Generalized Spatial Modulation Research Articles

Performance evaluation of magic square based spatial modulation in UAV communication

This study proposes a method to reduce the bit error rate (BER) in communications by unmanned aerial vehicles (UAVs). The method involves using specific active antennas that transmit at precise times with a particular mapping, ensuring orthogonality among transmitting antennas. This technique can accommodate numerous transmit antennas and amplitude-phase modulation orders. When applied to spatial modulation (SM) and generalized spatial modulation (GSM), it demonstrates clear superiority and significantly improved results compared to traditional SM and GSM methods, especially at high altitudes where conventional methods result in high BER. Introducing a new modulation method called magic square (MS) further enhances the results. The MS method provides a unique orthogonality pattern for the transmitting antenna sets. Additionally, the study introduces the utilization of magic squares in the modulation field. The MS-based SM model shows a BER rate almost 103 times lower than traditional SM at the 25 dB signal-to-noise ratio (SNR) level for various fly altitudes. Similarly, the MS-based GSM model demonstrates a BER rate almost 100 times lower than traditional GSM. The proposed method yields better results as the altitude increases, making it suitable for UAV communication at various altitudes.

RIS-Assisted Receive Generalized Space-Shift Keying and Receive Generalized Spatial Modulation

RIS-Assisted Receive Generalized Space-Shift Keying and Receive Generalized Spatial Modulation

Covert Information Mapped Generalized Spatial and Direction Modulation toward Secure Wireless Transmission.

In this paper, for the sake of enhancing the security of wireless transmission, we proposed a novel system based on spatial and direction modulation (SDM) combined with generalized spatial modulation (GSM) which is aided by covert information mapping (CIM), termed as the CIM-GSDM system. In such a system, the legitimated user is equipped with distributed receivers so as to demodulate the conveyed signal by exploiting its indices while disturbing eavesdroppers for information security. More specifically, part of the information is modulated into the indices of the legitimated distributed receiver subsets with the aid of the mapped covert information and the interference matrix, while another part of the message is arranged by conventional amplitude-phase modulation. The proposed system can reap the benefits from both GSM and CIM to make eavesdropper suffer great mixture. Furthermore, the detection scheme and theoretical analysis of error performance are discussed as well. The simulation results exhibit that the bit error rate (BER) performance of legitimate user is much better than that of the eavesdropper while the proposed scheme improves the security compared to the original CIM-SDM system at the same spectral efficiency.

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.

Capacity, Convergence, and Complexity Improvements for LDPC-Coded MIMO-VLC Systems With Generalized Spatial Modulation

Capacity, Convergence, and Complexity Improvements for LDPC-Coded MIMO-VLC Systems With Generalized Spatial Modulation

Blind Signal Reception in Downlink Generalized Spatial Modulation Multiuser MIMO System Based on Minimum Output Energy

Blind Signal Reception in Downlink Generalized Spatial Modulation Multiuser MIMO System Based on Minimum Output Energy

CNN-based automatic modulation recognition for index modulation systems

Automatic modulation recognition (AMR) has garnered significant attention in both civilian and military domains, with applications ranging from spectrum sensing and cognitive radio (CR) to the deterrence of adversary communication. Index modulation (IM) represents an innovative digital modulation technique that exploits the indices of parameters of communication systems to transmit extra information bits. This paper aims to examine the performance of a convolutional neural network (CNN)-based AMR across various IM systems, including spatial modulation (SM), quadrature spatial modulation (QSM), and generalized spatial modulation (GSM) with eight digital modulation schemes. In this study, we leverage confusion matrices, receiver operating characteristic (ROC) curves, and F1 scores to illustrate the recognition model’s outputs.

Energy Efficient Multi User Spatial Modulated NOMA for mmWave Communications

In this paper, we propose a downlink multi-user (MU) generalized spatial modulation (GSM) aided non-orthogonal multiple access (MU-GSM-NOMA) transmission technique for mmWave communications. Given a set of users, a user grouping algorithm is presented to partition the users into different clusters, and each of them is served by a dedicated uniform linear array (ULA) of antennas. The ULAs generate analog beams to steer the amplitude and phase-modulated symbols by employing the principles of NOMA. Further, the analog beams carry additional spatial information bits encoded in GSM for a particular cluster user. We propose simple digital combiners for receiver processing based on matched filtering, for which we have characterized the theoretical guarantee of the perfect detection of spatially modulated analog beams. Also, the work proposes an optimization algorithm to allocate power to the users, ensuring stable successive interference cancellation for a specific case of two users in each cluster. Finally, we present the numerical results, which demonstrate the outperformance of our proposed approach over the existing ones in terms of average sum rate and energy efficiency.

