QAM Modulation Research Articles

Super-Regenerative Receiver Wake-Up Radio Solution for 5G New Radio Communications

Wake-up radio is a promising solution to reduce the energy wasted by mobile devices during an idle state. In this paper, we propose a new wake-up radio solution for 5G mobile devices based on a super-regenerative receiver characterized by its low cost and low power consumption and investigate how to build on the orthogonal frequency-division multiplexing (OFDM) modulation capability at the base station to generate optimal wake-up signals. After presenting the relevant features and limitations of super-regenerative receivers operating in different 5G New Radio (NR) frequency bands, we evaluate how the numerology, the number of resource blocks, and the quadrature amplitude modulation (QAM) scheme used affect the sensitivity of the super-regenerative wake-up receiver. The results show that a 256-QAM modulation scheme, together with the highest numerology values, achieves optimal receiver sensitivity with a minimal number of resource blocks, yielding higher duty cycle pulses that also facilitate symbol synchronization tasks.

Performance analysis of OFDM with variations in cyclic prefix and FFT lengths

Orthogonal Frequency Division Multiplexing (OFDM) is a modern and suitable modulation strategy for commercial high-speed broadband wireless communication systems. This is because wireless services and demands have grown so quickly in recent years. While creating wireless communication, the channel environment is crucial. A square grid with identical vertical and horizontal spacing is used for the constellation points in quadrature amplitude modulation (QAM). More bits can be transferred per symbol to higher-order modulation forms. This research has looked at how Orthogonal Frequency Division Multiplexing OFDM systems perform using different modulation techniques on channels with additive white Gaussian noise (AWGN). Using MATLAB software to do an experiment with different modulation methods and parameters such as FFT length and cyclic prefix findings showed that 64-QAM modulation sends the same amount of data faster and with fewer symbols than QPSK 16-QAM. Here, the 64-QAM modulation technique performs better. An extensive literature survey has been carried out. The work done here involved working on many parameters to improve the performance of OFDM, i.e., by reducing BER, changing modulation techniques, and analyzing the trade-off between cyclic prefix length and Bit Error Rate. Compared to the existing work, the proposed system provides better performance.

EMG signal transmission system under RF schemes

With the rise in pathological conditions during the post-pandemic era, particularly concerning the management of biomedical signals, a significant surge has been observed. This research endeavors to develop a self-adaptive algorithm for the discretization and data encapsulation of electromyographic (EMG) signals. The synthetic signal used for analysis is acquired from the PhysioNet database, specifically focusing on the implementation of the tibialis anterior muscle. A transmission chain is established utilizing the AD9361 transceiver, while a power amplifier is employed for base radio applications, operating at a carrier frequency of 2.45 GHz. The spectral validation of this system reveals that the 16-QAM modulation, which is subjected to testing, yields an accuracy of -15.5 dB NMSE. As a further work, an EMG signal acquisition stage is proposed, based on a high-resolution analog-to-digital converter (ADC) card, alongside the exploration of higher order n-QAM schemes to enhance accuracy in the receiver stage.

QAM Modulation Based on Lowest Energy Consumption in Passive CRFID

QAM Modulation Based on Lowest Energy Consumption in Passive CRFID

All-Optical Modulation Format Conversions from PAM4 to QPSK and 16QAM Using Silicon-Rich Nitride Waveguides

Quadrature phase-shift keying (QPSK) and 16-quadrature amplitude modulation (16QAM) formats are deployed in inter-data center networks where high transmission capacity and spectral efficiency are required. However, in intra-data center networks, a four-level pulse amplitude modulation (PAM4) format is deployed to satisfy the requirements for a simple and low-cost transceiver configuration. For the seamless and effective connection of such heterogeneous networks without an optical-electrical-optical conversion, an all-optical modulation format conversion technique is required. In this paper, we propose all-optical PAM4 to QPSK and 16QAM modulation format conversions using silicon-rich nitride waveguides. The successful conversions from 50-Gbps-class PAM4 signals to 50-Gbps-class QPSK and 100-Gbps-class 16QAM signals are demonstrated via numerical simulations.

