Scaled Selection Combining for SSK in Decode and Forward Cooperative Relaying

Space Shift Keying (SSK) is a multiple-input multiple-output technique that has drawn more attention in recent years because of its low complex transceiver design. In this paper, an investigation on the Symbol Error Probability (SEP) performance of SSK in a Decode-and-Forward (DF) cooperative relaying system is done. The DF cooperative relaying scenario considers an origin node, an intermediate node and an end node with a direct link between origin and end node, and an indirect link between origin to the intermediate node and intermediate to end node. The SSK modulation is considered at the origin and intermediate nodes with Full Euclidean Distance based Selection Combining (FED-SC) employed at the end node for SSK symbol detection. The SEP expression of the SSK FED-SC in the DF cooperative relaying scheme is derived using the Order Statistics Approach (OSA). Further, a closed-form SEP expression is obtained using a Combined Order Statistics Approach (COSA) considering the number of receive antennas at the intermediate node is equal to the number of receive antennas at the end node. In addition, the closed-form asymptotic SEP expression is presented to evaluate the diversity order of the system. The SEP expressions derived through OSA and COSA are verified using the Monte Carlo simulations. The simulation results revealed that the proposed SSK FED-SC outperforms all the existing SSK DF cooperative selection combining schemes.

Analysis of SWIPT based dual-hop AF relay with SSK modulation over Nakagami-m fading channel

Visible light communication (VLC) is considered a breakthrough wireless communication technology that has been proven capable of achieving very high data rates. This is a key advantage in indoor communication scenarios, since the vast majority of wireless traffic is witnessed in indoor communications. In every wireless system, the trade-off between achievable throughput, transmit signal power and corresponding error rate performance is largely dependent upon the considered modulation format. This is also the case in VLC systems, which are typically characterized by stringent performance requirements. Motivated by this, in the present contribution we introduce the space shift keying (SSK) modulation scheme in the context of non-orthogonal-multiple-access (NOMA) communications, which have been shown to be a performance enhancer of indoor based VLC systems. Based on this, all network users in the considered set up receive the same superimposed signal of all NOMA users, which is transmitted from the activated transmitters corresponding to the multiplexed SSK users information. Based on this and assuming a unique maximum likelihood detection, we quantity the system performance in terms of the corresponding bit error rate (BER) performance at each receiver. This analysis leads to the development of useful insights of theoretical and practical interest, which are expected to be useful in the effective design, implementation and deployment of SSK in NOMA based VLC systems.

In this letter, we propose a cooperative multiple-input multiple-output (MIMO) scheme combining transmit antenna selection (TAS) and space shift keying (SSK). In this scheme, source transmit antennas are selected and SSK is applied by using the selected antennas. Besides the direct link transmission, the relays, that decode the source signal correctly, take part in the transmission. Exact expressions and a considerably accurate approximate expression for the symbol error rate of the proposed SSK system are derived. It is shown that the proposed scheme outperforms the SSK system without TAS and also the conventional cooperative MIMO system, which employs source TAS, at practical signal-to-noise ratio values for especially high data rates and sufficient number of receive antennas at the destination.

In this paper, transmit antenna selection (TAS) is applied to space shift keying (SSK) modulation to obtain diversity gain. The receiver selects a transmit antenna subset in each transmission block according to the channel state information (CSI) and sends the subset index to the transmitter through feedback. Several antenna selection schemes are evaluated for SSK from perspectives of performance, feedback overhead and complexity. A greedy transmit antenna selection scheme is proposed to reduce the computation complexity, which shows almost the same performance as exhaustive search. In the special case that the number of active antennas equals two, an antenna selection scheme with one transmit antenna fixed (Fix-1 scheme) is proposed to reduce the amount of feedback, whose exact bit error ratio (BER) performance is derived. Through asymptotic BER analysis we show that Fix-1 scheme has the same diversity order as exhaustive search.

Space shift keying (SSK) is a special case of spatial modulation (SM), which is a relatively new modulation technique that is getting recognized to be attractive in multi-antenna communications. Our new contribution in this paper is an analytical derivation of exact closed-form expression for the end-to-end bit error rate (BER) performance of SSK in decode-and-forward (DF) cooperative relaying. An incremental relaying (IR) scheme with selection combining (SC) at the destination is considered. In SSK, since the information is carried by the transmit antenna index, traditional selection combining methods based on instantaneous SNRs can not be directly used. To overcome this problem, we propose to do selection between direct and relayed paths based on the Euclidean distance between columns of the channel matrix. With this selection metric, an exact analytical expression for the end-to-end BER is derived in closed-form. Analytical results are shown to match with simulation results.

In this letter, we present a reconfigurable intelligent surface (RIS)-assisted space shift keying (SSK) modulation and reflection phase modulation (RPM) scheme, where RIS embeds its own information in the reflection phase shift of the reflected radio frequency (RF) signal. More specifically, the RIS simultaneously performs two tasks: i) reflecting the impinging RF signal with a discrete phase shift and ii) embedding the information bits in the phase shift. We perform joint detection for the RPM and SSK symbols using a maximum likelihood detector, and a unified analytical framework is presented for theoretical analysis of the average bit error rate (ABER) and ergodic capacity of the proposed scheme. All numerical results are thoroughly verified through Monte Carlo simulation. Numerical results reveal that the proposed scheme outperforms the conventional SSK scheme.

In recent years, multiple-input-multiple-output communication has a great demand due to its flexibility and well technical implementation. Though it has been approached by many researchers, in this paper, authors taken an approach with Nakagami-m fading channel as it is a generalized fading channel for the performance of space shift keying (SSK) modulation. Simple closed form expression for the probability of bit error of SSK modulation is presented using probability density function based method for independent and identically distributed (IID) Nakagami-m fading channel. An upper bound expression for IID and correlated Nakagami-m fading channel is also presented. Obtained probability of error are in the form of Gauss hypergeometric function, confluent hypergeometric function and Gamma function which can be numerically evaluated and verified by Monte Carlo simulation.

