A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> This paper proposes and studies a transmitter preprocessing aided spatial modulation (PSM) scheme, which conveys information jointly by a conventional amplitude-phase modulation (APM) and a preprocessing aided space shift keying (pre-SSK) modulation. In contrast to the existing SSK modulation, which carries information using the indexes of transmitter antennas and assumes channel state information at receiver (CSIR), the pre-SSK modulation extracts the transmitted information using the indexes of receive antennas and assumes channel state information at transmitter (CSIT). This paper addresses the issues of preprocessing optimization and detection of PSM signals. Furthermore, the bit-error-rate (BER) performance of the PSM is investigated, when assuming that the channel from any transmit antenna to any receive antenna experiences independent Rayleigh fading. Our studies show that, when appropriately designed, the pre-SSK and APM invoked can enhance each other, resulting in that the PSM is capable of attaining a better BER performance than the corresponding pure pre-SSK and pure APM. <s> BIB001 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this paper, motivated by the relatively new concept of Spatial Modulation (SM), we are addressing the problem of Receive-Spatial Modulation (R-SM) under two cases of imperfect channel knowledge at the transmitter side. In the first case, we adopt a statistical model for the channel uncertainties, whereas in the second one a worst-case approach is followed and the channel uncertainties are expressed as a bounded set. Based on Zero-Forcing (ZF) precoding and using standard tools from optimization theory, we derive closed form solutions that turn out to be robust. Simulation results show that the proposed schemes have a performance close to the perfect channel knowledge scenario in low and mid-low SNRs. Furthermore, these designs can be applied to wide range of channels with different correlation states combined with a transmit power gain. <s> BIB002 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> A new Multiple Input Multiple Output (MIMO) transmission scheme termed as Generalised Pre-coding aided Spatial Modulation (GPSM) is proposed, where the key idea is that a particular subset of receive antennas is activated and the activation pattern itself conveys useful information. This is in contrast to the previously proposed Spatial Modulation (SM) schemes, which operated by activating a specific subset of transmit antennas. We provide both analytical and numerical results characterizing the GPSM scheme proposed for both conventional as well as for large-dimensional MIMO configurations subject to both realistic imperfect Channel State Information at the Transmitter (CSIT) and to the low-rank approximation invoked for large-dimensional MIMO configurations. We also design a so-called reinforcement matrix for attaining substantial performance improvements for our proposed GPSM scheme. Our investigations show that the GPSM scheme constitutes a flexible alternative to the state-of-the-art MIMO transmission schemes, especially because it is capable of achieving a high throughput. Moreover, the benefits of mapping information to the spatial domain rather than relying on conventional modulation has substantial benefits in the medium to high Signal to Noise Ratio (SNR) region. Quantitatively, GPSM is capable of supporting the same throughput as the conventional full-multiplexing gain based MIMO arrangements at an SNR gain of about 1dB at the same receiver complexity. Furthermore, the reinforcement matrix aided GPSM scheme attains a further 3-4dB performance improvement as compared to the conventional GPSM scheme. <s> BIB003 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> The recently proposed multiple input multiple output (MIMO) transmission scheme termed as generalized pre-coding aided spatial modulation (GPSM) is analyzed, where the key idea is that a particular subset of receive antennas is activated and the specific activation pattern itself conveys useful implicit information. We provide the upper bound of both the symbol error ratio (SER) and bit error ratio (BER) expression of the GPSM scheme of a low-complexity decoupled detector. Furthermore, the corresponding discrete-input continuous-output memoryless channel (DCMC) capacity as well as the achievable rate is quantified. Our analytical SER and BER upper bound expressions are confirmed to be tight by our numerical results. We also show that our GPSM scheme constitutes a flexible MIMO arrangement and there is always a beneficial configuration for our GPSM scheme that offers the same bandwidth efficiency as that of its conventional MIMO counterpart at a lower signal to noise ratio (SNR) per bit. <s> BIB004 