BER Estimation Research Articles

Optimum Threshold Value and BER Estimation of Remodulated OOK Signal Based on RSOA

A loop-back WDM-PON based on a RSOA has lots of merits, however one-level of the upstream signal has downstream information under OOK modulation. These effects make difficult to define decision threshold and estimate BER. In order to solve this, we propose a mathematical model of remodulated OOK signal and experimentally demonstrate BER performance with the near optimum decision threshold achieved by the proposed model.

Extension of the exhaustive Gaussian approach for BER estimation in experimental direct-detection OFDM setups

An extension of the exhaustive Gaussian approach to estimate the bit error ratio from a set of experimental runs in direct-detection orthogonal frequency division multiplexing optical communication systems is proposed. The approach provides fast and accurate bit error ratio estimates avoiding the high amount of data required by direct error counting. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2772–2775, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25595

Stochastic BER estimation for coherent QPSK transmission systems with digital carrier phase recovery

We propose a stochastic bit error ratio estimation approach based on a statistical analysis of the retrieved signal phase for coherent optical QPSK systems with digital carrier phase recovery. A family of the generalized exponential function is applied to fit the probability density function of the signal samples. The method provides reasonable performance estimation in presence of both linear and nonlinear transmission impairments while reduces the computational intensity greatly compared to Monte Carlo simulation.

System Performance of High-Order Optical DPSK and Star QAM Modulation for Direct Detection Analyzed by Semi-Analytical BER Estimation

Recently, higher order modulation formats are intensively investigated to further increase spectral efficiency for building next generation optical transport networks. Direct detection receivers are capable of detecting arbitrary modulation formats with differentially encoded phases such as differentially phase shift keying (DPSK) and star shaped quadrature amplitude modulation (Star QAM) formats. In an earlier publication of the authors (M. Seimetz , ¿Optical systems with high-order DPSK and star QAM modulation based on interferometric direct detection,¿ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J. Lightw. Technol.</i> , vol. 25, no. 6, pp. 1515-1530, Jun. 2007) a system analysis was performed where performance was mainly characterized by eye opening penalties. Here, these investigations are extended. A tool for semi-analytical BER estimation is developed allowing to calculate the BER down to small values such as 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> for a wide range of modulation formats, as well as for different receiver structures. Using this module, the back-to-back OSNR requirements are calculated. CD and SPM tolerances are characterized by optical signal-to-noise ratio (OSNR) penalties at BER = 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> . As far as the authors know, this is the first analysis of the transmission characteristics of optical 16DPSK and Star 16QAM based on the BER. Moreover, further novel aspects such as optimization of the optical and electrical receiver filter bandwidths are investigated.

An efficient technique to estimate the realisation bit error rate of multiband OFDM based UWB systems

AbstractIn this paper, we present a simple method to estimate the realisation bit error rate (RBER) of a multiband orthogonal frequency division multiplexing (OFDM)‐based ultra‐wide band (UWB) system. Under time‐varying channels, error event based BER estimation of convolutionally encoded systems requires the knowledge of error events in the Viterbi decoding. In this work, we show that the upper‐bound of instantaneous outage capacity is a function of the percentage of subcarriers, whose signal‐to‐noise (SNR) ratio is less than a predefined outage threshold which we call as realisation outage ratio (ROR). Simulation results reveal that the RBER of the channel realisations and their corresponding ROR are highly correlated at an optimally selected outage threshold. Using this correlation, we form a simple mathematical model between ROR and RBER and obtain quite accurate and consistent RBER estimates with respect to the error event based RBER estimates and the empirical RBER simulation results. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Bit error rate estimation for turbo decoding

In this paper we propose a method for on-line estimation of bit error rate during turbo decoding. We model the log-likelihood ratios as a mixture of two Gaussian random variables and derive estimators for the mean and variance of these distributions based on a maximum-likelihood approach. The parameter estimates are then employed to calculate the cross-over area of the Gaussian tails to estimate BER at each decoder iteration. The performance of the BER estimator is analysed and compared.

BER Performance of Space-Time Coded MMSE DFE for Wideband Code Division Multiple Access (WCDMA)

In recent times, there has been growing interests in integration of voice, data and video traffic in wireless communication networks. With these growing interests, WCDMA has immerged as an attractive access technique. The performance of WCDMA system is deteriorated in presence of multipath fading environment. The paper presents space-time coded minimum mean square error (MMSE) Decision Feedback Equalizer (DFE) for wideband code division multiple access (WCDMA) in a frequency selective channel. The filter coefficients in MMSE DFE are optimized to suppress noise, intersymbol interference (ISI), and multiple access interference (MAI) with reasonable system complexity. For the above structure, we have presented the estimation of BER for a MMSE DFE using computer simulation experiments. The simulation includes the effects of additive white Gaussian noise, multipath fading and multiple access interference (MAI). Furthermore, the performance is compared with standard linear equalizer (LE) and RAKE receiver. Numerical and simulation results show that the MMSE DFE exhibits significant performance improvement over the standard linear equalizer (LE) and RAKE receiver.

More accurate simulation of dynamic transparent optical wavelength division multiplex networks

Novel modulation schemes and higher bit rates as well as dynamically switched networks make it necessary to consider effects, which could be neglected in system simulations so far. In this paper, we present simulation methodologies needed for the accurate characterisation of the signal quality in such transparent optical networks. The combined effects of polarisation mode dispersion (PMD) and polarisation-dependent loss (PDL) are investigated, and a more accurate method for the BER estimation based on histograms is described. Furthermore, dynamical transient effects in the physical layer require extending the regarded time scale to the millisecond range. An efficient way how to simulate the effects on different time scales is presented.

