Joao Pedro Pedro - Academia.edu (original) (raw)

Papers by Joao Pedro Pedro

Journal of Lightwave Technology

Multi-band optical fiber transmission is generally proposed for capacity upgrades in optical tran... more Multi-band optical fiber transmission is generally proposed for capacity upgrades in optical transport networks. To comprehensively assess the potential of multi-band transmission, key metrics such as the potential capacity increase, energy consumption, and the number of required interfaces must be evaluated for different transmission scenarios. We consider progressive spectral exploitation, starting from the C-band only and up to C+L+S+U-band transmission, for both transparent and translucent solutions that exploit optical signal regeneration. By considering accurate state-of-the-art physical layer models, we derive a networking performance metric that enables the comparison of different solutions in terms of capacity allocation and energy consumption. For a translucent network design, different regenerator placement algorithms are compared, with the aim of minimizing energy consumption. The proposed network-wide numerical analysis shows that, for spectral occupations exceeding the C+L-band, translucent solutions can significantly increase network capacity, while leading to a similar energy consumption per transmitted bit as in the transparent design case, but they require the deployment of additional line interfaces. Significantly, these results provide evidence that the transparent exploitation of an additional transmission band produces a capacity increment that is at least comparable to that of a translucent solution based on already-in-use bands. Since this is attained at the expense of fewer line interfaces, it is a key finding suggesting that extending the number of bands supported is a cost-effective approach to scaling the capacity of existing fiber infrastructures.

Optical Fiber Communication Conference, 2018

This paper proposes an architecture combining high density muxponders, universal OTN switching, f... more This paper proposes an architecture combining high density muxponders, universal OTN switching, flexi-rate line interfaces and a cost-optimized node clustering scheme to enhance network resiliency without compromising the total cost of ownership (TCO).

2018 20th International Conference on Transparent Optical Networks (ICTON), 2018

This work evaluates the effectiveness of various machine learning (ML) models when used to predic... more This work evaluates the effectiveness of various machine learning (ML) models when used to predict the Quality of Transmission (QoT) of an unestablished lightpath, speeding up the process of lightpath provisioning. Three network scenarios to efficiently generate the knowledge database used to train the models are proposed as well as an overview of the most used ML models. The considered models are: K nearest neighbors (KNN), logistic regression, support vector machines (SVM), and artificial neural networks (ANN). Results show that, in general, all ML models are able to correctly predict the QoT of more than 95% of the lightpaths. However, ANN is the model presenting better generalization, correctly predicting the QoT of up to 99.9% of of the lightpaths.

2017 19th International Conference on Transparent Optical Networks (ICTON), 2017

The ever-increasing demand for capacity in optical networks is driving the development of transpo... more The ever-increasing demand for capacity in optical networks is driving the development of transponders capable of achieving spectral efficiencies of up to 8 bit/s/Hz using advanced modulation formats and coherent-detection. However, operating at the highest spectral efficiency is accomplished at the expense of shorter transparent reach, potentially requiring the deployment of additional expensive optical signal regenerators (3Rs). This limitation can be mitigated to a certain extent by exploiting enhanced optical amplification strategies, such as Raman amplification. Interestingly, the prevalent paradigm of only using Raman amplification in the longer fibre spans of long-haul networks may be on the verge of being challenged. This paper provides insight on the potential of Raman amplification in next-generation flexible optical networks by showing the network-level benefit provided by Raman amplification when transmitting a wide assortment of channel formats in meshed optical networks.