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> Developed from the recently emerged generalized pre-coding aided spatial modulation (GPSM) concept, a novel non-linear GPSM scheme based on the powerful vector perturbation philosophy is proposed, where a particular subset of receive antennas is activated and the specific activation pattern itself conveys useful implicit information in addition to the conventional modulated and perturbed symbols. Explicitly, both the infinite and finite alphabet capacities are derived for the proposed non-linear GPSM scheme. The associated complexity, energy efficiency, and error probability are also investigated. Our numerical results show that, as the only known non-linear realization within the spatial modulation family, the proposed scheme constitutes an attractive solution to the flexible design of green transceivers, since it is capable of striking a compelling compromise amongst the key performance indicators of throughput, energy consumption, complexity, and performance. In particular, in the challenging full-rank scenario, conveying information through receive antenna indices exhibits a lower complexity, a higher energy efficiency, and a better error resilience than that of the conventional arrangement. <s> BIB005 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this letter, the diversity order and the coding gain of Receive Space Modulation (RSM) in the Multiple-Input Multiple-Output (MIMO) broadcast channel are derived by taking into account both small and large scale fading. The considered linear precoding method is Zero Forcing (ZF). Note that the proposed framework is directly applicable to the conventional spatially multiplexed broadcast channel. Based on the derived mathematical framework, a theoretical criterion is provided, which determines the superiority between the deployment of RSM and Spatial MultipleXing (SMX) in the shadowing MIMO broadcast channel. Finally, the provided theoretical results are validated via Monte Carlo simulation results. <s> BIB006 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> This letter generalizes the precoding-aided spatial modulation (PSM) to a multiuser (MU) downlink scenario. With precoding vectors elaborately designed, a proposed MU-PSM scheme has the capability to resist a multiple antenna eavesdropper. Specifically, signal precoding matrices (SPMs) are designed to cancel the MU interference and modulate partial information bits on the indices of receive antennas. To improve physical layer security, scrambling on SPMs is conceived to construct a fast-varying precoding matrix, which contributes to the degradation at Eve’s blind estimation and detection. Moreover, issues of detection algorithms and a lower bound of secrecy rate are addressed to verify security enhancement in the proposed scheme. <s> BIB007 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> Precoding-aided spatial modulation (PSM), which conveys information partially by the indices of receive antennas, has some advantages over conventional spatial modulation (SM) using the indices of transmit antennas. In PSM, the precoder may be optimized for different purposes. In this paper, the authors study the transmitter design in the PSM systems, which motivates to provide secrecy communications. Specifically, the authors consider a pair of communication terminals overheard by an eavesdropper. The precoder is optimized by jointly minimizing the power received by the eavesdropper and maximizing the power received by the desired terminal. Both the error performance and the ergodic secrecy rate achievable are studied when assuming communications over independent Rayleigh fading channels. The authors studies show that positive secrecy rate and low-complexity detection can be attainable simultaneously for the desired receiver even when the eavesdropper employs more receive antennas than the desired receiver. <s> BIB008 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this paper, the performance analysis of Receive Space Modulation (RSM) in the shadowing Multiple-Input Multiple-Output (MIMO) broadcast channel is presented. This is undertaken by considering Zero Forcing (ZF) precoding and both small and large scale fading. In particular, a closed form and accurate framework for the evaluation of the Symbol Error Rate (SER) is derived. In addition, the diversity order and the coding gain of the new architecture are also obtained. The derived framework can be directly extended to the conventional spatially multiplexed shadowing MIMO broadcast channel. It is shown that RSM achieves the same diversity order and, in certain scenarios which are well defined, higher coding gain than spatially multiplexing (SMX). Also, the performance difference between RSM and SMX in the shadowing broadcast channel is mathematically quantified. Finally, numerical results that