‐unconstrained searching space. To decrease the computational complexity of MER calculation, this paper proposes the CUPSO with IBO Signal‐to‐Distortion Ratio (IBO‐SDR), enabling it to meet more practical applications. The simulation results show that the proposed scheme outperforms conventional IBO and HPA efficiency schemes.

Performance analysis of FBMC/OQAM systems in frequency-selective channels

Filter bank multicarrier (FBMC) systems based on offset QAM modulation (FBMC/OQAM) represent an interesting alternative to the widely used OFDM scheme for machine type communications or cognitive radio. In this paper the performance of FBMC/OQAM systems exploiting a single-tap receiver in frequency-selective Rayleigh fading channels, is analyzed. In particular, the SER and the asymptotic SER (i.e., for a large number of subcarriers) for any prototype filter, is derived. Moreover, a simple closed-form approximate expression of the asymptotic SER is obtained by taking into account, for each active subcarrier, only intersymbol interference terms due to the considered subcarrier and the adjacent subacarriers, and intercarrier interference terms due to the adjacent subcarriers. The numerical results show that the obtained SER expression can predict the actual performance of the system while the asymptotic SER expression provides a useful upper-bound. Moreover, the curves obtained by exploiting the derived simple closed-form approximate expression can be used to predict the asymptotic upper-bound when the considered prototype filter is adopted.

Sustainable and Robust Techniques of Wireless Communications for Industry 4.0: Towards Efficient PAPR Reduction Models

This work presents the concerns of reliable, comprehensive, and high-quality communication networks essential in wireless communications for Industry 4.0. These are considered critical requirements of wireless technology for Industry 4.0. For a reliable transmission of digital data over broadband widths and Giga Hertz channels, the corresponding Peak-to-Average-Power Ratio (PAPR) must be under control. Industry standards Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing With Offset Quadrature Amplitude Modulation (MIMO-OFDM/OQAM) system has been considered as the modulation technique with less Computational Complexity (CC). It usually produces phase sequence sets with different PAPR, a complex phenomenon to control. For robustness in PAPR control, the technique proposed has a receiver that initially restores the frequency domain rotation signal according to the sequence selection of the transmitter. Then it compares the distance between the reverse rotation sequence and the nearest constellation point to restore the original sequence. The proposed method simulation results can efficiently suppress the PAPR of MIMO-OFDM/OQAM signals. The proposed method is compared with the traditional Selective Mapping (SLM) algorithm. The proposed method reduces the CC, and can obtain the approximate Bit-Error Rate (BER) performance of the conventional SLM method when the sideband side information is known.