Spatial Modulation Scheme Research Articles

Offset Spatial Modulation With Multiple Receive Antennas

Recently, a class of novel spatial modulation (SM) schemes, termed offset spatial modulation (OSM), were developed to reduce the radio frequency (RF) switching frequency, in the context of multiple-input single-output (MISO) transmission. In this paper, the structure of original OSM is extended to adapt multiple-input multiple-output (MIMO) systems by introducing multiple receive antennas (MRA). The detailed system design is presented and further developed for offset space shift keying (OSSK). Furthermore, the theoretical bounds of bit-error rate (BER) performance for the proposed OSM-MRA and OSSK-MRA systems are both quantified. It is demonstrated that the proposed OSM-MRA and OSSK-MRA systems outperform their counterparts including conventional OSM and OSSK with improved spectral efficiency.

High-Rate Spatial Modulation Transmission Scheme With Block-Orthogonal Structure and Block-by-Block Sphere Decoding

The work in this paper is an extension of the recently proposed stacked Alamouti based spatial modulation (SA-SM) scheme. The motivation is that by taking advantage of the existing full-diversity full-rate (FDFR) space-time code, to construct SM transmission with the properties of higher spectral efficiency, non-vanishing determinants (NVD) property, as well as fast decoding. In the proposed scheme, we still use the stacked structure to construct the signal matrix, but Alamouti code in the SA-SM scheme is replaced by the FDFR Sezginer-Sari-Biglieri (SSB) code. The combination of stacked structure with SSB code can contribute to attaining the goals of our motivation. Since the proposed SM scheme has block-orthogonal (BO) property, we call it as BO-SM. We then present a low-complexity block-by-block sphere decoding for the BO-SM scheme owing to the variables corresponding to the same block are independent. Simulation results of bit error rate (BER) performance show that the proposed BO-SM scheme outperforms some newly presented diversity-achieving SM schemes.

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.

Low-Complexity Differential Spatial Modulation Schemes for a Lot of Antennas

Spatial modulation (SM) uses a single antenna for transmission each time to avoid synchronization and interferences among transmitter antennas, and differential SM (DSM) is a kind of SM technique that does not need pilot symbols and channel estimation. The original noncoherent detection for DSM is very complicated, so various low-complexity detectors have been proposed. However, they are still too complicated to be applied to DSM with many transmitter antennas. In this paper, low-complexity DSM schemes for dozens or hundreds of transmitter antennas are designed. Two bit-mapping schemes are proposed: one is group arrangement for maximizing data rates, and the other is full mapping so that DSM can be easily detected at the receiver. A low-complexity detection algorithm that is less complicated than all existing fixed-complexity detectors is proposed as well. In addition, two detection strategies for the proposed bit mapping methods are proposed. Simulation results show that the proposed low-complexity DSM schemes have satisfactory error performance.

Underwater Image Transmission Using Spatial Modulation Unequal Error Protection for Internet of Underwater Things.

A spatial modulation (SM) scheme has been developed as a hopeful candidate for spectral and energy-efficient wireless communication systems, as it provides a great judgment for the system performance, data transmission rate, receiver complexity, and energy/spectrum efficiency. In SM, the data is conveyed by both habitual M-ary signal constellations and the transmit antennas indices. Therefore, the system data rate improvement due to the side information bits transmitted, encapsulated in indices of the transmit antennas, improves the SM transmission efficiency compared to the different MIMO players. The information bits transmitted over the antenna index and data symbol constellation using M-ary signal performance have different levels of bit error rate (BER) performance. This paper proposes unequal error protection (UEP) scheme for image transmission over the Internet of Underwater Things (IoUTs) using SM. The Set Partitioning in Hierarchical Trees (SPIHT) coders encode the underwater image and classify the encoded bits in two categories: critical and uncritical bits. The critical bits are transmitted over the SM index bits and have a low BER while the uncritical bits are transmitted over high order M-ary signal constellation to resolve the underwater acoustic channel bandwidth limitation problem. The proposed SM-UEP technique has been developed carefully with enough justification and evaluation over the measured underwater acoustic channel and the simulated channel. The simulation results show that the proposed SM-UEP can increase the average peak signal-to-noise ratio (PSNR) of the reconstructed received image considerably, and significantly.