A synthetic approach toward the synthesis of vindoline (3) and a reinvestigation of the total syn... more A synthetic approach toward the synthesis of vindoline (3) and a reinvestigation of the total synthesis of vincaminoridine (4) and epivincaminoridine (4a) is described. The synthetic sequence involves alkylation with benzyl chloride of the monosodium salt of propane-l,3-diol to give y-benzyloxypropanol (197). Treatment of 197 with thionyl chloride afforded benzyl-ychloropropyl ether (198). Alkylation of ethyl diethyl malonate with 198 provided diethyl Y~D enz yl ox yP ro Pyl etn yl malonate (134). Basic hydrolysis of 134 gave y-benzyloxypropylethyl malonic acid (199), which upon decarboxylation provided 2-(y-benzyloxypropyl)-butanoic acid (200). The monoacid (200) was esterified with ethanol to provide ethyl tx-(y-benzyloxypropyl)-butanoate (135). Alkylation of 135 with allyl bromide gave ethyl-a-(y-benzyloxypropyl)-a-allylbutanoate (201), which upon treatment with osmium tetroxide and sodium periodate gave ethyl a(y-benzyloxypropyl)-a-(a-formylmethyl)butanoate (140). Condensation of 140 with 6-methoxy tryptamine afforded the tetracyclic lactam (150). Lithium aluminum hydride reduction of the latter, followed by hydrogenolysis of the benzyl group gave two isomeric tetracyclic alcohols (204). These intermediates were converted via their mesylate derivatives to the quaternary salts (205), which upon treatment with potassium cyanide gave the isomeric cyanides (216). Acid hydrolysis of 216 gave the corresponding carbomethoxy derivative (151). Alkylation of 151 i i iwith methyl iodide provided dl-vincaminoridine (4) and dlepivincaminoridine (4a). Transannular cyclization of the latter substances gave the pentacyclic aspidosperma-type system (195). The degradation sequence involved acid hydrolysis of vindoline (3) to provide desacetyl vindoline (224), which upon catalytic hydrogenation gave desacetyldihydrovindoline (225). Pyrolysis of 225 afforded the ketone (86), which upon treatment with dimethyl carbonate provided the g-ketoester (226). Treatment of the sodium enolate of 226 with oxygen-hydrogen peroxide gave the hydroxy ketoester (227). Treatment of desacetyldihydrovindoline (225) with N,Nthiocarbonyldiimidazole gave the thiocarbonate derivative (230), which upon desulfurization with Raney nickel afforded the unsaturated ester (231). Catalytic hydrogenation of 231 gave the saturated ester (232) , which upon treatment with lithium diisopropyl amide and oxygen-hydrogen peroxide provided the hydroxyester (234). The saturated ester 232 was converted to the alcohol derivative (237) by reduction with aluminum hydride. Oppenauer oxidation of 237 gave the aldehyde (238). Finally potassium permanganate oxidation of the unsaturated ester (231) gave 5-membered lactam (240), 6-membered lactam (241), N-formyl-5-membered lactam (242), ct and N Q-formyl-6-membered lactam (243) .

2021 IEEE Photonics Society Summer Topicals Meeting Series (SUM), 2021

This paper compares cost-effective solutions to increase the capacity of regional optical transpo... more This paper compares cost-effective solutions to increase the capacity of regional optical transport networks. The possibility to explore additional fiber bandwidth is compared to the benefit of improving optical system performance by deploying hybrid EDFA/Raman instead of EDFA amplification only.

2021 IEEE Photonics Society Summer Topicals Meeting Series (SUM), 2021

We apply a launch power control to a C+L+S multiband system, showing an increase in quality of tr... more We apply a launch power control to a C+L+S multiband system, showing an increase in quality of transmission average and flatness, and almost doubling the offered capacity in S-band for long optical line systems.

Journal of Lightwave Technology, 2019

Data explosion and higher service level agreements (SLA) are common terminologies in modern commu... more Data explosion and higher service level agreements (SLA) are common terminologies in modern communication networks. Recent advancements towards 5G networks add to the complexity where billions of devices, both static and mobile are connected generating trillions of megabits of data flooding the network and where service providers scuffle daily to deliver key performance indicators: lower latency, longer battery life, higher data rates, ultra-high reliability and more connected devices. The optical-fiber world simultaneously witnesses a denser, fiber-rich network infrastructure which is critically challenged in fast economically developing countries by heavy construction of roads and other infrastructures that inflicts repeated and unpredictable cuts to the extent that traffic is simultaneously interrupted in up to 10% of the optical links. Thus, network resiliency to fiber failures is already and will continue to be a top priority for operators. Depending on the SLA, operators choose from various resiliency options, e.g. at single network layers or across multiple ones, with dedicated protection or shared restoration, depending on decisive factors like network availability and total cost of ownership (TCO). With traditional network architectures, high resiliency comes with significantly increased TCO involving optical transport network (OTN) switches, L1 protection switching and L1 restoration. This translates into high CAPEX and excessive space and power consumption, hampering the desirable seamless scalability with the continuously increasing demand for more capacity. This paper explores an alternative hyperscale network architecture which is adaptable and resilient to multiple fiber failures, thus delivering committed service levels to the end-users and which, at the same time, significantly reduces network cost compared to a traditional all OTN-switched network. The hyperscale architecture exploits low footprint carrier-grade, data center interconnect (DCI) type high-density transponders and cost-effective optical protection switching and restoration via software defined networking (SDN) control. The paper also describes a routing and grooming algorithm to dimension a shared resource pool for optical restoration and a statistical simulation method for time effective execution, simulating failures over a carefully selected subset of failure scenarios to guarantee a high degree of network availability. Via network simulation, the paper demonstrates that multiple failure resiliency and cost-effectiveness do not necessarily represent a contradiction in transport networks as long as an appropriate network architecture is chosen and that efficient network planning and optimization are applied.

