Spatial Modulation Systems Research Articles

Error performance of DF cooperative SMTs with I/Q imbalance over Beckmann fading channels

The direct down-conversion principle, which has generally been used in the design of multiple-input multiple-output (MIMO) schemes, including space modulation techniques (SMTs), is attractive to researchers because of its low cost, low power consumption with fewer components, flexible and simple structure. However, hardware imperfections such as in-phase (I) and quadrature-phase (Q) imbalance (IQI) negatively affect the performance of the systems with direct down-conversion in practice. On the other hand, cooperative communication is a promising technology that can be utilized in the design of future wireless networks due to its significant advantages such as increasing system reliability, extending network coverage, reducing channel degradation, and providing high quality of service. In this study, SMT-based methods are integrated into cooperative systems, and a flexible and comprehensive model is presented that is applicable to many channel structures. Specifically, the error performance analysis of space shift keying (SSK), spatial modulation (SM), and quadrature SM (QSM) systems in the presence of IQI in decode-and-forward (DF) cooperative communication is carried out by analytical derivations and computer simulations over generalized Beckmann fading channels. The obtained results show that the performance of SMT-based DF cooperative systems is superior to the conventional schemes, and the effects of receiver IQI can be eliminated by optimal detector designs.

Numerical investigation of non-uniform arrays of directive antennas for radiation pattern analysis using spatial modulation schemes

This research presents a novel Non-Uniform Array (NUA) design for Spatial Modulation (SM) systems, aiming to improve Bit Error Rate (BER) performance. The NUA utilizes directional antennas with low-similarity radiation patterns, enabling the receiver to effectively distinguish between signals transmitted from different antenna elements. This enhanced signal discrimination capability directly contributes to improved system capacity and potential spectral efficiency gains for massive MIMO systems employing SM techniques. The proposed NUA was optimized for operation at 5.2 GHz, achieving a high degree of pattern distinguishability. Measured results confirm the effectiveness of the design, demonstrating good agreement with simulations. Moreover, an analysis based on the similarity of the radiation pattern was conducted

An innovative method for improving the performance of unmanned aerial vehicle‐based generalized spatial modulation and non‐orthogonal multiple access in 6G networks

AbstractThe rapid evolution of wireless networks is leading to the emergence of 6G, promising unprecedented performance. We propose a nonorthogonal multiple access (NOMA)‐based multiuser generalized spatial modulation (GSM) system that allows various transmitting antennas. Integrating unmanned aerial vehicles (UAVs) with NOMA and GSM enhances overall network performance. This paper proposes optimizing UAV‐GSM‐NOMA systems in 6G using the butterfly optimization algorithm (BOA) in the two‐wave with diffuse power (TWDP) channel. Results are compared with those obtained from Nakagami and Rayleigh channels. Objectives include enhancing the sumrate, outage probability (OP), and energy efficiency (EE) in perfect and imperfect channel state information (CSI). Simulation results yield significant improvements in the TWDP channel compared with the Nakagami and Rayleigh channels. The OP is reduced, the sumrate is enhanced, and the EE is notably improved. These findings underscore the BOA's potential for 6G UAV‐GSM‐NOMA networks in challenging channel environments, ensuring reliable and efficient communication.

An Enhanced System Model for Differential Spatial Modulation System Under Fast Fading Channels and a Corresponding DFDD Based Low- Complexity Detector

An Enhanced System Model for Differential Spatial Modulation System Under Fast Fading Channels and a Corresponding DFDD Based Low- Complexity Detector

Antenna Selection For Receive Spatial Modulation System Empowered By Reconfigurable Intelligent Surface

Antenna Selection For Receive Spatial Modulation System Empowered By Reconfigurable Intelligent Surface

Deep learning based signal detection for quadrature spatial modulation system

Deep learning based signal detection for quadrature spatial modulation system

Joint Subchannel and Power Allocation in NOMA-Based Spatial Modulation Systems

Joint Subchannel and Power Allocation in NOMA-Based Spatial Modulation Systems

Joint Antenna Selection and Multicast Precoding in Spatial Modulation Systems

Joint Antenna Selection and Multicast Precoding in Spatial Modulation Systems

Physical Layer Security for Frequency Diverse Array-Based Dual-Hop Spatial Modulation

In this paper, we design the physical layer security of a dual-hop spatial modulation system provided the relay node transmits its own private information. Meanwhile, the quadrature virtual channel spatial modulation (QVCSM) is proposed to enhance the physical layer security in the second hop. To achieve system security in both angle and range dimensions, the frequency diverse array (FDA) is used in the relay node with a decode-and-forward (DF) protocol. Moreover, the baseband directional modulation (DM) and artificial noise (AN) are jointly utilized to suppress the received signal at the passive eavesdropper. Additionally, the Ergodic secrecy rate of the proposed system is analyzed, whereas the closed-form expressions for tight upper bounds on the bit error rates (BERs) of the source and relay are derived for both the destination and eavesdropper. The simulation results show that the proposed FDA relay design outperforms the traditional phase array (PA) relay system in terms of the system secrecy rate. In contrast to the quadrature spatial modulation (QSM) method, the proposed designs achieve an improved suppression performance of the eavesdropper.

