Noise Analysis and Comparison of an ‘M’ Repeated/Regenerator Link
14 Dec 2020-pp 1-6
TL;DR: In this article, the unconditional superiority of regenerators over repeaters for given link parameters was shown for WDM WDM systems, and a few approximations were used to represent the Q function analytically and corresponding expressions were used for comparing the performance of repeaters and regenerators.
Abstract: The advent of optical amplifiers have revolutionized optical communications, facilitating (Wavelength Division Multiplexed) WDM systems and leading to an explosion in bandwidth and data rates. But long amplified links degrades the optical Signal to Noise Ratio (SNR) with each stage of amplification due to the addition of Amplified Spontaneous Emission (ASE). This is overcome by using regenerators which does the Optical-Electrical and back to Optical (OEO) conversion to detect the signal and regenerating it anew thereby removing all the noise and hence restoring the SNR. But this electrical conversion introduces delays and prohibitively increases the cost of the link. A potential solution for this is the use of all optical regenerators, which does the amplification and reshaping in the optical domain itself. This paper undertakes a BER analysis proving the unconditional superiority of regenerators over repeaters for given link parameters. It also demonstrates the better power savings and extra reach of all optical regenerators. Further, a few approximations are used to represent the Q function analytically and the corresponding expressions are used for comparing the performance of repeaters and regenerators.
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01 Jan 1992TL;DR: In this article, the authors present an overview of the main components of WDM lightwave communication systems, including the following: 1.1 Geometrical-Optics Description, 2.2 Wave Propagation, 3.3 Dispersion in Single-Mode Fibers, 4.4 Dispersion-Induced Limitations.
Abstract: Preface. 1 Introduction. 1.1 Historical Perspective. 1.2 Basic Concepts. 1.3 Optical Communication Systems. 1.4 Lightwave System Components. Problems. References. 2 Optical Fibers. 2.1 Geometrical-Optics Description. 2.2 Wave Propagation. 2.3 Dispersion in Single-Mode Fibers. 2.4 Dispersion-Induced Limitations. 2.5 Fiber Losses. 2.6 Nonlinear Optical Effects. 2.7 Fiber Design and Fabrication. Problems. References. 3 Optical Transmitters. 3.1 Semiconductor Laser Physics. 3.2 Single-Mode Semiconductor Lasers. 3.3 Laser Characteristics. 3.4 Optical Signal Generation. 3.5 Light-Emitting Diodes. 3.6 Transmitter Design. Problems. References. 4 Optical Receivers. 4.1 Basic Concepts. 4.2 Common Photodetectors. 4.3 Receiver Design. 4.4 Receiver Noise. 4.5 Coherent Detection. 4.6 Receiver Sensitivity. 4.7 Sensitivity Degradation. 4.8 Receiver Performance. Problems. References. 5 Lightwave Systems. 5.1 System Architectures. 5.2 Design Guidelines. 5.3 Long-Haul Systems. 5.4 Sources of Power Penalty. 5.5 Forward Error Correction. 5.6 Computer-Aided Design. Problems. References. 6 Multichannel Systems. 6.1 WDM Lightwave Systems. 6.2 WDM Components. 6.3 System Performance Issues. 6.4 Time-Division Multiplexing. 6.5 Subcarrier Multiplexing. 6.6 Code-Division Multiplexing. Problems. References. 7 Loss Management. 7.1 Compensation of Fiber Losses. 7.2 Erbium-Doped Fiber Amplifiers. 7.3 Raman Amplifiers. 7.4 Optical Signal-To-Noise Ratio. 7.5 Electrical Signal-To-Noise Ratio. 7.6 Receiver Sensitivity and Q Factor. 7.7 Role of Dispersive and Nonlinear Effects. 7.8 Periodically Amplified Lightwave Systems. Problems. References. 8 Dispersion Management. 8.1 Dispersion Problem and Its Solution. 8.2 Dispersion-Compensating Fibers. 8.3 Fiber Bragg Gratings. 8.4 Dispersion-Equalizing Filters. 8.5 Optical Phase Conjugation. 8.6 Channels at High Bit Rates. 8.7 Electronic Dispersion Compensation. Problems. References. 9 Control of Nonlinear Effects. 9.1 Impact of Fiber Nonlinearity. 9.2 Solitons in Optical Fibers. 9.3 Dispersion-Managed Solitons. 9.4 Pseudo-linear Lightwave Systems. 9.5 Control of Intrachannel Nonlinear Effects. Problems. References. 10 Advanced Lightwave Systems. 10.1 Advanced Modulation Formats. 10.2 Demodulation Schemes. 10.3 Shot Noise and Bit-Error Rate. 10.4 Sensitivity Degradation Mechanisms. 10.5 Impact of Nonlinear Effects. 10.6 Recent Progress. 10.7 Ultimate Channel Capacity. Problems. References. 11 Optical Signal Processing. 11.1 Nonlinear Techniques and Devices. 11.2 All-Optical Flip-Flops. 11.3 Wavelength Converters. 11.4 Ultrafast Optical Switching. 11.5 Optical Regenerators. Problems. References. A System of Units. B Acronyms. C General Formula for Pulse Broadening. D Software Package.
