Jaume Comellas | Universitat Politecnica de Catalunya (original) (raw)
Papers by Jaume Comellas
Network resources are poorly used in Elastic Optical Networks under dynamic traffic conditions. A... more Network resources are poorly used in Elastic Optical Networks under dynamic traffic conditions. A hybrid scheme where some resources are statically allocated and the remaining ones are devoted to dynamic traffic, is proposed and evaluated.
A distributed telemetry system integrating optical measurement and event data collection is demon... more A distributed telemetry system integrating optical measurement and event data collection is demonstrated. Measurements of optical spectra from Nokia Bell Labs, of optical transponders from ADVA and SDN controller events from CTTC will be showcased.
A module to re-shape optical constellations making the optical signal resembles as it has travers... more A module to re-shape optical constellations making the optical signal resembles as it has traversed some distance is presented. Armed with this module, Main-in-the-Middle attacks can be performed, which could be undetectable by security systems.
Soft failure localization to early detect service level agreement violations is of paramount impo... more Soft failure localization to early detect service level agreement violations is of paramount importance in elastic optical networks (EONs), while it allows anticipating possible hard failure events. Nowadays, effective and automated solutions for soft failure localization during lightpaths' commissioning testing and operation are still missing. In this paper, we focus on presenting soft failure localization algorithms based on two different active monitoring techniques. First, the Testing optIcal Switching at connection SetUp timE (TISSUE) algorithm is proposed to localize soft failures during commissioning testing phase by elaborating the estimated bit-error rate (BER) values provided by low-cost optical testing channel (OTC) modules. Second, the FailurE causE Localization for optIcal NetworkinG (FEELING) algorithm is proposed to localize failures during lightpath operation using cost-effective optical spectrum analyzers (OSAs) widely deployed in network nodes. Results are presented to validate both algorithms in the event of several soft failures affecting lasers and filters.
Zenodo (CERN European Organization for Nuclear Research), Jul 2, 2023
Network Services automation requires predictable Quality of Service (QoS) performance, measured i... more Network Services automation requires predictable Quality of Service (QoS) performance, measured in terms of throughput, delay and jitter, to allow making proactive decisions. QoS is typically guaranteed by overprovisioning capacity dedicated to the packet connection, which increases costs for customers and network operators, especially when the traffic generated by the users and/or the virtual functions highly varies over the time. This paper presents the PILOT methodology for modeling the performance of packet connections during commissioning testing in terms of throughput, delay and jitter. PILOT runs in a sandbox domain and constructs a scenario where an efficient traffic flow simulation environment, based on the CURSA-SQ model, is used to generate large amounts of data for Machine Learning (ML) model training and validation. The simulation scenario is tuned using real measurements of the connection obtained from a set of active probes.
Space division multiplexing (SDM) has been proposed to cost-effectively increase the capacity of ... more Space division multiplexing (SDM) has been proposed to cost-effectively increase the capacity of optical transmission systems. The cost savings can be realized by introducing some levels of spatial integration of elements. However, spatial densification increases the crosstalk (XT) interactions among spatial channels. The XT is expected to be mitigated by MIMO processing, however, it increases the power consumption which in turn can make MIMO based SDM solutions impractical. This is a major issue for datacenters exploiting SDM solutions. Therefore, removing/lightening the burden imposed by MIMO processing can make SDM a more favorable solution. In this paper, we propose a datacenter interconnection network (DCIN), utilizing PAM-M transceivers, which can circumvent MIMO processing. It can be achieved by designing proper fibers (e.g. elliptical core FMF) in which the likelihood of mixing between mode-groups can be reduced. A key contribution of this work is the development of an analytical model to estimate the maximum reach that PAM-M (M = 4,8) signals can travel through coupled SDM fibers, targeting intra- and inter-DCs applications. We then demonstrate that FMF with MIMO-less PAM-M transceivers can significantly reduce the cabling complexity, and consequently, the cost of DCINs compared to single wavelength multi-mode or single-mode fibers based deployments.