verify the new framework and conclusions are provided. <s> BIB009 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this paper, we propose a novel scheme, which is called generalized precoding-aided quadrature spatial modulation (GPQSM), that extends the conventional quadrature spatial modulation to the receiver side. In GPQSM, spatial modulation works in both the in-phase and quadrature parts of the received signals, thus conveying additional information bits compared with conventional generalized precoding-aided spatial modulation (GPSM). The proposed scheme is general and can degenerate into the conventional multiple-input multiple-output (MIMO) scheme. A closed-form upper bound on the average bit error probability of GPQSM is derived. Simulation results verify the theoretical analysis and show that GPQSM outperforms the conventional GPSM scheme and the MIMO scheme under the same spectral efficiency. <s> BIB010 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this paper, we study the performance of receive spatial modulation (RSM) with simultaneous wireless information and power transfer (SWIPT) capabilities. RSM is a multi-antenna modulation scheme, where the information bits are encoded into complex constellation symbols and the indices of the receive antennas. We show how RSM can be combined with SWIPT, by allowing the receivers to increase their data rate and, at the same time, to recharge their batteries. An optimization problem is formulated in order to optimize the fraction of transmit power to be used for information decoding and energy harvesting, as well as the covariance matrix of the energy waveform. Efficient numerical algorithms to tackle the associated optimization problems are proposed. Our analysis shows that RSM-SWIPT is a flexible transmission scheme that is capable of achieving different rate-energy demands. RSM-SWIPT, in particular, can be configured to leverage only the energy waveform for transmitting information data and power simultaneously. Compared with conventional SWIPT-enabled multiple-antenna systems, the proposed RSM-SWIPT scheme increases the amount of harvested energy for low values of the rate and avoids the need of using energy cancellation algorithms if information and power are transmitted only through the energy waveform. <s> BIB011 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> We propose and investigate a precoding-aided spatial modulation (PSM) scheme, which can simultaneously achieve transmit and receive diversity and, hence, is referred to as the TRD-PSM scheme. In TRD-PSM systems, information is transmitted jointly using an amplitude-phase modulation (APM) and a receive antenna based space-shift keying (SSK) modulation. We consider two types of linear precoders, namely transmitter zero-forcing (TZF) and transmitter minimum mean-square error (TMMSE), so as to facilitate low-complexity signal detection. In order to satisfy the different requirement for complexity and reliability, we introduce/propose a range of detection algorithms, which include joint maximum likelihood detector (JMLD), simplified JMLD, successive MLD (SMLD), simplified SMLD, and ratio threshold test assisted MLD (RTT-MLD). We address the principles, characteristics, complexity and performance of these detection algorithms. Furthermore, we analyze the average bit error probability (ABEP) of the TZF- and TMMSE-assisted TRDPSM systems employing respectively the JMLD and simplified JMLD and at both small- and large-scale. Finally, numerical and simulation results are provided to demonstrate and compare the achievable performance of TRD-PSM systems employing various precoding and detection algorithms, as well as to validate the formulas derived. <s> BIB012 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> Receive antenna shift keying (RASK) is a multiple-input multiple-output transmission scheme that applies the spatial modulation concept at the receiver. Zero-forcing (ZF) precoding can be used at the transmitter side to steer the signal toward the targeted antenna. Different detection schemes can be implemented in order to detect the RASK information. Moreover, for the sake of low complexity and low power consumption, decreasing the number of RF chains by the use of switched antennas can also be implemented. In this paper, we lead a theoretical analysis of the transmission of spatial symbols in RASK, using the ZF precoding. Two detection schemes relying on maximum likelihood (ML) detection are presented and proved to be implemented as a simple single-tap detector. One, called coherent ML (CML), needs one RF chain per receive antenna and the other one, named incoherent ML (IML), is based on an envelope detector and needs only one RF chain for the entire antenna array. Theoretical expressions of the bit error rate (BER) are derived for each scheme and validated