Quadrature Amplitude Modulation Modulation Research Articles

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.

High Order QAM Modulation in Massive MIMO Systems With Asymmetrically Quantized 1-Bit ADCs

Deploying 1-bit analog-to-digital converters (ADCs) in massive multiple-input multiple-output (MIMO) systems is promising to reduce the energy consumption. However, serious quantization errors limit the feasibility of high order quadrature amplitude modulation (QAM). This paper focuses on the performance analysis of 1-bit ADC massive MIMO systems with high order QAM. Firstly, we theoretically analyze the relationship between the quantization error and various quantization parameters. We reveal that there exists an overlapping of constellations at high signal to noise ratio (SNR) with symmetric quantization. This is because the amplitude information in the detected signal at high SNR is lost which is multiplied by the zero quantization threshold in the symmetric quantization. To overcome this problem, asymmetric quantization should be considered. Based on the analysis of the quantization error, we propose two approaches to recover the amplitude information. One is a near unbiased detection (NUD) by scaling the traditional linear detector and optimizing the quantization threshold. The other is a sub-array detection based on non-uniform quantization (SAD-NQ) to correct the deviation of the detection result by averaging over sub-arrays. Simulation results show that the proposed approaches can significantly improve the detection performance of high order QAM signal in the 1-bit ADC massive MIMO systems.

Impulsive Noise Cancellation in OFDM System Using Low Density Parity Check

An effective communication application necessitates the cancellation of Impulsive Noise (IN) from Orthogonal Frequency Division Multiplexing (OFDM), which is widely used for wireless applications due to its higher data rate and greater spectral efficiency. The OFDM system is typically corrupted by Impulsive Noise, which is an unwanted short-duration pulse with random amplitude and duration. Impulsive noise is created by humans and has non-Gaussian characteristics, causing problems in communication systems such as high capacity loss and poor error rate performance. Several techniques have been introduced in the literature to solve this type of problem, but they still have many issues that affect the performance of the presented methods. As a result, developing a new hybridization-based method is critical for accurate method performance. In this paper, we present a hybrid of a state space adaptive filter and an information coding technique for cancelling impulsive noise from OFDM. The proposed method is also compared to Least Mean Square (LMS), Normalized Least Mean Square (NLMS), and Recursive Least Square (RLS) adaptive filters. It has also been tested using the binary phase-shift keyed (BPSK), four quadrature amplitude modulation (QAM), sixteen QAM, and thirty-two QAM modulation techniques. Bit error Rate (BER) simulations are used to evaluate system performance, and improved performance is obtained. Furthermore, the proposed method is more effective than recent methods.

A Deep Learning-Based Robust Automatic Modulation Classification Scheme for Next-Generation Networks

Due to stochastic wireless environment, the process of modulation classification has become a challenging task. Because of its powerful feature extraction ability and promising performance over the conventional schemes, deep learning (DL) models are employed to automatic modulation classification (AMC) problems. Most of the conventional models proposed are tested for the limited set of modulation schemes transmitted over additive white Gaussian noise (AWGN) channels without considering the effect of multipath fading and Doppler shift. The next-generation networks use adaptive and higher-order quadrature amplitude modulation (QAM) schemes for higher spectral efficiency. The classification accuracy of conventional DL-based AMC schemes drastically reduces, when different order QAM modulation schemes are accommodated. In this work, different scaling factors are selected for the generation of [Formula: see text]-QAM frames. The combination of scaling factors, which maximize the classification accuracy is chosen. A convolutional neural network (CNN) with six stages is employed for AMC. The simulation results show that the classification accuracy of proposed scheme is higher than the conventional DL-based schemes under various signal-to-noise ratio (SNR) conditions. The proposed scheme shows at least 4% improvement in classification accuracy over the other DL-based schemes.

