Mean Bit Error Rate Research Articles

Robust and Energy Efficient Sparse-Coded OFDM-DCSK System via Matrix Recovery

In this paper, we devise a sparse-coded orthogonal frequency division multiplexing (OFDM) differential chaos shift keying (DCSK) communication system based on low-rank matrix recovery which can handle Gaussian background noise and outlier-contaminated symbols simultaneously. As the noise-free OFDM-DCSK symbol matrix has rank 1, we exploit the vector outer product for its modeling, while sparse coding is also applied to reduce the transmission energy. To demodulate information bits from the sparse-coded signal, we formulate an objective function which consists of a sum of Frobenius norm for rank-1 matrix recovery and ℓ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -norm for identifying the possibly outlier-contaminated symbols, with a self-adaptive weight parameter. The resultant optimization problem is solved iteratively via block coordinate descent, and the Laplacian kernel with the Silverman’s rule is adopted for outlier detection. Theoretical analysis including convergence of the objective function, bit error rate (BER), energy efficiency and computational complexity, are provided. Simulation results show that the proposed system has comparable mean square error and BER performance with the ℓ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>p</i></sub> -norm minimization based matrix recovery approach at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</i> = 2 in additive white Gaussian noise, and is superior to that of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</i> = 1 in Middleton class A noise, even when sparse coding is applied. Moreover, compared with other binary DCSK systems, our system achieves higher energy efficiency thanks to the sparse coding.

Aperture-averaged scintillation for a weak underwater turbulence-affected Gaussian beam using the OTOPS model.

The calculation of optical system performance for laser beam propagation in optical turbulence, such as bit error rate (BER), signal-to-noise ratio, and probability of fade, requires the knowledge of scintillation. In this paper, we show the analytical expressions of the aperture-averaged scintillation using a new recently introduced power spectrum of the refractive index fluctuations for underwater turbulence, the oceanic turbulence optical power spectrum (OTOPS). In addition, we use this main result to investigate the impact of weak oceanic turbulence on free-space optical system performance for a propagating Gaussian beam wave. Similar to the atmospheric turbulence case, results show that aperture averaging can reduce the mean BER and the probability of fade several orders of magnitude if the receiver aperture is chosen with a diameter larger than the Fresnel zone, L/k. Being valid for weak turbulence regime in any natural waters, results present the variations of irradiance fluctuations and the performance of underwater optical wireless communication systems depending on the practical values of average temperature and average salinity concentration that can be encountered in any world's waters.

Energy efficient data detection with low complexity for an uplink multi-user massive MIMO system

The current development of the Internet of Things (IoT) network in sixth-generation (6G) communication opens up various opportunities. When IoT devices with edge platforms connect to the telecommunication network, mobility, interferences, and intelligent device capacity issues might occur. The challenge with uplink MU-MIMO systems is data detection owing to noise, frequency allocations, and dense deployment of intelligent devices. The exponential complexity of extensive wireless networks makes optimal maximum likelihood detection impossible. Using MATLAB simulation-based analysis, we suggested an iterative data detection strategy based on a coordinate descent method (CDM) to reduce computing complexity while preserving an acceptable bit error rate (BER). Linear systems demand low co-channel interference (CCI) MU-MIMO uplink communications (CCI). A superior mean square error or BER performance is achieved using Maximum ratio combining with CDM. The proposed system outperforms the Richardson Method (RM), approximation message passing (AMP), and linear minimum mean square error (LMMSE) algorithms in terms of BER and complexity.