Some ideas about the effect of appropriately selecting the size of the connections conveyed by mu... more Some ideas about the effect of appropriately selecting the size of the connections conveyed by multi-rate flexgrid optical networks are discussed. The main focus is on illustrating the relation between spectrum consumption and effective carried traffic. It is demonstrated that by introducing some order in the spectrum use, so limiting the network flexibility, its global performance is notably improved. The main contribution consists in demonstrating that using single sized lightpaths, the network throughput at any given blocking probability value increases compared to the multi-rate case. This conclusion is supported by extensive simulations under dynamic traffic conditions, considering different network topologies and traffic profiles.
Multi-path allocation has been proposed as a simple way to achieve traffic protection in differen... more Multi-path allocation has been proposed as a simple way to achieve traffic protection in different networking domains. In this work dual-path allocation is proposed for Elastic Optical Networks (EON) assuming dynamic offered traffic, and its performance is quantified by simulation. Indeed, dual-path allocation is compared with partial dedicated path protection assuming different scenarios. In addition to a qualitative comparison where advantages and drawbacks of both schemes are analysed, quantitative results for different backbone network scenarios are presented.
Journal of Lightwave Technology, Jul 1, 2022
Secure communications have become a requirement for virtually all kind of applications. Currently... more Secure communications have become a requirement for virtually all kind of applications. Currently, two distant parties can generate shared random secret keys by using public key cryptography. However, quantum computing represents one of the greatest threats for the finite complexity of the mathematics behind public key cryptography. In contrast, Quantum Key Distribution (QKD) relies on properties of quantum mechanics, which enables eavesdropping detection and guarantees the security of the key. Among QKD systems, polarization encoded QKD has been successfully tested in laboratory experiments and recently demonstrated in closed environments. The main drawback of QKD is its high cost, which comes, among others, from: i) the requirements for the quantum transmitters and receivers; and ii) the need of carefully selecting the fibers supporting the quantum channel to minimize the environmental effects that could dramatically change the polarization state of photons. In this paper, we propose a Machine Learning (ML)-based polarization tracking and compensation that is able to keep shared secret key exchange to high rates even under large fiber stressing events. Exhaustive results using both synthetic and experimental data show remarkable performance, which can simplify the design of both quantum transmitter and receiver, as well as enable the use of aerial optical cables, thus reducing total QKD system cost.
Space division multiplexing (SDM) has been proposed as the ultimate solution to address the capac... more Space division multiplexing (SDM) has been proposed as the ultimate solution to address the capacity crunch of optical transport networks. The efficient utilization of SDM requires some forms of spatial integration which is expected to bring huge cost savings for the deployment of SDM-based optical networks. Spatially integrated components with different characteristics have been largely explored and demonstrated for the realization of SDM networks, including; transmission media, transceivers with sophisticated digital signal processing (DSP) units, amplifiers, and ultimately optical switching nodes which are the key elements for the realization of transparent optical networks exploiting SDM technologies. As a consequence, in contrast to the currently deployed optical networks based on standard single mode fibers (SSMF), the next generation of optical networks exploiting SDM technologies can be realized utilizing various kinds of transmission media and the other corresponding elements. However, due in part to the physical properties of different components, their complexity, and the technology limitations not all of them meet the economic feasibility and a desired level of network-wide performance. Therefore, careful analysis should be done revealing the most appropriate and costeffective solutions. In this work, we review the recent developments and findings which pave the way for a simplified and efficient implementation of the spectrally and spatially flexible optical networks.
The main weakness of Elastic Optical Networks (EON) stems from spectrum fragmentation. An analysi... more The main weakness of Elastic Optical Networks (EON) stems from spectrum fragmentation. An analysis of periodic defragmentation in EONs under dynamic traffic conditions is carried out. The effects of different defragmentation parameters on the EON performance are evaluated, and appropriate values, guaranteeing suitable network performance while keeping the network control complexity at a reasonable point, are obtained through simulations. Different network topologies as well as traffic conditions are simulated to assess the validity of the obtained results.
