Planning fixed to flexgrid gradual migration: drivers and open issues

Abstract

Flexgrid technology has recently been presented as the most promising option for upgrading the currently operating fixed grid optical networks and extending their capacity to be able to deal with the massive traffic volumes forecast for the next decade. Although the current traffic is successfully supported on fixed grid networks, flexgrid technology brings features that are not offered by the fixed grid networks, such as transporting optical connections with a capacity beyond 100 Gb/s and elasticity against time-varying traffic. In light of this, a gradual fixed grid to flexgrid migration is generally accepted in order to add these useful features to the network. In this article, we study the migration process where flexgrid is deployed in the network progressively, and review the main drivers and open issues induced by its deployment.Peer ReviewedPostprint (published version

Ultra-High-Capacity Optical Packet Switching Networks with Coherent Polarization Division Multiplexing QPSK/16QAM Modulation Formats

“…For example, in a wavelength routed optical network (WRON), a wavelength channel named lightpath is open and remains open for the duration of the connection [1]. In dynamic optical networks, however, the information stream is packetized at the optical level, and this introduces a series of challenges in the optical receiver compared to the continuous-mode case.…”

“…Currently deployed optical networks are able to dynamically allocate network resources with a granularity of a wavelength channel in the so-called fixed grid optical networks [1], or, more recently, with some variability on the spectral width of each wavelength channel and adapting the modulation format in the flexible/elastic optical networks [2]. All these networks follow the connection oriented paradigm [3] and hence may collectively be referred to as optical circuit switching (OCS) networks [4].…”

On the Filter Narrowing Issues in Elastic Optical Networks

“…Thus, a total number of filters n = 2(3 + k) are crossed, being k the number of pass-through nodes [4] [6]. For example in a large regional network, 12 transparent crossed nodes are more than sufficient to include the longest conceivable protection or restoration path, giving a maximum n = 30.…”

“…On the other hand, the selectivity of the WSSes is also a critical point. Thus, a reasonable compromise could be to reduce the number of components by restricting the node capabilities to implement wavelength contention [6]. So, the number of filters to be traversed at the A&D nodes would be reduced to 2; and the total number of filters would be n = 2(2 + k).…”

Solving Large Instances of the RSA Problem in Flexgrid Elastic Optical Networks

“…The use of advanced transmission and modulation techniques, spectrum-selective switching technologies, and flexible frequency grids (flexgrids), will allow next-generation optical networks to be spectrally efficient and, in terms of optical bandwidth provisioning, scalable and elastic [2], [3], [4]. Among key concepts implemented in flexgrid elastic optical networks (EONs) we can distinguish distance-adaptive modulation format assignment [5] and multi-carrier (i.e., superchannel, abbreviated as SCh) transmission [6].…”