2016 21st European Conference on Networks and Optical Communications (NOC), 2016

Advancement of communication technologies and business patterns has contributed to the increase o... more Advancement of communication technologies and business patterns has contributed to the increase of consumer demand and machine-to-machine network traffic. Following this, a steep downward trend in revenue per bit and a slower decay in cost per bit transported is being observed. This poses serious challenge for network operators to correctly choose the technologies and architecture for transporting both packet and legacy TDM traffic. Thus, future expansion of the network should exploit the architecture that results in the most cost-effective transport of both packet and TDM traffic, aiming to keep TCO at its lowest while ensuring traffic meets its designated SLAs. In this paper we address metro, regional and long haul networks with varying traffic patterns (both packet and TDM) looking at the fundamental problems in network scalability and point to some solutions to ensure that cost-effective network traffic scaling can continue to enable future communications services.

2016 21st European Conference on Networks and Optical Communications (NOC), 2016

New technologies are emerging to make optical transport networks increasingly flexible and cost-e... more New technologies are emerging to make optical transport networks increasingly flexible and cost-effective. Transponder modules capable of rate adaptation and sliceability promise a scalable way to support the upcoming traffic growth. The deployment of these flexible modules on the line-side can be enhanced with a pay-as-you-grow approach also on the client-side, where capacity is provisioned on demand for maximum cost-efficiency. Bridging these two elements together with flexible client-to-line interconnection switch fabrics ties together the concept of a fully-flexible next-generation optical transport network. Such a high degree of configurability greatly expands the ability to automatically reuse equipment modules in multiple situations over the course of the network lifecycle. On the other hand, manual re-provisioning of available equipment is an alternative to improve resource reuse in otherwise rigid network designs based on fixed transponders and client-to-line interconnections. The policy each operator chooses regarding the level of manual reconfigurations it allows in its network to reuse idle hardware can have a lasting impact on the overall cost of deploying a transport infrastructure. This paper addresses, through a multi-period planning simulation, the effect of idle part handling on network deployment cost and resource efficiency. The analysis is conducted for multiple transport architectures, ranging from traditional transponders and muxponders to more flexible designs on both the client- and line-sides.

2016 IEEE Global Communications Conference (GLOBECOM), 2016

Typical optical transport networks dimensioning is performed disregarding the client to line port... more Typical optical transport networks dimensioning is performed disregarding the client to line ports interconnection restrictions imposed by the node architecture deployed. After the grooming and routing optimization, equipment is mapped in order to implement the obtained solution. However, as some node architectures can impose restrictions in the client to line ports interconnection, some grooming configurations may be unfeasible to map. This is particularly relevant in multi-period scenarios where traffic changes between periods and capacity is already installed at specific modules. In this work, we present an integer linear programming (ILP)-based framework that minimizes the additional number of line interfaces required to overcome unfeasible mappings. The node architectures considered are non-blocking electrical cross connect (EXC), partial non- blocking EXCs, EXCs with extendable backplanes, and EXCs with interconnection via high bit rate client ports. Using the proposed framework we evaluate the impact of node architecture flexibility in the number of line interfaces required.

Custos e Agronegocio

This article evaluate the production cost, investment return and risk expectations associated wit... more This article evaluate the production cost, investment return and risk expectations associated with two corn production productivity strategies, 120 bags of 60 kg/hectare and 150 bags of 60 kg/hectare, in the north altiplane of Santa Catarina State in Brazil. Investment analysis techniques and estimation of the cash flow representative of both production strategies was used to generate two set of indicators. The first set of financial indicators is composed by Net Present Value, Net Present Value Equivalent per Period, Cost Benefit Index and Added Rate of Return on Investment. The second set of risk indicators is composed by Minimum Attractive Rate of Return / Internal Rate of Return, Payback/N, Management Risk and Business Risk. Productivity and price are treated as random variables to represent the uncertainty in the agro business activity. The results of the analysis showed a low level of rentability and a high risk for both productivity levels. The results obtained with Monte Car...