In this paper, we explore the benefits of analysing the optical spectrum of lightpaths for soft-f... more In this paper, we explore the benefits of analysing the optical spectrum of lightpaths for soft-failure detection and identification in Spectrum Switched Optical Network. We present a framework exploiting machine learning (ML) based algorithms that uses descriptive models of the optical spectrum of a lightpath in different points along its route to detect whether the optical signal experiences anomalies reflecting a failure in the intermediate nodes. Our proposal targets the two most common filter-related soft-failures; filter shift (FS) and filter tightening (FT), which noticeably deform the expected shape of the optical spectrum. In this regard, filter cascading is a key challenge as it affects the shape of the optical spectrum similar to FT. Our proposals avoid the misclassification of properly operating signals when normal filter cascading effects is present. Extensive numerical results are presented to compare the performance of the proposed approaches in terms of accuracy and robustness.
![Research paper thumbnail of Learning from the Optical Spectrum: Soft-Failure Identification and Localization [Invited]](https://attachments.academia-assets.com/112273094/thumbnails/1.jpg)
](Optical Fiber Communication Conference, 2018
The availability of coarse-resolution cost-effective Optical Spectrum Analyzers (OSA) allows its ... more The availability of coarse-resolution cost-effective Optical Spectrum Analyzers (OSA) allows its widespread deployment in operators' networks. In this paper, several machine learning approaches for failure identification and localization that take advantage of OSAs are presented.
Journal of Optical Communications and Networking, Nov 9, 2017
In Elastic Optical Networks (EONs), effective soft failure localization is of paramount importanc... more In Elastic Optical Networks (EONs), effective soft failure localization is of paramount importance to early detect service level agreement (SLA) violations while anticipating possible hard failure events. So far, failure localization techniques have been proposed and deployed mainly for hard failures, while significant work is still required to provide effective and automated solutions for soft failures, both during commissioning testing and in-operation phases. In this paper, we focus on soft failure localization in EONs by proposing two techniques for active monitoring during commissioning testing and for passive inoperation monitoring. The techniques rely on specifically designed low-cost optical testing channel (OTC) modules and on the widespread deployment of cost-effective optical spectrum analyzer (OSA). The retrieved optical parameters are elaborated by machine learning-based algorithms running in the agent's node and in the network controller. In particular, the Testing optIcal Switching at connection SetUp timE (TISSUE) algorithm is proposed to localize soft failures by elaborating the estimated BER values provided by the OTC module. In addition, the FailurE causE Localization for optIcal NetworkinG (FEELING) algorithm is proposed to localize failures affecting a lightpath using OSAs. Extensive simulation results are presented, showing the effectiveness of the TISSUE algorithm to properly exploit OTC information to assess BER performance of QPSK-modulated signals and the high accuracy of the FEELING algorithm correctly detecting soft failures as laser drift, filter shift, and tight filtering.
Sensors
New 5 G and beyond services demand innovative solutions in optical transport to increase efficien... more New 5 G and beyond services demand innovative solutions in optical transport to increase efficiency and flexibility and reduce capital (CAPEX) and operational (OPEX) expenditures to support heterogeneous and dynamic traffic. In this context, optical point-to-multipoint (P2MP) connectivity is seen as an alternative to provide connectivity to multiple sites from a single source, thus potentially both reducing CAPEX and OPEX. Digital subcarrier multiplexing (DSCM) has been shown as a feasible candidate for optical P2MP in view of its ability to generate multiple subcarriers (SC) in the frequency domain that can be used to serve several destinations. This paper proposes a different technology, named optical constellation slicing (OCS), that enables a source to communicate with multiple destinations by focusing on the time domain. OCS is described in detail and compared to DSCM by simulation, where the results show that both OCS and DSCM provide a good performance in terms of the bit err...
