High-order Quadrature Amplitude Modulation Research Articles

Dual high-order QAM-modulated mm-wave signal transmission in the Q-band enabled by simple IM/DD architecture and bandpass delta-sigma modulation.

The intensity-modulation (IM)/direct-detection (DD) systems have been proven effective and low-cost due to their simple system architecture. However, the Mach-Zehnder modulator (MZM) of the IM/DD systems only reserves its driving signal intensity. Therefore, the IM/DD systems are generally unable to transmit vector signals and have a restricted spectrum efficiency and channel capacity. Similarly, the radio-over-fiber (RoF) transmission systems based on IM/DD are limited by their simple architecture and generally cannot transmit high-order quadrature amplitude modulation (QAM) signals, which hinders the improvement of their spectrum efficiency. To address the challenges, we propose a novel, to the best of our knowledge, scheme to simultaneously transmit the dual independent high-order QAM-modulated millimeter-wave (mm-wave) signals in the RoF system with a simple IM/DD architecture, enabled by precoding-based optical carrier suppression (OCS) modulation and bandpass delta-sigma modulation (BP-DSM). The dual independent signals can carry different information, which increases channel capacity and improves spectrum efficiency and system flexibility. Based on our proposed scheme, we experimentally demonstrate the dual 512-QAM mm-wave signal transmission in the Q-band (33-50 GHz) under three different scenarios: 1) dual single-carrier (SC) signal transmission, 2) dual orthogonal-frequency-division-multiplexing (OFDM) signal transmission, and 3) hybrid SC and OFDM signal transmission. We achieve high-fidelity transmission of dual 512-QAM vector signals over a 5 km single-mode fiber (SMF) and a 1-m single-input single-output (SISO) wireless link operating in the Q-band, with the bit error rates (BERs) of all three scenarios below the hard decision forward error correction (HD-FEC) threshold of 3.8 × 10-3. To the best of our knowledge, this is the first time dual high-order QAM-modulated mm-wave signal transmission has been achieved in a RoF system with a simple IM/DD architecture.

Analysis of phase noise for DFT-spread OFDM systems in coherent optical communication

Previous studies have revealed the similarity between phase noise in the symbol domain of discrete Fourier transform spread (DFT-Spread) coherent orthogonal frequency division multiplexing (CO-OFDM) systems and that in the time domain. This paper further details this characteristic through both formulas and simulation results, while also analyzing and summarizing its formation conditions and influencing factors. Based on this, a phase noise compensation (PNC) scheme based on DFT-Spread OFDM is proposed for high-order quadrature amplitude modulation (QAM) transmission with large fast Fourier transform (FFT) sizes. The proposed scheme effectively suppresses inter-carrier interference (ICI) introduced by phase noise in OFDM systems, as verified through simulations of dual-polarization (DP) 64-QAM CO-OFDM transmission over 80 km single-mode fiber (SMF). This work suggests that proposed PNC scheme enhance the tolerance for laser linewidth in OFDM systems, and may offer a possible solution for short distance high-baud-rate high-order QAM coherent transmission.

SC and OFDM hybrid coherent optical transmission scheme based on 1-bit bandpass delta-sigma modulation.

High-order quadrature amplitude modulation (QAM) can effectively improve the capacity and spectral efficiency of coherent optical transmission systems. However, as the modulation order increases, the signal becomes less tolerant to noise and nonlinear effects during transmission, and the implementation cost also increases. We propose a single carrier (SC) and orthogonal frequency division multiplexing (OFDM) hybrid coherent optical transmission scheme based on a 1-bit bandpass (BP) delta-sigma modulation (DSM). The driving I-channel and Q-channel signals for the optical in-phase/quadrature (I/Q) modulator carry SC-modulated and OFDM-modulated transmitter data, respectively. Optical quadrature-phase-shift-keying (QPSK) modulation is realized by the 1-bit DSM quantizer and I/Q modulator, which can effectively suppress quantization noise and reduce the complexity of digital signal processing (DSP) and the performance requirements of optoelectronic devices. In addition, the hybrid transmission of SC and OFDM can balance the advantages of both to meet the variable channel conditions and complex application scenarios. High-fidelity transmission of SC 512QAM and OFDM 512QAM hybrid signals, in the form of a 60 Gbaud optical QPSK signal, over 60 km single-mode fiber-28 (SMF-28) is verified by offline experiments, and the bit error rates (BERs) of both SC 512QAM and OFDM 512QAM are below the hard-decision forward-error correction (HD-FEC) threshold of 3.8e-3.

