Average Bit Error Rate Research Articles

Performance analysis of RF-FSO communication systems over the Málaga distribution channel with pointing error

Free Space Optical (FSO) communication systems are used for high speed, secure and cheaper optical connectivity between users. It can transport the data from a suitable relay which is multiplexing many RF users to the receiver. These kind of networks are known as dual hop and asymmetric RF-FSO links. In this work, such an RF-FSO cooperative system is studied which is based on the Decode-Forward (DF) relaying method. For the analysis, the generalized channel models are considered such that the existing results can be expressed under more generic performance expressions. The outage probability is initially derived for this system and subsequently the average bit error rate (ABER) is derived using it. The cooperative diversity performance is also investigated by deriving the asymptotic expressions for these metrics at high received signal-to-noise ratio (SNR).

Exact BER Analysis of NOMA With Arbitrary Number of Users and Modulation Orders

Non-orthogonal multiple access (NOMA) is a promising candidate for future mobile networks as it enables improved spectral-efficiency, massive connectivity and low latency. This paper derives exact and asymptotic bit error rate (BER) expressions under Rayleigh fading channels for NOMA systems with arbitrary number of users and arbitrary number of receiving antennas and modulation orders, including binary phase-shift keying and rectangular/square quadrature amplitude modulation. Furthermore, the power coefficients' bounds, which ensure users' fairness, and solve the constellation ambiguity problem, are derived for N=2 and 3 users cases with any modulation orders. In addition, this paper determines the optimal power assignment that minimizes the system's average BER. These results provide valuable insight into the system's BER performance and power assignment granularity. For instance, it is shown that the feasible power coefficients range becomes significantly small as the modulation order, or N, increases, where the BER performance degrades due to the increased inter-user interference. Hence, the derived expressions can be crucial for the system scheduler in allowing it to make accurate decisions of selecting appropriate N, modulation orders, and power coefficients to satisfy the users' requirements. The presented expressions are corroborated via Monte Carlo simulations.

Performance study of a serial relay CC-OGSM-SD free space optical system based on an M distribution model

This paper proposes a novel, to the best of our knowledge, convolutional coding (CC)-optical generalized spatial modulation (OGSM)-spatial diversity (SD) serial relay system under M distribution. In this work, two types of SD schemes are considered both at the relay node and receiver, and the decode-and-forward (DF) relay transmission protocol is adopted. Taking into account the combined effects of path loss, pointing error, and atmospheric turbulence, the closed-form expressions for the average bit error rate (ABER) of the serial relay uncoded and CC-OGSM-SD free space optical (FSO) system are derived using Meijer's G-function. On the basis of theoretical derivation, the ABER of the proposed system and other common multiple input multiple output schemes in FSO systems are compared through simulation. In addition, the effects of the number of relay nodes, link distance between relays, and different OGSM configurations, SD schemes, and coding rates on the ABER of the system are also analyzed via simulation. Monte Carlo simulations indicate the correctness of the numerical results. The simulation results show that the serial relay CC-OGSM-SD FSO system has lower ABER and higher spectral efficiency.

Time and Spatial Jitter Influence on the Performance of FSO Links with DF Relays and OC Diversity Over Turbulence Channels

FSO communication is a viral technology among optical wireless communications, gathering the interest of both researchers and manufacturers. This is because of the many advantages associated with FSO communication, including high data rates, reliability, safety, and economy. However, there are several unavoidable drawbacks that shadow the performance of FSO systems. For example, atmospheric turbulence is a well-known problem related to the weather conditions of the channel, which causes the scintillation effect. Also, spatial jitter due to pointing errors is a critical factor of the link’s performance, caused by occasional misalignments between the transmitter and the receiver. Moreover, time jitter is another limiting agent that deteriorates the total throughput, inducing bit stream misdetections, caused by the arrival of out-of-sync pulses. All three effects have been exhaustively studied and many statistical models and interesting solutions have been proposed in the literature to estimate their magnitude and compensate for their impact. In this work, the turbulence effect was treated by Málaga distribution, the spatial jitter effect was regulated by the non-zero boresight model, and the time jitter effect was modeled by the generalized Gaussian distribution. Various modulation schemes were studied, along with DF multi-hop and optimal combining diversity techniques at the receiver’s end. New, accurate mathematical expressions of average BER performance have been obtained, and valuable conclusions were drawn thanks to the presented numerical results.