Network resources are poorly used in Elastic Optical Networks under dynamic traffic conditions. A... more Network resources are poorly used in Elastic Optical Networks under dynamic traffic conditions. A hybrid scheme where some resources are statically allocated and the remaining ones are devoted to dynamic traffic, is proposed and evaluated.
A distributed telemetry system integrating optical measurement and event data collection is demon... more A distributed telemetry system integrating optical measurement and event data collection is demonstrated. Measurements of optical spectra from Nokia Bell Labs, of optical transponders from ADVA and SDN controller events from CTTC will be showcased.
A module to re-shape optical constellations making the optical signal resembles as it has travers... more A module to re-shape optical constellations making the optical signal resembles as it has traversed some distance is presented. Armed with this module, Main-in-the-Middle attacks can be performed, which could be undetectable by security systems.
Soft failure localization to early detect service level agreement violations is of paramount impo... more Soft failure localization to early detect service level agreement violations is of paramount importance in elastic optical networks (EONs), while it allows anticipating possible hard failure events. Nowadays, effective and automated solutions for soft failure localization during lightpaths' commissioning testing and operation are still missing. In this paper, we focus on presenting soft failure localization algorithms based on two different active monitoring techniques. First, the Testing optIcal Switching at connection SetUp timE (TISSUE) algorithm is proposed to localize soft failures during commissioning testing phase by elaborating the estimated bit-error rate (BER) values provided by low-cost optical testing channel (OTC) modules. Second, the FailurE causE Localization for optIcal NetworkinG (FEELING) algorithm is proposed to localize failures during lightpath operation using cost-effective optical spectrum analyzers (OSAs) widely deployed in network nodes. Results are presented to validate both algorithms in the event of several soft failures affecting lasers and filters.
Zenodo (CERN European Organization for Nuclear Research), Jul 2, 2023
Network Services automation requires predictable Quality of Service (QoS) performance, measured i... more Network Services automation requires predictable Quality of Service (QoS) performance, measured in terms of throughput, delay and jitter, to allow making proactive decisions. QoS is typically guaranteed by overprovisioning capacity dedicated to the packet connection, which increases costs for customers and network operators, especially when the traffic generated by the users and/or the virtual functions highly varies over the time. This paper presents the PILOT methodology for modeling the performance of packet connections during commissioning testing in terms of throughput, delay and jitter. PILOT runs in a sandbox domain and constructs a scenario where an efficient traffic flow simulation environment, based on the CURSA-SQ model, is used to generate large amounts of data for Machine Learning (ML) model training and validation. The simulation scenario is tuned using real measurements of the connection obtained from a set of active probes.
Space division multiplexing (SDM) has been proposed to cost-effectively increase the capacity of ... more Space division multiplexing (SDM) has been proposed to cost-effectively increase the capacity of optical transmission systems. The cost savings can be realized by introducing some levels of spatial integration of elements. However, spatial densification increases the crosstalk (XT) interactions among spatial channels. The XT is expected to be mitigated by MIMO processing, however, it increases the power consumption which in turn can make MIMO based SDM solutions impractical. This is a major issue for datacenters exploiting SDM solutions. Therefore, removing/lightening the burden imposed by MIMO processing can make SDM a more favorable solution. In this paper, we propose a datacenter interconnection network (DCIN), utilizing PAM-M transceivers, which can circumvent MIMO processing. It can be achieved by designing proper fibers (e.g. elliptical core FMF) in which the likelihood of mixing between mode-groups can be reduced. A key contribution of this work is the development of an analytical model to estimate the maximum reach that PAM-M (M = 4,8) signals can travel through coupled SDM fibers, targeting intra- and inter-DCs applications. We then demonstrate that FMF with MIMO-less PAM-M transceivers can significantly reduce the cabling complexity, and consequently, the cost of DCINs compared to single wavelength multi-mode or single-mode fibers based deployments.