IRS-Assisted Physical Layer Network Coding Over Two-Way Relay Fading Channels

This article investigates the performance of intelligent reflective surfaces (IRS)-aided physical layer network coding (PNC) in two-way relaying channels (TWRC). Specifically, IRS is used to eliminate carrier phase offset (CPO) at the relay node. To this end, the IRS reflectors’ phase shifts are optimized to align the received signals from two source nodes at the relay. This facilitates using a simple mapping function at the relay to map the superimposed signal to a network-coded signal. Two scenarios are considered, the first of which assumes that each source node is served by a separate IRS panel, while the second scenario considers the more challenging case where only one IRS panel is available for the two source nodes. In the latter case, the IRS panel is seen by both source nodes and its phase shifts are optimized to mitigate the CPO problem while maximizing the received signal amplitude at the relay. This optimization problem is formulated and solved over the complex circle manifold. Finally, we extend the IRS-assisted PNC system to include channel coding and higher modulation orders, for which a repeat accumulate (RA) channel-coded IRS-aided PNC scheme is proposed for general quadrature amplitude modulation (QAM) signals. A belief propagation (BP) based algorithm is designed to decode the network-coded sequences over a q-Ring using modular arithmetic. Our simulation results validate the theoretical error expressions derived for the two-IRS scenario as well as the efficacy of the proposed manifold optimization approach for the one-IRS scenario. The results also confirm the efficacy of the designed channel-coded IRS-aided PNC using high QAM modulation orders.

Data reduction and recovery in wireless communication system: An extensive experimental evaluation using PSK and QAM modulations

SummaryThe evolution of technologies in data communication system has resulted in generation of large data. With the availability of limited bandwidth and to maintain the energy efficiency of the wireless communication system, data reduction plays a significant amount of role in preserving the lifetime of wireless communication system. Considering the significance of this problem in wireless communication system, in this work, we present data reduction and recovery or reconstruction on multivariate data using principal component analysis (PCA). In general, we send the eigen coefficients from the source and use these coefficients at the destination to recover or reconstruct the original data back in wireless communication system. We employ in our work two different digital modulation techniques such as phase‐shift keying (PSK) and quadrature amplitude modulation (QAM) with seven different bit rate to demonstrate our approach. We carry the experiments independently using five different signal ensemble and four different multiple‐input, multiple‐output (MIMO) configuration along with Rayleigh fading. This work presents an extensive simulated benchmark results based on performance matrix such as root mean square error (RMSE) and bit error rate (BER) at different values of signal‐to‐noise ratio (SNR). We further validate our approach by presenting synthesis of our proposed model using Xilinx target device Virtex‐6 LX240T Field Programmable Gate Array (FPGA). The experimental results reported based on simulation, synthesis, and validation of model demonstrate the applicability of our proposed approach in real‐time scenario.

Bidirectional OFDM-MMWOF transport system based on mixed QAM modulation format using dual mode colorless laser diode and RSOA for next generation 5-G based network

A hybrid bidirectional orthogonal frequency division multiplexing–millimeter wave over fiber (OFDM-MMWOF) transport system based on mixed quadrature amplitude modulation (QAM) format using dual-mode colorless laser diode and reflective semiconductor optical amplifier for next-generation 5G based networks is proposed and experimentally demonstrated. Here, an orthogonal quadruple frequency MMW is generated via optical heterodyne scheme. In case of downlink transmission, 10 Gbps baseband signal is transmitted over 80-km single-mode fiber (SMF) plus 500-m free space optical (FSO) distance and for the uplink, 5 Gbps baseband signal is transmitted over 80-km SMF plus 100-m FSO distance. For wireless transmission, 12.5 Gbps/60 GHz downlink MMW signal is generated and transmitted over 80-km SMF as well as 100-m wireless distance. 6.5 Gbps/30 GHz uplink MMW signal is communicated over 80-km SMF plus 50-m wireless distance. OFDM scheme with mixed QAM modulation technique enhances our spectral efficiency and simultaneously reduces inter symbol interference, inter-carrier interference, dispersion, etc. for long reach communication. The feasibility and reliability of our system is established by achieving low bit error rate (10-3), good error vector magnitude (<10.5% for 32 QAM and < 12.5% for 16 QAM), appropriate signal to noise ratio, and clear constellation diagram.