Hierarchical blind phase search for correcting imperfect phase rotation in QAM signals synthesized via optical coherent superposition.

Coherent superposition has been proposed to synthesize high-order quadrature amplitude modulation (QAM) by coherently superposing low-order QAMs in the optical domain. These approaches could effectively relax the digital-to-analog converter resolution and reduce the complexity of the driving electronics. However, in the superposition process, imperfect phase rotations (IPRs) in low-order QAMs will be transferred to the resultant high-order QAM. Importantly, the induced IPR cannot be compensated for by conventional linear equalizers and carrier recovery methods. To combat the induced IPR, herein, we propose a hierarchical blind phase search (HBPS) algorithm to compensate for the IPRs in synthesized high-order QAMs. The proposed HBPS can match the generation mechanism of the IPRs in coherent superposition, by tracing back and estimating the IPR in the QPSK-like constellation of each hierarchy and finally correcting the induced IPRs. Simulation and experimental results verify that this algorithm could effectively compensate for the IPR in the resultant 16-QAMs synthesized using coherent superposition approaches. The proposed HBPS shows significant optical signal-to-noise ratio (OSNR) gains compared to the conventional blind phase search (BPS) method for high-order QAMs coherently superposed using optical signal processing (OSP) and tandem modulators (TMs). Specifically, at the BER of 2.4e-2, the HBPS achieves a 1.5-dB OSNR sensitivity enhancement over the BPS in either OSP or TMs-based schemes, even with an imperfection rotation of up to 20∘.

Battery configuration dependence to power line communication using high-order quadrature amplitude modulation

Power line communication (PLC) within future smart batteries facilitates the communication of high fidelity sensor data between smart cells and external systems, with application areas including intelligent vehicles and smart grids. This interconnected PLC system of smart cells will enhance cell utilisation and safety through cell-to-cell coordination at a system level, leveraging the existing bus bar within the battery and eliminating the need for additional wire harnesses. This paper studies the performance of a PLC system operating at carrier frequencies of 10MHz to 6GHz within four distinct configurations of lithium-ion batteries. This assessment focuses on changes in scattering parameters and data transmission error ratios. Furthermore, quadrature amplitude modulation (QAM) orders of up to 1024 are investigated for their viability within such environments. The results indicate that the addition of cells in parallel increases error ratios with high-order QAM, and that this effect varies substantially with carrier frequency. Using QAM increases data throughput, allowing for data transfers within large-scale battery systems without PLC bus bandwidth saturation. A prospective centre frequency of 3650MHz allows for a wide bandwidth of 300MHz and 1024-QAM with little signal attenuation and data error. At this frequency, the need for signal repeaters and higher signal output power is reduced. These results are used to determine the most suitable arrangement of cells within a smart battery with consideration of the PLC performance. The preliminary performance of a large-scale battery system with PLC in-situ could be derived from the findings in this research based upon the four battery configurations tested.

23.1-Gb/s 135-GHz Wireless Transmission Over 4.6-Km and Effect of Rain Attenuation

In this article, we have experimentally demonstrated a fiber-wireless-integration <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$</tex-math> </inline-formula> -band (110–170 GHz) transmission system. To extend the wireless transmission distance while maintaining the wireless bit rate as high as possible, we designed high-gain lens horn antenna modules consisting of a pair of dielectric plano-convex lenses and horn antennas for long-haul wireless links. In addition, we employ the Volterra nonlinear equalization (VNE) algorithm based on the multiple-input–multiple-output (MIMO) structure to precisely compensate for the in-phase/quadrature (I/Q) imbalance and nonlinear impairment of quadrature amplitude modulation (QAM) signals mainly caused by photoelectric (O-E) conversion and electric-photo (E-O) conversion. Meanwhile, one of the methods adopted in our experiment to decrease the influence of nonlinearity on high-order QAM signals is coupling the high-order modulation format with the probabilistic shaping (PS) technology. As a result of outdoor field experimental verification, the demonstration at 135 GHz carrier with a net rate of 23.1 Gb/s over 10 km optic-fiber and 4.6 km wireless transmission distance has been successfully carried out. It is, as we know, the first time that a record-breaking product of net bit rate and wireless transmission distance, i.e., 23.1 Gb/s <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 4.6 km <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$=$</tex-math> </inline-formula> 106.3 Gb/s <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot$</tex-math> </inline-formula> km, has been accomplished based on a fiber-wireless-integration system. Also, for the first time, we have measured the effect of rain attenuation for the 135 GHz millimeter-wave (mm-wave) wireless link and established more accurate rainfall models for the Shanghai region of China by comparing them with multiple rainfall models. This work can be used as a complement to the International Telecommunication Union-Radiocommunication sector (ITU-R) recommendations.

