Average Bit Error Rate Research Articles

Deep Learning-Assisted Transmit Antenna Classifiers for Fully Generalized Spatial Modulation: Online Efficiency Replaces Offline Complexity

In this work, deep learning (DL)-based transmit antenna selection (TAS) strategies are employed to enhance the average bit error rate (ABER) and energy efficiency (EE) performance of a spectrally efficient fully generalized spatial modulation (FGSM) scheme. The Euclidean distance-based antenna selection (EDAS), a frequently employed TAS technique, has a high search complexity but offers optimal ABER performance. To address TAS with minimal complexity, we present DL-based approaches that reframe the traditional TAS problem as a classification learning problem. To reduce the energy consumption and latency of the system, we presented three DL architectures in this study, namely a feed-forward neural network (FNN), a recurrent neural network (RNN), and a 1D convolutional neural network (CNN). The proposed system can efficiently process and make predictions based on the new data with minimal latency, as DL-based modeling is a one-time procedure. In addition, the performance of the proposed DL strategies is compared to two other popular machine learning methods: support vector machine (SVM) and K-nearest neighbor (KNN). While comparing DL architectures with SVM on the same dataset, it is seen that the proposed FNN architecture offers a ~3.15% accuracy boost. The proposed FNN architecture achieves an improved signal-to-noise ratio (SNR) gain of ~2.2 dB over FGSM without TAS (FGSM-WTAS). All proposed DL techniques outperform FGSM-WTAS.

Performance analysis of modulating retro-reflector optical communication system based on an Airy beam

Average Bit Error Rate (BER), outage probability and average channel capacity expressions of a Modulating Retro-Reflector (MRR) optical communication system based on an Airy beam under weak turbulence are derived. The effects of propagation distance, width parameter and exponential truncation factor of the Airy beam itself on the communication performance of the system are discussed. Meanwhile, the performance of the system based on the Gaussian beam is compared with the same turbulence condition and propagation distance. The simulation results show that under the same conditions, the system based on the Airy beam shows a lower outage probability, average BER and larger average channel capacity compared to the system based on the Gaussian beam. Moreover, the advantages of the Airy beam are more significant as the average signal-to-noise ratio (SNR) increases.

A Universal Framework of Superimposed RIS-Phase Modulation for MISO Communication

To fully exploit the additional dimension brought by reconfigurable intelligent surface (RIS), it is recently suggested by information theory that modulating information upon RIS phases is able to send extra information with increased communication rate. In this paper, we propose a novel superimposed RIS-phase modulation (SRPM) scheme to transfer extra messages by superimposing information-bearing phase offsets to conventionally optimized RIS phases. The proposed SRPM is interpreted as a universal framework for RIS phase modulation. Theoretical union bound of the average bit error rate (ABER) of the proposed SRPM is also derived with the maximum likelihood (ML) detection. The diversity order is characterized as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\frac{1}{2}$</tex-math></inline-formula> for all parameter settings, which is useful for determining the optimal choice of the phase modulation parameters. Furthermore, we discover that doubling the number of either RIS reflecting elements or the transmit antennas is equivalent to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$3\,$</tex-math></inline-formula> dB increment in the transmit power for SRPM. Numerical results demonstrate the effectiveness of SRPM and reveal that it achieves reliable communication of more bits than existing schemes.

Adaptive Transmission Based on MIMO Mode Switching Over Malaga Turbulence Channel With Pointing Error

In this paper, we propose a dynamic adaptive multiple input multiple output (MIMO) free space optical (FSO) system with spatial mode switching. Based on the channel conditions, the proposed system can select different MIMO transmission modes: diversity, multiplexing or hybrid mode that yields the maximum average channel capacity while satisfying the reliable average bit error rate (BER). Considering the combined effects of path loss, pointing error and atmospheric turbulence-induced fading modeled by Malaga distribution, we derive the closed-form expressions of average channel capacity and average BER of MIMO system for each transmission mode. From adaptive system performance evaluated results, we establish the signal-to-noise ratio (SNR) threshold look-up table (LUT) in different scenarios to select the optimal transmission mode. The extensive numerical results demonstrate that the proposed adaptive system has a significant improvement in average channel capacity compared with each stand-alone mode system. Finally, Monte Carlo simulation is also provided to verify the correctness of the proposed adaptive scheme and conclusions.