Differential scheme for reconfigurable intelligent surface-based spatial modulation system

Differential scheme for reconfigurable intelligent surface-based spatial modulation system

Intelligent Transmit Antenna Selection Schemes for High-Rate Fully Generalized Spatial Modulation

The sixth-generation (6G) network is supposed to transmit significantly more data at much quicker rates than existing networks while meeting severe energy efficiency (EE) targets. The high-rate spatial modulation (SM) methods can be used to deal with these design metrics. SM uses transmit antenna selection (TAS) practices to improve the EE of the network. Although it is computationally intensive, free distance optimized TAS (FD-TAS) is the best for performing the average bit error rate (ABER). The present investigation aims to examine the effectiveness of various machine learning (ML)-assisted TAS practices, such as support vector machine (SVM), naïve Bayes (NB), K-nearest neighbor (KNN), and decision tree (DT), to the small-scale multiple-input multiple-output (MIMO)-based fully generalized spatial modulation (FGSM) system. To the best of our knowledge, there is no ML-based antenna selection schemes for high-rate FGSM. SVM-based TAS schemes achieve ∼71.1% classification accuracy, outperforming all other approaches. The ABER performance of each scheme is evaluated using a higher constellation order, along with various transmit antennas to achieve the target ABER of 10−5. By employing SVM for TAS, FGSM can achieve a minimal gain of ∼2.2 dB over FGSM without TAS (FGSM-NTAS). All TAS strategies based on ML perform better than FGSM-NTAS.

Transmit antenna selection for multi-user VASM systems: Simplicity and fairness

Variable Active Antenna Spatial Modulation (VASM) systems have been shown to offer higher spectral efficiency and greater flexibility than conventional spatial modulation systems. In VASM systems, since a part of the information is carried on the indices of activated antennas, the transmit antenna selection (TAS) problem significantly impacts the systems’ quality. In this article, we propose two new TAS methods for multi-user VASM systems, namely, Hi-TAS and ObO-TAS. Specifically, Hi-TAS aims to reduce the system’s computational complexity, which is a hierarchical combination of two popular TAS methods, i.e., channel gain-based TAS (CG-TAS) and Euclidean distance-based TAS (ED-TAS). Meanwhile, the ObO-TAS alternately chooses each transmit antenna one by one for every user to ensure fairness among them. In addition, we propose the idea of reusable TAs to improve the quality of the system. The calculation and simulation results show that the proposed Hi-TAS has a computational complexity of only 7.74% compared to ED-TAS while achieving better average bit error rate performance for the system than ED-TAS. The proposed ObO-TAS also demonstrates the advantage of ensuring fairness among users, namely that the difference in bit error rate among users is very small compared to other TAS methods.

Differential Spatial Modulation with Lattice Reduction Aided Pre-coding

This paper presents a pre-coding scheme for recently proposed differential spatial modulation (DSM) systems. It employs a lattice reduction (LR) aided pre-coding approach. An approximated upper bound on average bit error rate (BER) is semi-analytically derived. It is analytically shown that it can achieve a full diversity gain. That is, the performance analysis demonstrates that the LR-aided pre-coding DSM (LR-PDSM) systems with N T transmit antennas and N R receive antennas can achieve the maximum transmit diversity order of N T . Meanwhile, it is well-known that the diversity order attained by the conventional zero-forcing (ZF) pre-coding is given as N T − N R + 1 . Simulation results verify the approximated theoretical analysis and show that LR-aided ZF pre-coding is capable of improving the BER performance of the conventional ZF pre-coding based DSM systems under the same spectral efficiency.

Asymmetric Dual-Mode Constellation and Protograph LDPC Code Design for Generalized Spatial MPPM Systems

To achieve reliable and efficient transmissions in free-space optical (FSO) communication, this paper designs a new protograph low-density parity-check (PLDPC) coded generalized spatial multipulse position modulation (GSMPPM) system over weak turbulence channels. Specifically, we investigate the PLDPC code, generalized space shift keying (GSSK) modulation, and MPPM constellation. First, we propose a type of novel GSMPPM constellations that intelligently integrates the GSSK into MPPM, referred to as asymmetric dual-mode (ADM) constellations, so as to improve the performance of the PLDPC-coded GSMPPM system. Furthermore, exploiting a protograph extrinsic information transfer (PEXIT) algorithm, we construct a type of improved PLDPC code, referred to as I-PLDPC code, which outperforms the existing PLDPC codes over weak turbulence channels. Analytical and simulation results show that the proposed ADM constellations and the proposed I-PLDPC code can obtain noticeable performance gains over their counterparts. Therefore, the proposed PLDPC-coded GSMPPM system with ADM constellations is competent to satisfy the high-reliability requirement for FSO applications.