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.

PDM-OFDM 1-bit DSM 1024QAM/4096QAM signals at W-band transmission over 4.6-km wireless distance.

In this Letter, we propose the application of delta-sigma modulation (DSM) higher-order quadrature amplitude modulation (QAM) technology in long-distance transmission of W-band wireless communication, and demonstrate, for the first time to the best of our knowledge, the wireless transmission of millimeter wave signals in the W-band based on 1-bit DSM quantization using polarization-division-multiplexed orthogonal frequency division multiplexing (PDM-OFDM) 1024QAM/4096QAM for 4.6 km. We successfully achieved a bit error rate (BER) of 40-Gbit/s PDM-OFDM 1024QAM and 48-Gbit/s PDM-OFDM 4096QAM after 4.6-km wireless transmission, both lower than the soft decision forward error correction (SD-FEC) of 4.2 × 10-2. To the best of our knowledge, this is the first time that up to 4096QAM signals have been quantized and transmitted based on 1-bit DSM in a 4.6-km-long distance W-band millimeter wave system.

On the performance of energy harvesting‐assisted Nth best relay cooperative networks in Nakagami‐m fading

SummaryWe study the energy harvesting (EH)‐assisted system model based on the performance of a dual‐hop cooperative communication system that is subjected to Nakagami‐ fading. Through the partial relay selection method, the selection of th best relay (BR) is performed among amplify and forward (AF) relays, which can harvest energy from radio frequency signals. At the receiver, the selection combining scheme is considered to select between the signals of th best relaying path and the direct path. For this considered system, we compute the closed‐form expressions of outage probability (OP) and the average symbol error rate (ASER) for higher order quadrature amplitude modulation (QAM) techniques, especially for rectangular QAM, cross QAM, and hexagonal QAM. Further, a new moment‐generating function expression is obtained which is used to derive the ASER expression related to the generalized non‐coherent modulation technique. We also give the asymptotic expression of OP to find out the diversity order. Furthermore, we study the effect of fading parameters, th BR, and other factors on system behavior. Finally, we verify the derived expressions with Monte Carlo simulations.

4096-QAM OFDM THz-Over-Fiber MIMO Transmission Using Delta-Sigma Modulation

A terahertz (THz)-over-fiber multiple-input multiple-output (MIMO) transmission of 4096-ary quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) supported by 46-GBaud quadrature phase shift keying (QPSK) signal at 320 GHz is experimentally demonstrated in this letter. By employing the polarization division multiplexing (PDM) technique and 1-bit delta-sigma modulation (DSM) quantization, we successfully implement 4.6-GHz 4096-QAM OFDM signal transmission over 20 km of standard single-mode fiber (SSMF) and a 3-m MIMO wireless link, and satisfy the soft-decision forward error correction (SD-FEC) threshold of 1.0 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> with 15% overhead, which corresponds to a net rate of 84.4 Gbps for THz-over-fiber transmission. To the best of our knowledge, fusing OFDM and PDM, this is the highest rate achievable for DSM applications in THz communication. This experimental demonstration can provide a promising solution for high-order QAM signals in a fiber-wireless seamless network in future 6G networks.

W-band RoF polarization multiplexing system supports 1048576 QAM with delta-sigma modulation.

We propose and experimentally verify a photonics-aided W-band millimeter wave (MMW) radio-over-fiber (RoF) polarization-multiplexed envelope detection system for high-order quadrature amplitude modulation (QAM) signals. To solve the problem of low spectral efficiency of common public radio interface (CPRI) and severe distortion of high-order QAM of envelope detection, quantization noise suppressed delta-sigma modulation (DSM) is introduced into the system. The experimental results show that the system can transmit 131072 QAM signals when meeting the error vector magnitude (EVM) requirements of 5G new radio (NR), and transmit 1048576 QAM signals when meeting the soft decision threshold (SD@20%).