Some ideas about the effect of appropriately selecting the size of the connections conveyed by mu... more Some ideas about the effect of appropriately selecting the size of the connections conveyed by multi-rate flexgrid optical networks are discussed. The main focus is on illustrating the relation between spectrum consumption and effective carried traffic. It is demonstrated that by introducing some order in the spectrum use, so limiting the network flexibility, its global performance is notably improved. The main contribution consists in demonstrating that using single sized lightpaths, the network throughput at any given blocking probability value increases compared to the multi-rate case. This conclusion is supported by extensive simulations under dynamic traffic conditions, considering different network topologies and traffic profiles.
Multi-path allocation has been proposed as a simple way to achieve traffic protection in differen... more Multi-path allocation has been proposed as a simple way to achieve traffic protection in different networking domains. In this work dual-path allocation is proposed for Elastic Optical Networks (EON) assuming dynamic offered traffic, and its performance is quantified by simulation. Indeed, dual-path allocation is compared with partial dedicated path protection assuming different scenarios. In addition to a qualitative comparison where advantages and drawbacks of both schemes are analysed, quantitative results for different backbone network scenarios are presented.
Journal of Lightwave Technology, Jul 1, 2022
Secure communications have become a requirement for virtually all kind of applications. Currently... more Secure communications have become a requirement for virtually all kind of applications. Currently, two distant parties can generate shared random secret keys by using public key cryptography. However, quantum computing represents one of the greatest threats for the finite complexity of the mathematics behind public key cryptography. In contrast, Quantum Key Distribution (QKD) relies on properties of quantum mechanics, which enables eavesdropping detection and guarantees the security of the key. Among QKD systems, polarization encoded QKD has been successfully tested in laboratory experiments and recently demonstrated in closed environments. The main drawback of QKD is its high cost, which comes, among others, from: i) the requirements for the quantum transmitters and receivers; and ii) the need of carefully selecting the fibers supporting the quantum channel to minimize the environmental effects that could dramatically change the polarization state of photons. In this paper, we propose a Machine Learning (ML)-based polarization tracking and compensation that is able to keep shared secret key exchange to high rates even under large fiber stressing events. Exhaustive results using both synthetic and experimental data show remarkable performance, which can simplify the design of both quantum transmitter and receiver, as well as enable the use of aerial optical cables, thus reducing total QKD system cost.
Space division multiplexing (SDM) has been proposed as the ultimate solution to address the capac... more Space division multiplexing (SDM) has been proposed as the ultimate solution to address the capacity crunch of optical transport networks. The efficient utilization of SDM requires some forms of spatial integration which is expected to bring huge cost savings for the deployment of SDM-based optical networks. Spatially integrated components with different characteristics have been largely explored and demonstrated for the realization of SDM networks, including; transmission media, transceivers with sophisticated digital signal processing (DSP) units, amplifiers, and ultimately optical switching nodes which are the key elements for the realization of transparent optical networks exploiting SDM technologies. As a consequence, in contrast to the currently deployed optical networks based on standard single mode fibers (SSMF), the next generation of optical networks exploiting SDM technologies can be realized utilizing various kinds of transmission media and the other corresponding elements. However, due in part to the physical properties of different components, their complexity, and the technology limitations not all of them meet the economic feasibility and a desired level of network-wide performance. Therefore, careful analysis should be done revealing the most appropriate and costeffective solutions. In this work, we review the recent developments and findings which pave the way for a simplified and efficient implementation of the spectrally and spatially flexible optical networks.