Receiver Algorithms for Single-Carrier OSM Based High-Rate Indoor Visible Light Communications

In intensity-modulation and direct-detection (IM/DD) multiple-input and multiple-output (MIMO) visible light communication (VLC) systems, spatial subchannels are usually correlated, and spatial modulation is a good choice to achieve the advantages of MIMO technology. Peak-to-average power ratio (PAPR) is a key issue in VLCs due to the limited linear dynamic range of light emitting diodes (LEDs). Single-carrier communication systems have a lower PAPR than orthogonal frequency division multiplexing (OFDM) communication systems. However, it is challenging to design a single-carrier spatial modulation for high-rate transmissions because of the time domain intersymbol interference. This paper develops an optical spatial modulation (OSM) scheme based on bipolar pulse amplitude modulation (PAM) and spatial elements for high-rate indoor VLC systems. Multiple data streams can be transmitted simultaneously in the proposed scheme. Based on the transmit strategy, we develop a low-complexity receiver algorithm that achieves better bit-error rate performance than reference schemes, and the proposed OSM scheme has a much lower PAPR than OFDM based OSM schemes. When the spatial subchannels are highly correlated, a spatial area division strategy is applied, and the receiver algorithm is investigated. The symbol-error rate expression of the proposed OSM scheme is derived, and the computational complexity is analyzed.

A Joint Data Mapping and Detection for High Performance Generalized Spatial Modulation

This letter proposes a novel joint data mapping generalized spatial modulation (JDM-GSM) scheme to remove the restriction on the number of active transmit-antenna (TA) combinations in conventional GSM systems. By increasing the number of active TA combinations, the constellation size for signal mapping can be reduced. Consequently, the overall bit error rate (BER) performance of the GSM system can be improved. To reduce the complexity of optimal maximum-likelihood (ML) detector, a joint compressed sensing (JCS) detector for JDM-GSM scheme is proposed. Simulation results and theoretical analysis show that the proposed scheme can be adapted to multiple-input multiple-output (MIMO) systems and achieves better BER performance than that of the conventional GSM.

A Low-Complexity Maximum Likelihood Detector for the Spatially Modulated Signals: Algorithm and Hardware Implementation

Aiming to increase the transmission data rate, the spatial modulation (SM) scheme maps each block of information bits to a digitally modulated symbol and additionally a transmit antenna index in a multiple transmit antenna system. In this brief, we focus on the maximum likelihood detection (MLD) scheme that detects SM signals with low computational complexity. By reformulating the MLD problem, we obtain a new mathematical expression as the MLD solution. To avoid the numerically unstable division operation, we apply the Givens rotation to realize this new expression and obtain a low-complexity MLD algorithm. We also propose a coordinate rotation digital computer-based hardware architecture to detect SM signals with 64-quaternary amplitude modulated (QAM) symbols over the correlated channel with eight transmit antennas and four receive antennas. The VLSI implementation results under the TSMC 90-nm CMOS technology reveal that our division-free architecture requires 70.5K gates and provides detection throughput 432.68 Mb/s, while operating at frequency 384.6 MHz. Our design is the first hardware architecture to achieve the exact MLD performance and is easily modified to detect SM signals with arbitrary ${M}$ -ary QAM symbols and arbitrary numbers of transmit and receive antennas.

Spatial Modulation With Multi-Dimensional Constellations

Quadrature spatial modulation (QSM) was proposed to strengthen conventional SM by creating a new spatial constellation dimension. Inspired by that, we present a spatial modulation scheme which expands spatial constellation to a new dimension and utilizes the spatial dimension to transmit multi-dimensional constellation signals. In the proposed scheme, Gallager mapping is used for spatial mapping to increase the transmission rate in spatial domain. The design method of multi-dimensional constellations is also described in this letter. We investigate both 5G LDPC codes and nonbinary LDPC codes with the designed multi-dimensional constellations. Simulation results show that the proposed scheme can achieve significant performance gains.

Code-Index Modulation Aided Quadrature Spatial Modulation for High-Rate MIMO Systems

In this correspondence paper, a novel code-index modulation (CIM) aided quadrature spatial modulation (QSM) scheme, called CIM-QSM, is proposed for highly spectrum and energy efficient multiple-input multiple-output (MIMO) systems. The CIM-QSM scheme transmits information over three different transmit entities: modulated symbols, activated antenna indices, and spreading code indices. Hence, a higher efficiency in terms spectrum and energy use, and better error performance compared to the conventional direct sequence spread spectrum, spatial modulation (SM), QSM, and CIM aided SS (CIM-SS) schemes are obtained by the CIM-QSM technique for MIMO communication systems. Analytical expressions for the average bit error rate, energy efficiency, and throughput of the CIM-QSM system are performed and the theoretical results are validated with Monte Carlo simulation results.