Performance Analysis of UAV-Based Mixed RF-UWOC Transmission Systems

In this paper, we investigate the performance of a mixed radio-frequency-underwater wireless optical communication (RF-UWOC) system where an unmanned aerial vehicle (UAV), as a low-altitude mobile aerial base station, transmits information to an autonomous underwater vehicle (AUV) through a fixed-gain amplify-and-forward (AF) or decode-and-forward (DF) relay. The analysis accounts for the main factors that affect the system performance, such as the UAV height, air bubbles, temperature gradient, water salinity variations, detection techniques, and pointing errors. Employing the fixed-gain AF and DF relays, expressions for some key performance metrics are derived, e.g., outage probability (OP), average bit error rate (ABER), and average channel capacity. Moreover, in order to get further insights, asymptotic analyses for the OP and ABER are also carried out. Additionally, for the two relaying systems, we derive analytical expressions for the optimal UAV altitude that minimizes the OP. Simulation results show that the UAV altitude influences the system performance and there is an optimal altitude which ensures a minimum OP. Furthermore, it is demonstrated that the diversity order of the fixed-gain AF relaying depends on the RF link and pointing errors, while the diversity order of the DF relaying depends on the detection techniques and pointing errors.

Impact of pointing error on SISO/MISO drones swarm-based free space optical system in weak turbulence regime

<p>Applying the drone-based free space optical (FSO) technology is recent in communication systems. The FSO technology hashigh-security features dueto narrow beamwidth, insusceptible to interferences, free license and landline connection is not appropriate. However, these advantages face many obstacles that affect the system's performance, such as random weather conditions and misalignment. The pointing error Hpis one of the critical factors of the channel gain H. The related parameters of the Hp factor: the pointing error angles θr and the path length Z, were manipulated to extract the applicable values at various receiver diameter values. The proposed system has two topologies: single input single output (SISO) and multiple input single output (MISO), flying in weak atmospheric turbulence. The simulation was done using MATLAB software 2020. The average bit error rate (ABER) for the system versus signal-to-noise ratio (SNR) were verified and analyzed. The results showed that at θr=10<sup>−3</sup>rad, Z increased in the range 10~100m for each one-centimeter increase of DR. At θr=10<sup>−2</sup>rad, the applicable Z was nearly 10% of the link distance Z when θr=10<sup>−3</sup>rad was applied. Consequently, an increase in θr must correspond decrease in Z and vice versa to maintain the system at high performance.</p>

Design and analysis of spatial modulation based orthogonal time frequency space system

In this paper, we design a spatial modulation based orthogonal time frequency space (SMOTFS) system to achieve improved transmission reliability and meet the high transmission rate and high-speed demands of future mobile communications, which fully utilizes the characteristics of spatial modulation (SM) and orthogonal time frequency space (OTFS) transmission. The detailed system design and signal processing of the SM-OTFS system have been presented. The closed-form expressions of the average symbol error rate (ASER) and average bit error rate (ABER) of the SM-OTFS system have been derived over the delay-Doppler channel with the help of the union bounding technique and moment-generating function (MGF). Meanwhile, the system complexity has been evaluated. Numerical results verify the correctness of the theoretical ASER and ABER analysis of the SM-OTFS system in the high signal-to-noise ratio (SNR) regions and also show that the SM-OTFS system outperforms the traditional SM based orthogonal frequency division multiplexing (SM-OFDM) system with limited complexity increase under mobile conditions, especially in high mobility scenarios.

Average BER performance of MPSK with noisy phase reference in Nakagami‐ m fading channel

This letter derives an approximate average bit error rate (BER) expression of M-ary phase shift keying with a noisy phase reference in a Nakagami-m fading channel. The proposed closed-form expression is general for the M-ary case, including previous results for both binary and quadrature phase shift keying. The accuracy of the proposed average BER expression is verified through a comparison with the exact BER.

