Space-time Block-coded Systems Research Articles

Evaluation of the security performance of artificial noise‐aided STBC systems

AbstractIn this paper, the security performance of artificial noise (AN)‐aided space time block coding (STBC) systems in wiretap channel is evaluated. The security performance is estimated in terms of the secrecy rate, which is defined as the difference of mutual information of the legitimate receiver and illegal eavesdropper. We derive a generalized secrecy rate formula for the system utilizing AN‐aided STBC, and also provide an expression for the approximated value with which the estimation time can be highly reduced. The simulation results reveal that the approximated formula well matches to the full estimation with a few orders of less complexity. In addition, it is proved that the maximum achievable secrecy rate for M‐ary modulation scheme approaches to bps/Hz when AN power is extremely high, showing perfect security protection at the expense of power efficiency.

Self-Super-Resolution of an MRI Image with Assistance of the DSTTD System.

Motivation. In the modern world of information technology, the need for ensuring the safety of wireless transmissions while transiting through a given network is growing rapidly. The process of transmitting images via a wireless network is fraught with difficulty. There is a possibility that data may be corrupted while being transmitted, which would result in an image with low resolution. Both of these issues were investigated head-on in this research methodology using the aiding double space-time block coding (DSTTD) system and the self-super-resolution (SSR) method. Description. In recent times, medical image transmission over a wireless network has received a significant amount of attention, as a result of the sharing of medical images between patients and doctors. They would want to make sure that the image was sent in a risk-free and protected manner. Arnold cat map, often known as ACM, is a well-known and widely implemented method of image transmission encryption that has been in use for quite some time. At the receiver end, SSR is now being employed in order to view the transmitted medical image in the finest possible resolution. It is anticipated that in the near future, image transmission through wireless DSTTD will be technically feasible. This is performed in order to maximize the benefits that the system has to offer in terms of both spatial diversity and multiplexing as much as is possible. Conclusion. The SSR approach is used in order to represent the image in a document pertaining to human resources. ACM is used so that the image may be sent in a risk-free and protected way. The adoption of a DSTTD-based architecture for wireless communication is suggested. A comparison of the results is provided, and PSNR and SSIM values are detailed towards the results and discussion of the article.

Research on the performance of multiple-input/multiple-output space-frequency block coded system with exponential Weibull distribution in the satellite laser communication

We propose an orthogonal frequency division multiplexing multiple-input/multiple-output space-frequency block-coded (MIMO-SFBC) system based on the exponential Weibull distribution model for uplink and downlink satellite laser communication. Considering the different effects of atmospheric turbulence on the laser beam, the closed expression of bit error rate (BER) was derived for the proposed system. The relationship between the BER and signal-to-noise ratio was analyzed under uplink and downlink, respectively, and compared with the single-input/single-output and space-time block-coded systems. Simultaneously, the effects of different numbers of transmitting and receiving antennas on the selection of zenith angle, receiving aperture, transmitting radius, and beam divergence of the MIMO-SFBC system were also studied. Finally, the Monte Carlo method was used to verify the experimental data. This study provides a theoretical reference for the engineering implementation of MIMO coding technology in satellite laser communication systems.

MIMO-Orthogonal space time block code system joint with BCH-TC in Rayleigh fading channel for performance of transmit antenna selection

Purpose To enhance the performance transmit antenna selection (TAS) of spatial modulation (SM), systems technique needs to be essential. This TAS is an effective technique for reducing the multiple input multiple output (MIMO) systems computational difficulty, and bit error rate (BER) can increase remarkably by various TAS algorithms. But these selection methods cannot provide code gain, so it is essential to join the TAS with external code to obtain cy -ode gain advantages in BER. Design/methodology/approach In this paper, Bose–Chaudhuri–Hocquenghem (BCH)-Turbo code TC is combined with the orthogonal space time block code system. Findings In some existing work, the improved BER has been perceived by joining forward error correction code and space time block code (STBC) for MIMO systems provided greater code gain. The proposed work can provide increasing code gain and the effective advantages of the TAS-OSTBC system. Originality/value To perform the system analysis, Rayleigh channel is used. In the case with multiple TAS-OSTBC systems, better performance can provide by this new joint of the BCH-Turbo compared to the conventional Turbo code for the Rayleigh fading.