Mean Bit Error Rate Analysis of High Rate IEEE 802.15.3.a UWB Channels

In this work, the performance of ultra-wide band systems (UWB) in high-speed wireless networks is studied. At the physical layer of wireless personal area networks, dual carrier modulation driving multiband orthogonal frequency division multiplexing is implemented for 480 Mbps data rates over 4 classes of UWB scattering channels (CM1, CM2, CM3, CM4) bundeled as per the IEEE 802.15.3a UWB standard. Generalized wireless fading models are presented and canonical expressions for mean bit error rates (MBER) are derived for different modulation and receiver diversity combining schemes. A generating model in terms of the characteristic function of the signal-to-noise ratio is introduced for MBER under general statistical fading conditions, which further develops our previous work. The power density spectral characteristic of the multi-user noise is tuned to a novel generalized innovation-matched filter (GIMF) which is at the core of the UWB receiver. Because of its robustness at also capturing the fading characteristics of the UWB channels, the GIMF detector yields better performance than the classical matched filter and a 10-finger RAKE receiver. The relatively flat CM1 channel is proven to have the best performance, while the highly frequency selective CM4 suffers from the worst performance. CM3 channel slightly outperforms CM4 channel between 0 and 5 dB and exhibits significant improvement over CM4 above 5 dB SNR. CM3 and CM4 channels are proven to have nearly identical performance below 0 dB margins. A comparative analysis was also conducted for the MBER of our model and that of the CF-based model at a 10-finger RAKE receiver developed by Wang et al. It was found that our model outperforms that of the CF-model for CM1 and CM2 channels for a wide dynamic range of SNR values. For CM3 and CM4 channels, our model's performance was superior for SNR values below 8 dB.

Research on performance of convex partially coherent flat-topped beams in vertical atmospheric turbulent paths

Previous studies on non-uniformly correlated (NUC) beams mainly focus on beams with Gaussian amplitude profiles. In this paper we research a new class of non-uniformly correlated flat-topped beams, which are called convex partially coherent flat-topped (CPCFT) beams. Using wave optics simulation (WOS), we investigate the propagation properties of such beams in vertical atmospheric turbulent paths in detail and calculated the mean signal-to-noise ratio (SNR) and bit-error rate (BER). It is found that CPCFT beams will self-focus during propagation, resulting in larger on-axis intensity than Gaussian Schell-model (GSM) and PCFT beams, and they also have smaller scintillation in most cases. These properties have made CPCFT beams effective for improving the mean SNR and reducing the mean BER. WOS results show that turbulence induced degradation can be dramatically reduced by using CPCFT beams under certain circumstances.

Scintillation index of an optical wave propagating through moderate-to-strong oceanic turbulence.

In this paper, based on the extended Rytov theory that combines modified large-scale and small-scale amplitude spatial-frequency filters, we theoretically derive the scintillation index (SI) of the plane and spherical waves by means of the approximate oceanic refractive-index spectrum with the variable eddy diffusivity ratio propagating through moderate-to-strong oceanic turbulence. The mean bit-error rate (BER) of the underwater optical wireless communication systems is analyzed by use of the predicted SI and the gamma-gamma distribution model. Numerical results show that the obtained SI models are in good agreement with the results in weak-fluctuation regions. Also, we find that in weak turbulence, the mean BER drops sharply with the increase in mean signal-to-noise ratio, while in moderate-to-strong turbulence, the situation is opposite. We also note that the mean BER differs between the cases of unity and the variable eddy diffusivity ratio.

Reduced Complexity BER Calculations in Large Scale Spatial Multiplexing Multi-User MIMO Orientations in Frequency Selective Fading Environments

In this article, a computationally-efficient approach is presented for Bit Error Rate (BER) calculations in multi-user Multiple Input Multiple Output (MIMO) frequency selective fading environments, operating in spatial multiplexing transmission mode. To this end, theoretical expressions for the equivalent Signal to Interference plus Noise Ratio (SINR) per active user and transmission mode, as well as mean BER, are derived. The key idea is that all parameters related to BER calculations can be expressed as sums of identically distributed random variables (RVs). Hence, computational burden can be reduced, since summation formulas take into account the parameters of a standalone RV along with the correlation of an arbitrary pair of RVs. As results indicate, the proposed approach can accurately estimate mean BER in multiuser MIMO orientations with increased reception diversity order, for arbitrary number of transmit/receive antennas, a modulation scheme, and a number of resolvable multi-path components.

Effect of aperture averaging on mean bit error rate for UWOC system over moderate to strong oceanic turbulence

In moderate to strong oceanic turbulence, a differential phase-shift-keying (DPSK) modulated underwater wireless optical communication (UWOC) system with an aperture receiver is presented. The analytical expressions for mean bit error rate (BER) of UWOC system over moderate to strong oceanic turbulence are derived based on Gamma–Gamma channel model by the help of the Whittaker function. The variations of mean BER are investigated versus modulation methods, beam types, aperture diameters as well as four oceanic turbulence parameters, i.e., the rate of dissipation of kinetic energy per unit mass of fluid, the rate of dissipation of mean-squared temperature, the ratio of temperature to salinity contributions to the refractive index spectrum and the kinetic viscosity.