A Full-Duplex Decode-and-Forward Relaying Approach Based on QAM Constellation Suitable for Small-Size Devices

The explosive growth of the Internet of Things (IoT) is putting higher requirements for the performance of co-time co-frequency full-duplex relaying (CCFD-R) due to small-size devices appearing in abundance. In this paper, we present a novel CCFD-R approach with very low complexity to deal with the issue above. Based on the orthogonality of its two components, a distributed usage mode of quadrature amplitude modulation (QAM) constellation is proposed to perform self-interference cancellation (SIC) without the complicated processing modules, as used widely in traditional full-duplex techniques. Instead of the conventional practice of assigning the entire QAM constellation to only one communication node, our scheme (termed as QAM-R) splits the constellation into two parts and further assigns them to different communication nodes, respectively. With the principle above, the mapping pattern and the frame format are carefully designed. Then, the corresponding signal model is established and the approximation of end-to-end bit error probability (BEP) is derived. Finally, numerical simulations validate the theoretical analysis and show that QAM-R can balance spectrum effectiveness and transmission reliability very well and, especially, performs even better in the low range of signal noise ratio (SNR) when adopting higher-order QAM constellations.

Impact and compensation of carrier synchronization errors in OFDM signals with very large QAM constellations

AbstractLow cost video sensors used for streaming video signals to help firefighters, require high bit rate due to uncompressed images. To increase spectral efficiency given a limited bandwidth, very high order constellations in high signal to noise ratio regimes can be used. However, noise is not the only factor effecting the high order constellations. These constellations are also sensitive to hardware impairments and system non‐linearities. Therefore, in this paper, the effect of carrier frequency offset (CFO) on the performance of an orthogonal frequency division multiplexing (OFDM) system with high order quadrature amplitude modulation (QAM) is studied. A closed form expression is derived for the maximum normalized residual CFO that an OFDM system with M‐QAM constellation can resist to have an error free symbol detection. Finally, the suitability of common previous CFO estimation techniques such as the cyclic prefix based technique and the Moose technique in these systems are investigate. The results show that the maximum residual CFO that an OFDM system with M‐QAM constellation can resist is proportional to the inverse of . The results also show that very large order QAM constellations such as 4096‐QAM are very sensitive to even small residual CFO values and their performance degrades, significantly. However, the bit error rate analysis indicate that the Moose CFO estimation technique can be used in these systems to compensate the CFO effect, accurately.

Over 23.43 Gbps visible light communication system based on 9 V integrated RGBP LED modules

In this paper, integrated transmitter modules with 9 V high-voltage light emitting diode (LED) chips and built-in hardware pre-equalization circuits are designed and fabricated for wavelength division multiplexing (WDM) visible light communication (VLC) system. The measured −3 dB electrical modulation bandwidths are 764.6 MHz, 929 MHz, 921.5 MHz and 756.6 MHz for the purple, blue, green and red channels, respectively, resulting in an aggregate bandwidth of about 3.37 GHz. Based on polar coding scheme combined with high-order quadrature amplitude modulation and orthogonal frequency division multiplexing (QAM-OFDM), experimentally, the maximum aggregate data rate for the offline VLC system exceeds 23.43 Gb/s in 1 m indoor free-space link and the bit error rates (BERs) of all wavelength channels are under 7% pre-forward error correction (pre-FEC) limit of 3.8×10−3. In particular, the blue-ray channel always presents zero BER, i.e. an infinity Q-factor, within the experiment condition range.

An Artificial Intelligence-Assisted Expectation Propagation Detection for MIMO Systems

Multiple-input multiple-output (MIMO) technology is one of the key technical approaches to improve the spectrum efficiency of wireless communication. Modern communication systems employ MIMO and high-order quadrature amplitude modulation (QAM) to maximize spectral efficiency. However, with the increase in the number of antennas and modulation orders, it is very challenging to design a low-complexity and high-efficiency MIMO receiver. In recent years, with the rapid development of new technologies such as artificial intelligence, more and more researchers have tried to apply machine learning techniques in the field of communication to break through the performance of traditional communication algorithms. In this paper, we propose a new low-complexity MIMO detection algorithm: an artificial intelligence-assisted expectation propagation (EP) detection algorithm. Neural network models are used to learn and map some of the time-consuming steps in the EP detection algorithm, converting the complex operation process into a few matrix multiplication operations in order to reduce the complexity of the detection algorithm. It is verified that the method proposed in this paper can approximate the performance of the original EP detection algorithm with reduced complexity and is applicable in different scenarios.

W-band radio-over-fiber transmission system with delta-sigma modulation and direct detection

We experimentally built a W-band photonics-aided millimeter-wave radio-over-fiber transmission system and demonstrated the delivery of up to 8192-ary quadrature amplitude modulation (QAM) signal. Discrete multitone signals are converted into 1-bit data streams through delta-sigma modulation and then modulated onto a 76.2 GHz carrier. An envelope detector is used at the receiver side for direct detection. The results prove that our proposed system can support 2048QAM and 8192QAM transmission while meeting the hard decision forward error correction threshold of 3.8×10-3 and the soft decision forward error correction threshold of 4.2×10-2, respectively. We believe this cost-effective scheme is a promising candidate for future high-order QAM millimeter-wave downlink transmission.

