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Background: Major depressive disorder (MDD) can have severe impacts on function and quality of life. Up to one third of patients will have an inadequate response to their first line of treatment, with subsequent lines of therapy associated with lower remission rates and higher relapse rates. Recently esketamine has become available for Australian patients, and this agent provides an additional treatment option for those with MDD who have had an inadequate response to two or more antidepressant therapies during the current moderate to severe depressive episode. This paper provides an expert panel's practical recommendations and clinical guidance for establishing esketamine clinics in Australia. Methods: An expert panel (n = 11) comprising psychiatrists, mental health care nurses, pharmacists, and individuals with experience establishing esketamine clinics was convened in Sydney. The panel developed practical recommendations and clinical guidance, which were then further refined. Results: Five key areas were identified: practical considerations for esketamine clinic set‐up, including multidisciplinary care considerations; patient selection; administering esketamine; adverse event management and long‐term follow‐up. Conclusions: Guidance presented in this paper should assist Australian clinicians to set up an esketamine clinic, and provide practical advice on the infrastructure and clinical requirements for treatment of patients with this agent. [ABSTRACT FROM AUTHOR]

Increased global traffic puts tough requirements not just on fiber communications links but on the entire network. This manifests itself in multiple ways, including how to optimize wavelength routing around the network, how to maximize the benefits arising from fine-control DSP with increasingly accurate real-time monitoring, and how to best deploy multiband or multiple fiber connectivity. This article will summarize research into all these areas to present a full picture of how future optical networks will play their role in supporting the continuing traffic demands of broadband, 5G, and associated applications. [ABSTRACT FROM AUTHOR]

Multiband elastic optical network (MB-EON) technology can help to sustain exponential traffic growth in the optical backbone network. However, multiband operation creates high inter-channel stimulated Raman scattering, leading to a high nonlinear impairment (NLI) that may severely affect the optical signal-to-noise ratio (OSNR) of a lightpath. Additionally, the severity of NLI on the channel of interest depends upon the choice of allocated wavelength. Hence, appropriate channel allocation may cumulatively lead to a higher network capacity. This paper proposes a quality-aware resource provisioning scheme in the context of MB-EON that selectively chooses the available channels from different bands in order to achieve the maximum network capacity in the long run. A deep neural network-assisted quality of transmission estimator is considered to estimate the OSNR of a lightpath with accuracy of 99.65% and 0.012 dB variance in estimation error. The performance of our algorithm in the proposed scheme, namely, optical signal-to-noise ratio adaptive first–last-fit (OA-FLF), is analyzed for two geographically diverse networks, namely, BT-UK and the 24-node USA network, in terms of traffic admissibility, quality of established lightpaths, and contiguous aligned available slot ratio (CAASR), and compared with four state-of-the-art baseline algorithms: first fit, last fit, route adaptive first–last-fit, and distance adaptive first–last-fit. Numerical results indicate that the proposed algorithm outperforms all of the baseline algorithms in terms of traffic admissibility. Reported results show that, compared to the baseline algorithms, consideration of the effect of NLI before resource allocation in the OA-FLF algorithm can provide a maximum gain of nearly 30% in terms of traffic admissibility for smaller networks such as BT-UK, whereas, for longer geography such as the 24-node USA network, this traffic admissibility gain becomes close to 61% till 1% blocking. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Fiber-optic multi-band transmission (MBT) aims at exploiting the low-loss spectral windows of single-mode fibers (SMFs) for data transport, expanding by $\sim\!11\times$ the available bandwidth of C-band line systems and by $\sim\!5\times$ C+L-band line systems’. MBT offers a high potential for cost-efficient throughput upgrades of optical networks, even in absence of available dark-fibers, as it utilizes more efficiently the existing infrastructures. This represents the main advantage compared to approaches such as multi-mode/-core fibers or spatial division multiplexing. Furthermore, the industrial trend is clear: the first commercial C $+$ L-band systems are entering the market and research has moved toward the neighboring S-band. This article discusses the potential and challenges of MBT covering the ITU-T optical bands O  $\rightarrow$  L. MBT performance is assessed by addressing the generalized SNR (GSNR) including both the linear and non-linear fiber propagation effects. Non-linear fiber propagation is taken into account by computing the generated non-linear interference by using the generalized Gaussian-noise (GGN) model, which takes into account the interaction of non-linear fiber propagation with stimulated Raman scattering (SRS), and in general considers wavelength-dependent fiber parameters. For linear effects, we hypothesize typical components’ figures and discussion on components’ limitations, such as transceivers,’ amplifiers’ and filters’ are not part of this work. We focus on assessing the transmission throughput that is realistic to achieve by using feasible multi-band components without specific optimizations and implementation discussion. So, results are meant to address the potential throughput scaling by turning-on excess fiber transmission bands. As transmission fiber, we focus exclusively on the ITU-T G.652.D, since it is the most widely deployed fiber type worldwide and the mostly suitable to multi-band transmission, thanks to its ultra-wide low-loss single-mode high-dispersion spectral region. Similar analyses could be carried out for other single-mode fiber types. We estimate a total single-fiber throughput of 450 Tb/s over a distance of 50 km and 220 Tb/s over regional distances of 600 km: $\sim\!10\times$ and 8× more than C-band transmission respectively and $\sim\!2.5\times$ more than full C+L. [ABSTRACT FROM AUTHOR]