Performance Analysis of MIMO-mQAM System with Pointing Errors and Beam Spreading in Underwater Málaga Turbulence Channel

Both the long-term beam spreading caused by ocean turbulence and the pointing errors induced by the jitter of transmitters and receivers degrade the performance of underwater wireless optical communication (UWOC) links. To effectively alleviate their effects, an in-depth study was carried out over the Málaga turbulence channel with pointing errors and beam spreading in multiple-input and multiple-output (MIMO) UWOC. First, we analyzed the long-term beam spreading and the received light power for the finite receiving aperture in the presence of pointing error displacements. Based on this, the relationship between beam spreading, pointing errors, and signal power was established. Second, the approximate expressions of the average bit error rate (BER) and the communication outage probability were derived theoretically for this MIMO system using maximal-ratio combining (MRC) diversity. Third, the effects of the pointing errors on the coding and the diversity gains were explored for the MIMO links. Finally, using the observed ocean data from the Global Ocean Argo gridded dataset, we numerically verified the combined effects of ocean turbulence strength, beam spreading, and pointing errors on the average BER and outage probability of this system. These results also proved that adjusting the size of the receiving aperture or the order of the multiple quadrature amplitude modulation (mQAM) could effectively mitigate their effects.

Performance Study of Generalized Space Time Block Coded Enhanced Fully Optical Generalized Spatial Modulation System Based on Málaga Distribution Model

This paper proposes a generalized space time block coded (GSTBC) enhanced fully optical generalized spatial modulation (EFOGSM) system based on Málaga (M) turbulent channel. GSTBC-EFOGSM adopts the hybrid concept of generalized space time block coded and optical spatial modulation to further utilize the high transmission rate of EFOGSM and the diversity advantage of GSTBC in free space optical (FSO) communication systems. Considering the combined effects of path loss, pointing error and atmospheric turbulence, the Meijer G function is used to derive the closed-form expression for the average bit error rate (ABER) of GSTBC-EFOGSM. Then, the ABER performance, data transmission rate, energy efficiency and computational complexity at the receiver of GSTBC-EFOGSM are compared with other optical spatial modulation schemes by simulation. In addition, the effects of key factors, such as data transmission rate, encoding ratio, number of photodetectors and modulation order, on the ABER performance of the system are also analyzed via simulation. Monte Carlo (MC) simulation is used to verify the correctness of the numerical simulation. The simulation results show that the GSTBC-EFOGSM system has better ABER performance and good performance gain.

Performance analysis of coherent DPSK SIMO laser-based satellite-to-ground communication link over weak-to-strong turbulence channels considering Kolmogorov and non-Kolmogorov spectrum models

The performance of satellite-to-ground laser-based communication links is highly affected by atmospheric turbulence. Coherent detection with spatial diversity at the ground station receiver can mitigate the scintillation effects caused by atmospheric turbulence. Traditionally, the scintillation effects are modeled based on the Kolmogorov spectrum model. However, the experiments have indicated that scintillation effects on the laser beam propagation have non-Kolmogorov properties. Our goal in the present work is to analyze the average bit error rate (BER), outage probability (OP), and ergodic capacity of the satellite-to-ground heterodyne optical communication system with receiver spatial diversity. A differential phase-shift keying modulation technique is considered in this work. The propagated laser signal from the satellite to the ground station is assumed to be subjected to Málaga-distributed atmospheric turbulence. The atmospheric turbulence statistics are carried out based on the conventional Kolmogorov spectrum model and the three-layer altitude (TLA) non-Kolmogorov spectrum model. The performance of popular diversity combining techniques, namely, maximum ratio combining (MRC) and equal gain combining (EGC) techniques are analyzed. The statistical models of the MRC technique under the Málaga-distributed atmospheric channel model are obtained in analytical form expressions. The statistical models of the EGC technique under the Málaga-distributed atmospheric channel model are obtained via the fast Fourier transform representation of the characteristic function method. Based on these statistical models, average BER, OP, and ergodic capacity expressions for each type of diversity combining technique are derived. For the communication system under investigation, the performance of MRC and EGC multiple aperture receiver systems are compared to a single aperture receiver with the same total aperture area. These comparisons are carried out under the same conditions in terms of zenith angle and signal-to-noise ratio. The obtained results show that the performance of the optical communication system under investigation with MRC and EGC receivers can be improved by increasing the order of diversity. In addition, it is found that the difference in the performance between Kolmogorov and TLA non-Kolmogorov spectrum models is not significant at low zenith angles, while this difference increases as the zenith angle increases. All numerical results are verified by Monte-Carlo simulations.