Performance analysis of space shift keying for AF relaying with relay selection

This paper provides an insightful discussion on the performance analysis of multiple-input multiple-output (MIMO) space modulation scheme. A mathematical expression for the average bit error probability of Space shift keying (SSK) with generalized selection combining (GSC) diversity scheme is presented. SSK modulation scheme uses antenna index for relaying information rather than symbol modulation. Due to the nature of the SSK transmission scheme, it is difficult to distinguish a transmitted pulse from two correlated branches at each receive antenna, if the correlation between the transmitted RF pulses from two different transmit-antennas is more. Under this circumstances, its bit error rate performance is severely degraded even though SNR is high. In general, SSK receiver employs maximal ratio combining (MRC) diversity scheme. The MRC diversity scheme is the optimal combining scheme which maximizes the SNR at the combiner output. However, MRC requires high signal processing complexity and more number of RF chains at the receiver end, which in turn, it consumes more power. It also needs the knowledge of the channel fading amplitude and phase for constructive combining. Analytical and simulation results show that the difference in the performance of SSK with MRC and GSC is insignificant.

In this letter, we consider an $N_{r} \times N_{t}$ multiple-input–multiple-output system in which $M$ -ary phase shift keying (MPSK) and space shift keying (SSK) are used in successive time slots. We call this system time successive SSK-MPSK (TSSM), and we show that this system achieves a transmit diversity order of 2. In TSSM, during the first time slot, information is transmitted with MPSK symbols using all $N_t$ transmitter antennas, with each antenna using $N_{t}^{\textrm{th}}$ of the total transmitter power. During the second time slot, SSK modulation is used to transmit the same information. We further derive the optimal detection criterion, pairwise error probability, and the average union bound of the bit error rate (BER) of TSSM. We show the diversity order using asymptotic approximation of the average union bound of the BER of TSSM. We compare the BER of TSSM with that of time orthogonal signal design assisted SSK, coherent space time shift keying, and other schemes. The simulation results show that TSSM performs considerably better.

In this article, space shift keying (SSK) modulation is used to study a wireless communication system when multiple relays are placed between the transmitter and the receiver. In SSK, the indices of the transmit antennas form the constellation symbols and no other data symbol are transmitted. The transmitter and the receiver communicate through a direct link and the existing relays. In this study, two types of relays are considered. Conventional amplify and forward relays in which all relays amplify their received signal and forward it to the destination in a round-robin fashion. In addition, decode and forward relays in which the relays that correctly detect the source signal will forward the corresponding fading gain to the destination in pre-determined orthogonal time slots are studied. The optimum decoder for both communication systems is derived and performance analysis are conducted. The exact average bit error probability (ABEP) over Rayleigh fading channels is obtained in closed-form for a source equipped with two transmit antennas and arbitrary number of relays. Furthermore, simple and general asymptotic expression for the ABEP is derived and analyzed. Numerical results are also provided, sustained by simulations which corroborate the exactness of the theoretical analysis. It is shown that both schemes perform nearly the same and the advantages and disadvantages of each are discussed.

In this paper, we propose space-polarization shift keying (SPSK) modulation scheme for multiple-input multiple-output (MIMO) systems employing dual-polarized antenna array, where the concept of space shift keying (SSK) is extended to include both the space and polarization dimensions. In the SPSK, polarization index also been used to relay the information along with the antenna index. As a result, the proposed transmission scheme reduces the signal processing complexity at the receiver exponentially when compared to the SSK scheme, for a given target transmission rate. In this correspondence, we investigate the performance of $$ 4\times 4 $$4×4 SPSK---MIMO configurations over different wireless channel scenarios for a range of values of the correlation coefficient and the Rician K-factor. We also highlight the effect of random orientation of antennas at the mobile unit on the bit error rate performance of SSK and SPSK transmission scheme. By using analytical results and simulations, we show that the proposed scheme outperforms the SSK scheme under line-of-sight channel conditions and its performance is comparable to SSK under non-line-of-sight channel conditions, for various receive-antenna inclination angle.

Spatial modulation (SM) is a novel and promising approach that has been introduced as an alternative to classical multiple-input multiple-output (MIMO) spatial multiplexing techniques. Cooperative communications, on the other hand, provides additional diversity gains and high data rates by improving coverage. Combining the advantages of SM and cooperative communications would then further improve efficiency. Most of the studies in the literature of cooperative SM systems consider the space shift keying (SSK) modulation, which is a special case of SM, and single receive/transmit antenna relay (R) and destination (D). In this work, we investigate the average bit error probability (ABEP) of a decode-and-forward (DF) cooperative SM system where all nodes have multiple transmit and/or receive antennas which has not been studied before. It is shown that the derived analytical expressions for the ABEP are in close match with the computer simulation results. Furthermore, it is demonstrated that the cooperative SM scheme provides 4 dB SNR gain compared to classical M-ary modulated cooperative systems.

Space shift keying (SSK) modulation and its extension, the generalized SSK (GSSK), present an attractive framework for the emerging large-scale MIMO systems in reducing hardware costs. In SSK, the maximum likelihood (ML) detector incurs considerable computational complexities. We propose a compressed sensing based detector, NCS, by formulating the SSK-type detection criterion as a convex optimization problem. The proposed NCS requires only O(ntNrNt) complexity, outperforming the O(NrNtnt) complexity in the ML detector, at the cost of slight fidelity degradation. Simulations are conducted to substantiate the analytical derivation and the detection accuracy.