2015 17th International Conference on Transparent Optical Networks (ICTON), 2015

Journal of Optical Communications and Networking, 2015

Flex-rate transmission is seen as a core element in the realization of programmable backbone netw... more Flex-rate transmission is seen as a core element in the realization of programmable backbone networks. The ability to adjust the channel bit rate in response to traffic changes in the network can potentially bring longterm savings by future-proofing capacity and simplifying network operations. The key issue in this topic is quantifying the degree of traffic dynamics and growth that justify the higher initial investment in flexible-rate (flex-rate) technology. In dense wavelength division multiplexing (DWDM) networks, traditionally featuring long lifespans and stable traffic growth outlooks, this question can be answered with a multi-period analysis that simulates the requirements for hardware provisioning throughout multiple planning periods with incremental traffic. In a scenario featuring sliceable bandwidth-variable transponders composed of line cards (LCs) with multiple transceiver ports, we use a multi-period planning framework to assess the advantages and drawbacks of using fixed-rate and/or flex-rate technology in the LCs and transceivers. The simulation is performed resorting to an integer linear programming (ILP) model that chooses, in each period, the routing and format selection for a set of demands that yields the minimum hardware cost, reusing any idle equipment resulting from traffic churn. The analysis of the results shows that the initial investment in flex-rate LCs and transceivers pays off for small-to medium-sized networks where the upgrade to higher bit rates does not require extra regeneration. Long and ultralong-haul scenarios benefit from the use of fixed-rate interfaces. In terms of operational issues, it is shown that flex-rate hardware provides clear benefits through reduced footprint and extended capacity due to better spectral efficiency.

2011 13th International Conference on Transparent Optical Networks, 2011

DWDM optical transport networks are at the turning point from simply providing semi-permanent con... more DWDM optical transport networks are at the turning point from simply providing semi-permanent connections to start being engineered for efficiently supporting dynamic optical connection services. A successful transition can only be accomplished via augmenting existing/adding new functionalities to the DWDM transport networks and has implications spanning from optical node design to network planning and network operation. This paper discusses current trends in DWDM networks with emphasis on the expected evolution in the architecture of the optical nodes for dynamic connection establishment and rerouting. In order to gain insight on the relevance of having nodes characterized as colourless, directionless and contentionless, the impact of node architecture in blocking performance of a DWDM transport network is assessed using network simulation.

2014 The European Conference on Optical Communication (ECOC), 2014

We evaluate how solutions based on fixed and flex-rate line-card modules and transceivers perform... more We evaluate how solutions based on fixed and flex-rate line-card modules and transceivers perform in planning scenarios with multiple planning periods. The results show up to 30% less linecards and 13% less transceivers are required with flex-rate hardware.

Optical burst switching (OBS) networks rely on complex and costly contention resolution strategie... more Optical burst switching (OBS) networks rely on complex and costly contention resolution strategies to reach reasonable bandwidth utilization efficiency. Recent research efforts have suggested that proactive contention minimization strategies based on selectively delaying bursts at the ingress edge nodes, exploiting their inexpensive electronic buffers, can assist in the task of relaxing the hardware requirements of the network core nodes. This

2012 IEEE 13th International Conference on High Performance Switching and Routing, 2012

ABSTRACT In order for transport networks to cost-effectively provide higher capacity, it is expec... more ABSTRACT In order for transport networks to cost-effectively provide higher capacity, it is expected that channel bit-rates beyond 100 Gb/s will be accomplished by resorting to a flexible WDM grid with variable channel spacing. Among the implications of this concept is the need for planning tools that fully exploit the additional degrees of freedom enabled by a flexible grid to further optimize network cost and spectral efficiency. This paper proposes an optimization framework to minimize the transponder and regenerator deployment cost in a translucent WDM network featuring channel bit-rates of 40, 100 and 400 Gb/s and multiple transmission formats per bit-rate, each characterized by its own spectral width, optical reach and cost properties. Firstly, we formulate the problem via a novel Integer Linear Programming (ILP) model, whose resolution finds the optimal (cheapest) feasible network configuration. Secondly, we propose an efficient heuristic called Narrowest First-Iterative Cost Reduction (NF-ICR) to handle network scenarios for which solving the ILP entails an unreasonable computational burden. The NF-ICR heuristic is shown to provide tight optimality bounds where the benchmark given by the ILP solution is attainable. For larger networks, we show that the use of a flexible grid and multiple format options for each bit-rate results in around 10% less cost in transponders and regenerators for metro networks, and a substantial increase in the total traffic load supported by the network. We also conclude that a distinction emerges between metro/regional scenarios and long-haul networks with long paths, wherein the shorter transparent reach of 400 Gb/s channels drives up the cost due to extra regeneration, favoring the use of parallelized solutions of lower bit-rate channels.

2009 International Conference on Photonics in Switching, PS '09, 2009

Abstract The cost-effectiveness of optical burst-switched (OBS) networks can be improved by reduc... more Abstract The cost-effectiveness of optical burst-switched (OBS) networks can be improved by reducing the number of contention resolution devices used without excessively penalizing performance. Proactively minimizing wavelength contention can assist in the task of ...

