Role of Self Phase Modulation and Cross Phase Modulation on Quality of Signal in Optical Links

Author(s):  
Karamjit Kaur ◽  
Anil Kumar

Background: In WDM networks, there is a crucial need to monitor signal degradation factors in order to maintain the quality of transmission. This is more critical in dynamic optical networks as non-linear impairments are network state dependent. Moreover, PLIs are accumulative in nature, so the overall impact is increased tremendously as the length of signal path is increased. The interactions between different impairments along the path also influence their overall impact. Objective: Among the different impairments, the present work focus on phase modulations owing to intensities of signals themselves as well as the neighboring signals. It includes the influence of SPM, SPM and XPM, system parameters like signal power, wavelength and fiber parameters like attenuation coefficient, dispersion coefficient and their influence on Q-value and BER. Method: The analysis is done through a single and two-channel transmitter system with varied power, wavelengths and system parameters. The corresponding optical spectrums are analysed. Result & Conclusion: It has been found that SPM and XPM pose broadening effect on spectrum without any effect on temporal distributions. The magnitude of signal power is among the parameters significantly influencing the broadening of spectrum. Higher is the power, more is the magnitude of broadening. It has been found that in order to neglect the impact of input power; its magnitude must be kept below 20 mW. Also, the dispersion and attenuation value need to be carefully as they pose counteracting effect to SPM and XPM for certain values and hence can be used as compensation measure without any additional cost.

Author(s):  
Héctor Cancela

We are glad to present the last issue of 2015, completing Volume 18 of the CLEI Electronic Journal. This issue is comprised by the following regular papers.The first paper, “Quality of Protection on WDM networks: A Recovery Probability based approach”, by M. D. Rodas-Brítez and D. P. Pinto-Roa, features a proposal of a new quality of protection (QoP) paradigm for Wavelength Division Multiplexing optical networks. The new approach is flexible, allowing the network administrator to define and select a set of protection levels, based on recovery probabilities which measure the degree of conflict among primary lightpaths sharing backup lightpaths. To show the interest of the approach, a Genetic Algorithm is used to design a routing strategy by multi-objectiveoptimization, minimizing the number of blocked requests, the number of services without protection, the total differences between the requested QoP and the assigned QoP, and the network cost.The second paper, “Towards Scalability for Federated Identity Systems for Cloud-Based Environments”, by A.A. Pereira, J. B. M. Sobral and C. M. Westphall, addresses scalability issues in identity management for cloud computing environments. The authors propose an adapted sticky-session mechanism, as an alternative approach to the more common distributed memory approach, and discuss the implications in therms of computational resources, throughput and overall efficiency. The following work, “Formal Analysis of Security Models for Mobile Devices, Virtualization Platforms, and Domain Name Systems”, by G. Betarte and C. Luna,tackles security models for security-critical applications in three areas: mobile devices, virtualization platforms, and domain name systems. The authors develop formalizations using the Calculus of Inductive Constructions, to study different usual variants of security models in these platforms and their properties.The last paper of this issue is “Digi-Clima Grid: image processing and distributed computing for recovering historical climate data”, by authors S. Nesmachnow, G. Usera and F. Brasileiro. This paper reports an experience of implementing semi-automatic techniques for digitalizing and recovering historical climate records applying parallel computing techniques over distributed computing infrastructures, which was applied to Uruguayan historical climate data.As we complete now the eighteenth year of continued existence of CLEIej, we thank the regional community for its continued support, and we encourage researchers working in computer science and its applications to consider submitting their work to CLEIej, as the the leading electronic, open access journal in Computer Science in Latin America.


2018 ◽  
Vol 21 ◽  
pp. 00011
Author(s):  
Dariusz Strzęciwilk ◽  
Krzysztof Ptaszek ◽  
Paweł Hoser ◽  
Izabella Antoniku

The following article presents the results on the impact of encryption algorithms and the cryptographic hash function on the QoS (Quality of Service) transmission in a computer network. A network model supporting data encryption using the AES algorithm and the MD5 and SHA hash functions used in VPN tunnels was designed and tested. The influence of different data length on the quality of transmission in a secured network was studied. The measurements and tests of networks were performed according to two methodologies ITU-T Y.1564 and RFC 2544. The impact of the data encryption mechanism on bandwidth, data loss and maximum delays was examined. The secured network tests were performed with different combinations of encryption algorithms and hash functions of the VPN tunnel in the ESP (Encapsulating Security Payload) transport mode.


2020 ◽  
Vol 10 (1) ◽  
pp. 363 ◽  
Author(s):  
Xiaomin Liu ◽  
Huazhi Lun ◽  
Mengfan Fu ◽  
Yunyun Fan ◽  
Lilin Yi ◽  
...  

With the development of 5G technology, high definition video and internet of things, the capacity demand for optical networks has been increasing dramatically. To fulfill the capacity demand, low-margin optical network is attracting attentions. Therefore, planning tools with higher accuracy are needed and accurate models for quality of transmission (QoT) and impairments are the key elements to achieve this. Moreover, since the margin is low, maintaining the reliability of the optical network is also essential and optical performance monitoring (OPM) is desired. With OPM, controllers can adapt the configuration of the physical layer and detect anomalies. However, considering the heterogeneity of the modern optical network, it is difficult to build such accurate modeling and monitoring tools using traditional analytical methods. Fortunately, data-driven artificial intelligence (AI) provides a promising path. In this paper, we firstly discuss the requirements for adopting AI approaches in optical networks. Then, we review various recent progress of AI-based QoT/impairments modeling and monitoring schemes. We categorize these proposed methods by their functions and summarize advantages and challenges of adopting AI methods for these tasks. We discuss the problems remained for deploying AI-based methods to a practical system and present some possible directions for future investigation.


2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Namita Kathpal ◽  
Amit Kumar Garg

AbstractIt is known that the high bandwidth demands are accomplished by deploying the concept of wavelength division multiplexing in optical networks which involves the transmission of multiple wavelength signals spaced very close to each other. Due to closely spaced wavelengths, the signal power of one channel phase modulates the adjacent channel which in turn produces nonlinear effects such as cross-phase modulation (XPM), self-phase modulation (SPM) and four-wave mixing (FWM). Thus, in this paper, PC-DCF (pre-compensating dispersion compensating fiber) technique has been demonstrated and evaluated in the transmission link to compensate the XPM effects, and this result seems to significantly enhance w.r.t. transmission performance and system capacity considering performance metrics such as Optical Signal to Noise Ratio (OSNR), bit rate, Q-factor and bit error rate (BER). It is evident from the simulation results as well as through mathematical modeling that the proposed technique (PC-DCF) provides optimum results at the channel spacing of 100 GHz, bit rate of 10 Gbps and input power of 5 mW which collectively provides a 5 dB increase in OSNR as compared to the existing compensating technique.


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