On Media-Based Modulation Using RF Mirrors

Media-based modulation (MBM) is a recently proposed modulation scheme which uses radio frequency (RF) mirrors at the transmit antenna(s) in order to create different channel fade realizations based on their ON/OFF status. These complex fade realizations constitute the modulation alphabet. MBM has the advantage of increased spectral efficiency and performance. In this paper, we investigate the performance of some physical layer techniques when applied to MBM. Particularly, we study the performance of i) MBM with generalized spatial modulation (GSM), ii) MBM with mirror activation pattern (MAP) selection based on an Euclidean distance (ED) based metric, and iii) MBM with feedback based phase compensation and constellation rotation. Our results show that, for the same spectral efficiency, GSM-MBM can achieve better performance compared to MIMO-MBM. Also, it is found that MBM with ED-based MAP selection results in improved bit error performance, and that phase compensation and MBM constellation rotation increases the ED between the MBM constellation points and improves the performance significantly.

The idea of media-based modulation (MBM), introduced in [1] [2], is to embed information in the variations of the transmission media (channel states). This is in contrast to legacy wireless systems which embeds data in a radio frequency (RF) source prior to the transmit antenna. MBM offers several advantages over legacy systems, including “additivity of information over multiple receive antennas” and “inherent diversity over a static fading channel”. MBM is particularly suitable for transmitting high data rates using a single transmit unit and multiple receive antennas (single input multiple output MBM, or SIMO-MBM). Furthermore, layered multiple input multiple output MBM (LMIMO-MBM) [3] addresses hardware and decoding complexity along with training overhead when transmitting high data rates using a single MBM transmit unit. The current article compares the performance of MBM and LMIMO-MBM vs. legacy multiple input multiple output (MIMO) and emerging modulation techniques, spatial modu-lation (SM), and its variants, such as generalized SM (GSM) and quadrature SM (QSM). These comparisons demonstrate considerable performance gains for MBM and LMIMO-MBM vs. these notable schemes.

Media-based modulation (MBM) is an attractive modulation scheme that offers MIMO benefits by placing digitally controlled parasitic elements as radio frequency (RF) mirrors near the transmit antenna. Different realizations of the ON/OFF status of these mirrors result in different channel fades which constitute the channel modulation alphabet. In this paper, we investigate full-duplex (FD) communication using MBM. First, we study full-duplex MBM (FD-MBM) scheme with full channel state information (CSI). Our numerical results show that, for the same spectral efficiency, FD-MBM outperforms FD with conventional modulation (FD-CM). Next, in order to relax the full CSI assumption, we investigate FD with differential MBM (FD-DMBM) with no CSI/partial CSI, where partial CSI refers to the availability of either self-interference CSI or desired-signal CSI. We propose detectors for the FD-DMBM with no CSI/partial CSI and illustrate their bit error performance.

Compressive sensing based multiuser detector for massive MBM MIMO uplink

In this paper, we introduce and analyze the performance of a two-hop three-node full-duplex (FD) relay network, where the source and relay nodes transmit using media-based modulation (MBM). An MBM is a promising new modulation scheme that conveys information bits by digitally controlling the parasitic elements (known as radio frequency mirrors) placed near the transmit antenna. The relay uses decode-and-forward relaying protocol. We refer to this system as FD relaying system with MBM (FDR-MBM). We first derive an upper bound on the end-to-end average bit error probability of FDR-MBM with maximum-likelihood detection at the relay and destination nodes. The bound is increasingly tight with increasing signal-to-noise ratios. Numerical results show that, for the same spectral efficiency, FDR-MBM can perform better than FD relaying using conventional modulation schemes. We then derive the diversity order achieved in FDR-MBM. The analytically predicted diversity orders are validated through simulations. Finally, we derive lower and upper bounds on the achievable rate in FDR-MBM.

