scholarly journals A State-Variable Approach to Submarine Links Capacity Optimization

2021 ◽  
Author(s):  
Alberto Bononi ◽  
Paolo Serea ◽  
Jean-Christophe Antona
Keyword(s):  
Optimal Allocation ◽  
Signal To Noise Ratio ◽  
Realistic Model ◽  
Input Power ◽  
Capacity Optimization ◽  
Constant Input ◽  
Wavelength Division ◽  
State Variable ◽  
Variable Approach ◽  
Submarine Links

We consider the capacity optimization of submarine links when including a realistic model of the gain-flattened constant-pump erbium doped fiber amplifiers (EDFA). While Perin et al. [1] numerically attacked this optimization for Constant-Gain (CG) amplified links, we extend the analysis also to more realistic submarine constant power-spectral-density (CPSD) links. As in [1], we concentrate on a single spatial mode of a spatial division multiplexed (SDM) link at low EDFA pump power Pp, and thus consider only the impairments of amplified spontaneous emission noise. Here we adopt a novel semi-analytical approach which consists of fixing the inversion x1 of the first EDFA (the state-variable of the link) and analytically finding capacity C(x1) by searching over the x1-feasible input wavelength division multiplexed (WDM) PSD distributions. Then the optimum inversion x1 that maximizes C(x1) is numerically obtained. This approach enables us to get both approximate (for CG links) and exact (for CPSD links) capacity-maximizing WDM input distributions, which vary inversely with the EDFA gain profile. For CG links the optimal WDM allocation is called the gain-shaped water-filling. Other practical allocations are analyzed, such as the signal to noise ratio equalizing allocation (CSNR), and the constant input power (CIP) allocation which uses a flat WDM distribution. We find that, for typical submarine span attenuations around 10dB and when the link works at the optimal inversion x1, CIP and CSNR achieve essentially the same capacity as the optimal allocation. At sufficiently large pump Pp (>= 30 mW) the optimal inversion x1 is such that the EDFA gain at 1538nm equals the span attenuation, for EDFA emission and absorption as in [1]. When span attenuations increase to 20dB, then we start seeing an advantage of the optimal allocation. Another key finding is that optimized CG and CPSD links behave roughly the same, with a slightly superior capacity for CPSD.

scholarly journals A State-Variable Approach to Submarine Links Capacity Optimization

2021 ◽  
Author(s):  
Alberto Bononi ◽  
Paolo Serea ◽  
Jean-Christophe Antona
Keyword(s):  
Optimal Allocation ◽  
Signal To Noise Ratio ◽  
Realistic Model ◽  
Input Power ◽  
Capacity Optimization ◽  
Constant Input ◽  
Wavelength Division ◽  
State Variable ◽  
Variable Approach ◽  
Submarine Links

We consider the capacity optimization of submarine links when including a realistic model of the gain-flattened constant-pump erbium doped fiber amplifiers (EDFA). While Perin et al. [1] numerically attacked this optimization for Constant-Gain (CG) amplified links, we extend the analysis also to more realistic submarine constant power-spectral-density (CPSD) links. As in [1], we concentrate on a single spatial mode of a spatial division multiplexed (SDM) link at low EDFA pump power Pp, and thus consider only the impairments of amplified spontaneous emission noise. Here we adopt a novel semi-analytical approach which consists of fixing the inversion x1 of the first EDFA (the state-variable of the link) and analytically finding capacity C(x1) by searching over the x1-feasible input wavelength division multiplexed (WDM) PSD distributions. Then the optimum inversion x1 that maximizes C(x1) is numerically obtained. This approach enables us to get both approximate (for CG links) and exact (for CPSD links) capacity-maximizing WDM input distributions, which vary inversely with the EDFA gain profile. For CG links the optimal WDM allocation is called the gain-shaped water-filling. Other practical allocations are analyzed, such as the signal to noise ratio equalizing allocation (CSNR), and the constant input power (CIP) allocation which uses a flat WDM distribution. We find that, for typical submarine span attenuations around 10dB and when the link works at the optimal inversion x1, CIP and CSNR achieve essentially the same capacity as the optimal allocation. At sufficiently large pump Pp (>= 30 mW) the optimal inversion x1 is such that the EDFA gain at 1538nm equals the span attenuation, for EDFA emission and absorption as in [1]. When span attenuations increase to 20dB, then we start seeing an advantage of the optimal allocation. Another key finding is that optimized CG and CPSD links behave roughly the same, with a slightly superior capacity for CPSD.