Design of high-order QAM modem algorithm

More and more attention has been paid on the issue of bandwidth utilization. Nowadays, with limited frequency spectrum resources, the capacity of traditional communication system has not been able to meet the demands of users. Quadrature Amplitude Modulation (QAM) has become a critical technical solution for broadband wireless access and wireless video communication due to its advantages of high frequency spectrum utilization and high-power spectrum density. In order to further improve the control information transmission performance of high-order QAM, we propose a high-order QAM modulation and demodulation algorithm, which is designed from the aspects of interleave between channels, leading sequence, constellation modulation, frequency domain sampling and (Orthogonal Frequency Division Multiplexing) OFDM generation, etc. The simulation results demonstrate that the algorithm can ensure the reliable reception of control information.

Shaping duo binary turbo-coded BICM scheme for JPWL image transmission using a link adaptation strategy over wireless channels

In order to guarantee a robust transmission of JPWL (JPEG Wireless: Joint Photographic Experts Group Wireless) images through time and frequency selective wireless channels, an efficient adaptive communication strategy is proposed. It is based on an optimization of a closed-loop adaptive multiple-input multiple-output, orthogonal frequency division multiplexing (MIMO-OFDM) scheme associated with a shaping BICM (bit-interleaved coded modulation) technique composed of a duo binary turbo code (DBTC), high-order modulations such as 64–256 QAM (Quadrature Amplitude Modulation) and a shaping code. According to the CSI (channel state information) knowledge at the transmitter side, an algorithm based on unequal error protection (UEP) and unequal power allocation (UPA) is used to select the transmitter key parameters (source/channel encoder rate, modulation order, power, number of quality layers and number of iterations of the Turbo decoder) to achieve the target Quality of Service (QoS). The proposed DBTC-shaping BICM scheme reaches a shaping gain of 1.2 dB for a 256 QAM modulation over a SISO Gaussian channel, whereas only 0.7 dB of shaping gain can be achieved in a scheme that uses the LDPC shaping BICM scheme for the same modulation order. Based on a DBTC shaping BICM scheme and an adaptive algorithm, the proposed MIMO-OFDM strategy achieves better performance compared to a strategy using an iterative process between an RS (Reed-Solomon) and arithmetic decoders. As a result, and on the one hand, a gain of 5.38 dB can be achieved in terms of PSNR (peak signal-to-noise ratio). On the other hand, a gain of 78% in terms of power consumption is obtained for the same QoS level. Moreover, the adaptive number of iterations in the proposed strategy can minimize the computational complexity of the turbo decoding compared to a scheme using four iterations whatever the channel conditions.

Investigation on the PAPR performance of odd-bit QAM constellations for DFT spread OFDM systems

&lt;p&gt;Adaptive quadrature amplitude modulation (QAM) is a crucial scheme that enables the modern communication systems to overcome the adverse effects of channel fluctuations and maintain an acceptable spectral efficiency. In order to enhance adaptive modulation even further, adoption of odd-bit QAM constellations alongside even constellations had been suggested to improve the transmission efficiency of adaptive QAM modulation. Hence, odd-bit QAM had been extensively studied, analyzed, and tested by many researchers for various patterns, sizes, and communication systems in terms of bit error rate (BER) and peak to average power ratio (PAPR). However, the PAPR performance of odd-bit QAM constellation with single carrier transmission systems adopted in the uplink of the 4G long term evolution (LTE) standards caught almost no research interest. In this paper, the PAPR performance of both cross and rectangular odd-bit QAM constellations are investigated for DFT-S-OFDM systems. Complementary cumulative distribution functions (CCDFs) and probability density functions (PDFs) curves for PAPR are also obtained. Finally, an equation for PAPR PDF is empirically derived for odd-bit cross QAM based DFT-S-OFDM. The results show that cross odd-bit QAM outperforms the rectangular odd-bit QAM in terms of PAPR by 1.02 dB for 8-QAM and 1.3 dB for 32-QAM. This proves that cross odd-bit QAM is a better choice in terms of PAPR for DFT-S-OFDM systems. &lt;/p&gt;