Generalized Spatial Modulation Aided mmWave Massive MIMO Systems With Switch-and-Inverter Hybrid Precoding Design

This article concentrates on the generalized spatial modulation (GenSM) aided millimeter-wave (mmWave) massive multiple-input and multiple-output (MIMO) switch-and-inverter (SI) based hybrid precoding design technology. As the technological advancements, the great demands for the scales of antenna arrays and frequency bands adopted in mobile communications become imperative. The essential radio frequency (RF) chains and phase shifters (PSs) turn into the principal causes of excessive energy dissipation in the massive MIMO mmWave systems. Accordingly, a complexity-efficient SI-based network is being substituted for a massive volume of energy-consuming high-resolution PSs in the analog RF precoder. As a consequence, the need of hardware complexity and energy consumption is alleviated significantly and thus results in superior energy efficiency (EE) performance. In addition, an innovative integration of the GenSM and the SI-based hybrid precoder is exploited as well in the article. The updated version of the coordinate update algorithm is developed and utilized to the analog precoding design. Furthermore, the spatial multiplexing gain acquired by the extra space-domain information of the GenSM mechanism improves substantially the spectral efficiency of the system. Finally, simulation results demonstrate remarkable performances on both the achievable sum-rate and the EE.

Passive Beamforming Design and DNN-Based Signal Detection in RIS-Assisted MIMO Systems With Generalized Spatial Modulation

Reconfigurable Intelligent Surfaces (RISs) have recently gained significant attention as they enable controlling the wireless propagation environment to improve information transmission with the help of reflective elements. This paper studies a RIS-assisted generalized spatial modulation (GSM) multiple input multiple output (MIMO) system to improve the signal quality and spectral efficiency. Due to inter-channel interference, signal detection in GSM becomes a critical issue. Therefore, we propose a low complexity block deep neural network (DNN) detector for the RIS-GSM MIMO system to detect the active antennas and the transmitted symbols at the receiver. In order to optimize the phase shifts at the RIS elements, we propose cosine similarity-based and semidefinite relaxation (SDR)-based algorithms. Further, conventional signal detectors such as maximum likelihood (ML), block zero-forcing (B-ZF), and block minimum mean square error (B-MMSE) are applied. In addition, we explore and analyze the performance of the proposed framework in terms of bit error rate (BER) and time complexity. Numerical results reveal that both optimize-phase-shifts algorithms assisted DNN signal detector has almost the same BER performance as ML, but it is four times faster than the linear detector (B-ZF and B-MMSE), and seven times faster than ML. Clearly, this scheme outperforms the alternative traditional signal detectors with the least time complexity.

Signal Detection in GSM-Based In-Band Full-Duplex Communication Using DNN

An in-band full-duplex (IBFD) multiple-input multiple-output (MIMO) radio's self-interference (SI) cancellation strength usually determine its performance gains over conventional half-duplex ones. Accordingly, this letter explores an alternative to traditional optimization driven design (ODD) techniques available in literature for beamformer design in IBFD radios. In particular, we consider a generalized spatial modulation (GSM) based bi-directional IBFD system, that provides the flexibility of choosing active antennas among a set of antennas for the spatial symbol. We propose a run-time data-driven prediction approach to solve the multiple multivariate regression problem of detection of the transmitted signal in this GSM based IBFD system in the presence of residual SI arising from non-ideal SI cancellation. We compare the performance of the proposed detector with respect to conventional detectors under several communication parameters that are of practical interest. The proposed DNN-based detector learns the deviations from a standard model without SI and achieves performance that is superior to zero forcing and minimum mean squared error detectors and very close to maximum likelihood detector at faster computation time.

Design and Implementation of a 6.5-Gb/s Multiradix Simplified Viterbi-Sphere Decoder for Trellis-Coded Generalized Spatial Modulation With Spatial Multiplexing

A simplified Viterbi-sphere decoder (VSD) for trellis-coded generalized spatial modulation (GSM) with spatial multiplexing (TCGSMX) is designed and implemented to exploit the soft information for achieving better performance. Multiple code rates are supported to combat different levels of spatial correlations in fading channels and to offer options for various transmission efficiencies. Hence, the proposed multiradix simplified VSD is configurable to process four radix-2 stages for 1/2 code rate, two radix-4 stages for 2/3 code rate, and one radix-8 stage for 3/4 code rate in one clock cycle to upgrade the throughput by fully pipelined architecture. To reduce the complexity, several techniques are employed, including the efficient settings of survival nodes of sphere decoding and sequence length for backtracing by Viterbi decoding. The chip has been fabricated in TSMC 40-nm CMOS technology. Compared to related works, the implementation provides higher throughput up to 6.5 Gb/s at 1.1-V supply voltage as well as 180.8-MHz operating frequency and consumes 374.3 mW for TCGSMX systems using 16-QAM and code rate of 1/2.