On the Reduction of Transmission Complexity in MIMO-WCDMA Frequency-Selective Fading Orientations via Eigenvalue Analysis

In this paper, a novel transmission strategy for Mutliple Input Multiple Output Wideband Code Division Multiple Access (MIMO-WCDMA) orientations operating in frequency-selective fading environments is investigated, in terms of overall algorithmic complexity reduction. To this end, Principal Component Analysis (PCA) is employed on the received data matrix, in order to define the significant terms that are taken into account during transmission matrix formulation. According to the presented results, feedback information of only the primary eigenvector of the corresponding covariance matrix of the received data matrix is required, in order to maintain the mean Bit Error Rate (BER) at acceptable levels. In particular, a complexity reduction of up to 10% can be achieved, when comparing BER values derived by the selection of all components of the received covariance matrix during transmission matrix formulation, and the corresponding BER when selecting half of the components. This reduction is maintained to 10%, when considering a realistic four-element antenna design; however, in this case mean BER inaccuracy is further reduced to 1%.

Scintillation and bit error rate analysis of a partially coherent flat-topped array laser beam in maritime and terrestrial non-Kolmogorov atmospheric environments on a slant path.

In this paper, on the basis of the extended Huygens-Fresnel principle, a semi-analytical expression for describing the on-axis scintillation index of a partially coherent flat-topped laser beam through non-Kolmogorov maritime and terrestrial atmospheric environments on a slant path is derived. Consequently, by using the log-normal intensity probability density function, the bit error rate (BER) is evaluated. The effects of source factors (such as wavelength, order of flatness, and beam width) and the non-Kolmogorov turbulent atmosphere parameters (such as the Kolmogorov inner scale, the spectral power-law exponent, and the turbulence structure constant) on propagation behavior of the scintillation index, and hence on the BER, are studied in detail. Results indicate that an increase in the average SNR causes a greater influence of the power-law exponent on the BER. Also, it can be deduced that the mean BER increases while the power-law exponent decreases. In addition, the scintillation index and BER as communication link parameters represent the fact that increasing the atmospheric refractive-index structure parameter on the ground and decreasing the inner scale of turbulence eddies causes an increase in these parameters.

Mean Bit Error Rate Evaluation of MC-CDMA Cellular Systems Employing Multiuser-Maximum-Likelihood Detector

In this paper, we evaluate the uplink bit error rate (BER) of multicarrier-code-division-multiple-access (MC-CDMA) cellular systems with multiuser-maximum-likelihood detector (MU-MLD). The scenario considers perfect power control, own-cell interference (or multiple access interference—MAI), interference from co-cells (or co-cell interference—CCI), additive white Gaussian noise, exponential path-loss and slow frequency-selective Rayleigh fading. Upper bound expressions to evaluate the mean BER are obtained, which are functions of the signal-to-noise ratio (SNR), the number of users, the spreading factor, and the channel reuse factor. For BPSK and 4-QAM (quadrature amplitude modulation), closed-form expressions involving the analytical calculation of pairwise error probabilities are obtained. For 16-QAM and 64-QAM, we show that the number of pairwise error probabilities needed to obtain the BER can be simplified through the constellations symmetry. The procedure for obtaining this simplification is detailed. Also, by considering BER asymptotes, expressions for the SNR penalty due to MAI are derived. Monte Carlo simulations verify the analytical expressions accuracy. In the simulations, the MU-MLD is implemented through the sphere decoder algorithm with MMSE QR factorization. Results show that MC-CDMA does not lose diversity due to MAI. Moreover, CCI significantly affects the system performance. As a consequence, it produces floors in the BER curves.