Digital Orthogonal-Filters Enhanced Spatial Modulation for High-Speed Indoor Optical Wireless Communications

Spatial modulation (SM) has been proposed and studied in high-speed indoor optical wireless communication systems to improve the spectral efficiency and system capacity by exploring the spatial domain information of transmitters. However, the correct detection of active transmitter(s) is critical, and it typically requires precise channel state information (CSI) and low correlation between channel gains. To overcome this limit, in this paper an orthogonal-filters enhanced SM scheme is proposed for high-speed indoor optical wireless communication systems, where the use of orthogonal-filters can improve the correct detection of active transmitter(s) significantly. The proposed scheme is experimentally demonstrated, and results show that with 4-pulse amplitude modulation (PAM-4) and two transmitters, 7.5 Gb/s optical wireless data transmission is achieved with 2.5 GS/s symbol rate. The power penalty of proposed scheme on the receiver sensitivity is negligible, and the active transmitter(s) can be correctly detected even under high channel correlations and without CSI. The scalability of proposed orthogonal-filters enhanced SM scheme is also studied, and it is shown that higher dimensions can be realized to achieve higher spectral efficiency, which provides a promising solution in indoor optical wireless communications to achieve ultra-high bit rate.

On the Secrecy Rate of Spatial Modulation-Based Indoor Visible Light Communications

In this paper, we investigate the physical-layer security for a spatial modulation (SM) based indoor visible light communication (VLC) system, which includes multiple transmitters, a legitimate receiver, and a passive eavesdropper (Eve). At the transmitters, the SM scheme is employed, i.e., only one transmitter is active at each time instant. To choose the active transmitter, a uniform selection (US) scheme is utilized. Two scenarios are considered: one is with non-negativity and average optical intensity constraints, the other is with non-negativity, average optical intensity and peak optical intensity constraints. Then, lower and upper bounds on the secrecy rate are derived for these two scenarios. Besides, the asymptotic behaviors for the derived secrecy rate bounds at high signal-to-noise ratio (SNR) are analyzed. To further improve the secrecy performance, a channel adaptive selection (CAS) scheme and a greedy selection (GS) scheme are proposed to select the active transmitter. Numerical results show that the lower and upper bounds of the secrecy rate are tight. At high SNR, small asymptotic performance gaps exist between the derived lower and upper bounds. Moreover, the proposed GS scheme has the best performance, followed by the CAS scheme and the US scheme.

Optical Spatial Modulation for FSO IM/DD Communications With Photon-Counting Receivers: Performance Analysis, Transmit Diversity Order and Aperture Selection

This paper investigates two pulse-based Optical Spatial Modulation (OSM) schemes as cost-efficient solutions for multi-aperture Free-Space Optical (FSO) communications with Intensity-Modulation and Direct-Detection (IM/DD). Namely, we consider Optical Space Shift Keying (OSSK) where information is encoded in the index of the pulsed optical source and Spatial Pulse Position Modulation (SPPM) where additional bits determine the position of the transmitted optical pulse resulting in higher transmission rates. A performance analysis is carried out over gamma-gamma channels with the exact Poisson photon-counting detection model. Exact Symbol Error Probability (SEP) expressions, simple upper bounds and the achievable transmit diversity orders are derived for both the open-loop and closed-loop scenarios. Based on the presented performance analysis, a transmit aperture selection scheme capable of maximizing the transmit diversity order is proposed for OSSK and SPPM in the closed-loop case. Results show that for open-loop OSSK, open-loop SPPM and closed-loop OSSK, the transmit diversity order does not depend on the severity of scintillation unlike the closed-loop SPPM case.

Large-System Mutual Information Analysis of Receive Spatial Modulation in Correlated Multi-Cell Massive MIMO Networks

In this paper, the receive spatial modulation (RSM) scheme is studied in the downlink of the multi-cell multi-user systems, assuming that the base station (BS) is equipped with a large number of antennas and serves a large number of multi-antenna users, while the user-antenna ratio is bounded. The system model is practical and applicable in a comprehensive manner, accounting for channel estimation, spatially correlated channels, pilot contamination, and path loss. Combining the concepts of RSM and massive multiple-input multiple-output (MIMO), the spectral efficiency of linear preprocessing zero-forcing (ZF) and regularized ZF (RZF) methods is studied by approximating the probability of antenna detection and deriving a lower bound for the spatial-domain mutual information. With the aid of the large-system analysis, the deterministic equivalent expressions are provided for the achievable rates that are asymptotically exact. The Monte Carlo simulations validate this claim and show that for limited dimensions, the proposed deterministic equivalents yield accurate approximations, even for strongly correlated channels. The results further show that in comparison with the conventional massive MIMO systems with single-antenna users, equipping each user with multiple antennas and applying the RSM scheme enhances the spectral efficiency when each cell is not heavily loaded.