Performance comparison of 40 Gb/s ULH transmissions using CSRZ-ASK or CSRZ-DPSK modulation formats on UltraWave fiber ^TM fiber

In this work we present extensive comparisons between numerical modelling and experimental measurements of the transmission performance of either CSRZ-ASK or CSRZ-DPSK modulation formats for 40-Gb/s WDM ULH systems on UltraWave(TM) fiber spans with all-Raman amplification. We numerically optimised the amplification and the signal format parameters for both CSRZ-DPSK and CSRZ-ASK formats. Numerical and experimental results show that, in a properly optimized transmission link, the DPSK format permits to double the transmission distance (for a given BER level) with respect to the ASK format, while keeping a substantial OSNR margin (on ASK modulation) after the propagation in the fiber line. Our comparison between numerical and experimental results permits to identify what is the most suitable BER estimator in assessing the transmission performance when using the DPSK format.

System-independent threshold and BER estimation in optical communications using the extended generalized gamma distribution

Two important tasks with respect to the optimized configuration of an optical communications system are those of the performance evaluation and the receiver decision threshold estimation. In this paper, a new training-based BER and threshold estimation technique is proposed relaxing the assumption of Gaussian distributed received signals. The proposed method is similar in philosophy to the Gaussian Approximation one, and is system-independent and simulation-based. This means that the probability density function (pdf) of the sampled electrical current is estimated based on training data provided via simulations without any assumptions on the specific configuration of the communications system under consideration. The novelty of the paper is that for the first time a combination of a generalized form of the gamma distribution together with the noncentral chi-square distribution have been used for the modeling of the pdfs of the spaces and the marks, respectively.

Noise statistics of and BER estimation using demodulated signals for direct detection differential polarization-phase-shift keying

The noise statistics of optically demodulated signal of the recently proposed modulation format, namely differential polarization-phase-shift keying, are analyzed. It is found that, in the linear regime, the Gaussian approximation is reasonably accurate in estimating the BER. In the nonlinear regime, the noise of the demodulated signal is dominated by the effect of nonlinear phase noise and obeys chi-squared statistics with a degree of freedom of one. Gaussian approximation underestimates the BER in the nonlinear regime. A two-step BER estimation method accounting for both linear beat noise and nonlinear phase noise is proposed. The effectiveness of this two-step BER estimation method at all power levels has been established by comparison with direct error counting.

Robust joint channel and noise estimation in Bayesian blind equalizers

In this paper, we discuss the problem of reducing the complexity of Bayesian approaches to the joint channel and data detection issues in digital communications. Taking ideas from Bayesian Analysis and Evolutionary Computation, we propose and compare different equalization schemes whose complexity is kept moderate by applying pruning and merging operations over an otherwise growing population of channel estimates. Already existing deterministic methods for complexity limitation as well as new stochastic ones are analyzed and compared. Using the capability of Bayesian equalizers to estimate the symbol error probability during operation, a convergence control mechanism is introduced. The joint channel and noise Bayesian estimation is shown to offer more robust BER estimates.

Simple Q factor monitoring for BER estimation using opened eye diagrams captured by high-speed asynchronous electrooptical sampling

We propose a new signal-quality (Q factor) monitoring method that uses opened eye diagrams captured by asynchronous sampling. The use of high-speed asynchronous electrooptical sampling makes fixed timing Q factor monitoring simple to perform. The method is experimentally compared to the existing averaged Q factor method.

A new approach to BER estimation for ISI corrupted baseband transmission systems

AbstractThis paper derives two new formulae for BER estimation when the transmission system is subject to both intersymbol interference and additive Gaussian noise. The approach undertaken here was oriented to find a simple formula giving close estimation of the true BER, which may be useful for the transmission system designer for rapid evaluation of system performance. The obtained results are compared with commonly used BER estimations. Copyright © 2001 John Wiley &amp; Sons, Ltd.

Simulation von Zeitvarianten Indoor-Mobilfunkkanälen mit SPW ™

An essential hallmark of software for simulations of systems in the field of development of new products is the degree of nearness to reality. In this work the simulation tool SPW by Alta Group has been supplemented with three components, which are necessary to allow the modeling of time-variant indoor radio channels. With the use of the new functions TIME-VARIANT CHANNEL CARRIER & TIMING RECOVERY and QPSK BER ESTIMATOR a plausible and more realistic modeling of the transmission between transmitter and moving receiver is achieved. By exchanging the measured time-variant radio channel which has been used in this paper for a channel model, also predictions of the BER based on the used propagation model are possible.

Secure communications using chaotic digital encoding

A PAM communication link using a chaotic codec, proposed by Frey, has been simulated, and BER estimates obtained. The simulated link has also been used to investigate the performance of a modified decoder and of a filter designed to produce a signal with a more noise-like PDF.

Performance off 8-PSK trellis codes over nonlinear fading mobile satellite channels

In this paper a new analytical bound for large effective code length codes (ECL) is derived. The accuracy of the analytical bounds is validated by simulation. Based on the new bound a trellis code design procedure for fading channels is defined. A quasi-analytical technique for BER estimation on nonlinear channels is proposed. This method is used to estimate the performance degradation of nonlinear communication systems with the pilot tone.

On the Application of Importance Sampling to BER Estimation in the Simulation of Digital Communication Systems

Importance sampling (IS) is a useful technique for reducing the number of Monte Carlo trials in BER estimation. Two important aspects of recent research work in this area are to find more applications of IS BER estimation and to seek a good bias scheme in the implementation of the estimator. This correspondence presents a general and rigorous mathematical description of these aspects of this problem which, we hope, will be useful for further research. We also present a general result on how to choose a good bias scheme which may provide some insight into the problem.