through simulation. The CML detector is demonstrated to obviously outperform the IML detector in terms of the BER but at the cost of higher complexity and power consumption. We then proposed to use switches to reduce the number of RF chains, thus trading off some performance against complexity. At some point, IML is shown to outperform CML, depending on the number of switches, RF chains, and system configuration. This turning point is analytically calculated and validated through simulations, and so can be used for further system comparison studies. <s> BIB013 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> Pre-coding aided spatial modulation (PSM) constitutes a flexible closed-loop multiple-input multiple-output transmission scheme, which attracts substantial research interest recently. In this paper, an upper bound of the average bit error probability (ABEP) for the PSM system based on the minimum mean square error (MMSE) pre-coding is investigated. In addition, a theoretical analysis is given based on the assumption that the numbers of transmit and receive antennas are large but their ratio $\theta $ is constrained. Furthermore, the theoretical analysis shows that the ABEP upper bound of the PSM system based on MMSE pre-coding depends only on ratio $\theta $ . Simulation results demonstrate that the upper bound is asymptotically tight as the signal-to-noise ratio increases, and the proposed system outperforms its benchmark that is based on zero-forcing pre-coding. <s> BIB014 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this paper, a novel unified power allocation (PA) framework is proposed for receive (pre-coding aided) spatial modulation (RSM). We find that the PA matrix design can be formulated as a non-convex quadratically constrained quadratic program (QCQP) problem, whose solution is generally intractable. To tackle this problem, we propose a pair of solvers having different trade-offs in terms of bit-error-rate and complexity. Specifically, we first propose a successive convex approximation (SCA) method, to convert the non-convex QCQP problem under consideration into a series of linear convex subproblems, where the latter can be easily solved by the classic polynomial-time-based optimization method, i.e., the interior point method. To further reduce the computational complexity, we propose an augmented Lagrangian multiplier (ALM) method, which transforms the challenging non-convex constrained PA optimization problem into its unconstrained counterpart, which can be efficiently solved by an iterative manner. Our simulation results show that both the proposed SCA and ALM methods are capable of substantially improving the system error performance compared with the conventional RSM system without PA as well as conventional PA-aided RSM schemes. <s> BIB015 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this letter, power allocation (PA) algorithms based on the minimization of the upper bound of the instantaneous bit error probability (BEP) are investigated in pre-coding-aided spatial modulation (PSM) systems. First, an upper bound of the instantaneous BEP is derived when PA is taken into account for the antennas in the PSM system. Moreover, the optimal solution of the PA matrix is derived with the aid of convex optimization techniques, in order to minimize the BEP obtained. Furthermore, a low-complexity suboptimal PA algorithm is proposed, where only the dominant part of the BEP upper bound is considered in the optimization process. Simulation results demonstrate that the proposed algorithms improve on the conventional PSM scheme. Furthermore, when the number of receive antennas is large, the performance of the low-complexity suboptimal PA algorithm is close to that of the optimal PA algorithm. <s> BIB016 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> Spatial modulation is emerging as a promising signal transmission paradigm for future wireless communications relying on massive multiple-input multiple-output (MIMO) technology. In this paper, the receive spatial modulation (RSM) is applied to the downlink of multi-user MIMO systems with the base station equipped with a massive array of antennas. Due to the significant overhead associated with acquiring channel state information at the transmitter (CSIT) of frequency-division-duplex massive MIMO systems, herein we propose a preprocessing scheme for correlated channels that reduces the channel estimation overheads. The proposed preprocessing method relies on the partial CSIT and consists of two stages of beamforming and precoding. The beamforming is accomplished via block-diagonalization to combat multi-user interference while the precoding matrix is designed by formulating optimization problems aiming to eliminate inter-antenna interference and enhancing RSM transmission performance. The design criteria