Joint Beam-and-Probabilistic Shaping Scheme Based on Orbital Angular Momentum Mode for Indoor Optical Wireless Communications

In this paper, we propose a novel beam-and-probabilistic shaping technique based on orbital angular momentum (OAM) modes for indoor optical wireless communications (OWC) to improve the system effective coverage. Our results show that both Huffman coding (HC) and sign inversion coding (SIC) based probabilistic shaping schemes can improve the effective coverage for 16QAM modulation format while only SIC based probabilistic shaping can improve the effective coverage for 64QAM modulation under different beam shaping schemes with different power ratios of different modes. Furthermore, it can be seen that more significant performance improvement can be obtained by employing both of the probabilistic shaping schemes by decreasing the power ratio of the fundamental mode to the higher-order OAM mode. Therefore, further increment of the effective coverage can be predicted with the probabilistic shaping schemes by decreasing the power ratio.

Pushing Capacity Limits With Multi-Segment SiP Modulators

The use of multiple segments on a silicon photonic modulator can increase bandwidth at the cost of greater complexity in the driving signals. We propose and demonstrate a simple driving scheme for use with dual segment modulators that involves very little additional complexity when equal length segments are used. The increased bandwidth with segmentation scales linearly with the number of segments, but the net bit rate does not; net rate depends on many factors. With an IQ modulator with two 2 mm segments, we demonstrate an improvement of 14% in net bit rate as compared to a single 4 mm segment. We examine the trade-offs in moving to three-segment modulation. We explore implementation penalties and use probabilistic shaping and optical pre-emphasis to achieve a net rate of 1.07 Tb/s with dual polarization transmission over 80 km of fiber at 116 Gbaud using 64QAM modulation.

Perturbation-Aided Fiber Nonlinearity Compensation in Subcarrier-Multiplexing Systems

A perturbation-aided advanced digital backpropagation (P-ADBP) is proposed for subcarrier-multiplexing (SCM) coherent systems. To improve the nonlinearity compensation (NLC) performance, for the first time, the first-order perturbation analysis is introduced into the conventional ADBP. Based on the fact that the perturbation-based self-subcarrier nonlinearity (PSSN) has a similar form as the cross-subcarrier nonlinearity (CSN), we approximate that PSSN and CSN can be calculated in parallel and the compensation of them can be fused together. This compensation fusion scheme saves the computational complexity effectively by sacrificing only a little performance. Furthermore, to realize the best performance, gradient descent is used to jointly optimize the perturbation coefficients and other necessary parameters in P-ADBP. Verified by 9 × 120-GBaud 1600-km wavelength-division multiplexing SCM systems with dual-polarization 16QAM modulation format, 1-Step P-ADBP provides identical Q <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula> improvement as 5-Step ADBP but saves about 72.3% complexity. 5-Step P-ADBP and 10-Step P-ADBP also leapfrog into the NLC level of 10-Step ADBP and 20-Step ADBP, but save about 44.4% and 46.0% complexity, respectively. The proposed algorithm helps achieve an improved performance-complexity trade-off compared to the conventional ADBP and its state-of-the-art modifications.

Hybrid Radio over Fiber with Radio over Free Space Optic for 5G Fronthaul Network Implementation in Urban Areas