Efficient constellation design is important for improving performance in communication systems. The problem of multidimensional constellation design has been studied extensively in the literature in the context of multidimensional coded modulation and space-time coded MIMO systems. Such constellations are formally called as lattice codes, where a finite set of points from a certain high dimensional lattice is chosen based on some criteria. In this paper, we consider the problem of constellation/signal set design for media-based modulation (MBM), a recent MIMO channel modulation scheme with promising theoretical and practical benefits. Constellation design for MBM is fundamentally different from those for multidimensional coded modulation and conventional MIMO systems mainly because of the inherent sparse structure of the MBM signal vectors. Specifically, we need a structured sparse lattice code with good distance properties. In this work, we show that using an (N,K) non-binary block code in conjunction with the lattice based multilevel squaring construction, it is possible to systematically construct a signal set for MBM with certain guaranteed minimum distance. The MBM signal set obtained using the proposed construction is shown to achieve significantly improved bit error performance compared to conventional MBM signal set. In particular, the proposed signal set is found to achieve higher diversity slopes in the low-to-moderate SNR regime.

Mirror activation pattern (MAP) in media-based modulation (MBM) refers to the ON/OFF status of radio-frequency mirrors, which create different near field geometries for different ON/OFF combinations. In this letter, we introduce a novel coding scheme for MBM in which indices are assigned to MAPs, such that these indices are used as labels for the elements in a Galois field. The MAP indices are then coded across time, and the block transmission is carried out. The resulting signal set has good distance distribution, which leads to good bit error performance. Structured sparse matrix sketching-based signal detection algorithms for the proposed scheme are presented.

Media-based modulation (MBM) is a new and promising transmission scheme that employs reconfigurable antennas to create different channel fade realizations and appears as an emerging index modulation (IM) application. In this paper, we present a novel multiple-input multiple-output (MIMO) transmission scheme called multidimensional media-based modulation (M-MBM) by redesigning the classical Alamouti's space-time block coding (STBC) scheme with MBM through the use of the additional dimension of channel states. The error performance of the proposed M-MBM scheme is theoretically analyzed for correlated and uncorrelated channel states and a union bound is obtained for the average bit error probability (ABEP). Moreover, through computer simulations, the superior error performance of the M-MBM scheme over the emerging IM techniques is demonstrated.

For reducing the complexity of equalization, linear equalization can be adopted for generalized spatial modulation (GSM) which is a special case of multiple-input-and-multiple-output (MIMO). However, because of its inferior performance, linear equalization may be infeasible for practical GSM systems which has large number of antennas and constellation. On the other hand, lattice-reduction (LR) is an effective method to improve the performance of linear equalization. The lattice reduction can’t be utilized by GSM directly, because signals on some antennas don’t exist. For tackling this problem, we propose a compatible 8-QAM constellation scheme integrating LR-aided linear equalization with GSM effectively. Next, we prove that LR-aided linear equalizers collect the same diversity order as that exploited by the ML detector under Rayleigh fading channels, and implement some simulations. Simulation results show the superior of the proposed 8-QAM over traditional 4-QAM and 8-QAM under Rayleigh fading channel. Moreover, our scheme obtains the full receive diversity under correlated channel.

Massive multiple‐input multiple‐output (MIMO) systems with hundreds of correlated antennas at base station are capable of offering abundant spatial resources. When spatial‐domain modulation is applied to these systems, the spatial modulation (SM) using only one radiofrequency chain benefits practical implementation, but suffers from significantly reduced multiplexing gain offered by the massive number of antennas. By contrast, the generalised SM (GSM) allows to simultaneously activate multiple transmit antennas, which improves spatial multiplexing gain, but degrades the achievable error performance, as its design pays no attention to the antenna correlation. The authors propose an antenna grouped SM (GrSM) scheme, which is capable of circumventing the shortcomings of both the SM and GSM schemes suffered in massive MIMO scenarios. In the proposed GrSM scheme, transmit antennas are partitioned into multiple groups, where the relatively strongly correlated antennas within individual groups are used to implement component SM schemes, while the relatively weakly correlated antennas in different groups are beneficial to obtain multiplexing gain. In order to further improve the spectral efficiency, adaptive modulation is integrated with GrSM to form the adaptive GrSM (AGrSM). The achievable error and spectral efficiency performance of GrSM and AGrSM systems are investigated based on both mathematical analysis and Monte‐Carlo simulations, which are also compared with that of the conventional SM and GSM schemes, when massive MIMO communication scenarios are considered. Their studies and performance results show that GrSM is a promising transmit scheme for massive MIMO, which can outperform both the SM and GSM schemes.

