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This paper targets a Denoising Dynamic Statistical Threshold (DDST) detection algorithm to detect the “presence” of Fiber Bragg Grating (FBG) spectral peaks in noise with changing Signal-to-Noise Ratio (SNR) in a sensing channel. Computing the DDST is based on statistical parameters of the background noise. The DDST is determined by adjusting it using the SNR via determining the targeted probability of false alarms (pFA). The proposed algorithm incorporates the effect of background noise fluctuations, nonlinear signal attenuation of a Single-Mode Fiber (SMF), as well as influence of the short-term interference. The implemented sliding wavelength window technique in conjunction with the FBG spectral peaks power scaling allow automatic adjusting of pFA and the DDST. During the possible FBGs resonant wavelengths overlap resulting from approaching/colliding spectral power responses of FBGs, the proposed algorithm also improves the detection robustness and resolving of these overlaps. The DDST marginally takes into account spectral shapes of FBGs resonant wavelength peaks. Advantageously, DDST wavelength resolving is independent of FBG spectral peaks shapes. Our DDST algorithm is also simple to implement. Measurements done by two Optical Spectral Analyzers (OSAs) confirmed significant improvements in the background noise reduction (i.e. signal denoising), noisy FBG spectral peaks shapes smoothing and SNR, improved adjacent FBG spectral peaks detectability and resolving. Our experiments also confirmed usability of the DDST algorithm under severe network conditions (with low reflected FBG power below $-$75 dB and low SNR $< $ 4 dB resulting a standard deviation of $\sigma >$ 7 dB in the background noise fluctuations) with resolution of 3.43 pm.

The objective of this paper is to investigate nonlinear effects in Wavelength-Division Multiplex (WDM) systems in the case when different types of high-order M-PSK and M-QAM modulation formats for various structures of channel spacing are used optical signals. In general, the degradation mechanisms are caused by transmitted optical signals and their impact on each optical channel in WDM can be very different. Therefore, it is suitable to investigate possibilities for channel arrangement from the point of view of equidistant and non-equidistant channel spacing, respectively, what would lead to the suppression of nonlinear effects. In this article we investigate new types of high-order modulation formats that have ability for increasing of spectral efficiency and total improvement of performance of the transmission WDM system. The attention is put on two classes of channel spacing in WDM system, equidistant channel spacing (f= 100, 50, 25 and 12.5 GHz) and non-equidistant channel spacing (f≠ const.), respectively. For investigation of signal propagation the numerical model is created. The model is based on mathematical method Symmetrical-Split Step Fourier Method (S-SSFM), which is utilized for solving the coupled nonlinear Schr�dinger's equations (CNLSE) describing the transmission of signals in multichannel systems. The results of the created numerical model are analyzed, compared to each other and interpreted in a way that leads to the determination of suitable high-order modulation formats and we try to propose the optimal arrangement of optical channels in WDM system. The key issue is to suppress the impact of nonlinearities on modulated signals for each channel with respect to the employed types of digital modulation formats, various system parameters, different types of optical fibers and localization of reference channel in the wavelength area.

This paper deals with time analysis of the Segment-based Robust Fast Optical Reservation Protocol and it is divided into three parts: discovery, reservation and blocking recovery. The S-RFORP protocol consists of two parts: inter segments and intra segments. In this paper we focused only on intra segment time analysis.

This paper deals with using of distributed computing for the simulation of chosen optical network parts. Described are the abilities of algorithm for multi-space distributed computing network with feedback for quasi real-time simulation. The main idea of this approach is using more PC's for the time saving during computer simulations of an optical communication systems.