Optical metro networks evolution driven by 5G requirements face enormous challenges. Network functions virtualized in the data centers spread to the metro nodes, IP, and optical technologies must cooperate to meet the metro traffic aggregation role. Multiple technological options exist, and carriers confront the need to economically assess them, benchmarked in realistic deployments. This paper gives relevant insights to this aim. We first construct a set of metro network benchmarks. A strategic and distinctive effort is made to incorporate metro WDM topologies, traffic profiles and daily variation patterns, fault-tolerance requisites, and network operational choices, that faithfully reflect the expected 5G metro progression for a national carrier. Then, we use these networks to assess two technological choices. On one hand, the cost-effectiveness limits in terms of CAPEX reductions and energy efficiency brought from the possibility of having an agile control plane in the metro, capable of on-demand instantiation of IT and network resources. On the other hand, we investigate the benefits of replacing ROADMs by more cost-effective filterless technologies, but just limiting this replacement to degree-1 and degree-2 optical nodes, that are prevalent (e.g. >50%) in regional metro topologies. A novel capacity planning algorithm has been developed for IT, IP and optical resources allocation and dimensioning, providing fault-tolerant designs for the realistic scenarios defined. Simulation results have been obtained using the Net2Plan NIW (NFV over IP over WDM) open-source framework. Developed algorithms and part of the testing scenarios are available for inspection in public repositories of the EU METRO-HAUL project, the umbrella for our work. Our results show CAPEX benefits in the order of 10% and energy savings in the order of 20–30% stemming from the on-demand resource allocation in the metro. In addition, degree 1 and degree 2 optical nodes have shown to be a sweet spot for applying filterless switching, with mitigated impact of the associated spectrum waste. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The migration of DataCenters into Metropolitan Area Networks creates new challenges which include the need for rapid service provisioning and recovery and new, cost-effective, connectivity schemes. Here we propose and demonstrate a truly dynamic transportation platform tailored for a metro network. The novelty of the proposed architecture is that the dynamic data-plane exploits available commercial PON technology while the dynamic control-plane is SDN-enabled using OpenFlow/Netconf. The dynamic operation of the platform in several interesting scenarios is demonstrated on an experimental test-bed. [ABSTRACT FROM AUTHOR]