Low-complexity soft-output signal detector based on AI-SSOR preconditioned conjugate gradient method over massive MIMO correlated channel

Massive multiple-input multiple-output (MIMO) techniques with a large number of antenna elements at base station (BS) have been proved as an alternative to provide potential opportunity to increase the spectrum and energy efficiency. However, in the system, there generally exists a spatial correlation effect due to insufficient antenna elements spacing and/or the lack of rich scattering at BS. The minimum mean square error (MMSE) method performs signal detection at the expense of large-scale matrix inversion operation. Thus, the conjugate gradient (CG) method has received a lot of attentions to realize the MMSE detection efficiently. Unfortunately, this efficiency can be compromised due to the ill-conditioned equalization matrix of MMSE method over the correlated channel environments. Moreover, the hard output signal detection exhibits a sharply degradation in performance for higher-order quadrature amplitude modulation (QAM). Therefore, the modern communication systems use the soft-output information, i.e., log-likelihood ratio (LLR) along with the forward error-correcting code (FEC) to achieve satisfactory performance. The LLR computation along with a higher-order QAM remains challenging due to the exhaustive search of symbol in the modulation constellation. In this paper, a low-complexity soft-output signal detector based on approximate inverse symmetric successive over-relaxation preconditioned conjugate gradient (AI-SSOR-CG-SOD) method is proposed to realize MMSE method detection for uplink multiuser massive MIMO correlated channel. In the proposed method, a new preconditioner, an AI-SSOR, which is based on the Neumann series approximation of the inverse of the conventional SSOR preconditioner is firstly developed to handle ill-conditioned matrix, and then incorporated with CG method to improve the convergence rate and performance. According to the characteristic of the Gray-coding that adjacent symbols in the constellation set have only one different bit, the constellation set is divided multiple times based on the bits of the inphase and the quadrature components of the symbol, which reduces the complexity of the LLR computation of the transmitted bits by avoiding the exhaustive search process. Simulation results show that the AI-SSOR preconditioner is robust against spatial correlation effect, and the proposed detector converges at 3 iterations. Simulation results also show that the proposed detector achieves a better trade-off between the complexity and the performance compared to other existing detectors.

Demonstration of Intelligent Hybrid FSO/RF System Based on Enhanced GRU Prediction and Real-World Meteorological Dataset

Hybrid free space optical (FSO)/radio frequency (RF) system has emerged as a high-data-rate solution for the last mile access network. In this paper, we establish a hybrid FSO/RF testbed including an intensity modulation/direct detection (IM/DD) FSO subsystem with space diversity and a high-order quadrature amplitude modulation (QAM) RF subsystem with polarization diversity, respectively. Based on the testbed, we propose and experimentally validate an intelligent transmission system where the link selection and switching technology is implemented. In particular, we propose a gated recurrent unit (GRU) neural network enhanced by time attention mechanism for the hybrid system. The experimental results demonstrate that the proposed system can achieve the prediction of FSO channel fading with a high precision where absolute percentage error (APE) values lower than 3% account for up to 90% of the prediction results. The implemented intelligent hybrid system can significantly reduce the link switching frequency and link interruption duration. Then the BER is further verified on the testbed, and results show that the intelligent hybrid system can improve the BER from the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> to the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> during the time periods when link switching occurs.

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.

Efficient QAM Signal Detector for Massive MIMO Systems via PS/DPS-ADMM Approaches

In this paper, we design two efficient quadrature amplitude modulation (QAM) signal detectors for massive multiple-input multiple-output (MIMO) communication systems via the penalty-sharing alternating direction method of multipliers (PS-ADMM). The content of the paper is summarized as follows: first, we transform the maximum-likelihood detection model to a non-convex sharing optimization problem for massive MIMO-QAM systems, where a high-order QAM constellation is decomposed to a sum of multiple binary variables, integer constraints are relaxed to box constraints, and quadratic penalty functions are added to the objective function to result in a favorable integer solution; second, a customized ADMM algorithm, called PS-ADMM, is presented to solve the formulated non-convex optimization problem. In the implementation, all variables in each vector can be solved analytically and in parallel; and third, in order to solve the penalty-sharing distributively, we improve the proposed PS-ADMM algorithm to a distributed one, named DPS-ADMM. In the end, performance analyses of the proposed two algorithms, including convergence properties and computational cost, are provided. Simulation results demonstrate the effectiveness of the proposed approaches.