This paper explores the optimal number of antennas within generalized spatial modulation (GSM) scheme with single and multiple radio frequency (RF) chains. The main focus of our work is on the number of total transmit antennas and active transmit antennas as per the GSM transmission, that optimizes the system's power efficiency. Accordingly, the bandwidth efficiency of the transmission and receiver complexity are analytically calculated. The performance of the multiple-RF-chain GSM scheme is compared with SM and GSM. Moreover, Monte Carlo simulations are carried out to analyze and verify the analysis of power efficiency as a function of the number of transmit antennas.

The concept of generalized spatial modulation (GenSM) aided millimeter wave (mm-wave) multiple-input multiple-output (MIMO) has recently attracted substantial research interest, as it benefits from the large bandwidth of mm-wave MIMO, while maintaining a reduced number of radio frequency (RF) chains. However, due to the lack of precoding design, the preceding GenSM-aided mm-wave MIMO schemes suffered from severe performance loss. Inspired by the reduced-RF-chain structure making implementation cost low while maintaining the benefit of GenSM, in this paper, we incorporate the technique of hybrid precoding into GenSM-aided mm-wave MIMO, where a hybrid digital and analog precoding regime is proposed to enhance the system's achievable rate. Moreover, a closed-form expression is proposed to provide an accurate approximation to the spectral efficiency (SE) achieved by the proposed scheme. The proposed expression is further simplified in the region of high signal-to-noise ratio (SNR). By exploiting the proposed SE expressions as low-complexity cost functions, two algorithms, i.e. the gradient ascent algorithm and the high-SNR approximation algorithm, are exploited to optimize the hybrid precoders in terms of SE maximization. Finally, numerical simulations are provided to substantiate the superior SE performance achieved by the proposed scheme over other GenSM-aided mm-wave MIMO schemes as well as the state-of-the-art mm-wave MIMO systems.

Reconfigurable intelligent surface (RIS) is highly promising to be applied to enable media-based modulation (MBM) transmissions, which is expected to greatly reduce the hardware cost at the transmitter. In this paper, we propose the two MBM schemes for RIS communications, which are non-differential and differential schemes. In the non-differential scheme, we utilize the phase variations of the RIS to achieve a higher transmission rate compared to the conventional MBM schemes with radio frequency (RF) mirrors. Particularly, in the differential scheme, we decompose the space time block (STB) matrix into a phase state space (PSS) matrix and a selection-permutation (SP) matrix for enhancing the flexibility of differential modulation. The proposed treatment breaks through two inherent design limitations in the traditional differential space time block code (DSTBC). Moreover, the upper bound on the average symbol error rate (SER) of both schemes are derived. Finally, the theory and simulation results show that our proposed schemes can achieve higher transmission rates than the benchmark schemes.

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.

In this letter, we propose a novel bit-to-symbol mapping for generalized spatial modulation (GSM) in visible light communication (VLC) systems. The proposed mapping first sorts the GSM symbol pairs according to their Euclidean distance (ED) and then iteratively assigns each GSM symbol to the bit sequence that satisfies the Gray codes. We also present an exhaustive sorting method and a reduced-complexity sorting method which can be used to obtain an effective mapping algorithm. Our simulation results show that the proposed ED-based mapping outperforms the conventional mapping rule for the GSM MIMO-VLC systems.