Objective: High caseload is considered one of the most important factors for good outcomes after high-risk surgeries such as oesophagectomy. However, many Australian centres perform low volumes of oesophagectomies due to demographics. The aim of the present study was to audit outcome after oesophagectomy in an Australian low-volume centre over a period of 13 years and to discuss potential contributors to outcome other than just case volume. Methods: Perioperative and long-term outcomes of all oesophagectomies over a 13-year period in a low-volume Australian tertiary care centre were analysed retrospectively. Data were compared in subgroups of patients in two separate time periods: 2000–05 (n = 23) and 2006–12 (n = 24). Results: There were two perioperative deaths over the entire 13-year period with no postoperative mortality in the last decade. The complication and long-term survival rates for each of the two separate time periods were similar to those from high-volume centres, more so in the second half of the study period. Conclusions: The data suggest that under specific conditions, oesophagectomies can be safely performed even in smaller- or low-volume centres in Australia. The policy of centralisation for these procedures in Australia needs to be carefully tailored to the needs of the population, clinical outcomes, cost-effectiveness and optimal utilisation of existing facilities rather than on caseload alone. What is known about the topic?: High caseload is considered one of the most important factors for good outcomes after oesophagectomy and a driving force behind centralisation of this procedure. However, other factors may also affect outcome – such as availability of experienced surgeons, specialist nurses, interventional radiology, gastroenterology, etc. What does this paper add?: With the availability of appropriate levels of expertise, infrastructure and specialist nursing staff as is the case in most Australian tertiary centres, good perioperative outcomes can be obtained despite low volumes. Case load only should not be used as a surrogate marker of quality. What are the implications for practitioners?: The policy of centralisation for oesophagectomy in Australia needs to be carefully thought out on the basis of population demographics, outcomes and cost-effectiveness, with the appropriate use of existing facilities, rather than on a caseload basis alone. [ABSTRACT FROM AUTHOR]

Hardware and software disaggregation is a recognized strategy for achieving efficiency and cost reduction within datacentre warehouse. More recently this approach has been applied to high-bandwidth inter-datacenter connectivity at the transport layer. Telecom Operators look with great interest at this approach which promises savings that could make the difference in years of ever decreasing margins on revenues. This paper presents and analyzes how disaggregation models in the wavelength division multiplexing (WDM) transport layer could replace the established aggregated model based on mono-vendor systems. Three optical disaggregation models are presented implying different levels of involvement of the telecom operator in WDM system design, assembly, and integration. The impact on the network lifecycle of each model is then analyzed with particular reference to the roles of the operator, the equipment vendors, and the system integrator. The issue of organizational changes and heavy redefinition of processes is addressed and a comparative techno economic analysis is also offered. [ABSTRACT FROM AUTHOR]

Intensive video and cloud computing services are putting much pressure on metro networks to meet stringent requirements such as low latency, low power consumption, and high spectral efficiency, where the system cost is sensitive. To address this challenge, we introduce a special elastic optical network paradigm called the ultradense wavelength switched network (UD-WSN) for metro optical networks. The architecture supports a spectrum granularity (e.g., 6.25 GHz or even 5 GHz) finer than the current smallest standardized 12.5 GHz, which enables more efficient spectrum utilization when provisioning metro lowspeed service connections (e.g., sub-1G/1G/10G services). The performance of UD-WSN is evaluated from the techno-economic perspective in comparison with the conventional OTN over DWDM network. Case studies demonstrate the merits of the proposed architecture. Considering the promising potential of UD-WSN, we also suggest several open research issues for it. [ABSTRACT FROM AUTHOR]

In high speed optical transmission networks, OSNR is the key optical performance parameter. We propose a novel technique for non-intrusive in-band OSNR derivation based on real-time pre-FEC bit error rate (BER) measurement from optical transponders, which exploits pre-measured and calibrated pre-FEC BER versus OSNR curves and multiple modulation formats to ensure accurate OSNR derivation over a wide range. We report a successful field trial of this novel in-band OSNR technique, in which we have demonstrated and verified the accurate OSNR derivation over both a 359 km field trial link and a live 727 km flexible grid optical link using 64 GBaud flexible rate optical transponders with modulation formats 100G DP-QPSK, 200G DP-16QAM, and 200G DP–QPSK. Compared with standard signal “on” and “off” measurement, an OSNR accuracy within ±1 dB was achieved for all three modulation formats. We also investigated the impact of fiber nonlinearity at different signal powers on the accuracy of this technique. It is shown that this novel technique provides reliable and accurate OSNR derivation for the optical signals operating in normal power regime making it suitable for practical network applications. [ABSTRACT FROM PUBLISHER]