4,125 citations
TL;DR: New exponential bounds for the Gaussian Q function and its inverse are presented and a quite accurate and simple approximate expression given by the sum of two exponential functions is reported for the general problem of evaluating the average error probability in fading channels.
Abstract: We present new exponential bounds for the Gaussian Q function (one- and two-dimensional) and its inverse, and for M-ary phase-shift-keying (MPSK), M-ary differential phase-shift-keying (MDPSK) error probabilities over additive white Gaussian noise channels. More precisely, the new bounds are in the form of the sum of exponential functions that, in the limit, approach the exact value. Then, a quite accurate and simple approximate expression given by the sum of two exponential functions is reported. The results are applied to the general problem of evaluating the average error probability in fading channels. Some examples of applications are also presented for the computation of the pairwise error probability of space-time codes and the average error probability of MPSK and MDPSK in fading channels.
835 citations
TL;DR: A novel, simple and tight approximation for the Gaussian Q-function and its integer powers is presented, and an accuracy improvement is achieved over the whole range of positive arguments.
Abstract: We present a novel, simple and tight approximation for the Gaussian Q-function and its integer powers. Compared to other known closed-form approximations, an accuracy improvement is achieved over the whole range of positive arguments. The results can be efficiently applied in the evaluation of the symbol error probability (SEP) of digital modulations in the presence of additive white Gaussian noise (AWGN) and the average SEP (ASEP) over fading channels. As an example we evaluate in closed-form the ASEP of differentially encoded QPSK in Nakagami-m fading.
242 citations
TL;DR: Amplitude regeneration schemes for ON-OFF keying signals using self-phase modulation and four-wave mixing in fibers and regeneration schemes of phase-encoded signals are reviewed.
Abstract: Fiber-based all-optical signal regeneration techniques are reviewed. In the first half of the paper, amplitude regeneration schemes for ON-OFF keying signals using self-phase modulation and four-wave mixing in fibers are classified and their features are described. In the second half of the paper, focus is placed on regeneration schemes of phase-encoded signals. In particular, we discuss the performance of the regenerators in which phase information is converted to/from amplitude information and noise suppression is done on the amplitude. Usefulness of phase-preserving amplitude-only regeneration in reducing nonlinear phase noise is also discussed. Some experimental results are shown. Finally, issues in applying all-optical regeneration to real transmission systems are mentioned.
67 citations
TL;DR: New lower and upper bounds on the Gaussian Q-function are presented, unified in a single and simple algebraic expression which contains only two exponential terms with a constant and a rational coefficient, respectively, which are found to be as tight as multi-term alternatives obtained e.g. from the Exponential and Jensen-Cotes families of bounds.
Abstract: We present new lower and upper bounds on the Gaussian Q-function, unified in a single and simple algebraic expression which contains only two exponential terms with a constant and a rational coefficient, respectively. Lower- and upper-bounding properties are obtained from such unified expression by selecting the coefficients accordingly. Despite the remarkable simplicity, the bounds are found to be as tight as multi-term alternatives obtained e.g. from the Exponential [2] and Jensen-Cotes [3] families of bounds. A corollary result is that the n-th integer power of Q(x) can also be tightly bounded both below and above with only n+1 algebraic terms. In addition to offering remarkable accuracy and mathematical tractability combined, the new bounds are very consistent, in which both lower and upper counterparts are similarly tight over the entire domain.
34 citations