Rafael Sanchez

Rafael Sanchez

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    Oversubscription Dimensioning of Next-Generation PONs with Different Service Levels
    Jose Alberto Hernández
    David Larrabeiti
    IEEE Communications Letters, PP(2016), PP
    Preview abstract This letter provides a methodology for planning Passive Optical Networks using the oversubscription concept and shows its applicability in the dimensioning of 1 Gb/s access to both basic (i.e. residential) and premium (i.e. business) users with different service level requirements and activity patterns. We show that only Next-Generation PON networks can reach a large number of users with acceptable service levels. View details
    Preview abstract Today more than ever before, service providers are under enormous pressure to reduce operational costs while increasing business effectiveness. This often means optimizing cur- rent infrastructure investments and implementing novel networking technologies. Customer demand is quickly evolving away from traditional one-way content consumption to a much more participative social network model that demands high capacity bidirectional information flows. Ethernet-based networking technology has become ubiquitous in both the enterprise and home broadband arenas. The combination of simplicity and rigorous specification has permitted a degree of integration and commoditization that other networking technologies could not achieve. On the other hand, optical fiber has become the technology of choice in the medium and long term in the access and metro networks, thanks to its speed, reach and future-proof. While it seems clear that fiber is the right technology to support emerging services in the access network, there are a large variety of technologies available in the industry. This thesis reviews the main technologies available today for access and metro networks, and proposes contributions about network planning and optimization. Firstly, main innovations added to Ethernet are analyzed, namely improvements related to scalability, OAM functionality and forwarding capabilities, in order to permit Ethernet to assume a much larger role in metro networks. After that, some of the Ethernet enhancements previously discussed are applied to access networks. Specifically, physical and link-layer information are combined in order to effectively set management procedures for passive optical networks (PON). We propose an Integrated Troubleshooting Box (ITB) and show its applicability in a number of realistic troubleshooting scenarios, including failure situations involving either the feeder fibre or one of its branches. Secondly, this thesis explores fiber access protocols available in the industry to support high-speed symmetrical services. It compares four Next-Generation PON protocols from a performance and economical perspective in a real scenario, and analyzes under which conditions 1 Gb/s symmetrical services can operate by selecting the right parameters of quality of service, oversubscription and split ratio. Finally, a novel access network planning method is proposed to provide 1Gb/s symmetrical services in a mixed environment of business and residential services. In this case, a converged cost-optimized access network is implemented, using Integer Linear Programming, which guarantees respective service level specifications in a real scenario. View details
    Provisioning 1 Gb/s symmetrical services with next-generation passive optical network technologies
    Jose Alberto Hernández
    Julio Montalvo
    David Larrabeiti
    IEEE Communications Magazine, 54(2016), pp. 72-77
    Preview abstract Service providers spend billions upgrading their broadband access networks to the latest access standards. Fiber has become the technology of choice in the medium and long term, thanks to its speed, reach, and future-proofness. A differential advantage of fiber over other broadband access technologies is that it makes it possible for operators to deliver symmetric-rate services. Most of today's commercial offers based on regular PON range from 10 to 100 Mb/s of committed information rate, and higher rates are advertised as peak rates with unspecified guarantees. In this article we focus on delivering symmetrical 1 Gb/s access to residential users with a target temporal guarantee at the least cost using next-generation PON technologies. We compare four NG-PON standard access technologies, GPON, XGPON, WDM-PON, and the emerging TWDM-PON, from technical and economic perspectives. The study shows that if a service provider wants to keep up with the growing user traffic pattern in the long run, only TWDM-PON can provide 1 Gb/s nearly guaranteed at a moderate cost with respect to the fully dedicated 1 Gb/s point-to-point connection available in WDM-PON technologies. View details
    Network Planning for Dual Residential-Business Exploitation of Next-Generation Passive Optical Networks to Provide Symmetrical 1  Gb/s Services
    Jose Alberto Hernandez
    David Larrabeiti
    Journal of Optical Communications and Networking, 8(2016), pp. 249-262
    Preview abstract Demand for high-speed access for business and residential subscribers has grown rapidly in recent years; thus, service providers need to offer cost-effective solutions to cover this demand. Convergence within the same infrastructure for clients requiring different service levels may have benefits in terms of cost, but their respective service-level specifications need to be guaranteed. This article compares different flavors of next-generation passive optical networks (PONs), namely, gigabit PON (GPON), 10-gigabit PON (XG-PON), time and wavelength division multiplexing PON (TWDM-PON), and wavelength division multiplexing PON (WDM-PON), and evaluates which one can provide 1 Gb/s symmetrical service at the more affordable cost when there is a mix of residential and business subscribers. Results show that the recommended technology depends on the percentage of business subscribers in the scenario. View details
    Troubleshooting PON networks effectively with Carrier-grade Ethernet and WDM-PON
    Jose Alberto Hernandez
    David Larrabeiti
    IEEE Communications Magazine, 52(2014), pp. 7-13
    Preview abstract WDM-PONs have recently emerged to provide dedicated and separated point-to-point wavelengths to individual Optical Network Units (ONTs). In addition, the recently standardised Ethernet OAM capabilities under the IEEE 802.1ag standard and the ITU-T Y.1731 recommendation, together with state-of-the-art Optical Time-Domain Reflectometry (OTDR) provide new link-layer and physical tools for the effective troubleshooting of WDM-PONs. This article proposes an Integrated Troubleshooting Box (ITB) for the effectively combination of both physical and link-layer information into an effective and efficient set of management procedures for WDM-PONs. We show its applicability in a number of realistic troubleshooting scenarios, including failure situations involving either the feeder fibre, one of its branches and even Ethernet links after the ONT. View details
    Using transparent WDM metro rings to provide an out-of-band control network for OpenFlow in MAN
    Jose Alberto Hernandez
    David Larrabeiti
    ICTON 2013, 15th International Conference on Transparent Optical Networks (ICTON'13)
    Preview abstract OpenFlow is a protocol that enables networks to evolve and change flexibly, by giving a remote controller the capability of modifying the behavior of network devices. In an OpenFlow network, each device needs to maintain a dedicated and separated connection with a remote controller. All these connections can be described as the OpenFlow control network, that is the data network which transports control plane information, and can be deployed together with the data infrastructure plane (in-band) or separated (out-of-band), with advantages and disadvantages in both cases. The control network is a critical subsystem since the communication with the controller must be reliable and ideally should be protected against failures. This paper proposes a novel ring architecture to efficiently transport both the data plane and an out-of-band control network. View details
    Ethernet as a Carrier Grade Technology: Developments and Innovations
    Lampros Raptis
    Kostas Vaxevanakis
    IEEE Communications Magazine, 46(2008), pp. 88-94
    Preview abstract Recent innovations in the Ethernet networking technology are enhancing both the scalability and capability of Ethernet as a carrier-grade and transport technology. This article explains four main innovations recently added to Ethernet, namely improvements related to scalability, OAM functionality and enhanced forwarding capability in order to permit Ethernet to assume a much larger role in carrier networks with substantial economic and operational benefits. View details