We propose and investigate an ultradense wavelength switched network (UD-WSN) for metro and regional applications. The UD-WSN provides all-optical switching and end-to-end wavelength connections at fine granularity (e.g., 12.5 and 6.25 GHz, or lower), and thus can carry high-bandwidth services directly in the optical layer with low latency and low power consumption. Two typical UD-WSN architectures, i.e., symmetric and asymmetric, are introduced. The symmetric architecture is applied in the core segment of optical metro network, where a coherent transceiver is used at each node to send and receive multiple ultradense-wavelength subchannels. The asymmetric architecture is applied in the aggregation or access segment of optical metro network, where multiple subchannels are transmitted between a high-bandwidth coherent transceiver at a metro core node and multiple low-bandwidth noncoherent transceivers at dispersed metro access nodes. Techno-economic analyses show that the UD-WSN is effective in both aspects of cost and power consumption compared to existing solutions. To verify the concept, we also experimentally demonstrate the asymmetric UD-WSN system, in which four optical subchannels with 12.5-GHz frequency spacing are transmitted between a coherent transceiver and four noncoherent transceivers. 20 Gb/s 4-ary pulse-amplitude modulation bidirectional signals in each subchannel are successfully transmitted over 300-km single-mode fiber. [ABSTRACT FROM PUBLISHER]

Quantum key distribution (QKD) is a state-of-the-art method of generating cryptographic keys by exchanging single photons. Measurements on the photons are constrained by the laws of quantum mechanics, and it is from this that the keys derive their security. Current public key encryption relies on mathematical problems that cannot be solved efficiently using present-day technologies; however, it is vulnerable to computational advances. In contrast QKD generates truly random keys secured against computational advances and more general attacks when implemented properly. On the other hand, networks are moving towards a process of softwarization with the main objective to reduce cost in both, the deployment and in the network maintenance. This process replaces traditional network functionalities (or even full network instances) typically performed in network devices to be located as software distributed across commodity data centers. Within this context, network function virtualization (NFV) is a new concept in which operations of current proprietary hardware appliances are decoupled and run as software instances. However, the security of NFV still needs to be addressed prior to deployment in the real world. In particular, virtual network function (VNF) distribution across data centers is a risk for network operators, as an eavesdropper could compromise not just virtualized services, but the whole infrastructure. We demonstrate, for the first time, a secure architectural solution for VNF distribution, combining NFV orchestration and QKD technology by scheduling an optical network using SDN. A time-shared approach is designed and presented as a cost-effective solution for practical deployment, showing the performance of different quantum links in a distributed environment. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

We report the first successful real-time optical superchannel field trials of 5.6 Tb/s over 359 km and 2 Tb/s over a live 727 km flexible grid link using production grade 64 GBaud flexible rate optical transponders. Up to 5.6 Tb/s optical superchannels were successfully demonstrated over a 359 km fully managed flexible grid optical link, where the superchannel comprises a maximum of 28 × 64 GBaud 200 G DP – QPSK subchannels. A 100 GE client signal was transported over all the subchannels, demonstrating stable, long term end-to-end error free performance. A record net spectral efficiency of 3.92 bit/s/Hz was achieved for the 64 GBaud 200 G DP – QPSK, with channel spacing as narrow as 51 GHz. We also successfully demonstrated fast superchannel capacity turn-up, via software configuration of the flexible rate transponders, from 2.6 to 5.2 Tb/s including 100 GE client mappings, which is equivalent to a capacity up-lift of approximately 2 Tb/min. In a further trial over a 727 km live flexible grid optical link between London and Dublin, we successfully demonstrated real-time 2 Tb/s superchannel transport using long reach 64 GBaud 200 G DP – QPSK operating together with 100 G DP – QPSK and 200 G DP – 16 QAM channels enabled by the flexible rate transponders. Stable, long term error free performance was measured of the terabit optical channels alongside live customer traffic. [ABSTRACT FROM PUBLISHER]