Journal of Lightwave Technology

Multi-band optical fiber transmission is generally proposed for capacity upgrades in optical tran... more Multi-band optical fiber transmission is generally proposed for capacity upgrades in optical transport networks. To comprehensively assess the potential of multi-band transmission, key metrics such as the potential capacity increase, energy consumption, and the number of required interfaces must be evaluated for different transmission scenarios. We consider progressive spectral exploitation, starting from the C-band only and up to C+L+S+U-band transmission, for both transparent and translucent solutions that exploit optical signal regeneration. By considering accurate state-of-the-art physical layer models, we derive a networking performance metric that enables the comparison of different solutions in terms of capacity allocation and energy consumption. For a translucent network design, different regenerator placement algorithms are compared, with the aim of minimizing energy consumption. The proposed network-wide numerical analysis shows that, for spectral occupations exceeding the C+L-band, translucent solutions can significantly increase network capacity, while leading to a similar energy consumption per transmitted bit as in the transparent design case, but they require the deployment of additional line interfaces. Significantly, these results provide evidence that the transparent exploitation of an additional transmission band produces a capacity increment that is at least comparable to that of a translucent solution based on already-in-use bands. Since this is attained at the expense of fewer line interfaces, it is a key finding suggesting that extending the number of bands supported is a cost-effective approach to scaling the capacity of existing fiber infrastructures.

Optical Fiber Communication Conference, 2018

This paper proposes an architecture combining high density muxponders, universal OTN switching, f... more This paper proposes an architecture combining high density muxponders, universal OTN switching, flexi-rate line interfaces and a cost-optimized node clustering scheme to enhance network resiliency without compromising the total cost of ownership (TCO).

2018 20th International Conference on Transparent Optical Networks (ICTON), 2018

This work evaluates the effectiveness of various machine learning (ML) models when used to predic... more This work evaluates the effectiveness of various machine learning (ML) models when used to predict the Quality of Transmission (QoT) of an unestablished lightpath, speeding up the process of lightpath provisioning. Three network scenarios to efficiently generate the knowledge database used to train the models are proposed as well as an overview of the most used ML models. The considered models are: K nearest neighbors (KNN), logistic regression, support vector machines (SVM), and artificial neural networks (ANN). Results show that, in general, all ML models are able to correctly predict the QoT of more than 95% of the lightpaths. However, ANN is the model presenting better generalization, correctly predicting the QoT of up to 99.9% of of the lightpaths.

2017 19th International Conference on Transparent Optical Networks (ICTON), 2017

The ever-increasing demand for capacity in optical networks is driving the development of transpo... more The ever-increasing demand for capacity in optical networks is driving the development of transponders capable of achieving spectral efficiencies of up to 8 bit/s/Hz using advanced modulation formats and coherent-detection. However, operating at the highest spectral efficiency is accomplished at the expense of shorter transparent reach, potentially requiring the deployment of additional expensive optical signal regenerators (3Rs). This limitation can be mitigated to a certain extent by exploiting enhanced optical amplification strategies, such as Raman amplification. Interestingly, the prevalent paradigm of only using Raman amplification in the longer fibre spans of long-haul networks may be on the verge of being challenged. This paper provides insight on the potential of Raman amplification in next-generation flexible optical networks by showing the network-level benefit provided by Raman amplification when transmitting a wide assortment of channel formats in meshed optical networks.

