Increasing traffic in the optical backbone network has made it incumbent upon operators to extend the use of optical spectrum beyond the C-band. In this work we estimate network performance over the ...C+L band using a physical layer model for estimating the optical signal to noise ratio (OSNR) for lightpaths operating over the C+L band optical spectrum. The model considers nonlinear interference (NLI) due to inter-channel stimulated Raman scattering (ISRS) and the impact of ISRS gain on amplified spontaneous emission (ASE) noise generated by in-line amplifiers while estimating the OSNR. This model is used to account for the capacity benefits associated with OSNR estimation while considering current state of spectral occupancy to account for NLI as compared to the fully-filled, worst-case NLI assumption. OSNR estimation based on current state of spectral occupancy provide higher capacity benefits for smaller networks like the BT-UK while for larger networks like the USA NSFNET the capacity benefit is significantly reduced. Further network capacity benefits of operating over C+L band as compared to C band have been reported. For BT-UK the capacity benefit is more than 100% while for larger networks like USA NSFNET the maximum capacity benefit is 73% with 37.5 GHz of bandwidth until 10% of demands are blocked.
Telecommunication networks are becoming the central linking institution of the Fourth Industrial Revolution. To cope with the associated capacity and connectivity challenges, transportation networks ...may explore the -neglected so far- remaining transmission bands in the second and third low attenuation windows of the optical fibre overcoming the C-band barrier. To assess the potential of optical multi-band transmission systems to upgrade a European Operator's network, we have developed a planning tool based on a routing engine that exploits a novel Physical Layer Aware, Routing, Modulation and Spectral Assignment algorithm. We considered unrepeatered transmission exploiting fibre amplifiers tailored to each transmission band. Taking into account the performance of close to commercialization fibre amplifier devices, we estimated the impact for the most detrimental effects in multi-band transmission like ASE accumulation, FWM and SRS. With the aid of this planning tool, we demonstrate the potential of multi-band systems to upgrade network capacity without compromising the connectivity between Core nodes, albeit new physical layer challenges. Nevertheless, it is shown that multi-band systems allow higher operational flexibility that may slow-down the need to deploy additional C-band fibres. Moreover, we have shown that the roll out of these multi-band systems could be planned in phases in order to limit first-day capital expenditure.
This study seeks to determine the prevalence and risk factors for smoking among students aged 12-18 years in two cities in Botswana. Using a sample of 2554 students we adapted the Global Youth ...Tobacco Survey (GYTS) methodology to assess students' smoking practices, knowledge, beliefs and attitudes. Logistic regression models were used to evaluate factors associated with smoking. The results revealed that 10% of students were current tobacco smokers with 29% reporting having tried smoking. Self-image and acceptance by peers were the strongest predictors of smoking overall (adjusted Odds Ratio aOR: 3.13, 95%, Confidence Interval CI: 2.67-3.66). Intention to smoke or to continue to smoke and perceived norms in conformity with smoking were also independently associated with smoking (aOR: 1.81, 95% CI: 167-2.11 and aOR: 1.31, 95% CI: 1.10-1.57, respectively). Perceived prevalence and exposure to smoking by peers and family and access to tobacco products was stronger among females (aOR: 1.69, 95% CI: 1.52-1.91) compared to males (aOR: 0.93, 95% CI: 0.70-1.24). Our results indicate that anti-tobacco interventions in Botswana should prioritize intra-personal factors associated with smoking. Our findings also suggest that different interventions targeting male and female students should be explored.
Background Behavioral intentions (motivational factors), attitudes, subjective norm (social pressures), and perceived behavioral control promote or discourage smoking behavior among adolescents. ...Objective To assess students' behavioral intentions, attitudes, subjective norms and perceived behavioral control on smoking using the Theory of Planned Behavior. The prevalence of smoking among the adolescents is also calculated. Methods In this cross-sectional study, structured self-administered questionnaires were used to collect data from adolescents in primary and secondary schools. Data on demographics, behavioral intentions, attitudes, subjective norms, and perceived behavioral control towards smoking were collected. Pearson product moment correlations and logistic regression models were used to determine factors associated with current smoking. Results A total sample of 2554 (mean age = 15; Range = 12-18 years) students participated in the study. Twenty-nine percent (n = 728) of the students had tried smoking at least once. Smoking was predicted by attitudes, subjective norms, perceived behavioral control and intention.There was a strong association between having a parent or guardian, caregiver or close friend who smoked (p 0.001) and being a smoker. The majority of students (57%) conveyed that adults talked to them about the harmful effects of cigarette smoking and 50% had discussed smoking concerns with their friends. Students who had positive attitudes towards smoking like smoking makes you confident were more likely to be current smokers (OR: 1.63, 95% CI: 1.03-2.59). The feeling or conviction that they could refuse a cigarette if offered was an impediment from smoking (OR: 0.18, 95% CI: 0.13-0.26). Conclusions Attitudes, subjective norms, and perceived behavioral control contributed significantly to the students' smoking. Right attitudes must be cultivated and behavioral control must be strengthened for early effective interventions to curtail smoking among adolescents.
We present two complementary routing and spectrum assignment (RSA) algorithms that use a quantitative fragmentation metric using the concept of Shannon entropy in flexgrid networks. Applying the ...minimum-entropy (MinEnt) approach to the BT network, support for almost 10% more demands in a static growth scenario is shown. We also present results for a maximum-entropy (MaxEnt) RSA approach, implemented using a genetic algorithm, and operated on the same real BT network topology. The MaxEnt approach avoids fragmentation problems, and it is anticipated that this can increase network utilization.
This special issue includes extensions of optical networking papers that were presented at the European Conference on Optical Communication (ECOC) 2023, held 1–5 October 2023 in Glasgow, Scotland.
Introduction to the OFC 2023 Special Issue Lord, Andrew
Journal of optical communications and networking,
2024-January, 2024-01-01, Letnik:
16, Številka:
1
Journal Article
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Odprti dostop
Each year JOCN has the privilege of inviting the best optical networking papers presented at the Optical Fiber Communication Conference (OFC) for an extended write-up. The January and February issues ...of the journal include a Special Edition covering OFC 2023, and there are 15 excellent papers to explore between the two issues.
This special issue includes extensions of optical networking papers that were presented at the European Conference on Optical Communication (ECOC) 2022, held 18–22 September 2022 in Basel Switzerland.
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