Optical fiber can meet the demand for fronthaul on 5G networks that offer high bandwidth, large capacity, high data rate and is free from electromagnetic interference. However, deploying infrastructure faces issues like permits and high costs. Hybrid Radio over Fiber (RoF) technology with Radio over Free Space Optic (RoFSO) can be a solution in urban areas, where the installation requires high costs. This research investigates a hybrid RoF-RoFSO scheme at a frequency of mmWave 26 GHz by considering atmospheric attenuation values arising from meteorological effects, such as rain, smog, and dust, using Optisystem. This research considers QPSK, 16-QAM, and 64-QAM modulation schemes, distance variations on the FSO and the meteorological data from the Indonesian Meteorology, Climatology and Geophysics Agency (BMKG) from March 2022 to May 2022. The results show that attenuation due to high rainfall is the main cause of signal quality degradation and limits the transmission distance on the FSO link. The maximum distance is 600 m using the QPSK and 16-QAM modulation schemes, while for the 64-QAM modulation scheme, the maximum transmission distance is 500 m. Meanwhile, damping values caused by foggy and dusty conditions can reach distances of up to 1000 m for the three modulation schemes.

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.

Low-complexity algorithms for coherent optical systems with transceiver IQ imbalance.

The next-generation coherent optical communication relies on higher symbol transmission rates with higher modulation cardinality. The imbalance between the in-phase (I) and the quadrature (Q) arms in such systems leads to deteriorated performance if not corrected. In this work, we propose a reference constellation adaptation-based single-tap, novel carrier phase recovery algorithm, tolerant to the transmitter IQ imbalance and a pilot-free geometric parameter extraction-based receiver IQ imbalance correction method for MQAM signals. The proposed scheme is numerically investigated through extensive simulations for 32 GBaud polarization multiplexed (PM)-16QAM, and 64QAM modulation formats and experimentally verified for 32 GBaud PM-16QAM signal. The proposed pilot-free scheme is applicable to any modulation format and offers lower computational complexity than traditional algorithms.

Optical Transport Architecture for the Fronthaul Segment in a 5G NR Network based on Polarization and Wavelength Multiplexing

This paper presents the design of an optical transport architecture for the fronthaul segment in a 5G New Radio (NR) network based on both polarization and wavelength multiplexing using Polarization Splitters (PS) and an Arrayed Waveguide Grating (AWG), respectively. The proposed architecture is assessed by the transport of Orthogonal Frequency Division Multiplexing (OFDM) services, which allows the definition of different numerologies and service profiles; those are key aspects in the framework of 5G RN. The proposed design shows a flexible and scalable management of numerologies per polarized light component, featuring a suitable response in terms of Bit Error Rate (BER) and Error Vector Magnitude (EVM) measurements for 15 kHz, 30 kHz, and 60kHz subcarrier spacing of an OFDM based on 4QAM modulation format.

Encryption in phase space for classical coherent optical communications

Optical layer attacks on optical fiber communication networks are one of the weakest reinforced areas of the network, allowing attackers to overcome security software or firewalls when proper safeguards are not put into place. Encrypting data using a random phase mask is a simple yet effective way to bolster the data security at the physical layer. Since the interactions of the random phases used for such encryption heavily depend on system properties like data rate, modulation format, distance, degree of phase randomness, laser properties, etc., it is important to determine the optimum operating conditions for different scenarios. In this work, assuming that the transmitter and the receiver have a secret pre-shared key, we present a theoretical study of security in such a system through mutual information analysis. Next, we determine operating conditions which ensure security for 4-PSK, 16-PSK, and 128-QAM formats through numerical simulation. Moreover, we provide an experimental demonstration of the system using 16-QAM modulation. We then use numerical simulation to verify the efficacy of the encryption and study two preventative measures for different modulation formats which will prevent an eavesdropper from obtaining any data. The results demonstrate that the system is secure against a tapping attack if an attacker has no information of the phase modulator and pre-shared key.

