Quadrature Spatial Modulation System Research Articles

Deep learning based signal detection for quadrature spatial modulation system

Deep learning based signal detection for quadrature spatial modulation system

Performance analysis of signed quadrature spatial modulation system over Nakagami-m fading channels with spatial correlation

Novel performance analysis of the recently proposed signed quadrature spatial modulation (SQSM) multiple-input–multiple-output (MIMO) system is presented in this paper. This study covers the effects of Nakagami-m fading channels for different m values and the impact of spatial correlation impairment. The pairwise error probabilities (PEP) of SQSM over Nakagami-m fading channel with and without spatial correlation effects are computed. Moreover, a tight upper bound of average bit error ratio (ABEP) is derived. Monte Carlo simulation results for a wide range of signal to noise ratios (SNR) are introduced to corroborate the accuracy of the theoretical analyses. The performance of SQSM is compared with the quadrature spatial modulation (QSM) system.

Extended Signed Quadrature Spatial Modulation System With Multi-User Support

Signed quadrature spatial modulation (SQSM) was recently introduced to enhance the throughput of spatial modulation (SM) in multiple-input multiple-output (MIMO) systems. This strategy involves independently transmitting the real and imaginary components of a symbol and its inverse from four independent antennas. In this paper, an extended SQSM (ESQSM) system is proposed. It combines <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> SQSM constellations and transmits them from the same transmit-antenna set with the aim of realizing a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -fold improvement in the spectral efficiency (SE). The proposed ESQSM employs the average power of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> SQSM constellations as an additional dimension for transmission. Performance of the proposed ESQSM surpasses that of other state-of-art SM systems such as the QSM, DSM, IQSM SQSM, and EQSM by 13 dB, 11 dB, 10.55 dB, 10 dB, and 6.8 dB, respectively. In this paper, we also propose an efficient ESQSM with a multi-user (ESQSM-MU) system inspired by the ESQSM ability in increasing the SE. The proposed ESQSM-MU system offers a significant bit error rate (BER) improvement and a higher capacity (i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5K$ </tex-math></inline-formula> -users) compared to the current non orthogonal multiple access-SM (NOMA-SM) and SM-assisted multi-antenna NOMA (SM-AMA-NOMA) systems. Moreover, an efficient low-complexity detector is introduced for the ESQSM signal detection, promising a 91.2% reduction in the computational complexity of ESQSM and ESQSM-MU systems relative to the maximum likelihood (ML) with a trivial loss in performance.

Modified generalized quadrature spatial modulation performance over Nakagami‐m fading channel

SummaryThe modified generalized quadrature spatial modulation (mGQSM) scheme is introduced to improve the transmission rate of the spatial modulation (SM) and quadrature SM (QSM). In mGQSM, the information symbols are separated as real and imaginary coefficients, which are modulated on in‐phase and quadrature dimensions, respectively. In addition, this scheme presented a novel codebook design to enhance the rate of 1 bit per channel use over generalized QSM (GQSM). In this paper, we present mGQSM and reduced codebook mGQSM (RC‐mGQSM) system performances over Nakagami‐m, Rayleigh, and Rician fading channels. However, the Rayleigh fading is a special case of Nakagami‐m fading when m = 1. For the computer simulations, we use several values for the Nakagami parameter, m, and Rician factor, K. We present the mGQSM and RC‐mGQSM system performances and compare them to the GQSM, QSM, and SM system performances, using the maximum‐likelihood (ML) detection. For the RC‐mGQSM scheme, we present a low‐complexity detection method. We also present the performances of mGQSM and SM systems in the presence of imperfect channel conditions.