Simulation of M-ary QAM and M-ary PSK Modulation Techniques Using MATLAB GUI

The world has seen a transformation due to the recent pandemic. The field of education is drastically affected by it. There is a need to move from classroom teaching to online teaching, and the biggest hurdle is to impart practical knowledge. This paper attempts to study the concepts like M-ary Phase shift keying (PSK) and M-ary Quadrature amplitude modulation (QAM), used in modern-day communication systems, using a simulation platform. For this purpose, simulation using a graphical user interface (GUI) is proposed to study various M-ary PSK and M-ary QAM types. MATLAB is used to implement the GUI. The modulation, transmission, demodulation, and recovery of a signal implemented through the GUI will help learners understand the concepts better. Moreover, the constellation diagrams for M-ary PSKs and M-ary QAMs can be examined using the developed GUI.

A Novel Low Complexity Faster-than-Nyquist (FTN) Signaling Detector for Ultra High-Order QAM

Faster-than-Nyquist (FTN) signaling is a promising non-orthogonal pulse modulation technique that can improve the spectral efficiency (SE) of next generation communication systems at the expense of higher detection complexity to remove the introduced inter-symbol interference (ISI). In this paper, we investigate the detection problem of ultra high-order quadrature-amplitude modulation (QAM) FTN signaling where we exploit a mathematical programming technique based on the alternating directions multiplier method (ADMM). The proposed ADMM sequence estimation (ADMMSE) FTN signaling detector demonstrates an excellent trade-off between performance and computational effort enabling, for the first time in the FTN signaling literature, successful detection and SE gains for QAM modulation orders as high as 64K (65,536). The complexity of the proposed ADMMSE detector is polynomial in the length of the transmit symbols sequence and its sensitivity to the modulation order increases only logarithmically. Simulation results show that for 16-QAM, the proposed ADMMSE FTN signaling detector achieves comparable SE gains to the generalized approach semidefinite relaxation-based sequence estimation (GASDRSE) FTN signaling detector, but at an experimentally evaluated much lower computational time. Simulation results additionally show SE gains for modulation orders starting from 4-QAM, or quadrature phase shift keying (QPSK), up to and including 64K-QAM when compared to conventional Nyquist signaling. The very low computational effort required makes the proposed ADMMSE detector a practically promising FTN signaling detector for both low order and ultra high-order QAM FTN signaling systems.

Employment of Generalized Receiver in DS-CDMA with STBC over Fading Channels: Capacity and Error Probability

The capacity and error probability of orthogonal space-time block codes (STBCs) are considered for the pulse-amplitude modulation (PAM), phase shift keying (PSK), quadrature-amplitude modulation (QAM) in fading channels. The suggested approach is based on employment of the generalized approach to signal processing in noise over the equivalent scalar additive white Gaussian noise channel with a channel gain proportional to the Frobenius norm of the matrix channel for the STBC. Using this effective channel, the capacity and probability of error expressions are derived for the PSK, PAM, and QAM modulation with space-time block coding. The Rayleigh, Rician and Nakagami fading channels are considered. As an application, these results are extended to obtain the capacity and probability of error for a multiuser direct sequence code-division multiple-access (CDMA) system constructed on the basis of the generalized approach to signal processing in noise employing the space-time block coding.

Signal Processing by Generalized Receiver Using DS-CDMA with STBC Technology in Multidimensional Systems over Fading Channels: Capacity and Error Probability

The capacity and error probability of orthogonal space-time block codes (STBCs) are considered for the pulse-amplitude modulation (PAM), phase shift keying (PSK), quadrature-amplitude modulation (QAM) in fading channels. The suggested approach is based on employment of the generalized approach to signal processing in noise over the equivalent scalar additive white Gaussian noise channel with a channel gain proportional to the Frobenius norm of the matrix channel for the STBC. Using this effective channel, the capacity and probability of error expressions are derived for the PSK, PAM, and QAM modulation with space-time block coding. The Rayleigh, Rician and Nakagami fading channels are considered. As an application, these results are extended to obtain the capacity and probability of error for a multiuser direct sequence code-division multiple-access (CDMA) system constructed on the basis of the generalized approach to signal processing in noise employing the space-time block coding