In elastic optical networks, the success of providing high network capacity depends on the optical signal-to-noise ratio (OSNR) values of network lightpaths. As each lightpath's OSNR value defines the modulation format and capacity it can support, having high OSNR light-paths is always beneficial. Hence, with a given set of modulation formats, service providers need to optimize their optical infrastructure, including in-line amplifiers and reconfigurable optical add-drop multiplexers (ROADMs), given the size and topology of their core networks. This also will have a direct impact on vendors who need strong insight into the requirements of service providers and their networks in terms of equipment and new technology. Therefore, in this paper a comprehensive model based on the local optimization which leads to a global network optimization (LOGON) strategy of the Gaussian noise (GN) model has been proposed, which helps in estimating the lightpath OSNR and clearly quantifies the noise contributions from in-line amplifiers and post-amplification at the ROADMs. The model introduces closed-form expressions to calculate nonlinear impairment (NLI) contributions for various span lengths while using either erbium-doped fiber amplifiers (EDFAs) or H-Raman amplifiers, which helps in optimizing the signal launch power to achieve maximum link OSNR In addition to this, an offline strategy has been proposed that can help service providers to optimize their procurement of network equipment upfront and give insight into how much of the capacity bottleneck is alleviated in their networks if they do this. To demonstrate all of the above, the UK, Pan-European, and US Core networks have been considered, which illustrate differences in link lengths and reduced node density. It is seen that improving the OSNR conditions at the ROADM increases the network capacity when noise from in-line amplifiers is significantly reduced. Among the three networks, we found that the UK network responded the most to improved OSNR conditions at the ROADM nodes due to small link lengths and less line noise. Among the amplifiers, we found that improving ROADMs while having H-Raman in the links resulted in a maximum capacity increase. For the UK network at FG = 12.5 GHz, the capacity increases by 6650 Gbps, while for the larger Pan-European and US networks, the capacity increase reduces to 4550 and 1600 Gbps due to increased link lengths and line noise. Further, following the offline strategy, we are able to accommodate 1737, 1481, and 615 100G demands using H-Raman for the UK, Pan-EU, and US networks at FG = 12.5 GHz until 10% blocking is reached. Thereby, H-Raman provides 7.5%, 35.8%, and 94.9% extra capacity, respectively, for the UK, Pan-EU, and US. Finally, using H-Raman, all lightpaths in the UK network operate at PM-64QAM with maximum capacity at the end of the procedure. [ABSTRACT FROM PUBLISHER]

The switchless elastic rate node (SERANO) is an elastic optical network block architecture facilitating reduction in network cost and blocking due to spectral fragmentation while extending the capacity-reach product in translucent optical networks. We present an analytical mathematical method for minimizing the number of transceivers that are solely used to construct this block, albeit a finite blocking probability. Moreover, based on a realistic traffic matrix and making use of a networking planning tool, we deduce a SERANO's block dimension for BT's national backbone network. Finally, we estimate the conditions under which the cost of a SERANO block is lower to the corresponding electronic switch for providing important networking functions like 3R regeneration, defragmentation, and network reoptimization. [ABSTRACT FROM PUBLISHER]

For transmission within optical mesh networks, different signal routes acquire different impairments and are received with different signal-to-noise ratios (SNRs). The SNR can be utilized through adaptive bit- and code-rate modulation, which leads to data rates that are not multiples of the preferred 100 GbE client rate. This paper considers the use of slower 25 GbE lanes both with inverse multiplexed 100 GbE client rates and with native 25 GbE client rates and compares network blocking performance. The use of inverse multiplexed 100 GbE client data on four 25 GbE lanes accesses the lion's share of stranded capacity within the network. [ABSTRACT FROM PUBLISHER]

We report the first successful field trial of up to 3 Tb/s real-time DP-16 QAM optical superchannel transport over 359-km EDFA-amplified fully managed flexible grid optical infrastructure using production grade hardware and management software from a live network operation center. The spectrum of the flexible grid ROADM was configured according to the requirement of the optical superchannel from a minimum of 37.5 up to 400 GHz with a resolution of 12.5 GHz. Spectral windows larger than 400 GHz were achieved by configuring multiple adjacent spectral slots enabling higher superchannel capacities. The optical superchannels of up to 3 Tb/s propagated alongside standard 50-GHz grid wavelength channels at 100 Gb/s. Stable error-free performance was measured for all sub-channel spacings down to 33.5 GHz, where a record net spectral efficiency of 5.97 b/s/Hz was achieved, an improvement of 49.25% over standard 50 GHz grid. We also show results on optical margin requirements when operating across a range of sub-channel spacings corresponding to different spectral efficiencies. Furthermore, a key technology building block for the 3-Tb/s optical superchannel, 200 G DP-16 QAM was trialed in a live WDM network to evaluate and demonstrate its applicability for deployment. [ABSTRACT FROM PUBLISHER]