Performance analysis of Hexagonal QAM constellations on quadrature spatial modulation with perfect and imperfect channel estimation

In this study, the quadrature spatial modulation (QSM) technique, which is a rational multiple-input multiple-output (MIMO) transmission technique and frequently encountered in recent studies in the literature, and the hexagonal quadrature amplitude modulation (HQAM) constellation technique, which combines symbols in an “optimum” way are combined. This new MIMO scheme has been named by the authors as HQAM-QSM. Also, the impact of imperfect channel knowledge on the performance of the proposed scheme is examined. The HQAM constellation technique is a technique that provides better results under the same power assumption than the conventional QAM constellation in terms of symbol separation and is more often encountered when it comes to energy-efficiency. Due to the nature of HQAM symbols, error-floor occurs when the QSM system is applied. Hence, the optimum angle is obtained by rotating the HQAM symbols. With this optimum angle, it has been seen that the error-floor disappeared and the performance of the system is improved. Besides, the HQAM technique performs similar bit error rates (BER) to QAM at high signal-to-noise ratio (SNR) values. From this point forth, in our study, the rational HQAM-QSM technique, which uses energy-efficient HQAM symbols instead of traditional modulated QAM symbols and also carries information effectively on two active antennas, is proposed. Performance analysis of the HQAM-QSM technique is performed on Rayleigh fading channels.

Generalized Code Index Modulation and Spatial Modulation for High Rate and Energy-Efficient MIMO Systems on Rayleigh Block-Fading Channel

In this article, a high data rate and energy-efficient multiple-input multiple-output transmission scheme is considered by combining two popular and rational modulation techniques: spatial modulation (SM) and code index modulation-spread spectrum (CIM-SS). Since in the considered system, called generalized CIM-SM (GCIM-SM), incoming information bits determine modulated symbols, activated transmit antenna indices as well as their corresponding spreading code indices, data bits are conveyed not only by modulated symbols but also by the indices of the active antenna and spreading codes. Hence, a GCIM-SM scheme accommodates faster data rates while spending less transmission power and possessing better error performance compared to the conventional direct sequence spread spectrum (DS-SS), SM, quadrature SM (QSM), and CIM-SS systems. The mathematical expressions of the GCIM-SM system for bit error rate, throughput, energy efficiency, and the system complexity are derived to analyze the overall system performance. Besides, it has been shown via computer simulations that the GCIM-SM system has lower transmission energy, faster data transmission rate, and better error performance than DS-SS, SM, QSM, and CIM-SS systems. Performance analysis of the considered system was performed on Rayleigh block-fading channels for quadrature amplitude modulation technique.

Transmit Antenna Selection for Quadrature Spatial Modulation Systems with Power Allocation

Transmit Antenna Selection for Quadrature Spatial Modulation Systems with Power Allocation

User Grouping and Power Allocation for Downlink NOMA-Based Quadrature Spatial Modulation

Conventional non-orthogonal multiple access (NOMA)-based spatial modulation (SM) systems utilize only the real part of amplitude-phase modulation (APM) symbols for transmission, but quadrature spatial modulation (QSM) can extend this to two orthogonal components to improve the spectral efficiency. In this way, we propose a NOMA-based QSM system in multiple-input multiple-output scenarios, where APM symbols are divided into real and imaginary components for transmission and then these two components are sent by real and imaginary transmit antennas, respectively. To further improve the performance of our proposed system, we also propose a user grouping and a power allocation with relatively low complexity. Different from previous schemes, the user grouping scheme is designed for considering channel conditions, user locations, and channel correlations jointly. Moreover, the power allocation scheme is performed in each group to meet users’ quality-of-service requirements, i.e., target-rate requirements. Simulation results demonstrate the effectiveness of proposed schemes by comparing with existing ones.

Performance Analysis of Variant MIMO Systems Over 3-D Vehicular to Vehicular Channel

This article analyzes the performance of variant multiple-input multiple-output (MIMO) systems over three-dimensional (3D) vehicular to vehicular (V2V) wireless communication channel. In particular, quadrature spatial modulation (QSM), spatial multiplexing (SMX) and spatial modulation (SM) MIMO techniques are considered. A unified framework to analyze the average bit error rate (BER) for all considered MIMO techniques is developed while considering the 3D geometry dependent stochastic V2V channel model and substantiated through Monte Carlo simulation results. Reported results corroborate the accuracy of the derived formulas and the impact of different system and channel parameters is studied. Specifically, the encroachment of Doppler effect, channel estimation errors, 3D features and vehicle traffic density (VTD) on the BER performance of all systems are examined and discussed. It is revealed that QSM system achieves substantial gains as compared to its counterpart SM and SMX schemes. Gains of up to 2-4 dB in signal-to-noise-ratio are reported for different scenarios.