Minimization of power and area of digital modulator for cellular communication using cadence in 180nm, 90nm and 45nm CMOS technology

Background/Objectives: Low power modulators are most efficient for wireless communication. Quadrature Amplitude Modulation (QAM) is used widely for high data rate communication than BPSK and QPSK, since it carries more bits of information per symbol over the channel. The objective of this work is to minimize the power consumption and area utilization of 32-bit QAM modulator. Methods/Statistical analysis: In this work, three new procedures are introduced for 32QAM modulator. In the first approach, sine and cosine data generated using conventional technique are stored in ROM and the stored data is selected based on the input sequence to generate the output signal. This approach reduces the power consumption and area utilization. In the second approach, information bit stream is modulated with sine and cosine waves generated by iterative algorithm to minimize power and area requirement. In the third approach, booth multiplication algorithm is employed to generate QAM signal. This method of generating QAM signal consumes less power and area in comparison with the conventional modulator. The work is synthesized, analyzed, and compared in 180nm, 90nm and 45nm CMOS technology using Cadence software. Findings: In 180nm CMOS technology power consumption noticed is 60662.740nW, 617020.071nW and 133679.687nW with the proposed method1, method2 and method3 respectively. An Area utilized in 180nm CMOS technology is 1341mm2, 20746.757mm2, and 2754mm2 respectively in proposed 32QAM modulator with ROM, 32QAM modulator with proposed Iterative algorithm and 32QAM modulator with Booth multiplication algorithm. Novelty/Applications: The conventional 32QAM devours additional power and area. In this work area and power reduction is achieved with respect to the conventional method. The same work is carried out with 90nm and 45nm CMOS technology. Three novel approaches to 32QAM are proposed. The proposed work is synthesized, analyzed, tabulated and compared with conventional method and shown that power consumption and area utilization are minimum than compared to the conventional method. Keywords: QAM; multiplier; power; area; communication; cadence

Effects of Different Modulation Techniques on Charging Time in RF Energy-Harvesting System

Radio-frequency (RF) energy harvesting is a promising technology that obtains energy from electromagnetic waves. As an alternative energy source, this modern technology can provide power wirelessly enabling the practical use of battery-free devices and it is also expected to be widely used in future applications. Many studies have examined the effects of different modulation techniques on power or efficiency in RF energy-harvesting systems. In this article, the effects of different modulation techniques, such as amplitude shift keying (ASK), quadrature amplitude modulation (QAM), phase-shift keying (PSK), and frequency shift keying (FSK) on charging time, were measured and theoretically analyzed in detail. The measurement system was designed using a signal generator, an RF energy-harvesting circuit, and other auxiliary devices. The signal generator produced four different modulated signals as transmit power signals from 1 to 10 dBm at the interval of 1 dBm, and then, the RF energy-harvesting circuit was fed with these power signals. According to the measurement results, four different modulation techniques charged the RF energy-harvesting circuit at different times. It was observed that the 4-ASK modulation technique had the shortest charging time in the range of 1-10 dBm when comparing to QAM, PSK, and FSK modulation techniques, and thus, it was evaluated to be the most suitable modulation technique for the RF energy-harvesting system among these modulation techniques in terms of charging time.

Simulation and Performance Study of Quadrature Amplitude Modulation and Demodulation System

Both traditional frequency modulation and phase modulation digital modulation methods have low spectral utilization, poor multipath fading resistance, slow power spectrum attenuation, and severe out-of-band radiation. Quadrature Amplitude Modulation (QAM) is a digital modulation technique that combines phase and amplitude control. It not only achieves higher spectral efficiency, but also transmits higher rate data in a defined frequency band. In this paper, the basic principle, system structure and performance parameters of QAM modulation and demodulation are studied in depth to realize simulink simulation and performance analysis of QAM modulation and demodulation system. The basic theory and implementation method of analog signal digitization are analyzed in detail to realize simimlink of differential pulse code modulation. Based on the above theory, the analog source QAM transmission system is constructed, and simulink is used for modeling and simulation and performance verification.The simulation results show that the constructed QAM digital transmission system can achieve good transmission of analog signals.