Comparative BER Analysis of Free Space Optical System Using Wavelength Diversity over Exponentiated Weibull Channel

Atmospheric turbulence is considered as major threat to Free Space Optical (FSO) communication as it causes irradiance and phase fluctuations of the transmitted signal which degrade the performance of FSO system. Wavelength diversity is one of the techniques to mitigate these effects. In this paper, the wavelength diversity technique is applied to FSO system to improve the performance under different turbulence conditions which are modeled using Exponentiated Weibull (EW) channel. In this technique, the data was communicated through 1.55 µ m, 1.31 µ m, and 0.85 µ m carrier wavelengths. Optimal Combining (OC) scheme has been considered to receive the signals at receiver. Mathematical equation for average BER is derived for wavelength diversity based FSO system. Results are obtained for the different link length under different turbulence conditions. The obtained average BER results for different turbulence conditions characterized by EW channel is compared with the published result of average BER for different turbulence which is presented by classical channel model. A comparative BER analysis shows that maximum advantage of wavelength diversity technique is obtained when different turbulence conditions are modeled by EW channel.

Anti-Interference Design Based on Prime Interleaving for a Combined FH and DS Spreading Spectrum System

A combined prime interleaving design is proposed for a spreading spectrum system with frequency hopping (FH), direct sequence (DS), and coherent detection. Obtaining a lower bit error rate (BER) is the object of classical anti-jamming communication systems. By employing combined prime interleaving, we get lower BER results compared with conventional block interleaving under the same signal-to-noise ratio (SNR) level by merit of superior storage and interleaving effects. Prime interleaving requires only one row to interleave while both block and random interleaving require the whole interleaving matrix, which results in lower latency time. Simulations reveal that the proposed combined interleaving design has comparative performance with random interleaving, and has advantages in transmission reliability and system delay. Moreover, the prime interleaving outputs slightly worse BER compared with random interleaving over the same SNR. Compared with random interleaving, the proposed combined interleaving has 0.25 dB worse SNR over the same average BER.

Back Propagation Artificial Neural Network for Improving the Performance of STBC-based OFDM with Subcarrier Power Modulation

Orthogonal Frequency Division Multiplexing with Subcarrier-Power Modulation (OFDM-SPM) has recently been proposed as a promising, potential transmission technique for future wireless communications (i.e., 6G and beyond) due to its multiple beneficial characteristics, including higher spectral efficiency, low latency with good reliability while maintaining low complexity. In this paper, Orthogonal Frequency Division Multiplexing with Subcarrier-Power Modulation and Space-Time Block Coding (OFDM-SPM-STBC) technique is compounded with Back Propagation Artificial Neural Network (BPANN) in a multiple-input-single-output (MISO) setup to study, investigate and quantify the wireless system's performance of their combination over a multi-path Rayleigh fading channel. Particularly, we analyze two main performance metrics: bit-error-rate (BER) and throughput of the newly designed technique called OFDM-SPM-STBC-BPANN, and then quantify the amount of resulting gains in both BER and throughput due to using the proposed system. We also consider two scenarios for OFDM-SPM-STBC-BPANN transmission. The first one is the power re-assignment policy (PRP), and the second one is the power saving policy (PSP). It is found that the sub-carrier optimized power-reassignment scheme provides the best BER performance for the proposed transmission scheme. In contrast, the PSP for SPM is seen to provide an intermediate improvement in the average BER. The performance of the system in terms of BER and Throughput is improved furthermore by implementing Feed-Forward Back-Propagation Artificial Neural Network (BPANN) at the receiver side. It is observed an average SNR gain of about 7 dB in the BER by implementing BPANN with OFDM-SPM-STBC. It is also found that the optimized power-reassignment scheme provides the best BER performance for the proposed OFDM-SPM-STBC transmission scheme with BPANN at the receiver.