A synthetic approach toward the synthesis of vindoline (3) and a reinvestigation of the total syn... more A synthetic approach toward the synthesis of vindoline (3) and a reinvestigation of the total synthesis of vincaminoridine (4) and epivincaminoridine (4a) is described. The synthetic sequence involves alkylation with benzyl chloride of the monosodium salt of propane-l,3-diol to give y-benzyloxypropanol (197). Treatment of 197 with thionyl chloride afforded benzyl-ychloropropyl ether (198). Alkylation of ethyl diethyl malonate with 198 provided diethyl Y~D enz yl ox yP ro Pyl etn yl malonate (134). Basic hydrolysis of 134 gave y-benzyloxypropylethyl malonic acid (199), which upon decarboxylation provided 2-(y-benzyloxypropyl)-butanoic acid (200). The monoacid (200) was esterified with ethanol to provide ethyl tx-(y-benzyloxypropyl)-butanoate (135). Alkylation of 135 with allyl bromide gave ethyl-a-(y-benzyloxypropyl)-a-allylbutanoate (201), which upon treatment with osmium tetroxide and sodium periodate gave ethyl a(y-benzyloxypropyl)-a-(a-formylmethyl)butanoate (140). Condensation of 140 with 6-methoxy tryptamine afforded the tetracyclic lactam (150). Lithium aluminum hydride reduction of the latter, followed by hydrogenolysis of the benzyl group gave two isomeric tetracyclic alcohols (204). These intermediates were converted via their mesylate derivatives to the quaternary salts (205), which upon treatment with potassium cyanide gave the isomeric cyanides (216). Acid hydrolysis of 216 gave the corresponding carbomethoxy derivative (151). Alkylation of 151 i i iwith methyl iodide provided dl-vincaminoridine (4) and dlepivincaminoridine (4a). Transannular cyclization of the latter substances gave the pentacyclic aspidosperma-type system (195). The degradation sequence involved acid hydrolysis of vindoline (3) to provide desacetyl vindoline (224), which upon catalytic hydrogenation gave desacetyldihydrovindoline (225). Pyrolysis of 225 afforded the ketone (86), which upon treatment with dimethyl carbonate provided the g-ketoester (226). Treatment of the sodium enolate of 226 with oxygen-hydrogen peroxide gave the hydroxy ketoester (227). Treatment of desacetyldihydrovindoline (225) with N,Nthiocarbonyldiimidazole gave the thiocarbonate derivative (230), which upon desulfurization with Raney nickel afforded the unsaturated ester (231). Catalytic hydrogenation of 231 gave the saturated ester (232) , which upon treatment with lithium diisopropyl amide and oxygen-hydrogen peroxide provided the hydroxyester (234). The saturated ester 232 was converted to the alcohol derivative (237) by reduction with aluminum hydride. Oppenauer oxidation of 237 gave the aldehyde (238). Finally potassium permanganate oxidation of the unsaturated ester (231) gave 5-membered lactam (240), 6-membered lactam (241), N-formyl-5-membered lactam (242), ct and N Q-formyl-6-membered lactam (243) .

2021 IEEE Photonics Society Summer Topicals Meeting Series (SUM), 2021

This paper compares cost-effective solutions to increase the capacity of regional optical transpo... more This paper compares cost-effective solutions to increase the capacity of regional optical transport networks. The possibility to explore additional fiber bandwidth is compared to the benefit of improving optical system performance by deploying hybrid EDFA/Raman instead of EDFA amplification only.

2021 IEEE Photonics Society Summer Topicals Meeting Series (SUM), 2021

We apply a launch power control to a C+L+S multiband system, showing an increase in quality of tr... more We apply a launch power control to a C+L+S multiband system, showing an increase in quality of transmission average and flatness, and almost doubling the offered capacity in S-band for long optical line systems.

Journal of Lightwave Technology, 2019

Data explosion and higher service level agreements (SLA) are common terminologies in modern commu... more Data explosion and higher service level agreements (SLA) are common terminologies in modern communication networks. Recent advancements towards 5G networks add to the complexity where billions of devices, both static and mobile are connected generating trillions of megabits of data flooding the network and where service providers scuffle daily to deliver key performance indicators: lower latency, longer battery life, higher data rates, ultra-high reliability and more connected devices. The optical-fiber world simultaneously witnesses a denser, fiber-rich network infrastructure which is critically challenged in fast economically developing countries by heavy construction of roads and other infrastructures that inflicts repeated and unpredictable cuts to the extent that traffic is simultaneously interrupted in up to 10% of the optical links. Thus, network resiliency to fiber failures is already and will continue to be a top priority for operators. Depending on the SLA, operators choose from various resiliency options, e.g. at single network layers or across multiple ones, with dedicated protection or shared restoration, depending on decisive factors like network availability and total cost of ownership (TCO). With traditional network architectures, high resiliency comes with significantly increased TCO involving optical transport network (OTN) switches, L1 protection switching and L1 restoration. This translates into high CAPEX and excessive space and power consumption, hampering the desirable seamless scalability with the continuously increasing demand for more capacity. This paper explores an alternative hyperscale network architecture which is adaptable and resilient to multiple fiber failures, thus delivering committed service levels to the end-users and which, at the same time, significantly reduces network cost compared to a traditional all OTN-switched network. The hyperscale architecture exploits low footprint carrier-grade, data center interconnect (DCI) type high-density transponders and cost-effective optical protection switching and restoration via software defined networking (SDN) control. The paper also describes a routing and grooming algorithm to dimension a shared resource pool for optical restoration and a statistical simulation method for time effective execution, simulating failures over a carefully selected subset of failure scenarios to guarantee a high degree of network availability. Via network simulation, the paper demonstrates that multiple failure resiliency and cost-effectiveness do not necessarily represent a contradiction in transport networks as long as an appropriate network architecture is chosen and that efficient network planning and optimization are applied.