Adaptive Switching Hybrid Blast-STBC MIMO System

Fading in a wireless channel has negative effects on the performance of communication systems. Bell Laboratories layered space-time (BLAST) has been used to get a high data rate while space-time block codes (STBC) have been used to get a low bit error rate (BER) performance. Under deep faded channels, hybrid BLAST-STBC systems are considered as a trade-off between BLAST and STBC systems. By exploiting the benefits of both systems, a new method to represent a 4 × 4 multiple-input and multiple-output (MIMO) system is proposed and studied, in which the transmission process is carried out adaptively between both 4 × 4 VBLAST, Quasi-Orthogonal STBC (QOSTBC) and Hybrid systems according to the transmit links state. The proposed adaptive switching hybrid system (ASHS) reduces the total transmitted power, achieves the maximum throughput by obtaining the best BER. An adaptive switching transmission scheme using the strategy of measuring the transmit links fading is investigated as well. The simulated results are obtained in an environment of a 4 × 4 MIMO system using MATLAB platform where the total transmitting power is normalized to unity. The detections are done using the maximum likelihood (ML) receiver. The proposed ASHS system shows a lot of advantages such as maximum throughput is obtained in bad channel states, no additional transmit power is needed and no additional bandwidth is needed. Finally, under deep fading condition, the proposed ASHS transmission scheme obtains the best BER, reduces wasting the total transmitted power, achieves the maximum throughput and obtains the best BER.

Studying and Modeling the Performance of the TCM-STBC Systems in the Rayleigh Channel

Multiple-input multiple-output (MIMO) systems will play an important role in future generations of wireless networks. Space-time block code (STBC) and space-time trellis code (STTC) are two techniques that may be used in multi-antenna radio systems. This paper aims, most importantly, to study the performance of STBC systems at different vallues of such parameters as spectral efficiency, matrix codes and constellations. A performance comparison between STBC and STTC schemes is performed. In order to show the efficiency of the system’s ability to communicate with uncoded and coded transmission structures over AWGN and Rayleigh channels, the trellis-coded modulation (TCM) is introduced. The results obtained show that the proposed TCM-STBC system model, using one and two receiving antennas, improves the performance of Rayleigh channel communication systems at 9.5 dB and 11.5 dB for a BER of 10−5

Wavelet Channel Coding: An Algebraic Approach

In this paper, the wavelet channel coding (WCC) is revisited in a more general analysis embracing flat real wavelet matrices derived from a Haar matrix and complex input symbols. WCC encoding and decoding are algebraically described and a probability distribution of wavelet symbols is formulated. Signal constellations for transmission of wavelet symbols are proposed and the constellation average energy is deduced from probability generating functions of the wavelet symbols. System performance over a flat Rayleigh channel is analyzed and compared with symbol-by-symbol detecting systems and diversity two space-time block coding (STBC) systems. Simulation results show that WCC presents better performance than ordinary symbol-by-symbol detecting systems, particularly at higher signal-to-noise ratios for higher spectral efficiencies, and STBC systems for spectral efficiency of 1 bit/s/Hz.

Deep Learning-Based Wireless Channel Estimation for MIMO Uncoded Space-Time Labeling Diversity

Uncoded space-time labeling diversity (USTLD) is a space-time block coded (STBC) system with labeling diversity applied to it to increase wireless link reliability without compromising the spectral efficiency. USTLD achieves higher link reliability relative to the traditional Alamouti STBC system. This work aims to design a bandwidth-efficient and blind wireless channel estimator for the USTLD system. Traditional channel estimation techniques like the least-squares (LS) and the minimum mean squared error (MMSE) methods are generally inefficient in using the channel bandwidth. The LS and MMSE channel estimation schemes require the prior knowledge of transmitted pilot symbols and/or channel statistics, together with the receiver noise variance, for channel estimation. A neural network machine learning (NN-ML) channel estimator with transmit power-sharing is proposed to facilitate blind channel estimation for the USTLD system and to minimize the required channel estimation bandwidth utilization. We mathematically model the equivalent noise power and derive the optimal transmit power fraction that minimizes the channel estimation bandwidth utilization. The blind NN-ML channel estimator with transmit power-sharing is shown to utilize 20% of the LS and MMSE wireless channel estimators’ bandwidth to achieve the same bit error rate (BER) performance for the USTLD system in the case of 16-QAM and 16-PSK modulation.