Pergroup and Joint Optimization of Max-Dmin Precoder for MIMO with LDPC Coding Using QAM Modulation

MIMO technology not only offers diversity and capacity gains, but also provides higher spectral efficiency and significant link reliability over SISO systems. Many methods are developed to exploit the diversity offered by multi-antenna systems such as Alamouti code and spatial multiplexing that do not require transmitter-side channel status information (Tx-CSI). Other power allocation optimization techniques, also known as precoding, require a full or partial Tx-CSI. These techniques aim to transform the signal before transmission according to different criteria, among which the minimal Euclidean distance seems to be very effective and continues to interest the researchers. Given perfect channel state information at both sides of the communication, we propose in this paper a novel design of wireless transmission schemes that joint the minimal Euclidean distance precoder and error correction coding based on the non-binary low-density parity-check code (NB-LDPC), to finally determine a power allocation optimization solution that adapts a linear precoding block to an NB-LDPC encoded MIMO transmission. In this paper we use a quadrature amplitude modulation (QAM), over a Rayleigh fading channel with a maximum likelihood detection. Simulations results in term of bit error rate confirmed that NB-LDPC codes are particularly well suited to be jointly used with precoding schemes based on the maximization of the minimum Euclidean distance criterion.

Performance Evaluation and Simulation of M-Ary Quadrature Amplitude Modulation Schemes with VisSim/Comm Software

M-ary modulation schemes are considered one of widely used digital modulation in practice because of its high efficiency in power and bandwidth. Therefore, this necessity the need to study and evaluate the performance of M-ary schemes using simulation techniques. In this paper, the performance of M-ary modulations schemes M-ary quadrature amplitude modulation (QAM) is considered. Because of its efficiency in power and bandwidth, M-ary QAM (M-QAM) is one of the widely used modulation techniques in practice. Therefore, a need for studying and evaluating the performance of QAM modulation schemes is an important task for designers. In this paper, M-QAM modulation schemes for even number of bits per symbol (16, 62, and 256-QAM) and an odd number of bits per symbol (32- and 128-QAM), over Additive White Gaussian Noise channel, are studied. A VisSim/Comm simulation[1] model for M-QAM is designed. Theoretical and simulation results for bit error ratio (BER) performance of QAM modulation schemes are obtained using VisSim/Comm software. The results are evaluated and compared.

A Cost-Effective Adaptive Overlapped Cluster-Based MIMO Detector in a Frequency Domain Reconfigurable Modem

Not only to reduce the candidates but also to maintain detection performance in multiple-input multiple-output (MIMO) detection, an adaptive overlapped cluster (AOC) scheme to balance detection error and computing cost is built for $4\times 4$ and $8\times 8$ MIMO-OFDM systems with up to 256 quadrature amplitude modulation (QAM). The constellations are partitioned into several clusters. A cluster with size decided by channel status is chosen for signal decoding. Different partition schemes are combined to minimize the numbers of clusters required to cover a candidate symbol as the pre-estimated signal falls at cluster edges, namely overlapped clustering. The simulations of a $4\times 4$ MIMO OFDM with 64 QAM and $8\times 8$ MIMO OFDM with 256 QAM hint that the AOC-based detection requires an additional 0.57 dB and 1.02 dB compared to maximum likelihood (ML). Compared with K-best sphere decoding (SD), it is reduced the computing complexity to 24.50% ~ 56.25% in $4\times 4$ MIMO OFDM and, 35.00% ~ 56.25% in $8\times 8$ MIMO OFDM. In addition, the proposed scheme is ported to a reconfigurable frequency-domain (FD) modem, which is designed and implemented via TSMC 45-nm technology, with multi-rate clocking and processing elements (PEs) upgrading for supporting the proposed MIMIO detection. The results show that the throughput is 1077.8 Mbps with $4\times 4\,\,64$ -QAM modulations.