We demonstrate how maximum entropy (MaxEnt) allocation strategies can optimally determine links within a flexgrid elastic optical network, thus requiring multiple fiber pairs to support 100% capacity growth with 34.3% improvement in the uniformity of spectrum allocations. We show how adding additional fiber to those links, which feature the highest number of demands in a link, allows optimum allocation of network capacity resources to all source-destination (S-D) demand pairs and maximizes the available spectral capacity to each demand. We also analyze the case of adding additional fiber to a link in order to reduce the number of contiguous demands present in the associated fiber, as an additional means to maximize the allowable channel capacity for each S-D demand. [ABSTRACT FROM PUBLISHER]

This paper reviews the status of research into elastic optical networks and flexgrid, illustrating the benefits of new flexible technologies to allow higher network capacities and support superchannel flows. The paper assesses the potential for the various forms of elasticity and describes open questions of a currently active research area. [ABSTRACT FROM PUBLISHER]

We report the first successful field trial of a realtime alien superchannel over a 410-km DCM-less optical fiber link using only EDFA amplification. We have demonstrated a record 1.4-Tb/s alien superchannel transported alongside native 40G and 100G wavelengths over a third party optical infrastructure using software reconfigurable DP-16QAM/QPSK production hardware, achieving spectral efficiency of up to 5.7 bit/s/Hz. Stable long term error-free performance was measured in a real network environment for subchannel spacing as narrowas 36 GHz, giving a spectral efficiency improvement of~40% compared with standard 50 GHz grid. We have also demonstrated, for the first time, software reconfigurable modulation and capacity of an optical superchannel with subminute switching time. The subchannels can be flexibly and independently reconfigured to enable variable capacity in future flexible optical networks. In addition, robust PMD tolerance of the DP-16 QAM superchannel is measured, which allows network operators to make use of their old, high PMD fibers without the requirement of fiber measurement and selection. [ABSTRACT FROM AUTHOR]

This article reports the work on next generation transponders for optical networks carried out within the last few years. A general architecture supporting super-channels (i.e., optical connections composed of several adjacent subcarriers) and sliceability (i.e., subcarriers grouped in a number of independent super-channels with different destinations) is presented. Several transponder implementations supporting different transmission techniques are considered, highlighting advantages, economics, and complexity. Discussions include electronics, optical components, integration, and programmability. Application use cases are reported. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

The papers in this special issue were presented at the Optical Fiber Communications Conference (OFC) 2015, which took place in March in Los Angeles, CA. These papers document the state of the art in optical fiber technology and networks in greater depth than is possible in the limited format of the conference technical digest. [ABSTRACT FROM PUBLISHER]

This publisher's note corrects an author's affiliation in J. Opt. Commun. Netw.12, A9 (2020). [ABSTRACT FROM AUTHOR]

This short introductory paper sets the scene for this special edition of the Journal of Optical Communications and Networking, which is focused on elastic optical networks (EONs). A brief overview of the field is given, followed by a summary of the five invited papers. This special edition is designed to provide a review of current EON technology. [ABSTRACT FROM PUBLISHER]

This paper discusses both UK-based and global Internet data bandwidth growth, beginning with historical data for the BT network. We examine the time variations in consumer behaviour and how this is statistically aggregated into larger traffic loads on national core fibre communications networks. The random nature of consumer Internet behaviour, where very few consumers require maximum bandwidth simultaneously, provides the opportunity for a significant statistical gain. The paper looks at predictions for how this growth might continue over the next 10-20 years, giving estimates for the amount of bandwidth that networks should support in the future. The paper then explains how national networks are designed to accommodate these traffic levels, and the various network roles, including access, metro and core, are described. The physical layer network is put into the context of how the packet and service layers are designed and the applications and location of content are also included in an overall network overview. The specific role of content servers in alleviating core network traffic loads is highlighted. The status of the relevant transmission technologies in the access, metro and core is given, showing that these technologies, with adequate research, should be sufficient to provide bandwidth for consumers in the next 10-20 years., (© 2016 The Author(s).)

We present results from the first field-trial of a quantum-secured DWDM transmission system, in which quantum key distribution (QKD) is combined with 4 × 10 Gb/s encrypted data and transmitted simultaneously over 26 km of field installed fiber. QKD is used to frequently refresh the key for AES-256 encryption of the 10 Gb/s data traffic. Scalability to over 40 DWDM channels is analyzed.