Physical layer security for indoor GSM VLC

We consider the physical layer security (PLS) of the generalized spatial modulation (GSM) enabled indoor multiple-input single-output (MISO) visible light communication (VLC) downlink, wherein an optical artificial noise (OAN)-assisted scheme is proposed to enhance the secrecy of the considered system. Due to the transmitter (Alice) sending confidential messages and OAN with the power and amplitude constraints, a truncated Gaussian distribution is exploited. With a finite discrete distribution of the input signals, the secrecy performance is analyzed in the OAN-assisted GSM VLC system. Specifically, the average mutual information (AMI) is first proposed, then the lower bound and approximation of AMI, and the achievable secrecy rate (ASR) are evaluated as well. In addition, considering the proposed power allocation problem of the considered OAN-assisted GSM VLC system, the particle swarm optimization (PSO) algorithm is explored to attain the global optimal power allocation coefficient, which is capable of maximizing the ASR. The numerical and simulation results validate our theoretical results of the OAN-assisted secrecy performance of the considered indoor GSM VLC system.

Generalized Spatial Modulation in Full-Duplex Two-Way Relay Channel

In this letter, we propose generalized spatial modulation (GSM) in full duplex system equipped with two way relay channel (FD-GSM-TWRC). We propose a couple of receiver algorithms, structured complex orthogonal matching pursuit (S-COMP) and structured ordered block OMP (S-OBOMP) by casting the observation model suitably to apply compressive sensing framework. We substantiate that FD-GSM-TWRC with the proposed receiver algorithms, offer an optimal trade-off among bit-error rate (BER) performance, throughput and complexity.

Efficient Memory-Bounded Optimal Detection for GSM-MIMO Systems

We investigate the optimal signal detection problem in large-scale multiple-input multiple-output (MIMO) system with the generalized spatial modulation (GSM) scheme, which can be formulated as a closest lattice point search (CLPS). To identify invalid signals, an efficient pruning strategy is needed while searching on the GSM decision tree. However, the existing algorithms have exponential complexity, whereas they are infeasible in large-scale GSM-MIMO systems. In order to tackle this problem, we propose a memory-efficient pruning strategy by leveraging the combinatorial nature of the GSM signal structure. Thus, the required memory size is squared to the number of transmit antennas. We further propose an efficient memory-bounded maximum likelihood (ML) search (EM-MLS) algorithm by jointly employing the proposed pruning strategy and the memory-bounded best-first algorithm. Theoretical and simulation results show that our proposed algorithm can achieve the optimal bit error rate (BER) performance, while its memory size can be bounded. Moreover, the expected time complexity decreases exponentially with increasing the signal-to-noise ratio (SNR) as well as the system’s excess degree of freedom, and it often converges to squared time under practical scenarios.

Low-Complexity GSM Detection Based on Maximum Ratio Combining

Generalized spatial modulation (GSM) technology is an extension of spatial modulation (SM) technology, and one of its main advantages is to further improve band efficiency. However, the multiple active antennas for transmission also brings the demodulation difficulties at the receiver. To solve the problem of high computational complexity of the optimal maximum likelihood (ML) detection, two sub-optimal detection algorithms are proposed through reducing the number of transmit antenna combinations (TACs) detected at the receiver. One is the maximum ratio combining detection algorithm based on repetitive sorting strategy, termed as (MRC-RS), which uses MRC repetitive sorting strategy to select the most likely TACs in detection. The other is the maximum ratio combining detection algorithm, which is based on the iterative idea of the orthogonal matching pursuit, termed the MRC-MP algorithm. The MRC-MP algorithm reduces the number of TACs through finite iterations to reduce the computational complexity. For M-QAM constellation, a hard-limited maximum likelihood (HLML) detection algorithm is introduced to calculate the modulation symbol. For the M-PSK constellation, a low-complexity maximum likelihood (LCML) algorithm is introduced to calculate the modulation symbol. The computational complexity of these two algorithms for calculating the modulation symbol are independent of modulation order. The simulation results show that for GSM systems with a large number of TACs, the proposed two algorithms not only achieve almost the same bit error rate (BER) performance as the ML algorithm, but also can greatly reduce the computational complexity.