On Performance Analysis of Wireless Network over Double Shadowed Rician Fading Channel

In the wireless network, many physical conditions may arise where received signal power is shadowed by moving objects along the propagation paths, and further shadowing of the received signal may result from moving objects around the transmitters or receivers. This phenomenon is mathematically modelled in terms of the double (or dual) shadowing process brought about by fading channels where both dominant and scattered wave components fluctuate together. In this present study, the outcome aspects of dual-shadowed wireless fading channels are explored in accordance with outage analysis, channel capacity, and average bit error rate (ABER) for coherent as well as non-coherent modulation schemes. Here, the Rician envelope, which undergoes two shadowing effects, is assumed. The channel format described here is such that both dominant and scattered signals are impacted by the Nakagami m random variable (RV). As a model, the mathematical expressions are derived for channel capacity, outage analysis, and ABER for dual-shadowed Rician fading channels. The effects of different shadowing parameters are explored, and corresponding results are plotted. All the evaluative results are recognised by emulating the simulation results for various values of the fading parameters.

Caching popularity-unknown contents for massive communication channels via deep Q-learning

In order to reduce the backhaul link pressure of wireless networks, edge caching technology has been regarded as a promising solution. However, with massive and dynamical communication connections, it is challenging to provide analytical caching solution to achieve the best performance, particularly when the requested contents are changing and their popularities are unknown. In this paper, we propose a deep Q-learning (DQN) method to address the issue of caching placement. Considering a content caching network containing multiple cooperating SBSs with unknown content popularity, we need to determine which content to cache and where to cache. Therefore, the learning network has to be designed for dual aims, one of which is to estimate the content popularities while the other is to assign contents to the proper channels. An elaborate DQN is proposed to make decisions to cache contents with limited storage space of base-station by considering channel conditions. Specifically, the content requests of users are first collected as one of the training samples of the learning network. Second, the channel state information for the massive links are estimated as the other training samples. Then, we train the network based on the proposed method thereby improving spectral efficiency of the entire system and reducing bit-error rate. Our major contribution is to contrive a caching strategy for enhanced performance in massive connection communications without knowing the content popularity. Numerical studies are performed to show that the proposed method acquires apparent performance gain over random caching in terms of average spectral efficiency and bit-error rate of the network.

Joint Effects of Co-Channel Interferences and Pointing Errors on Dual-Hop Mixed RF/FSO Fixed-Gain and Variable-Gain Relaying Systems

The performance of a dual-hop mixed radio frequency (RF)/free space optical (FSO) system with co-channel interferences (CCIs) is studied for both fixed-gain and variable-gain amplify-and-forward(AF) relaying scenarios. The RF link and interference link undergo the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\kappa$</tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> shadowed fading and the FSO link experiences the Fisher-Snedecor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\cal F}$</tex-math></inline-formula> distribution with pointing errors. For the considered system, we derive new closed-form expressions for the probability density function (PDF), cumulative distribution function (CDF), and average bit error rate (BER) of the end-to-end signal-to-interference-plus-noise ratio (SINR). In addition, efficient numerical expressions for the ergodic capacity are also obtained. Moveover, the asymptotic expressions for the CDF and average BER are derived. Our results can be regarded as a generalization of the previous results. Finally, numerical and simulation results are presented to verify the correctness of the proposed expressions.

Joint channel model for fog and atmospheric turbulence and performance analysis of unmanned aerial vehicles’ free-space optical communication

To study the joint effects of turbulence and fog on free-space optical (FSO) communication, a joint fog-turbulence-pointing error probability model for FSO is derived based on the random fog channel, Malaga turbulence model, and pointing error model. The closed-form expressions for the average signal to noise ratio (SNR), outage probability, average bit error rate (BER), ergodic channel capacity, and moment generating function in FSO communication under intensity modulation/direct detection are derived based on the joint model. Based on the unmanned aerial vehicle (UAV) working scenario, applying these expressions, the performance analysis of the inter-UAVs optical wave communication is implemented under the conditions for different beam widths, turbulence intensity and fog density and the pointing error caused by position, orientation, and jitter deviations. The calculated results are in good agreement with the Monte Carlo simulations. The analytical results for the average BER and outage probability show that the increase in beam width can significantly degrade the BER and outage probability, for the UAVs optical communication link. The analysis for the ergodic channel capacity shows that it increases with the increase of average transmission power; however, it increases slowly with the increase of beam width. And the increase in turbulence intensity, fog density, and drone jitter will degrade the communication performance of the system. Our study lays an important theoretical foundation for the development of FSO communication and UAV communication performance improvement in joint fog and turbulent environment.