of the problems include bit-error-rate minimization and discrete-input continuous-output (DCMC) capacity maximization with a transmit power constraint. The arising non-convex problems are cast as semi-definite and second-order cone programs that can be solved efficiently. The proposed schemes are readily extended to generalized RSM as the most comprehensive case in RSM-MIMO scenarios. Simulation results demonstrate that the proposed schemes outperform the imperfect-CSIT based and two-stage zero-forcing procedures and offer similar or significant performance compared to conventional MIMO counterparts at low to mid signal-to-noise ratio regimes, depending on the configurations. <s> BIB017 </s> A Survey on Spatial Modulation in Emerging Wireless Systems: Research Progresses and Applications <s> D. Receive (R)SM <s> In this letter, we propose an orthogonality structure design (OSD) for the generalized precoding aided spatial modulation (GPSM) to overcome the performance degradation caused by correlated fading channels. To improve the bit error rate (BER) performance of GPSM system, we devise an efficient receive antenna subset selection (RAS) technique relied on the mechanisms of maximizing the equivalent channel gain. To facilitate a better trade-off between performance and computational complexity, we study the peculiarities of the Hermitian matrix which provides an important insight for conceiving orthogonality conditions to the channel matrix of GPSM system. We prove that the performance gain in terms of BER can be attained with the aids of the proposed efficient RAS, and OSD-aided schemes with low-complexity. In particular, our results demonstrate that the OSD-aided scheme is capable of providing significant BER performance improvement for GPSM systems, compared to that of current strategies. <s> BIB018
As a reciprocal scheme of SM technology, RSM, a.k.a. precoding aided SM (PSM), has also received a lot of research interest due to its simplified receive structure. Specifically, by applying the concept of SM at the receiver-side, RSM utilizes the indices of receive antennas to convey spatial information in addition to conventional constellation information of PSK/QAM symbol. With the aid of transmitter precoding, RSM benefits from both high beamforming gain and low complexity design at the receiver side, which is highly desired for the downlink MIMO transmission. With the perfect CSI available at the transmitter, the initial RSM is explored in BIB001 , where both zero-forcing (ZF) and minimum mean-squared error (MMSE) pre-coding schemes are considered. Two precoding schemes for RSM under imperfect CSI at the transmitter-side are then developed in BIB002 . Moreover, the concept of RSM is also generalized by activating more than one antennas at the receiver-side BIB003 , BIB004 , in which error performance and the low-complexity detectors are investigated. In BIB005 , a non-linear RSM scheme is developed with the leverage of vector perturbation, which conveys implicit information via the activation pattern at the receiver-side. The authors of BIB012 develop a new RSM scheme to achieve both transmit and receive diversity, where several associated detection algorithms are introduced to meet different requirements in terms of complexity and reliability. To reduce the significant channel estimation overheads required at the transmitter, a two-stage RSM based on partial CSI is proposed in BIB017 for correlated channels. Moreover, to overcome the performance degradation due to the channel correlation, an orthogonality structure is designed for generalized RSM BIB018 . Based on the ML criterion, both coherent and incoherent detection schemes are studied in BIB013 , which are then simplified to the single-tap detection problem. More recently, the performance of RSM in various application scenarios are also studied and discussed. An upper bound on the error performance of the MMSE-based RSM system is derived in BIB014 . In BIB015 - BIB016 , the power allocation problem for RSM is formulated, where new approximate solutions are proposed to achieve a higher performance gain. The error performance, diversity order, and coding gain of RSM under the shadowing MIMO channel are analyzed in BIB009 and BIB006 . In  , the integration of multi-stream RSM under a broadcast channel is studied for the multi-user scenario, where the error performance, diversity order, and coding gain are derived. The authors of BIB010 develop an amalgamated scheme of QSM and RSM and derive a closed-form upper bound on its error performance. Moreover, the designs of RSM for secure communication are also considered in BIB007 - BIB008 . In BIB011 , the integration of RSM into the simultaneous wireless information and power transfer system is studied, where the rate-energy trade-off problem is revealed with performance optimization.