Multi-task neural network for solving the problem of recognizing the type of QAM and PSK modulation under parametric a priori uncertainty

Objectives. Automatic modulation recognition of unknown signals is an important task for various fields oftechnology such as radio control, radio monitoring, and identification of interference and sources of radio emission. The paper aims to develop a method for recognizing the types of signal modulation under conditions of parametric a priori uncertainty, including the uncertainty of carrier frequency- and initial signal phase values. An additional task consists in estimating the offset values of the carrier frequency or signal phase at the initial stage of the recognition process.Methods. A multi-task learning with artificial neural network and the theory of cumulants of random variables are used.Results. For signals with a carrier frequency and initial phase shift, cumulant approaches for QAM-8, APSK-16, QAM-64, and PSK-8 modulations are calculated. A multi-task learning with artificial neural network using cumulant features and a data standardization algorithm is presented. The results of the experiment show that using multi-task learning with an artificial neural network provides high accuracy of recognizing QAM-8 and APSK-16, QAM-64 and PSK-8 modulations with small mismatches of the carrier frequency or initial phase. The accuracy of determining the offset values from the carrier frequency or the initial phase for QAM-8, APSK-16, QAM-64, and PSK-8 modulation is high.Conclusions. The multi-task learning with neural network using high-order signal cumulants makes it possible not only to recognize modulation types with high accuracy under conditions of a priori uncertainty of signal parameters, but also to determine the offset values of carrier frequency or initial signal phase from expected values.

Analysis of throughput and error rate of 16-QAM, 64-QAM, and 256-QAM O-NOMA waveforms

Abstract This study presents a comprehensive analysis of the throughput performance, spectrum efficiency, and block error rate (BLER) of optical non-orthogonal multiple access (O-NOMA) waveforms using 16-quadrature amplitude modulation (QAM), 64-QAM, and 256-QAM modulation schemes. The aim is to assess the trade-offs between data rate, spectral efficiency, and error performance in O-NOMA systems. The analysis reveals that higher-order modulations, such as 64-QAM and 256-QAM, offer higher data rates and improved spectrum efficiency compared to 16-QAM. Furthermore, the study investigates the spectrum performance of the O-NOMA waveforms. The results indicate that higher-order modulations may utilise the spectrum more efficiently, maximising the data throughput within the available bandwidth. Moreover, the BLER analysis provides insights into the error performance of the O-NOMA waveforms. It quantifies the probability of errors occurring in a block of transmitted data and evaluates the system’s reliability. The analysis reveals that 256-QAM O-NOMA achieves lower BLER and high throughput in uplink and downlink as compared with the 16 and 64-QAM O-NOMA frameworks.

Performance Evaluation and Comparison Between LDPC and Turbo Coded MC-CDMA

This work presents a comparison between the Convolutional Encoding CE, Parallel Turbo code and Low density Parity Check (LDPC) coding schemes with a MultiUser Single Output MUSO Multi-Carrier Code Division Multiple Access (MC-CDMA) system over multipath fading channels. The decoding technique used in the simulation was iterative decoding since it gives maximum efficiency at higher iterations. Modulation schemes used is Quadrature Amplitude Modulation QAM. An 8 pilot carrier wereused to compensate channel effect with Least Square Estimation method. The channel model used is Long Term Evolution (LTE) channel with Technical Specification TS 25.101v2.10 and 5 MHz bandwidth bandwidth including the channels of indoor to outdoor/ pedestrian channel and Vehicular channel. The results showed that the performance of the proposed system was better when the LDPC was used as a coding technique

Performance of PAPR for Different Modulation Technique Using Cluster Scrambling Codeword Shifting Technique in F-OFDM Systems

Filtered-OFDM (F-OFDM) is one of the proposed 5G system candidates. In order to achieve service diversification, it must be able to support a large number of asynchronous subband transmissions. However, the transmitted signal in a multi-carrier transmission system with different subcarriers has a high peak-to-average power ratio (PAPR). Therefore, the main problem of F-OFDM systems is the high PAPR in the system, which leads to poor performance and excessive power consumption due to numerous distortions. This study introduces a technique based on codeword structure manipulation known as Cluster Scrambling Codeword (CSC) to achieve better reduction of PAPR with the evaluation of the performance of QAM and APSK modulation. This is a new formulation of the bit data sequence shifting approach that can reduce PAPR more effectively than the conventional scheme. Simulation results show that CSC with 256 QAM modulation scheme provides a PAPR reduction better than the conventional F-OFDM system.