Performance Improvement of Space-Time Block Coding Using Flexible Feedback Bits Over Rician Channels

This paper addresses the concept of multiple-input multiple-output system using space-time block coding with the partial presence of channel state information at the transmitter. An efficient orthogonal space-time block coding system with 4-transmit and multiple receive antennas is developed. By employing an additional transmit antenna, the channel state information of 1, 2 or 3 feedback bits are utilized to improve the performance. The proposed scheme considers Rician flat fading channel with different line of sight power values. Moreover, the proposed system achieves full diversity order and a code rate of 3/4. In addition to that, the effect of different scales of partial feedback information on the performance is evaluated. Several examples of one and two receive antennas with different values of Rician factor and different number of feedback bits are simulated. Numerical results show that sizable performance improvement of the proposed scheme is obtained accordingly with increasing the number of feedback bits.

Performance Analysis of MIMO STBC System in Flat Fading and Frequency Selective Fading Channels

Multiple Input Multiple Output (MIMO) technology is a technique that can be used to overcome multipath fading. The multipath fading is caused by signals coming from several paths that experience different attenuations, delays and phases. In a multipath condition, an impulse that sent by the transmitter, will be received by the recipient not as an impulse but as a pulse with a spread width that called delay spread. Delay spread can cause intersymbol interference (ISI) and bit translation errors from the information received. To determine the effect of delay spread on the MIMO system, then MIMO system performance research was performed on flat fading and frequency selective fading channels using the Space Time Block Code (STBC) coding technique. This research was conducted using MatLab 2018a software. The simulation results show that the MIMO STBC system performance on flat fading channels is better than the MIMO STBC system performance on the frequency selective fading channel. This result is analyzed based on the value of BER vs. Eb/No and eye diagram.

Power efficient 2 × 1 space–time block code system with antenna shuffling

A transmit antenna shuffling method is proposed for a power efficient 2 × 1 space–time block code (STBC) system. Unlike a conventional STBC system that has identical power amplifiers (PAs), an asymmetric STBC (A-STBC) transmitter considered in this Letter has two asymmetric PAs, i.e. low-power and high-PAs. Considering the asymmetric PAs, the authors propose an antenna shuffling method with 1-bit feedback to improve the power efficiency (PE) of the STBC system. Numerical results verify that the proposed A-STBC system with 1-bit feedback antenna shuffling achieves a better PE-and-rate tradeoff and the potential ability of the small amount of feedback information for the power efficient systems.

Compressed sensing image reconstruction by low density parity check codes and soft decoding of space time block codes

To meet the demand of the energy and bandwidth efficient transmission of image/video data in 5G with an improved visual quality at the receiver end, this work suggests an integration of compressed sensing (CS) with low density parity check (LDPC) codes and space time block codes (STBC). An algorithm for soft decision decoding of STBC followed by performance comparison with zero and no-zero entry STBCs is also reported. Upper bounds of error for a CS–LDPC and a CS–STBC system are also developed. The proposed soft decision algorithm gives a bit error rate (BER) of ∼10−3 at around −2 dB for 8 antenna STBC.

Channel estimation for high speed unmanned aerial vehicle with STBC in MIMO radio links

This paper proposes a channel estimation method based on Kalman filter and adaptive estimation with space-time block code (STBC) and multiple antenna systems [multiple input single output (MISO) and multiple input multiple output (MIMO)\ for high speed UAVs. Simulations have been done in time-varying Rayleigh faded channels for BPSK and QPSK. The proposed technique shows a very good error for severely faded channels. Application of Alamouti STBCs with diversity based on multiple antennas provides improved performance in faded wireless channels. Alamouti transmit diversity scheme, however, relies on the availability of accurate channel state information (CSI) for unmanned aerial vehicles (UAVs). Simulation results show that our proposed method achieves accurate estimation for the SNR and Doppler shift in a wide range of velocities and SNRs.