Performance of power scaling‐based quadrature spatial modulation systems with limited feedback

A power scaling (PS) scheme is examined in quadrature spatial modulation (QSM) systems with limited feedback. Here, a scaling factor is introduced for weighing the modulated symbols in the transmitter. The minimum Euclidean distance metric is exploited to select scaling factors for QSM systems. It is shown via simulation results that the proposed power scaling‐based quadrature spatial modulation systems provide better error performance than the conventional QSM with the limited feedback amount. Additionally, their error performance is compared with that of the PS‐assisted spatial modulation systems. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

QSM-IDM – A novel quadrature spatial modulation based on interleaving division multiplexing for multiple antenna system

Quadrature Spatial Modulation (QSM) is a high spectral efficiency Multiple-Input Multiple Output (MIMO) technique used to improve the spectral efficiency of wireless communication systems. The main concept of QSM is to extend the spatial constellation of the conventional Spatial Modulation (SM) in both the in-phase and quadrature components of the data symbol. In this paper, because QSM-based on Interleaving Division Multiplexing (IDM) has not been introduced in the literature as a multiple antenna system, we introduced a novel scheme, called QSM system based on Interleaving Division Multiplexing (QSM-IDM). The antenna sets are also applied to a spreader, before being used to assign an antenna number for information transmission. Analysis and simulations for a flat fading channel show that the proposed QSM-IDM method significantly outperforms the original QSM system with the same data rate, while maintaining a relatively acceptable complexity. The obtained simulation results show that the conducted analysis yields significant improvements for the accuracy of the proposed scheme, with satisfactory complexity.

Low Complexity Detection for Quadrature Spatial Modulation Systems

Quadrature spatial modulation (QSM), where the real and imaginary parts of the transmitted symbol are transmitted separately, was recently proposed to increase the spectral efficiency of spatial mo...

Quadrature Spatial Modulation for 5G Outdoor Millimeter–Wave Communications: Capacity Analysis

Capacity analysis for millimeter–wave (mmWave) quadrature spatial modulation (QSM) multiple-input multiple-output (MIMO) system is presented in this paper. QSM is a new MIMO technique proposed to enhance the performance of conventional spatial modulation (SM) while retaining almost all its inherent advantages. Furthermore, mmWave utilizes a wide-bandwidth spectrum and is a very promising candidate for future wireless systems. Detailed and novel analysis of the mutual information and the achievable capacity for mmWave–QSM system using a 3-D statistical channel model for outdoor mmWave communications are presented in this paper. Monte Carlo simulation results are provided to corroborate derived formulas. Obtained results reveal that the 3-D mmWave channel model can be closely approximated by a log–normal fading channel. The conditions under which capacity can be achieved are derived and discussed. It is shown that the capacity of QSM system can be achieved, by carefully designing the constellation symbols for each specific channel model.

Low Complexity Detection for Quadrature Spatial Modulation Systems

Quadrature spatial modulation (QSM), where the real and imaginary parts of the transmitted symbol are transmitted separately, was recently proposed to increase the spectral efficiency of spatial modulation. An optimum maximum likelihood (ML) detection was introduced in QSM systems, which leads to high complexity as the exhausting search of all possible transmit antennas. In this paper, a low complexity detection, called signal vector based minimum mean square error (SVMMSE), is proposed for QSM systems. In the proposed SVMMSE detection, we estimate the transmit antenna indices and the transmitted symbol by considering the active transmit antennas in two different scenarios. Simulation results show that the performance of our SVMMSE detection is very close to the ML detection and complexity analysis shows that the computational complexity of the proposed SVMMSE detection is significantly reduced compared with that of the ML detection.

Quadrature Spatial Modulation Performance Over Nakagami- $m$ Fading Channels

This paper analyzes the performance of the recently proposed quadrature spatial modulation (QSM) multiple-input-multiple-output (MIMO) system over Nakagami-m fading channel. In the analysis, the general distribution of the Nakagami-m channel phase is considered. In the literature, performance analysis of spatial modulation (SM) over Nakagami-m channel with uniform phase is conducted. However, apart from the very special case of m = 1, where Nakagami-m fading corresponds to Rayleigh fading, the phase of the Nakagami-m distribution is not uniformly distributed. It is shown in this paper that the phase of the channel has major impact on the performance of spatial multiplexing MIMO systems such as SM and QSM systems. A general upper bound expression for the average bit error ratio (ABER) performance of QSM is derived, and the impact of different channel parameters is studied. Monte Carlo simulation results are provided to corroborate the exactness of the derived analysis.

