On the Filter Narrowing Issues in Elastic Optical Networks

Abstract

Abstract-This paper describes the problematic of filter narrowing effect in the context of next generation elastic optical networks. First, three possible scenarios are introduced: the transition from actual fixed-grid to a flexi-grid network; the generic full flexi-grid network; and a proposal for filterless optical network. Next, we investigate different transmission techniques and evaluate the penalty introduced by the filtering effect when considering: Nyquist WDM, SSB DD-OFDM and symbol-rate variable DP-4QAM. Also, different approaches to compensate for the filter narrowing effect are discussed. Results show that the specific needs per each scenario can be fulfilled by the aforementioned technologies and techniques, or a combination of them, when balancing performance, network reach and cost.Index Terms-Networks, optical communications, elastic optical networks, flexi-grid, WSS. I. INTRODUCTIONThe future adoption of elastic optical network (EON), mainly fostered by the advent of next technologies (e.g., media, HDTV, 5G, Internet of Things, etc.) and backed by the considerable advances of transmission techniques in terms of flexibility and capacity, is heading to undertake new challenges and goals. In fact, when adopting the flexi-grid paradigm [1], optical channels with different bandwidth occupation can coexist within the same fiber. Some of these channels, denominated as super-channels, are wider in frequency and comprise multiple sub-channels transmitted

Meeting the future metro network challenges and requirements by adopting programmable S-BVT with direct-detection and PDM functionality

“…From the figures it can be seen that one polarization component is more affected by fiber impairments, as travels for a longer path, and hence lower bits per symbol are assigned to the subcarriers. As an additional remark, filtering effects due to passing through cascaded network nodes can be limited by the implementation of bit/power loading algorithms, according to [32].…”

Throughput Gains From Adaptive Transceivers in Nonlinear Elastic Optical Networks

“…It is assumed that linear impairments are ideally compensated at the receiver and that the only significant physical layer impairments are amplified spontaneous emission (ASE) noise from the EDFAs and nonlinear interference. The imperfections of non-ideal network components, for example crosstalk and optical filtering [29], [30], in the ROADMs along with PDL and EDFA imperfections, have not been included in this study. The ASE noise accumulates linearly with the number of spans, where the additional noise per span in the receiver matched filter bandwidth, n ASE , is given by…”

Experimental Assessment of Filter Narrowing Effect for Low Bandwidth Connections in EON

“…T HE future adoption of Elastic Optical Networks (EON) due to the increased in traffic demand by the advent of technologies, as Internet of Things or 5G, sets further requirements on the flexibility and scalability, making the conventional fixed-grid to evolve towards a flexi-grid networks [1], [2]. The adoption of flexi-grid networks implies that multiple optical channels with different bandwidths can coexist in the same fiber.…”

“…The adoption of flexi-grid networks implies that multiple optical channels with different bandwidths can coexist in the same fiber. This granularity enables the reduction of the channel width for low bit rate connections [2]. As a result, the flexibility of the network improves and CAPital EXpenditure (CapEx) is reduced.…”

“…When the optical signal traverses these nodes, the resulting signal bandwidth can be distorted, affecting the signal performance. Indeed, the major impact is for bandwidths of 12.5 GHz and 25 GHz with respect to 37.5 GHz [2], [4].…”