A Comparative Analysis of Dual-Order Bidirectional Pumping Schemes in Optical Fiber Raman Amplification

2019 ◽  
Vol 40 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Kulwinder Singh ◽  
Manjeet Singh Patterh ◽  
Manjit Singh Bhamrah
Keyword(s):  
Comparative Analysis ◽  
Fiber Length ◽  
Noise Figure ◽  
Signal To Noise Ratio ◽  
Optical Power ◽  
Optical Signal ◽  
Input Power ◽  
Q Factor ◽  
Wavelength Division ◽  
First Order

Abstract In this paper, dual-order bidirectional pumping schemes of distributed fiber Raman amplifier are compared with standard first-order pumping in wavelength division multiplexed optical transmission systems. The novel comparison analysis is carried out in terms of Optical signal-to-noise ratio and Q-factor, on-off gain and noise figure by varying optical input power and fiber lengths. The results indicate that dual-order schemes present 0.02 dB higher OSNR and 5 dB higher Q-factor in comparison to first-order pumping when input optical power is varied from −4 to 5 dBm. Similarly, there is 4 dB higher on-off gain with dual order comparatively to first order when fiber length varied from 10 to 100 km. However, there is degradation in noise figure and Q-factor due to DRBS noise with dual-order pumping when fiber length from 10 to 100 km. Further, the signal power evolutions along fiber length show that there is 5 dBm improvement for 100 km fiber. The novelty of the work is that comparative analysis exhibits improvement in OSNR, on-off gain and Q-factor using dual-order bidirectional pumping.

Comparative Simulation of Thermal Noise Effects for Photodetectors on Performance of Long-Haul DWDM Optical Networks

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
I. S. Amiri ◽  
Fatma Mohammed Aref Mahmoud Houssien ◽  
Ahmed Nabih Zaki Rashed ◽  
Abd El-Naser A. Mohammed
Keyword(s):  
Optical Networks ◽  
Wavelength Division Multiplexing ◽  
Thermal Noise ◽  
Signal To Noise Ratio ◽  
Avalanche Photodiode ◽  
Input Power ◽  
Superior Performance ◽  
Noise Effects ◽  
Wavelength Division ◽  
The Impact

AbstractLong-haul 16-channel dense-wavelength division multiplexing networks employing two different avalanche photodiode (APD) structures (Si and InGaAs) and positive-intrinsic-negative (PIN) photodetectors are simulated and compared under thermal noise effects for different fiber lengths. The effect of thermal noise level on the transmission quality with a variation of amplifying section length, number of amplifying sections and channel speed is discussed. The impact of thermal noise on the system performance is analyzed by varying input power from −5dBm to 20dBm for both 25 km and 50 km amplifying section at 100 km fiber length. The performance is evaluated for both 5 Gb/s and 10 Gb/s data rates over transmission distances up to 500 km. A comprehensive comparison is developed based on signal-to-noise ratio (SNR), quality factor (Q-factor) and bit error rate (BER). It is found that both APD structures achieve superior performance up to distance of 350 km comparing to PIN photodetectors for 50 km amplifying section. The system provides optimum performance at input power Pin = 10dBm in case of 50 km amplifying section, but then afterwards, the performance is degraded rapidly due to nonlinearities. The results revealed that the worst performance scenario is at 10–18 W/Hz thermal noise in terms of higher BER and lower Q-factor. Finally, the desirable BER of 10–12 is achieved at Q-factor of 6.78 and SNR of 23 dB.

scholarly journals The evaluation of noise- and threshold-induced bias in the integration of single-fish echoes

2004 ◽  
Vol 61 (3) ◽  
pp. 405-415
Author(s):  
Eckhard Bethke
Keyword(s):  
Signal To Noise Ratio ◽  
Threshold Level ◽  
Input Power ◽  
Measuring Error ◽  
Constant Input ◽  
Irminger Sea ◽  
Starting Point ◽  
Threshold Ratio ◽  
Echo Pulse

Abstract The echo integration of single-fish echoes shows that characteristically the received-signal energy of single targets is small compared with the echo energy of schooled fish. The measuring error is minimized by the application of an integration threshold. The echo energy, however, is often only slightly larger than the noise and reverberation level making the determination of the optimal integration threshold difficult. During the evaluation of data from the echo-integration surveys on redfish in the Irminger Sea it was observed that the integration value of single fish increased steadily with decreasing integration threshold. There is no way to determine the integration threshold by eye as for schooled fish. The approach taken in all past publications for the estimation of the influence of the integration threshold on the integration result has been based on the computation of an equivalent beam angle. The influence of “environment noise” was not considered. Here a model is presented, which considers both influences on the integration result during the integration of single-fish echoes. It is assumed that the targets are distributed evenly in the observed volume and that in each pulse volume of the beam only one target is present. The starting point of the computations is the equation for signal processing implemented in the EK500. The echo signal power received is converted pixel-by-pixel into the appropriate volume-backscattering coefficients, sv and stored as echograms. These echograms are available for post-processing in the Bergen Integrator BI500. To exclude noise and reverberation from the subsequent processing a threshold was introduced. We assume that the fish echoes are always larger than the noise and reverberation. This is a very common situation and the largest part of the energy of noise and reverberation can be eliminated in this way. When a fish echo is received outside the centre of the beam it is attenuated by the beam pattern of the transducer and may therefore lie below the threshold and could be cut off. This leads to the reduction of the measured values and a measuring error. An opposite error arises when the signal crosses the threshold. In practice the signal received always consists of noise and echo signals and has more power than it should have. The measured value is larger and this is another error of the measurement process per se. The object of this paper is to calculate the influence of the threshold level on the result of measurement and to derive a practicable rule for the determination of the threshold level. The noise is modelled as a constant input power. The computations are carried out with model functions of the transducer beam and the received-echo pulse. General statements can be met by defining a signal-to-noise ratio and a signal-to-threshold ratio. The results of the theoretical investigations are applied on acoustic data obtained during redfish survey WH229 in the Irminger Sea and adjacent waters.