Performance analysis of MC-CDMA cellular systems employing MMSE multiuser detector in presence of own-cell and co-cell interference

In this work, it is analyzed the uplink performance of MC-CDMA cellular systems in order to show that a MMSE multiuser detector can mitigate not only the own-cell interference, but also the co-cell interference. For the analysis, it is also considered a linear antenna array at the base station. The channel includes additive white Gaussian noise, exponential path-loss and slow frequency-selective Rayleigh fading. First, the interference in the cellular system is analyzed. Then, approximate expressions to evaluate the signal-to-interference ratio (SIR) are derived. Also, expressions to evaluate the bit error rate (BER) both for BPSK and M-QAM modulations are obtained. Monte Carlo simulations verify the tightness of the expressions. The results show that when we include the co-cell interference statistics in the MMSE detector design, the effects of this interference can be mitigated. Also, it is observed that the system can be overloaded when the number of antennas in the array is increased while the mean BER maintains reasonable values. Finally, with an asymptotic analysis of the BER expressions, the BER reduction with the MMSE multiuser detector when compared with the zero-forcing multiuser detector is obtained. This BER reduction has not been previously obtained in the literature.

Offset Phase Shift Keying Modulation in Multiple-Input Multiple-Output Spatial Multiplexing

The increasing demand for multimedia data transmission in mobile wireless communication poses a challenge to reliable signal reception. In order to have good signal quality, a robust digital modulation scheme is required at the transmitter. However, the conventional M-ary Phase Shift Keying (MPSK) commonly used in multiple-input multiple-output (MIMO) communication systems with non-linear radio frequency (RF) power amplifiers causes a relative increase in intercarrier interference (ICI). This paper presents a development of offset-MPSK (O-MPSK) modulation scheme in MIMO spatial multiplexing over the Rayleigh fading channel. The O-MPSK modulation schemes were developed for 4, 8, 16, 32 and 64 constellation sizes. The development of the O-MPSK was done by shifting the phase of the conventional QPSK, 8-PSK, 16-PSK, 32-PSK and 64-PSK by an odd multiple of pi (π) to give -QPSK, -8PSK, -16PSK, -32PSK and -64PSK, respectively, with a view to reducing the spectral spreading in the power amplifiers at the receiver of a MIMO system. The MIMO techniques used was MIMO Spatial Multiplexing (MIMO–SM). The system models were developed around these schemes and later simulated using MATLAB application toolkit. The performances of the O-MPSK schemes were evaluated using bit error rate (BER) at signal-to-noise ratio (SNR) range of 0 to 20 dB and compared with the conventional MPSK schemes. The results obtained for all the SNRs in MIMO-SM showed that mean BER of 0.0024, 0.0040, 0.0085, 0.0183 and 0.036 were obtained for -QPSK, -8PSK, -16PSK, -32PSK and -64PSK respectively as against mean BER of 0.0025, 0.0044, 0.0088, 0.0178 and 0.0358 obtained for conventional QPSK, 8PSK, 16PSK, 32PSK and 64PSK respectively. The mean BER values obtained reveal that the developed O-MPSK outperforms the conventional MPSK due to the relatively lower BER of O-MPSK schemes compared with the MPSK schemes. This is as a result of the reduction in the amplitude variations and spectral spreading at the receiver of the MIMO system.

Adaptive power loading with BER-constraint for OFDM systems

A novel adaptive power loading algorithm with the constraint of target overall bit error rate (BER) for orthogonal frequency division multiplexing (OFDM) systems is proposed in this article. The proposed algorithm aims to minimize the required transmit power with fixed data rate and uniform (nonadaptive) bit allocation, while guaranteeing the target overall BER. The power loading is based on the unequal-BER (UBER) strategy that allows unequal mean BERs on different subcarriers. The closed-form expressions for optimal BER and power distributions are derived in this article. Simulation results indicate the superiority of the proposed algorithm in terms of BER performance and algorithmic complexity.

Adaptive power loading based on unequal-ber strategy for OFDM systems

An adaptive power loading algorithm with uniform (nonadaptive) bit allocation is proposed for constant data rate OFDM systems in this letter. This algorithm aims to minimize the transmit power while guaranteeing the target mean bit error rate (BER). The power loading is based on the unequal-BER (UBER) strategy which permits unequal mean BERs on different subcarriers. The closed-form expressions for optimal BER and power distributions are derived. Simulation results indicate the superiority of the proposed algorithm.