Channel estimation for high speed unmanned aerial vehicle with STBC in MIMO radio links

This paper proposes a channel estimation method based on Kalman filter and adaptive estimation with space-time block code (STBC) and multiple antenna systems [multiple input single output (MISO) and multiple input multiple output (MIMO) for high speed UAVs. Simulations have been done in time-varying Rayleigh faded channels for BPSK and QPSK. The proposed technique shows a very good error for severely faded channels. Application of Alamouti STBCs with diversity based on multiple antennas provides improved performance in faded wireless channels. Alamouti transmit diversity scheme, however, relies on the availability of accurate channel state information (CSI) for unmanned aerial vehicles (UAVs). Simulation results show that our proposed method achieves accurate estimation for the SNR and Doppler shift in a wide range of velocities and SNRs.

High-Rate STBC Communication System Using Imperfect CSI Under Time-Selective Flat-Fading Environment

In this paper, a high-rate space-time block-coded (STBC) mobile communication system using imperfect channel-state-information (CSI) is presented, which is working over the time-selective flat-fading wireless channels. In the work, a flat-fading channel is modelled as a first-order Markov-process, taking into account Doppler shifts and carrier frequency offsets. The STBC data-rate 5/4 with two-transmitter antennas is attained by maximizing the coding gain and by minimizing the transmitted signal peak-to-minimum-power-ratio, while using the selective power scaling in combination with quadrature-phase-shift-keying digital modulation technique. The time-selective nature of underlying channel leads to reduction in the diversity gain, though optimum power scaling factor is incorporated. However, imperfect CSI usually arises due to the availability of noisy channel estimates at the receiver, which causes system performance degradation. Simulation results are presented to illustrate that the effective throughput in terms of frame-error-rate or symbol-error-rate of the presented data-rate $${5 \mathord{\left/ {\vphantom {5 4}} \right. \kern-0pt} 4}$$ STBC system is adversely affected because of the noisy channel estimates. But, an efficient channel estimator helps in combating the time-selectivity of channel, and in turn results in effective throughput improvement under the high signal-to-noise-ratio (SNR) conditions only. Subsequently, the data-rate $${9 \mathord{\left/ {\vphantom {9 8}} \right. \kern-0pt} 8}$$ STBC system with four-transmitter antennas is explored using similar strategy working over the time-nonselective (time-varying) flat-fading channels, which performs well under the high SNR and low channel estimation noise/error conditions.

Robust blind channel estimation algorithm for linear STBC systems using fourth order cumulant matrices

A novel blind channel estimation algorithm, based on fourth-order cumulant matrices, is proposed and applied to linear Space–Time Block Coded (STBC) for Multiple Input Multiple Output systems. Contrary to subspace and Second-Order Statistics (SOS) methods, the presented approach estimates the channel matrix without any modification of the transmitter. It takes advantage of the statistical independence of the signals in front of the space–time encoding. In this paper, the presented algorithm estimates the channel matrix by minimizing a cost function based on the higher cumulant matrices after Zero-Forcing equalization to mitigate the computational complexity and improve the performance. We employ the proposed method to the STBC systems including Spatial Multiplexing, Orthogonal, quasi-Orthogonal and Non-Orthogonal STBC systems. Symbol error rate and Normalized Mean Square Error simulations of the proposed algorithm are shown for a different number of users, signal to noise ratios and different number of symbols per user in comparison with subspace and Second-Order Statistics (SOS) methods. The results show that the presented method performs well and outperforms other methods in estimating the channel matrix from the received data. Moreover, the proposed method presents high convergence speed in estimating the channel matrix.