Physical Layer Authentication in Spatial Modulation

Spatial Modulation (SM) is a promising low-complexity modulation scheme for Multiple-Input Multiple-Output (MIMO) systems. In this paper, we address the problem of authenticating the transmitter device in the SM. We propose an authentication approach for an SM system by using Physical-Layer Authentication (PLA) mechanisms because the PLA has the following advantages: high security and low complexity. Based on the features of an SM system, we propose two PLA schemes: <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PLA with Superimposed Authentication Tag</i> (PLA-SAT) and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PLA with Superimposed Imaginary authentication Tag</i> (PLA-SIT). We provide performance analyses of our schemes over fading channels in terms of robustness, compatibility, and security. Moreover, we derive their closed-form expressions under both perfect and imperfect channel estimates, including the Probability of Detection (PD), Probability of False Alarm (PFA), and Average Error Probability (AEP). Although the two proposed schemes have the same robustness and security, the PLA-SIT scheme has better compatibility than the PLA-SAT scheme. Our schemes were implemented and extensive performance comparisons through simulations were conducted. We observe that the simulation results of the two proposed schemes perfectly match their corresponding theoretical analyses. The authentication accuracy of the two proposed schemes is close to one when the received SNR is greater than 20 dB and the security performances of the two proposed schemes improve as the variance of estimation errors increases.

Performance Study of Generalized Space Time Block Coded Enhanced Fully Optical Generalized Spatial Modulation System Based on Málaga Distribution Model

This paper proposes a generalized space time block coded (GSTBC) enhanced fully optical generalized spatial modulation (EFOGSM) system based on Málaga (M) turbulent channel. GSTBC-EFOGSM adopts the hybrid concept of generalized space time block coded and optical spatial modulation to further utilize the high transmission rate of EFOGSM and the diversity advantage of GSTBC in free space optical (FSO) communication systems. Considering the combined effects of path loss, pointing error and atmospheric turbulence, the Meijer G function is used to derive the closed-form expression for the average bit error rate (ABER) of GSTBC-EFOGSM. Then, the ABER performance, data transmission rate, energy efficiency and computational complexity at the receiver of GSTBC-EFOGSM are compared with other optical spatial modulation schemes by simulation. In addition, the effects of key factors, such as data transmission rate, encoding ratio, number of photodetectors and modulation order, on the ABER performance of the system are also analyzed via simulation. Monte Carlo (MC) simulation is used to verify the correctness of the numerical simulation. The simulation results show that the GSTBC-EFOGSM system has better ABER performance and good performance gain.

Symmetrical Z-Complementary code sets for optimal training in generalized spatial modulation

This paper considers the optimal training design for broadband generalized spatial modulation systems over frequency-selective channels using a novel class of code sets introduced, called “symmetrical Z-complementary code sets”, whose aperiodic auto- and cross- correlation sums exhibit zero-correlation zones at both the front-end and tail-end of the entire correlation window. Two constructions of (optimal) symmetrical Z-complementary code sets based on generalized Boolean functions are presented. Numerical evaluations indicate that the proposed training sequences for generalized spatial modulation can achieve optimal channel estimation performance and outperform other classes of sequences.

Partner selection method in cooperative spatial modulation (CSM) system

In this work, to achieve higher capacity, spatial modulation (SM) is utilized in a cooperative scheme in two different models of Cooperative SM, where SM is applied either at the source or the selected partner through an antenna array. A theoretical model of SM capacity is defined based on closed form lower and upper bound of the SM capacity. Based on the theoretical analysis of the channel capacity in both CSM systems the simplest and easier to implement selection criteria have been suggested to select a single partner to maximize CSM capacity. The CSM system in which SM is applied through the partner’s antenna array is providing significant enhancement over the other CSM model and cooperative multiple-input-multiple-output (CO-MIMO) networks based on multiple partners. Moreover, the system with a single randomly selected partner equipped with four antennas, behaves similarly as the best configuration of CO-MIMO based on the cooperation of four partners with the computational complexity linearly increases with the number of available partners to help. All of the theoretical findings are verified through simulation studies.

Integrated Polarization and Spatial Modulation

In this contribution, the concepts of polarization modulation (PM) and spatial modulation (SM) are integrated, to reap their respective advantages toward single-radio frequency (RF) multiple-input multiple-output (MIMO) transmissions. In the so-called polarization and spatial modulation (PSM) system, the information is conveyed by activated antenna indices as well as polarization modulated symbols, while at the receiver, a low-complexity near-optimal detection algorithm based on compressive sensing (CS) is proposed. Furthermore, a closed-form union bound of the average bit-error rate (BER) over fading channels is quantified by theoretical derivation, which is then extended to the case of spatial correlation (SC) as well as channel estimation error (CSE) toward practical use. Finally, our simulation results demonstrate the superiority of the developed PSM system over conventional PM in terms of BER performance over various fading channels.

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.