Performance of Modulating Retro-Reflector FSO Communication Systems With Nonzero Boresight Pointing Error

A comprehensive investigation of the impact of nonzero boresight pointing error on the performance of modulating retro-reflector (MRR) free space optical (FSO) communication systems is the goal of this work. In particular, the end-to-end signal-to-noise ratio (SNR) statistical characteristics including probability density function (PDF), cumulative distribution function (CDF), moments as well as moment generating function (MGF) are formulated. Capitalizing on these results, the system average BER and outage probability are derived. Moreover, the asymptotic performances of the system ergodic capacity at low and high SNR values are deduced as well. The obtained expressions are verified via Monte-Carlo simulation.

Discrete bit-loading for OFDM systems under BER-constraint and imperfect CSI

ABSTRACT In this paper, a low complexity discrete bit loading is proposed for OFDM systems over a fading channel and imperfect channel state information (CSI). The available CSI at the transmitter can be partially known due to imperfection in channel estimation, interferences or the Doppler spread. These imperfections increase the bit error rate (BER) for each subchannel. Uniform power allocation and finite granularity for constellation size are used to maximise spectral efficiency subject to a target average BER. The proposed bit loading algorithm, starts by loading all the subcarriers with an initial bit vector obtained using the available CSI and under constraint of the target BER and the maximum number of bits allowed. Then, we introduce the errors on the CSI in the new formula of the average BER calculated initially by using all the subcarriers indexes of the initial bit vector. Iteratively, only the subcarriers, which violate the constraint on the average BER, are used for the updating; they are unloaded until reaching the final bit vector. Therefore, the set of concerned sub-carriers decreases after each iteration, this results in a significant reduction in the computational complexity.

Performance analysis and optimal detector of wireless optical space-time shift keying over the Gamma-Gamma turbulence channel.

In this paper, an optical space-time shift-keying (OSTSK) scheme based on the space-time dispersion matrix block of orthogonal design and laser selection technology is proposed to improve the transmission bits per symbol (TBS) and bit error rate (BER) performance of the traditional optical space shift keying (OSSK). The average BER of OSTSK is investigated over the Gamma-Gamma channel and simulated using the Monte Carlo method. The results show that the proposed scheme has the highest TBS and best BER performance compared with OSSK and optical generalized space shift keying. In addition, we propose a threshold judgment orthogonal matching pursuit (TJ-OMP)-decoding algorithm near-optimal detector for the OSTSK scheme to reduce the computational complexity of the system. For the OSTSK system with Nt=4 and Nr=4, when the reasonable threshold is selected as θ=1.5, the computational complexity of OSTSK-(TJ-OMP) is 74.3% lower than that of the OSTSK-maximum likelihood sequence detection (OSTSK-MLSD), while the signal-to-noise ratio of the OSTSK-(TJ-OMP) decreases by about 1.5 dB at BER=1×10-3.

Experimental demonstration of OAM-based transmitter mode diversity data transmission under atmosphere turbulence.

Twisted light carrying orbital angular momentum (OAM), which features helical phase front, has shown its potential applications in diverse areas, especially in optical communications. For OAM-based free-space optical (FSO) links, a significant challenge is the power fading induced by atmospheric turbulence. In this paper, we experimentally demonstrate the mitigation of atmospheric turbulence effects with an OAM-based transmitter mode diversity scheme. By designing multi-OAM phase patterns, we successfully generate multiple OAM modes (OAM-1,0,1, OAM+2,+3,+4, OAM+5,+6,+7) carrying the same data stream for transmitter diversity without adding system complexity. An intensity-modulated direct-detection (IM-DD) system with 39.06 Gbit/s discrete multi-tone (DMT) signal is employed to confirm the feasibility of the OAM-based transmitter mode diversity scheme under atmosphere turbulence. The obtained experimental results show that the received power fluctuation and average bit-error rate (BER) are decreased under moderate to strong turbulence compared to the traditional single OAM mode transmission. In addition, the required transmitted power at 10% interruption probability is relaxed by nearly 2 dB under moderate to strong turbulence.