Trellis Code Design of Block Interleaved CIOD-STBCs for Time Varying Channels

A trellis-code design scheme is proposed for a coordinate interleaved orthogonal design space-time block code (CIOD-STBC) system employing a time interleaver. The pairwise error probability (PEP) for the block interleaved CIOD-STBC is analytically derived, and the PEPs are evaluated to search the best systematic feedback encoder to provide the maximum diversity and coding gain for several numbers of states. We expand the signal set such that the expanded set has the same transmit symbol set to keep both the bandwidth and the peak-to-average power ratio the same as the uncoded system. It is noteworthy that the proposed system provides approximately 9-dB SNR gain over the uncoded system at bit error rate ${10^{-5}}$ in the quasi-static Rayleigh fading channel with 32 state trellis coded CIOD. Simulation results are also provided to verify the theoretical analysis.

Performance Analysis of a Multi-layered SVD Based STBC System

Multiple-Input Multiple-Output transmission systems using orthogonal frequency-division multiplexing is a key solution in wireless communications. The performance of MIMO-OFDM systems can be improved using coding schemes such as Space–Time Block Coding (STBC), Singular Value Decomposition (SVD) and Vertical Bell Labs Layered Space–Time Architecture (VBLAST). In this paper we present a (4 × 4) cascaded STBC–SVD multi-layered encoder structured in a VBLAST architecture. The STBC output streams are SVD encoded to improve symbol error rate (SER) performance. The introduced system achieves both spatial multiplexing and diversity gains simultaneously and maintains reliable SER performance. We study the effect of ordering the output streams of the STBC before applying the SVD encoding. We show that there is an optimum ordering that guarantees a minimum overall SER. MATLAB® simulations show that the proposed system performs better over other conventional VBLAST systems. Moreover, we show that better performance is not associated with an increase in the computational complexity.

Full-Diversity QO-STBC Technique for Large-Antenna MIMO Systems

The need to achieve high data rates in modern telecommunication systems, such as 5G standard, motivates the study and development of large antenna and multiple-input multiple-output (MIMO) systems. This study introduces a large antenna-order design of MIMO quasi-orthogonal space-time block code (QO-STBC) system that achieves better signal-to-noise ratio (SNR) and bit-error ratio (BER) performances than the conventional QO-STBCs with the potential for massive MIMO (mMIMO) configurations. Although some earlier MIMO standards were built on orthogonal space-time block codes (O-STBCs), which are limited to two transmit antennas and data rates, the need for higher data rates motivates the exploration of higher antenna configurations using different QO-STBC schemes. The standard QO-STBC offers a higher number of antennas than the O-STBC with the full spatial rate. Unfortunately, also, the standard QO-STBCs are not able to achieve full diversity due to self-interference within their detection matrices; this diminishes the BER performance of the QO-STBC scheme. The detection also involves nonlinear processing, which further complicates the system. To solve these problems, we propose a linear processing design technique (which eliminates the system complexity) for constructing interference-free QO-STBCs and that also achieves full diversity using Hadamard modal matrices with the potential for mMIMO design. Since the modal matrices that orthogonalize QO-STBC are not sparse, our proposal also supports O-STBCs with a well-behaved peak-to-average power ratio (PAPR) and better BER. The results of the proposed QO-STBC outperform other full diversity techniques including Givens-rotation and the eigenvalue decomposition (EVD) techniques by 15 dB for both MIMO and multiple-input single-output (MISO) antenna configurations at 10 − 3 BER. The proposed interference-free QO-STBC is also implemented for 16 × N R and 32 × N R MIMO systems, where N R ≤ 2 . We demonstrate 8, 16 and 32 transmit antenna-enabled MIMO systems with the potential for mMIMO design applications with attractive BER and PAPR performance characteristics.

Average BER Performance of Orthogonal Space–Time Block Coding System with Antenna Selection Over Generalized η–μ Fading Channel

Generalized channel fading distributions such as κ–μ and η–μ are well suited for modelling various fading channels as they fit well to the experimental data. This paper is concerned with the performance analysis of orthogonal space–time block-codes system using M-ary Phase shift keying/quadrature amplitude modulation with antenna selection over generalized η–μ fading channel i.e., for non-line-of-sight applications. We derive the closed form expression of the average bit error rate by employing “moment generating function” based approach for different modulation schemes. Simulation results are finally presented to demonstrate the correctness of theoretical analysis by assuming different values for η and μ, where each value corresponds to different channels. The impact of actual number of antennas, i.e., number of antennas before antenna selection, were also shown.