The Achievable Rate Analysis of Generalized Quadrature Spatial Modulation and a Pair of Low-Complexity Detectors

Generalized quadrature spatial modulation (GQSM) seamlessly amalgamates the generalized spatial modulation (GSM), quadrature spatial modulation (QSM) and vertical Bell Laboratories layered space-time (V-BLAST) techniques. In contrast to traditional multiple-input multiple-output (MIMO) schemes transmitting information bits only through the constellation defined on the complex plane, GQSM transmits additional information bits implicitly by selecting the transmit antenna (TA) activation pattern. The philosophy of QSM is that of separating the indices of the real and the imaginary parts of the transmit symbols, which increases the attainable throughput. In this paper, we analyze the inherent benefits of GQSM in terms of throughput. More specifically, we first derive the achievable rate expression of the recent GQSM scheme and unveil the condition for GQSM to approach the maximum rate. Furthermore, we compare the rate of the GQSM scheme to that of other transmission schemes and reveal the conditions for the GQSM’s maximum throughput to exceed that of the benchmark schemes. Simulation results show that when the number of TAs is 40 and quadrature phase shift keying (QPSK) is adopted, the rate of the GQSM scheme may reach 150% of that of V-BLAST. Additionally, a pair of low-complexity detectors are conceived-one based on ordered successive interference cancellation (OSIC) and another one on the orthogonal matching pursuit (OMP) algorithm.

Expectation Propagation Aided Signal Detection for Uplink Massive Generalized Spatial Modulation MIMO Systems

In this paper, we propose a joint signal detection algorithm under the framework of the expectation propagation (EP) algorithm for uplink massive multiuser multiple-input multiple-output (MIMO) systems with generalized spatial modulation (GSM). By projecting the discrete probability distribution into a multivariate complex Gaussian function, the symbol beliefs of the tridimensional GSM constellation are calculated via the iterative propagation of the mean vectors and covariance matrices. To reduce the computational complexity, an efficient separate signal detection called two-stage EP (TS-EP) algorithm is designed. In the first stage, the active transmit antenna indices are determined via the EP. Each vector-valued variable node (VN) in the factor graph is decomposed into multiple sub-VNs, and the invalid sub-VNs of the determined silent transmit antennas are pruned from the factor graph. In the second stage, since the modulation symbols are independent conditioned on the active transmit antennas, the symbols are independently detected by adopting the EP with univariate complex Gaussian approximations, and the number of probability calculations for each symbol belief is significantly reduced in the subsequent EP update. Simulation results illustrate that the proposed EP and TS-EP signal detection schemes outperform the recently proposed counterparts. Moreover, the proposed TS-EP algorithm strikes a desirable and flexible performance-complexity tradeoff.

Low-complexity soft ML detection for generalized spatial modulation

Generalized Spatial Modulation (GSM) is a recent Multiple-Input Multiple-Output (MIMO) scheme, which achieves high spectral and energy efficiencies. Specifically, soft-output detectors have a key role in achieving the highest coding gain when an error-correcting code (ECC) is used. Nowadays, soft-output Maximum Likelihood (ML) detection in MIMO-GSM systems leads to a computational complexity that is unfeasible for real applications; however, it is important to develop low-complexity decoding algorithms that provide a reasonable computational simulation time in order to make a performance benchmark available in MIMO-GSM systems. This paper presents three algorithms that achieve ML performance. In the first algorithm, different strategies are implemented, such as a preprocessing sorting step in order to avoid an exhaustive search. In addition, clipping of the extrinsic log-likelihood ratios (LLRs) can be incorporating to this algorithm to give a lower cost version. The other two proposed algorithms can only be used with clipping and the results show a significant saving in computational cost. Furthermore clipping allows a wide-trade-off between performance and complexity by only adjusting the clipping parameter.

Network polar coded cooperative GSM scheme based on Plotkin’s construction

ABSTRACT The error performance of generalised spatial modulation (GSM) can be further enhanced by applying Plotkin polar codes (PPCs) to GSM. This motivates us to propose a Plotkin polar coded GSM (PPC-GSM) scheme where GSM signals are protected by the PPCs. We further extend the PPC-GSM scheme to cooperative scenarios based on a natural split in the Plotkin’s construction and propose the coded cooperative scheme with two sources called network polar coded cooperative GSM (NPCC-GSM). In the Plotkin’s construction, two shorter codes (subcodes) were derived from a longer code. The constructed polar subcodes were then utilised to achieve coded cooperation between two sources and offer a network coding. Furthermore, we investigate the network polar coded cooperative spatial modulation (NPCC-SM) scheme as a suitable benchmark to the proposed NPCC-GSM scheme. The simulation results reveal that for the same spectral efficiency the NPCC-GSM scheme performs nearly the same as the NPCC-SM scheme in terms of bit error rate performance, but with a significant reduction in the number of transmit antennas. Moreover, the NPCC-GSM scheme outperforms the PPC-GSM scheme under identical conditions. The enhanced performance is made possible due to the synergy between two sources and the joint decoding at the destination.