Adaptive identification methods of nonlinear random electrical signal

2020 ◽  
Vol 64 (1-4) ◽  
pp. 431-438
Author(s):  
Jian Liu ◽  
Lihui Wang ◽  
Zhengqi Tian
Keyword(s):  
Wavelet Transform ◽  
Electric Vehicle ◽  
Signal To Noise Ratio ◽  
Sudden Change ◽  
Electrical Signal ◽  
Signal Recognition ◽  
State Variable ◽  
Signal Characteristics ◽  
The Matrix ◽  
Kalman Filter Algorithm

The nonlinearity of the electric vehicle DC charging equipment and the complexity of the charging environment lead to the complex and changeable DC charging signal of the electric vehicle. It is urgent to study the distortion signal recognition method suitable for the electric vehicle DC charging. Focusing on the characteristics of fundamental and ripple in DC charging signal, the Kalman filter algorithm is used to establish the matrix model, and the state variable method is introduced into the filter algorithm to track the parameter state, and the amplitude and phase of the fundamental waves and each secondary ripple are identified; In view of the time-varying characteristics of the unsteady and abrupt signal in the DC charging signal, the stratification and threshold parameters of the wavelet transform are corrected, and a multi-resolution method is established to identify and separate the unsteady and abrupt signals. Identification method of DC charging distortion signal of electric vehicle based on Kalman/modified wavelet transform is used to decompose and identify the signal characteristics of the whole charging process. Experiment results demonstrate that the algorithm can accurately identify ripple, sudden change and unsteady wave during charging. It has higher signal to noise ratio and lower mean root mean square error.

scholarly journals Experimental demonstration of spectral domain computational ghost imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Piotr Ryczkowski ◽  
Caroline G. Amiot ◽  
John M. Dudley ◽  
Goëry Genty
Keyword(s):  
Signal To Noise Ratio ◽  
Michelson Interferometer ◽  
Spectral Domain ◽  
Proof Of Concept ◽  
Ghost Imaging ◽  
Spectral Measurements ◽  
Spectral Filter ◽  
Wavelength Division ◽  
Spectral Encoding ◽  
Light Effects

AbstractWe demonstrate computational spectral-domain ghost imaging by encoding complementary Fourier patterns directly onto the spectrum of a superluminescent laser diode using a programmable spectral filter. Spectral encoding before the object enables uniform spectral illumination across the beam profile, removing the need for light collection optics and yielding increased signal-to-noise ratio. In addition, the use of complementary Fourier patterns allows reduction of deleterious of parasitic light effects. As a proof-of-concept, we measure the wavelength-dependent transmission of a Michelson interferometer and a wavelength-division multiplexer. Our results open new perspectives for remote broadband spectral measurements.

Optical Networks Performance Optimization Based on Hybrid Configurations of Optical Fiber Amplifiers and Optical Receivers

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
I. S. Amiri ◽  
Fatma Mohammed Aref Mahmoud Houssien ◽  
Ahmed Nabih Zaki Rashed ◽  
Abd El-Naser A. Mohammed
Keyword(s):  
Optical Fiber ◽  
Optical Networks ◽  
Wavelength Division Multiplexing ◽  
Performance Optimization ◽  
Input Power ◽  
Fiber Amplifiers ◽  
Q Factor ◽  
Wavelength Division ◽  
Transmission Distance ◽  
Optical Fiber Amplifiers

AbstractThe 16-channels dense wavelength division multiplexing (DWDM) systems have been optimized by utilizing hybrid configurations of conventional optical fiber amplifiers (EDFA, RAMAN and SOA) and optical photodetectors (PIN, APD(Si) and APD(InGaAs)). The DWDM systems were implemented for 5 Gb/s channel speed using one of these configurations with 100 GHz channel spacing and 25 km amplifying section. The hybrid configurations are the combinations of (PIN + EDFA), (PIN + RAMAN), (PIN + SOA), (APD(Si) + EDFA), (APD(Si) + RAMAN), (APD(Si) + SOA), (APD(InGaAs) + EDFA), (APD(InGaAs) + RAMAN) and (APD(InGaAs) + SOA). Based on BER, Q-factor and eye diagrams, the performance was compared for these configurations under influences of various thermal noise levels of photodetectors over different fiber lengths ranging from 25 km up to 150 km. The results revealed that both APD structures give optimum performance at input power Pin = 5 dBm due to high internal avalanche gain. EDFA outperforms RAMAN and SOA amplifiers. SOA amplifier shows degraded performance because of nonlinearity effects induced. RAMAN amplifier seems to be the best alternative for long reach DWDM systems because it minimizes the effects of fiber nonlinearities. The configuration (APD(Si) + EDFA) is the most efficient and recommended to be used for transmission distance beyond 100 km due to its larger Q-factor.

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