The main weakness of Elastic Optical Networks (EON) stems from spectrum fragmentation. An analysi... more The main weakness of Elastic Optical Networks (EON) stems from spectrum fragmentation. An analysis of periodic defragmentation in EONs under dynamic traffic conditions is carried out. The effects of different defragmentation parameters on the EON performance are evaluated, and appropriate values, guaranteeing suitable network performance while keeping the network control complexity at a reasonable point, are obtained through simulations. Different network topologies as well as traffic conditions are simulated to assess the validity of the obtained results.
In this paper, we explore the benefits of analysing the optical spectrum of lightpaths for soft-f... more In this paper, we explore the benefits of analysing the optical spectrum of lightpaths for soft-failure detection and identification in Spectrum Switched Optical Network. We present a framework exploiting machine learning (ML) based algorithms that uses descriptive models of the optical spectrum of a lightpath in different points along its route to detect whether the optical signal experiences anomalies reflecting a failure in the intermediate nodes. Our proposal targets the two most common filter-related soft-failures; filter shift (FS) and filter tightening (FT), which noticeably deform the expected shape of the optical spectrum. In this regard, filter cascading is a key challenge as it affects the shape of the optical spectrum similar to FT. Our proposals avoid the misclassification of properly operating signals when normal filter cascading effects is present. Extensive numerical results are presented to compare the performance of the proposed approaches in terms of accuracy and robustness.
Optical Fiber Communication Conference, 2018
The availability of coarse-resolution cost-effective Optical Spectrum Analyzers (OSA) allows its ... more The availability of coarse-resolution cost-effective Optical Spectrum Analyzers (OSA) allows its widespread deployment in operators' networks. In this paper, several machine learning approaches for failure identification and localization that take advantage of OSAs are presented.
Journal of Optical Communications and Networking, Nov 9, 2017
In Elastic Optical Networks (EONs), effective soft failure localization is of paramount importanc... more In Elastic Optical Networks (EONs), effective soft failure localization is of paramount importance to early detect service level agreement (SLA) violations while anticipating possible hard failure events. So far, failure localization techniques have been proposed and deployed mainly for hard failures, while significant work is still required to provide effective and automated solutions for soft failures, both during commissioning testing and in-operation phases. In this paper, we focus on soft failure localization in EONs by proposing two techniques for active monitoring during commissioning testing and for passive inoperation monitoring. The techniques rely on specifically designed low-cost optical testing channel (OTC) modules and on the widespread deployment of cost-effective optical spectrum analyzer (OSA). The retrieved optical parameters are elaborated by machine learning-based algorithms running in the agent's node and in the network controller. In particular, the Testing optIcal Switching at connection SetUp timE (TISSUE) algorithm is proposed to localize soft failures by elaborating the estimated BER values provided by the OTC module. In addition, the FailurE causE Localization for optIcal NetworkinG (FEELING) algorithm is proposed to localize failures affecting a lightpath using OSAs. Extensive simulation results are presented, showing the effectiveness of the TISSUE algorithm to properly exploit OTC information to assess BER performance of QPSK-modulated signals and the high accuracy of the FEELING algorithm correctly detecting soft failures as laser drift, filter shift, and tight filtering.
Sensors
New 5 G and beyond services demand innovative solutions in optical transport to increase efficien... more New 5 G and beyond services demand innovative solutions in optical transport to increase efficiency and flexibility and reduce capital (CAPEX) and operational (OPEX) expenditures to support heterogeneous and dynamic traffic. In this context, optical point-to-multipoint (P2MP) connectivity is seen as an alternative to provide connectivity to multiple sites from a single source, thus potentially both reducing CAPEX and OPEX. Digital subcarrier multiplexing (DSCM) has been shown as a feasible candidate for optical P2MP in view of its ability to generate multiple subcarriers (SC) in the frequency domain that can be used to serve several destinations. This paper proposes a different technology, named optical constellation slicing (OCS), that enables a source to communicate with multiple destinations by focusing on the time domain. OCS is described in detail and compared to DSCM by simulation, where the results show that both OCS and DSCM provide a good performance in terms of the bit err...