Impact of IQ imbalance on the performance of QSM multiple‐input–multiple‐output system

Quadrature spatial modulation (QSM) is proposed recently as an efficient multiple-input–multiple-output wireless communication technique. In QSM, spatial multiplexing gain is achieved through modulating a two-dimensional spatial constellation diagram in addition to conventional signal modulation. It was demonstrated that QSM can be designed with single in-phase and quadrature (IQ) transmitter. However, the impact of IQ modulator imperfections, which degrade signal fidelity and overall system performance, has not been studied in the literature. In this study, typical IQ modulator/demodulator is considered for QSM system and the performance of the system is analysed and discussed. In particular, IQ imbalance channel modelling, pair-wise error probability, and average bit error ratio are discussed. Results reveal that IQ imbalance can lead to significant performance degradation of QSM system and should be carefully addressed for any future deployment.

Low-Complexity Signal Detection for Large-Scale Quadrature Spatial Modulation Systems

In this letter, a novel low-complexity detector based on the concept of compressive sensing (CS) is proposed for a novel multiple-input multiple-output system, namely, quadrature spatial modulation (QSM). In particular, the CS algorithm is performed in the real-valued system model, and the activated antenna indices, which are used to transmit the real and imaginary parts of QSM symbols, can be estimated separately. In order to further improve the performance of QSM, a novel search strategy is proposed. Simulation results show that the proposed detector is capable of achieving a considerable reduction in complexity compared with the maximum likelihood counterpart with negligible performance loss.

A Comprehensive Framework for Quadrature Spatial Modulation in Generalized Fading Scenarios

In this paper, we present a comprehensive framework for quadrature spatial modulation (QSM) in generalized fading channels. In particular, the performance analysis of QSM systems in the presence of imperfect channel knowledge and under correlated fading channels is presented. A simple and closed-form expression for the pairwise error probability (PEP) is provided. Based on the obtained PEP, a closed-form upper bound expression for the average bit error probability (BEP) is obtained. The analysis is unified in the sense that it is applicable for any fading channel once its envelope and phase distributions are available. As such, different generalized fading distribution models, namely, $\eta $ – $\mu $ , $\kappa $ – $\mu $ , and $\alpha $ – $\mu $ distributions, are considered. The obtained results clearly show the influence of the fading parameters on the average BEP. In the case of the $\alpha $ – $\mu $ fading channels, increasing $\alpha $ has larger negative impact on the average BEP compared with increasing $\mu $ . For the $\kappa $ – $\mu $ channels, increasing $\mu $ results in increasing the average BEP dramatically when compared with increasing $\kappa $ . In the same context, in $\eta $ – $\mu $ fading channels, as $\mu $ increases the average BEP degrades whereas increasing $\eta $ slightly improves the average BEP. In addition, it is demonstrated that transmit-antenna correlation significantly deteriorate the average BEP when compared with receive-antenna correlation.

Antenna Selection Schemes in Quadrature Spatial Modulation Systems

This paper presents antenna selection schemes for recently proposed quadrature spatial modulation (QSM) systems. The antenna selection strategy is...

Quadrature Spatial Modulation

This paper proposes a new multiple-input–multiple-output (MIMO) technique called quadrature spatial modulation (QSM). QSM enhances the overall throughput of conventional SM systems by using an extra modulation spatial dimension. The current SM technique uses only the real part of the SM constellation, and the proposed method in this paper extends this to in-phase and quadrature dimensions. It is shown that significant performance enhancements can be achieved at the expense of synchronizing the transmit antennas. Additionally, a closed-form expression for the pairwise error probability (PEP) of generic QSM system is derived and used to calculate a tight upper bound of the average bit error probability (ABEP) over Rayleigh fading channels. Moreover, a simple and general asymptotic expression is derived and analyzed. Obtained Monte Carlo simulation results corroborate the accuracy of the conducted analysis and show the significant enhancements of the proposed QSM scheme.