Adaptive bit and power loading algorithm with low complexity in MIMO-OFDM systems

Two adaptive power and bit loading algorithms to maximize the throughput of MIMO-OFDM systems in frequency selective fading environment are proposed. The two algorithms allocate bit based on maximizing the overall throughput. One algorithm allocates power based on guaranteeing that the bit error rate (BER) of each sub-carrier and the total allocated power remain below a target BER threshold and a power threshold, respectively; another one allocates power based on guaranteeing that the mean BER of sub-carriers and the total allocated power remain below a target BER threshold and a power threshold, respectively. The simulation results show that the proposed algorithms can achieve faster throughput with lower computational complexity, which indicates that the proposed algorithms are effective when compared to some existing algorithms.

Linear Predictive Detection for Power Line Communications Impaired by Colored Noise

Robust detection algorithms capable of mitigating the effects of colored noise are of primary interest in communication systems operating on power line channels. In this paper, we present a sequence detection scheme based on linear prediction to be applied in single-carrier power line communications impaired by colored noise. The presence of colored noise and the need for statistical sufficiency requires the design of an optimal front-end stage, whereas the need for a low-complexity solution suggests a more practical suboptimal front-end. The performance of receivers employing both optimal and suboptimal front-ends has been assessed by means of minimum mean square prediction error (MMSPE) analysis and bit-error rate (BER) simulations. We show that the proposed optimal solution improves the BER performance with respect to conventional systems and makes the receiver more robust against colored noise. As case studies, we investigate the performance of the proposed receivers in a low-voltage (LV) power line channel limited by colored background noise and in a high-voltage (HV) power line channel limited by corona noise.

Channel-aware priority transmission scheme using joint channel estimation and data loading for OFDM systems

This paper presents a data-loading technique that jointly considers the effect of channel estimation and the property of encoded multimedia data in Orthogonal Frequency Division Multiplexing (OFDM) systems. We observe that OFDM subchannels experience different average bit error rate (BER) due to channel estimation inaccuracy. The leakage effect in the fast Fourier transform (FFT)-based channel estimation method or the model mismatch in the polynomial-based channel estimation method results in a variation on the decoded BER across different OFDM subchannels. Thus, we are motivated to design the Priority Transmission (PT) scheme, which utilizes this BER variation across different OFDM subchannels and provides unequal error protection (UEP) for multimedia transmission. In addition, since OFDM has been adopted in many multimedia transmission standards, we compare the different channel estimation techniques, which were compared only for generic data transmission before, in the context of multimedia transmission with the PT scheme. In particular, we extend the polynomial-based channel estimation that was previously designed for a decision-directed scenario to a pilot-symbol-assisted (PSA) channel estimation scenario. Then, we investigate the channel estimation mean square error (MSE) and BER performance of individual OFDM subchannels for both the FFT-based and the polynomial-based channel estimation. Furthermore, we design the PT scheme that achieves significant gain in peak-signal-to-noise ratio (PSNR) of the reconstructed images for both channel estimation methods. Finally, we compare different OFDM channel estimation techniques for multimedia transmission. It is shown that for generic data transmission, the polynomial-based PSA channel estimation outperforms the FFT-based method in realistic channel conditions, and both types of channel estimation have similar performance when using the proposed PT scheme for multimedia transmission.

Bit loading with BER-constraint for multicarrier systems

We present discrete adaptive bit loading algorithms for multicarrier systems with uniform (nonadaptive) power allocation operating in a frequency selective fading environment. The algorithms try to maximize the overall throughput of the system while guaranteeing that the mean bit error rate (BER) remains below a prescribed threshold. We also study the impact of imperfect subcarrier signal-to-noise ratio information on throughput performance. Results show that the proposed algorithms have approximately the same throughput and mean BER as the optimal allocation while having a significantly lower computational complexity relative to other algorithms with near-optimal allocations. Moreover, when compared with algorithms that employ approximations to water filling, the computational complexity is comparable while the overall throughput is closer to the optimum.

Upper-bound performance of a wide-band adaptive modem

Adaptive modulation is applied in conjunction with a decision-feedback equalizer (DFE) in order to mitigate the effects of the slowly varying wide-band multipath Rayleigh fading channel in a noise-limited environment. An upper-bound mean bit-error rate and bits per symbol performance is introduced for this scheme by utilizing the pseudo signal-to-noise ratio at the output of the DFE in order to switch the modulation schemes on a burst-by-burst basis.