1,721,033 research outputs found
Energy Efficiency in Optical Network Planning
No full textTelecommunications operators are continuously exploring new lternatives to up-grade their networks in order to handle the ever increasing Internet traffic demand. However, increase in bandwidth have been accompanied with the increase in power consumption which is an important subject to be addressed. For the said purpose my research is focused on developing methods of bringing energy efficiency in the core telecommunications networks. The target of this thesis is the improvement of the energy efficiency in wired telecommunication networks. Indeed, several research studies have underlined that the already huge energy consumption is destined to increase in the next years since the traffic in telecommunication networks will continue to grow constantly due to the increasing popularity of new bandwidth-consuming applications, and the increase of population using them. This situation thus urges to find strategies that can mitigate the demand of energy in the networks. The main contributions concern the definition of algorithms and strategies that incorporate and exploit the knowledge of the network topology, the carried traffic and the power behavior of network devices to achieve energy efficiency in the network. In particular, during the three years, research work targeting the energy efficient designing of conventional fixed grid (Wavelength Division Multiplexing) WDM networks and Orthogonal Frequency Division Multiplexing (OFDM) based elastic optical networks is being carried out. The problem is tackled using Mixed Integer Linear Programming (MILP), greedy heuristics and sophisticated meta-heuristics. Results show that an appropriate design can increase energy efficiency in fixed-grid WDM and flexible-grid elastic optical networks. The problem of power-efficient design of IP-over-WDM networks is investigated through explicitly targeting the minimization of power consumption. Results, obtained over an extensive set of scenarios and networks, indicate that both the MILP and heuristics provide solutions for power-efficient networks. Moreover, it was observed that most of the power in an IP-over-WDM network is consumed by routers and line cards, even when high power consumption of OLAs and WDM terminals is assumed. The other topic covered during my research activity is the investigation of energy-efficient design of flexible-grid networks. The activity was mainly focused on the design of the logical layer, which is usually disregarded when dealing with flexible-grid networks. More precisely, the impact of introducing an energy-aware electronic traffic grooming in flexible-grid network design is evaluated. Two greedy heuristics for the network design are proposed, one exploiting traffic grooming, and their energy efficiency is compared. In summary, this thesis makes important contributions to the networking research community providing new methods and approaches for the definition of energy efficient networking technique
Physical Layer Strategies to Save Lightpath Regenerators
No full textWe investigate the viability of hybrid fiber
amplifiers (HFA) and advanced digital signal processing
(DSP)-based transceivers in translucent optical networks.
We focus on the reduction of optical-electro-optical (OEO)
regenerators required to support a 200 Gbps any-to-any
traffic. In this paper, two network topologies, PanEuropean and USNET, are quantitatively analyzed according to three different upgrade strategies. The first upgrade
strategy includes selective placement of HFA in a network
using different Raman amplification levels. The second upgrade strategy includes the use of two different DSP techniques of digital backpropagation and probability shaping
(PS) at the transceivers. The third upgrade strategy
involves a combination of both HFA and DSP techniques
in a network. Our results indicate that by using these
upgradation strategies, a prominent reduction in OEO
regenerators can be obtained, which can lead to full
transparency of a network. In the Pan-European topology,
improving the equivalent noise figure (ENF) of the optical
amplifiers by 5 dB, it is possible to reduce by 74% the
amount of required regenerators. Then, by applying
advanced DSP techniques like PS, this percentage grows
up to 82%. In the USNET topology, by reducing the ENF
by 2 dB, it is possible to reach full transparency. By using
PS, it is enough to reduce the ENF by just 0.5 dB to reach the
same results
Virtual DBA: virtualizing passive optical networks to enable multi-service operation in true multi-tenant environments
Full text linkThis paper presents the concept of virtual dynamic bandwidth allocation (DBA), a method we propose to virtualize upstream capacity scheduling in passive optical networks (PONs), which provides multiple independent virtual network operators with the ability to precisely schedule their upstream traffic allocation. After a brief introduction on the evolution of access network sharing, we present our virtual DBA architecture, detailing its main components. We then provide a summary of the work done in this area from both theoretical and practical implementation perspectives. In this paper, we propose a novel stateless algorithm for merging multiple independent virtual bandwidth maps based on priority classes and analyze its performance in terms of efficiency of capacity allocation and latency. Through our results, we discuss the existence of a trade-off between traffic load and grant size distribution versus efficiency and latency. We find that, different from a residential single-tenant application, when PONs are used for low-latency and multi-tenant applications, the system has better overall performance if grants are allocated in small size. In addition, our analysis shows that for high-priority, strict latency services, our proposed merging algorithm presents delay performance that is independent of the traffic distribution considered