Design electrical model noise and perform nonlinearities of SiGe bipolar phototransistor

This study uses a new model developed in this paper to investigate the performance of a heterojunction phototransistor (HPT) on SiGe technology. An electrical model of an optical window phototransistor was developed based on the Ebers &amp; Moll model, and its performance was evaluated by examining the error vector magnitude (EVM) when integrated into a mobile communication setup. Simulations showed that the HPT exhibited an EVM lower than 8%, enabling 64-Quadrature Amplitude Modulation (64-QAM) modulation for the mobile network. The third-order intercept point (IP3) measured 22 dBm, making the HPT suitable for Radio over Fiber (RoF) links in the detection block. The noise model of the HPT was also studied, resulting in a favorable power spectral density (PSD) that facilitates accurate modeling and prediction of the noise behavior of HPTs across various applications. This study provides valuable insights into the performance of HPTs on SiGe technology, enabling the development of more precise and efficient models for future research and practical applications. The results carry significant implications for the use of HPTs in optical communication systems.

Flexible mm-Wave Sigma-Delta-Over-Fiber MIMO Link

Millimeter-wave and multiple-input-multiple-output (MIMO) technologies combine broad bandwidth with spatial diversity to offer a greater data rate. This paper investigates a flexible millimeter-wave sigma-delta-over-fiber based transmitter solution with digital beamforming MISO and MIMO functionality. Those functions are controlled by a central unit connecting a remote radio head with a standardized QSFP28 fiber link. The central unit generates binary encoded intermediate frequency signals using bandpass sigma-delta modulation. The QSFP28 based fiber link transmits the intermediate frequency bitstreams to the remote radio head. The remote radio head consists of a QSFP28 module, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$90^{\circ }$</tex-math></inline-formula> hybrids, and upconverters. The remote radio head feeds four parallel, independent, coherent, and central-unit controlled 28 GHz signals to a linear array transmitting antenna. The transmitter performance is experimentally verified, demonstrating up to 800 Msym/s at an EVM/NMSE of 6.7%/-23.5 dB when tested with a 64 quadrature amplitude modulation (64-QAM) modulation scheme. Digital over-the-air beamforming MISO functionality is demonstrated up to 700 Msym/s across 1 m wireless distance. MIMO communication capabilities is demonstrated by over-the-air transmission of two independent 500 Msym/s to two spatially separated receivers. The results show that the proposed link can be used for realization of scalable, low-cost and flexible transmitter solution for emerging distributed antenna systems.

Wideband 120-GHz CMOS I/Q Transmitter With Suppressed IMRR and LOFT for Wireless Short-Range High-Speed 6G IoT Applications

In this study, a wideband 120-GHz I/Q transmitter with suppressed image rejection ratio (IMRR) and LO feedthrough (LOFT) is presented using 40-nm complementary metal oxide semiconductor technology. For the up-conversion mixer, an NMOS/PMOS pair with resistive feedback is used during the transconductance stage to increase the input bandwidth with gain boosting, and a novel switching core without LO-RF coupling is used to suppress the LOFT effect. For the quadrature injection locked tripler, an I/Q calibration circuit is inserted to minimize the I/Q mismatch; accordingly, the measured IMRR is greatly improved. The peak conversion gain of the proposed transmitter was 10.8 dB, and the 3-dB gain bandwidth was 20 GHz. The measured IMD2 and IMD3 were above 40 dBc. Moreover, the IMRR was measured as 43.1 dBc, applying I/Q calibration. The measured LOFT was 33.7 dBc. The data rate of the proposed transmitter was measured up to 20 Gbps and at a distance of 5 cm. Subsequently, the error vector magnitudes were 13.4 dB for QPSK and -19.1 dB for 16-QAM modulation. It is expected that such wireless high-speed communication can be applied to wireless short range high-speed 6G IoT applications.