2016 21st European Conference on Networks and Optical Communications (NOC), 2016

Advancement of communication technologies and business patterns has contributed to the increase o... more Advancement of communication technologies and business patterns has contributed to the increase of consumer demand and machine-to-machine network traffic. Following this, a steep downward trend in revenue per bit and a slower decay in cost per bit transported is being observed. This poses serious challenge for network operators to correctly choose the technologies and architecture for transporting both packet and legacy TDM traffic. Thus, future expansion of the network should exploit the architecture that results in the most cost-effective transport of both packet and TDM traffic, aiming to keep TCO at its lowest while ensuring traffic meets its designated SLAs. In this paper we address metro, regional and long haul networks with varying traffic patterns (both packet and TDM) looking at the fundamental problems in network scalability and point to some solutions to ensure that cost-effective network traffic scaling can continue to enable future communications services.

2016 21st European Conference on Networks and Optical Communications (NOC), 2016

New technologies are emerging to make optical transport networks increasingly flexible and cost-e... more New technologies are emerging to make optical transport networks increasingly flexible and cost-effective. Transponder modules capable of rate adaptation and sliceability promise a scalable way to support the upcoming traffic growth. The deployment of these flexible modules on the line-side can be enhanced with a pay-as-you-grow approach also on the client-side, where capacity is provisioned on demand for maximum cost-efficiency. Bridging these two elements together with flexible client-to-line interconnection switch fabrics ties together the concept of a fully-flexible next-generation optical transport network. Such a high degree of configurability greatly expands the ability to automatically reuse equipment modules in multiple situations over the course of the network lifecycle. On the other hand, manual re-provisioning of available equipment is an alternative to improve resource reuse in otherwise rigid network designs based on fixed transponders and client-to-line interconnections. The policy each operator chooses regarding the level of manual reconfigurations it allows in its network to reuse idle hardware can have a lasting impact on the overall cost of deploying a transport infrastructure. This paper addresses, through a multi-period planning simulation, the effect of idle part handling on network deployment cost and resource efficiency. The analysis is conducted for multiple transport architectures, ranging from traditional transponders and muxponders to more flexible designs on both the client- and line-sides.

2016 IEEE Global Communications Conference (GLOBECOM), 2016

Typical optical transport networks dimensioning is performed disregarding the client to line port... more Typical optical transport networks dimensioning is performed disregarding the client to line ports interconnection restrictions imposed by the node architecture deployed. After the grooming and routing optimization, equipment is mapped in order to implement the obtained solution. However, as some node architectures can impose restrictions in the client to line ports interconnection, some grooming configurations may be unfeasible to map. This is particularly relevant in multi-period scenarios where traffic changes between periods and capacity is already installed at specific modules. In this work, we present an integer linear programming (ILP)-based framework that minimizes the additional number of line interfaces required to overcome unfeasible mappings. The node architectures considered are non-blocking electrical cross connect (EXC), partial non- blocking EXCs, EXCs with extendable backplanes, and EXCs with interconnection via high bit rate client ports. Using the proposed framework we evaluate the impact of node architecture flexibility in the number of line interfaces required.

Custos e Agronegocio

This article evaluate the production cost, investment return and risk expectations associated wit... more This article evaluate the production cost, investment return and risk expectations associated with two corn production productivity strategies, 120 bags of 60 kg/hectare and 150 bags of 60 kg/hectare, in the north altiplane of Santa Catarina State in Brazil. Investment analysis techniques and estimation of the cash flow representative of both production strategies was used to generate two set of indicators. The first set of financial indicators is composed by Net Present Value, Net Present Value Equivalent per Period, Cost Benefit Index and Added Rate of Return on Investment. The second set of risk indicators is composed by Minimum Attractive Rate of Return / Internal Rate of Return, Payback/N, Management Risk and Business Risk. Productivity and price are treated as random variables to represent the uncertainty in the agro business activity. The results of the analysis showed a low level of rentability and a high risk for both productivity levels. The results obtained with Monte Car...