Merging Engine Implementation with Co-Existence of Independent Dynamic Bandwidth Allocation Algorithms in Virtual Passive Optical Networks
No full textWe implement the co-existence of independent DBA algorithms, at OLT, sharing the PON upstream capacity. Results indicate that service performance, in terms of packet loss and delay, is affected by virtual operator's choice of DBA
Energy awareness in the design of optical core networks
No full textWe evaluate the power savings achievable in the design of optical core networks considering design alternatives to solve LTD and RWA problems. Results show that an appropriate design can increase energy efficiency in WDM network
Traffic grooming and energy-efficiency in flexible-grid networks
Full text linkEnergy-efficient design of flexible-grid networks is investigated. We focus on the design of the logical layer, usually disregarded when dealing with flexible-grid networks. More precisely, we evaluate the impact of introducing an energy-aware electronic traffic grooming in flexible-grid networks design. We propose two greedy heuristics for the network design, one exploiting traffic grooming, and we compare their energy efficiency. Results have been retrieved for several randomly generated networks of different size, with different connectivity, average physical link length and traffic scenarios. Significant energy savings can be achieved for low traffic loads and large network size when performing traffic groomin
Impact of Fiber Type on Regenerator Placement in Reconfigurable DWDM Transparent Optical Networks
No full textWe evaluate the impact of three different fiber types on number of regenerators required in fixed grid optical networks. The analysis on a 28-node PAN-European topology confirms that number of regenerators required greatly depends on the fiber type used
Networking benefits of advanced DSP techniques and hybrid fiber amplification
No full textWe evaluate how the joint selective introduction of improved hybrid amplification technologies at inline amplification sites and advanced digital signal processing (DSP) techniques at transceivers allows to greatly reduce the number of required optical-electro-optical (OEO) regenerators in transparent optical networks. We perform quantitative studies on two different topologies, focusing on two different DSP techniques: digital back-propagation and probabilistic shaping. Different Raman pumping levels are considered. OEOs saving up to 100% is demonstrated for both DSP techniques
Energy-Aware Design of Multilayer Core Networks
No full textWe consider the power-efficient design of an Internet protocol (IP)-over-wavelength division multiplexing (WDM) network, tackling the problem of installing optical and IP layer equipment to satisfy traffic requirements. We take into account routing constraints and consider a comprehensive set of realistic scenarios defined by network topology, traffic matrix, and power consumption values of network devices in both layers. Furthermore, besides defining and solving an optimal integer linear programming model, we propose an efficient heuristic to solve the problem up to medium-sized networks. The proposed heuristic requires at most 30% of additional power with respect to the optimal solution, but with a significantly reduced complexity. We show that the largest power consumption is due to line cards and routers rather than WDM equipment. Furthermore, we find that multipath routing reduces the network power consumption with respect to single-path routing, but not significantly. Finally, we show that a two-step design procedure, in which power is separately minimized in each layer (i.e., IP and WDM layers), can find results with a total power consumption comparable to the one achieved by a more complex joint multilayer design procedure
Raman Pumping as an Energy Efficient Solution for NyWDM Flexible-grid Elastic Optical Networks
Get PDFThis paper investigates transparent wavelength routed optical networks using three different fiber types NZDSF, SMF and PSCF - and validates the effectiveness of Hybrid Raman/EDFA Fiber Amplification (HFA) with different pumping levels, up to the moderate 60% pumping regime. Nodes operate on the basis of flexible-grid elastic NyWDM transponders able to adapt the modulation format to the quality-of-transmission of the available lightpath, exploiting up to five 12.5 GHz spectral slots. Results consider a 37- node Pan-European network for variable Raman pumping level, span length and average traffic per node. We show that HFA in moderate pumping regime reduces the power consumption and enhances spectral efficiency for all three fiber types with particular evidence in NZDSF. In essence to that, introduction of HFA is also beneficial to avoid blocking for higher traffic loads
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