Adaptive Secure Transmission Based on Collaborative Communication in Smart Grids

In this paper, a collaborative power line communication (PLC) and generalized spatial modulation architecture (CPGA) is proposed to resolve the adaptive secure transmission problem in smart grid. In the proposed CPGA, the adaptive transmission is driven by the level of data in smart grid, which is achieved through a proposed antenna selection scheme based on interval quantification. And the anti-eavesdropping ability is improved through PLC-assisted transmission and the artificially designed jammer. Additionally, a better management ability of energy efficiency is guaranteed based on the data-driven adaptive transmission scheme. The closed-form expressions of the security capacity, the management ability of energy efficiency and average bit error rate (ABER) are derived for the performance of adaptive secure transmission. Finally, we analyze the security capacity, management capability of energy efficiency and ABER of the CPGA. Numerical results show that better ABER performance can be achieved in the CPAG compared with the traditional GenSM. Moreover, for the traditional multi-input multi-output, the better security capacity and management of energy efficiency can be achieved in the CPGA. And the adaptive balance between secure level and energy management are realized through the CPGA in smart grid.

Performance Analysis of Smart Grid Wide Area Network With RIS Assisted Three Hop System

In this paper, we investigate the performance of a wide area network (WAN) with three hops over a mixed radio frequency (RF), reconfigurable intelligent surface (RIS) assisted RF and Free space optics (FSO) channel. Here RIS and decode-and-forward (DF) relays are used to improve the coverage and system performance. For general applicability, the RF and FSO links are modelled with Saleh-Valenzuela (S-V) and Gamma-Gamma distribution, respectively. In the smart grid (SG) communication network, the smart meter (SM) communicates the information from the devices to the data aggregator unit (DAU) through the RIS-assisted RF link. As all the devices are not switched on all the time, the Markov chain is used to model the number of active devices. The DAU retransmits the data to the meter data management system (MDMS) through the FSO link, where the atmospheric turbulence and pointing error impairments exist. In this context, closed-form expressions for average bit error rate (ABER) and outage probability (OP) are derived using the H-fox function and extended generalized Bi-variant H-fox function. Here the numerical results demonstrate the effect of different FSO parameters, the number of reflectors in RIS, traffic intensity, and the number of total devices in the SG network.

Performance analysis of MPPM FSO transmission over Gamma–Chi-square strong atmospheric turbulence

In this paper, performance analysis of free space optical (FSO) system operating in conditions of strong atmospheric turbulence over Gamma–Chi-square turbulence model, has been carried out. We have observed reception over multi-pulse pulse-position (MPPM) modulation format for the case of strong atmospheric turbulence conditions modeled with Gamma–Chi-square turbulence model and have compared it with turbulence modeling distributions such are: Gamma–Gamma distribution, K-distribution, negative exponential distribution, log–normal distribution. First, we have provided closed-form analytical expressions for average bit error rate (ABER) at the reception for each observed case and then based on them, we have obtained numerical and Monte Carlo simulation results in order to observe turbulence level impact on system performance.

Solution for Self-Interference of NOMA-Based Wireless Optical Communication System in Underwater Turbulence Environment

Non-orthogonal multiple access (NOMA) is a multiple access technology of great potential and it has superior performance in underwater wireless optical communications (UWOC). In this paper, we investigate the self-interference problem caused by the superimposed transmission of NOMA-based wireless optical communication system in the underwater turbulent environment, and then propose an alternating composite phase shift (ACPS) coding scheme based on constellation optimization, which can effectively eliminate the decoding error caused by the self-interference within the NOMA paired group. To enhance the optimization efficiency of ACPS in the medium- and strong-turbulence environments, we design a golden-section-approach-based power allocation (GSPA) algorithm that minimizes the bit error rate (BER). The simulation results show that the BER of the low-power user within the NOMA paired group can be reduced by up to 3 orders of magnitude in the ACPS-based UWOC-NOMA system compared to the conventional UWOC-NOMA system. In addition, the proposed GSPA algorithm fully takes into account the light-intensity scintillation caused by the ocean turbulence, which not only significantly reduces the average BER of the NOMA system, but also accelerates the convergence rate.

Integrated Polarization and Spatial Modulation

In this contribution, the concepts of polarization modulation (PM) and spatial modulation (SM) are integrated, to reap their respective advantages toward single-radio frequency (RF) multiple-input multiple-output (MIMO) transmissions. In the so-called polarization and spatial modulation (PSM) system, the information is conveyed by activated antenna indices as well as polarization modulated symbols, while at the receiver, a low-complexity near-optimal detection algorithm based on compressive sensing (CS) is proposed. Furthermore, a closed-form union bound of the average bit-error rate (BER) over fading channels is quantified by theoretical derivation, which is then extended to the case of spatial correlation (SC) as well as channel estimation error (CSE) toward practical use. Finally, our simulation results demonstrate the superiority of the developed PSM system over conventional PM in terms of BER performance over various fading channels.