2015 17th International Conference on Transparent Optical Networks (ICTON), 2015

Journal of Optical Communications and Networking, 2015

Flex-rate transmission is seen as a core element in the realization of programmable backbone netw... more Flex-rate transmission is seen as a core element in the realization of programmable backbone networks. The ability to adjust the channel bit rate in response to traffic changes in the network can potentially bring longterm savings by future-proofing capacity and simplifying network operations. The key issue in this topic is quantifying the degree of traffic dynamics and growth that justify the higher initial investment in flexible-rate (flex-rate) technology. In dense wavelength division multiplexing (DWDM) networks, traditionally featuring long lifespans and stable traffic growth outlooks, this question can be answered with a multi-period analysis that simulates the requirements for hardware provisioning throughout multiple planning periods with incremental traffic. In a scenario featuring sliceable bandwidth-variable transponders composed of line cards (LCs) with multiple transceiver ports, we use a multi-period planning framework to assess the advantages and drawbacks of using fixed-rate and/or flex-rate technology in the LCs and transceivers. The simulation is performed resorting to an integer linear programming (ILP) model that chooses, in each period, the routing and format selection for a set of demands that yields the minimum hardware cost, reusing any idle equipment resulting from traffic churn. The analysis of the results shows that the initial investment in flex-rate LCs and transceivers pays off for small-to medium-sized networks where the upgrade to higher bit rates does not require extra regeneration. Long and ultralong-haul scenarios benefit from the use of fixed-rate interfaces. In terms of operational issues, it is shown that flex-rate hardware provides clear benefits through reduced footprint and extended capacity due to better spectral efficiency.

2011 13th International Conference on Transparent Optical Networks, 2011

DWDM optical transport networks are at the turning point from simply providing semi-permanent con... more DWDM optical transport networks are at the turning point from simply providing semi-permanent connections to start being engineered for efficiently supporting dynamic optical connection services. A successful transition can only be accomplished via augmenting existing/adding new functionalities to the DWDM transport networks and has implications spanning from optical node design to network planning and network operation. This paper discusses current trends in DWDM networks with emphasis on the expected evolution in the architecture of the optical nodes for dynamic connection establishment and rerouting. In order to gain insight on the relevance of having nodes characterized as colourless, directionless and contentionless, the impact of node architecture in blocking performance of a DWDM transport network is assessed using network simulation.

2014 The European Conference on Optical Communication (ECOC), 2014

We evaluate how solutions based on fixed and flex-rate line-card modules and transceivers perform... more We evaluate how solutions based on fixed and flex-rate line-card modules and transceivers perform in planning scenarios with multiple planning periods. The results show up to 30% less linecards and 13% less transceivers are required with flex-rate hardware.

Optical burst switching (OBS) networks rely on complex and costly contention resolution strategie... more Optical burst switching (OBS) networks rely on complex and costly contention resolution strategies to reach reasonable bandwidth utilization efficiency. Recent research efforts have suggested that proactive contention minimization strategies based on selectively delaying bursts at the ingress edge nodes, exploiting their inexpensive electronic buffers, can assist in the task of relaxing the hardware requirements of the network core nodes. This

2012 IEEE 13th International Conference on High Performance Switching and Routing, 2012

ABSTRACT In order for transport networks to cost-effectively provide higher capacity, it is expec... more ABSTRACT In order for transport networks to cost-effectively provide higher capacity, it is expected that channel bit-rates beyond 100 Gb/s will be accomplished by resorting to a flexible WDM grid with variable channel spacing. Among the implications of this concept is the need for planning tools that fully exploit the additional degrees of freedom enabled by a flexible grid to further optimize network cost and spectral efficiency. This paper proposes an optimization framework to minimize the transponder and regenerator deployment cost in a translucent WDM network featuring channel bit-rates of 40, 100 and 400 Gb/s and multiple transmission formats per bit-rate, each characterized by its own spectral width, optical reach and cost properties. Firstly, we formulate the problem via a novel Integer Linear Programming (ILP) model, whose resolution finds the optimal (cheapest) feasible network configuration. Secondly, we propose an efficient heuristic called Narrowest First-Iterative Cost Reduction (NF-ICR) to handle network scenarios for which solving the ILP entails an unreasonable computational burden. The NF-ICR heuristic is shown to provide tight optimality bounds where the benchmark given by the ILP solution is attainable. For larger networks, we show that the use of a flexible grid and multiple format options for each bit-rate results in around 10% less cost in transponders and regenerators for metro networks, and a substantial increase in the total traffic load supported by the network. We also conclude that a distinction emerges between metro/regional scenarios and long-haul networks with long paths, wherein the shorter transparent reach of 400 Gb/s channels drives up the cost due to extra regeneration, favoring the use of parallelized solutions of lower bit-rate channels.

2009 International Conference on Photonics in Switching, PS '09, 2009

Abstract The cost-effectiveness of optical burst-switched (OBS) networks can be improved by reduc... more Abstract The cost-effectiveness of optical burst-switched (OBS) networks can be improved by reducing the number of contention resolution devices used without excessively penalizing performance. Proactively minimizing wavelength contention can assist in the task of ...