Performance Analysis of Repeated Index Modulation with Coordinate Interleaving over Nakagami-m Fading Channel

In this paper, a new Space-Time Block Coded Spatial Modulation (SM) scheme based on the Golden Code, called the In this paper, we evaluate the symbol error performance of an extended Index Modulation for Orthogonal Frequency Division Multiplexing (IM-OFDM), namely repeated index modulation-OFDM with coordinated interleaving (abbreviated as ReCI), over the Nakagami-m fading channel. The ReCI system attains higher error performance than the conventional IM-OFDM with coordinate interleaving (IMOFDM-CI). In order to investigate the system performance over the Nakagami-m fading channel, we derive the closed-form expressions for the symbol error probability (SEP) and the bit error probability (BEP). The analytical results give interesting insights into the dependence of SEP on system parameters. Their tightness is also validated by numerical results, which show that our proposed scheme can provide considerably better error performance than the conventional IM-OFDM and IM-OFDM-CI at the same spectral efficiency. DOI: 10.32913/mic-ict-research.v2019.n1.863

Performance Analysis of Repeated Index Modulation with Coordinate Interleaving over Nakagami-m Fading Channel

In this paper, a new Space-Time Block Coded Spatial Modulation (SM) scheme based on the Golden Code, called the In this paper, we evaluate the symbol error performance of an extended Index Modulation for Orthogonal Frequency Division Multiplexing (IM-OFDM), namely repeated index modulation-OFDM with coordinated interleaving (abbreviated as ReCI), over the Nakagami-m fading channel. The ReCI system attains higher error performance than the conventional IM-OFDM with coordinate interleaving (IMOFDM-CI). In order to investigate the system performance over the Nakagami-m fading channel, we derive the closed-form expressions for the symbol error probability (SEP) and the bit error probability (BEP). The analytical results give interesting insights into the dependence of SEP on system parameters. Their tightness is also validated by numerical results, which show that our proposed scheme can provide considerably better error performance than the conventional IM-OFDM and IM-OFDM-CI at the same spectral efficiency.

Joint spatial modulation and beamforming based on statistical channel state information for hybrid massive MIMO communication systems

Spatial modulation is a promising transmission scheme for massive multiple-input multiple-output (MIMO) systems to improve energy efficiency. In this study, considering the low-complexity hybrid structure, the authors propose a joint spatial modulation and beamforming scheme for a hybrid massive MIMO system in both single user and multi-user scenarios. Specifically, a design criterion of the channel control parameter is provided to reduce the high correlation among different channel coefficients in the hybrid massive MIMO system. In addition, with the statistical channel state information acquired at the base station, the optimum analogue beamforming vectors are designed with the goal of maximising the signal to leakage and noise ratio in the multi-user scenario. Furthermore, the upper bound, the lower bound as well as the closed form approximation of achievable spectral efficiency of the proposed scheme are derived for both single user and multi-user scenarios. Numerical simulation results demonstrate that the proposed scheme outperforms the conventional MIMO scheme.

Generalized Precoding-Aided Spatial Modulation via Receive Antenna Transition

Receive antenna transition, which implies the transition of the active receive antennas during a symbol period, is investigated in this letter to enhance the error performance of the generalized precoding-aided spatial modulation (GPSM). Specifically, the precoding at the transmitter alters once at the midpoint of a symbol duration such that one group of active receive antennas transfers to another group. The antenna transition pattern is then capable to deliver extra spatial information bits. The proposed GPSM scheme has two main advantages. First, the system reliability is remarkably improved. Second, it requires less receive antennas to achieve the same spectral efficiency compared with the existing precoding-aided spatial modulation (PSM) and GPSM schemes. An analytical upper bound on average bit error probability of the proposed scheme is derived by exploring the Wishart distribution feature of the channel matrix and the Gamma approximation. Numerical results validate our analysis and show that the proposed scheme outperforms the existing PSM and GPSM schemes in terms of system reliability.

Adaptive Macro Spatial Modulation for mmWave Dense Networks

In this letter, an adaptive macro spatial modulation scheme is proposed for the uplink of a millimeter-wave dense network. In the proposed scheme, a user equipment (UE) adaptively establishes communication links with multiple small base stations (SBSs) and switches its beam direction between these SBSs according to part of its transmitting information. We first model the optimal signal transmission scheme that minimizes system symbol-error rate (SER) as an optimization problem and propose an iterative method with relative high computational complexity to solve it. To reduce the complexity, an approximation scheme is also provided, by ignoring the side lobe of the UE. Numerical results show that both proposed schemes can effectively reduce the system SER.

Spatial and directional modulation with scrambling

In this paper, a novel spatial and directional modulation scheme with scrambling (SDM-S) is proposed toward secure wireless transmission. Compared to the conventional directional modulation scheme with cooperative receivers (DM-CR), the proposed SDM-S scheme is capable of increasing the throughput without degrading the secrecy performance. Specifically, we introduce a scrambling matrix to impose barrier for the eavesdropper and introduce the concept of spatial modulation (SM) to directional modulation (DM) systems for the sake of increasing the system throughput. Furthermore, an upper bound is derived to theoretically analyze the average bit error probability (ABEP) of the proposed scheme. Our performance results demonstrate that, the proposed SDM-S scheme is capable of increasing the throughput than its conventional DM-CR counterpart, while guaranteeing the information security regardless of the location or direction of the eavesdropper.