Enhancing Performance of Air–Ground OAM Communication System Utilizing Vector Vortex Beams in the Atmosphere

The modified uplink and downlink atmospheric turbulence channel models were established and employed to assess the system performance of air–ground orbital angular momentum (OAM) communication. The advantage of the vector vortex beam taking the place of the scalar one in the OAM communication system operated in the atmospheric turbulence was verified, that vector vortex beam can guarantee the more homogeneous energy in the circular hollow beam profile and the less phase distortion on signal OAM in the turbulence, which can reduce OAM crosstalk and improve OAM communication performance, especially small topological charge in strong turbulent regime. With the increase in turbulence strength, the vortex beam with a larger topological charge suffered more OAM mode crosstalk, and the average BER of the OAM communication system increased. Bessel–Gaussian (BG) beams with larger beam shape parameters had the strong capability of turbulence disturbance rejection in short-distance atmospheric applications, conversely, Laguerre–Gaussian (LG) beams with suitable parameter selection were preferred for long-distance atmospheric applications. Additionally, compared to the downlink channel, the transmission of OAM mode and the related communication system in the uplink channel are dramatically deteriorated due to atmospheric turbulent effects.

CADEN: cellular automata and DNA based secure framework for privacy preserving in IoT based healthcare.

In the present E-healthcare industry, data breaches result in substantial economic losses due to cyber-attacks and hence create a trust deficit between the industry and users. The healthcare industry has rapidly adopted IoT frameworks but the trust deficit and privacy concerns limit its utilization among the masses. Along with privacy protection, content authentication is an important requirement in a number of critical applications and fragile watermarking provides an effective solution. However, existing fragile watermarking techniques lack the accuracy of tamper detection and hence are not reliable enough in terms of security and privacy of the data. This paper presents a novel low-complexity block-based fragile watermarking technique with high security against cyber-security attacks. This is achieved by embedding a fragile watermark in the host image using pixel domain blocking approach. The security of embedded watermark has been taken care of by using Cellular Automata and DNA based ENcryption (CADEN) framework to scramble the watermark bits using various secret keys. Experimental investigations show that besides being highly secure, the proposed technique is fragile to various signal processing and geometric attacks. The comparative analysis shows that the proposed scheme, despite having lower complexity, offers better efficiency in terms of imperceptibility, tamper detection and localization compared to other state-of-the-art techniques. Besides, the fragile watermark embedding makes the system capable to preserve the secret information in case of an attack with an average BER of 40%.

Quadrature spatial modulation based orthogonal time frequency spatial system

In this paper, we take the spatial and delay-Doppler dimensions into account and propose a novel transmission scheme combining quadrature spatial modulation (QSM) and orthogonal time frequency space (OTFS) to improve the spectral efficiency, achieve the diversity gains, and resist strong Doppler effect in high-mobility scenes. The system model and the specific signal transmission process of the OTFS with QSM (QSM-OTFS) scheme are presented first. Then, the theoretical average bit error rate (ABER) analysis for QSM-OTFS system is provided. Additionally, a linear enhanced minimum mean square error (EMMSE) detection is investigated to reduce the detection complexity in the QSM-OTFS system. Numerical results illustrate that the QSM-OTFS system is able to obtain an improved ABER performance compared with the typical spatial modulation (SM) based OTFS (SM-OTFS) and that the proposed EMMSE detection outperforms the other linear detection algorithms under the same spectral efficiency.

Dual-Hop Optical Communication Systems Over Málaga Turbulence Under Pointing Error Impairments With Decode-and-Forward Protocol

As a promising technology, free-space optical (FSO) communication plays an important role in the next generation of wireless communication. A dual-hop FSO communication system with decode-and-forward (DF) protocol is proposed in this paper, considering the influences of the atmospheric turbulence (AT), atmospheric absorption and pointing error impairments, in which the Málaga distribution model is used to characterize the fading caused by AT in each link. The end-to-end statistical expressions of our proposed dual-hop Málaga-Málaga communication system are derived, such as the cumulative distribution function (CDF), probability density function and moment generating function. Thereafter, using the above statistical results, the accurate end-to-end expressions of outage probability, average bit error rate (ABER) and ergodic capacity are deduced under the direct detection intensity modulation and heterodyne detection techniques. Furthermore, the end-to-end asymptotic expressions for CDF and the ABER at high signal-to-noise ratio as well as simplified expressions from simple basic functions are obtained. The effects of different AT and pointing error impairments conditions on the proposed system are analyzed based on theoretical and numerical results. Finally, Monte Carlo simulation results indicate that all our novel deduced expressions are basically consistent with the numerical results.