Statistical model for the weak turbulence-induced attenuation and crosstalk in free space communication systems with orbital angular momentum

A novel statistical model connected with turbulence strength is proposed to describe the attenuation and crosstalk in a vortex-based multi-channel free space optical (FSO) communication system. In this model, self-channel fading and interference between different orbital angular momentum (OAM) modes are characterized by the mixture exponential-generalized-gamma (EGG) distribution, and the analytical relations between turbulence strength and the distribution function's parameters are expressed by piecewise functions. The problems of obtaining parameters of this model are converted into optimization problems, and the algorithms based on the trust trigon algorithm are proposed to achieve more optimized parameters. This model is confirmed to have a good fit with the emulated data of OAM attenuation and crosstalk calculated by the square of the scalar product between the fields of two OAM modes. Furthermore, the application of the statistical model to the OAM-multiplexing FSO system with quadrature-phase-shift-keying modulation is presented, in which the theoretical average bit-error rate results match well with Monte Carlo simulation. This model can be used for FSO system design with OAM for continuous weak turbulence condition.

Performance analysis of multi-hop parallel FSO system over double generalized gamma distribution considering two transmission beams

The performances of multi-hop parallel free space optical (FSO) communication system are investigated over double generalized gamma (double GG) distribution for plane and spherical waves considering path loss and pointing errors (PE). Specifically, the closed-form expressions of outage probability and average bit error rate (ABER) are derived with Meijer-G function and further confirmed by Monte Carlo (MC) simulation. Subsequently, the outage performances of this system are analyzed in detail with the influence of PE, turbulence strengths, structure parameters and weather conditions for plane and spherical waves. Moreover, cyclic coding is used in this work to further optimize system performance.

Performance analysis of L-MRC receiver with estimation error over Beaulieu-Xie fading channels

A smart receiver is used in advanced wireless communication to trim down the fading and shadowing effects. Performance of such receivers depends on the accuracy of the channels estimation. This paper derived general expression of average bit error rate (BER) and outage probability for L branch Maximum Ratio Combining (L-MRC) receiver over Beaulieu-Xie (BX) fading channels with Imperfect Channel Estimation (ICE). The BX fading model characterizes dominant multiple specular components with some diffuse power. The probability density function (PDF) of output signal to noise ratio is evaluated for L-MRC receiver with channel estimation error over the BX model. The expression of average BER is formulated for binary coherent and non-coherent modulation and the outage probability of the system. The impacts of severity of fading and error estimation on the system performance are analyzed by using the numerical evaluation of the finding expressions.

A novel model to eliminate the doubly near‐far problem in wireless powered communication network

In this paper, the newly emerging wireless powered communication network is studied. In doing so, the performance of the global controller (GC) is evaluated, which coordinates the wireless energy transmissions between two sensor nodes. Both the sensors have the same harvested energy for uplink (UL) transmission of information through time-division-multiple-access. Afterwards, the information transmission time is optimised to maximise the common throughput of both the sensors with a total time constraint based on the user's UL channels along with the same harvested energy value. Further, due to the “doubly near-far” phenomenon, a remote sensor from the GC, which has poor channel conditions than a nearer user, has to transmit more time in the UL for maximum common throughput. To overcome this problem, the energy exchange (EEx) model is proposed where both sensors first harvest the same amount of wireless energy and then exchange energy to nullify the different channel conditions between sensors and GC to send their independent information in the UL. Simulation results demonstrate the EEx Model's effectiveness over without energy exchange (WEEx) model in eliminating the doubly near-far problem in wireless powered communication network but at the cost of maximum sum-throughput. The maximum sum-throughput of the proposed EEx model is 35 % lower than the WEEx model. However, the average BER in the proposed EEx model is 74.6 % lower than the WEEx model, which increases the reliability of the model.

Bit Error Rate Analysis of Mobile Ad Hoc Networks over η − µ Fading Channels

In this paper the performance analysis of Mobile ad hoc networks (MANETs) is conducted for a differential QPSK (DQPSK) signals with post-detection equal gain combining (EGC) receiver operating over additive white Gaussian noise (AWGN) as well as for slow frequency nonselective η − µ fading channels, in which the diversity branches can have unequal signal-to-noise ratios (SNRs) as well as different severity parameters. The average bit error probability (ABEP) is evaluated using MGF-based approach. The average BER per multi-hop route of MANETs for this communication is studied.