Raúl Duque

Traffic and power-aware protection scheme in Elastic Optical Networks

Currently, the need for “greener” telecommunication networks is stimulating research efforts to find new solutions to cope with power consumption and sustainability issues. Exploiting the potential of optical Wavelength Division Multiplexed (WDM) networks for this purpose has been identified as an attractive approach. However, the traditional WDM fixed-grid, where 50 GHz-spaced optical carriers are used with Single Line Rates (SLR), may result in lower efficiency from both the spectral occupation and power consumption perspectives. Higher flexibility can be provided by adopting Mixed Line Rates (MLR) and, especially, the so-called Elastic Optical Network (EON) paradigm, which is enabled by the Orthogonal Frequency Division Multiplexing combined with Coherent Detection (CO-OFDM). In this scenario a finer channel spacing is considered so the spectrum can be best fitted to actual traffic needs. Another critical issue is the network robustness to failures, accomplished by reserving additional resources as a backup for protection. Traditional approaches allocate dedicated (1+1) resources for protection and the peak-rate capacity is reserved in both working and protection paths for every traffic demand. Thus, the power consumed in resilient network is substantially increased compared to the unprotected case. In this paper, we evaluate the impact of the hourly network traffic variation to reduce the power consumed by backup resources, by adapting their rate to the current required bandwidth. We apply this paradigm to the SLR, MLR and EON scenarios and find that, especially in the EON case and for high traffic load conditions, substantial energy savings (up to 27%) can be obtained by exploiting the information on hourly traffic variation.

On the energy efficiency of survivable optical transport networks with flexible-grid

An energy efficiency comparison of conventional path protection schemes for fixed-grid WDM and flexible-grid OFDM-based networks has been carried out. The survivable elastic network with SP scheme was found to offer the best energy efficiency per GHz at any traffic load value.

Cost evaluation for flexible-grid optical networks

We have compared the total cost of an innovative elastic network with respect to the conventional WDM ones operating in realistic network scenarios. The results give an insight of the cost benefits that can be obtained with an elastic OFDM-based network for the operation of future optical transport networks with different protection schemes.

TREND in energy-aware adaptive routing solutions

Energy saving in telecommunications networks has become a well established topic in the research community. We look at the electrical and optical layers of IP-over-WDM networks, and present a list of evaluation criteria for energy- aware adaptive routing solutions (EA-ARSs) from the perspective of a network operator. Furthermore, we briefly explain the adaptive routing solutions originating from the European Unions TREND and the FP7 Network of Excellence, show saving of energy consumed by line cards in a reference scenario, and use the evaluation criteria to identify the next steps toward introduction of the EA-ARSs into real operation.

Differentiated quality of protection to improve energy efficiency of survivable optical transport networks

A differentiated quality of protection scheme is evaluated in terms of energy efficiency for fixed-grid WDM and flexible-grid OFDM-based networks. Significant energy savings can be achieved by exploiting the heterogeneous protection requirements.

Green Horizon: Looking at backbone networks in 2020 from the perspective of network operators

The problem of reducing power consumption in backbone networks by adopting sleep modes has been extensively studied in the literature. In contrast to previous work, we forecast power consumption and traffic in two operator networks (France Telecom (FT) and Telefónica Investigación y Desarrollo (TID)) for the year 2020, and consider both Single Line Rates (SLRs) and Mixed Line Rates (MLRs) deployments. Given these realistic scenarios, the set of devices in sleep mode is computed autonomously on each network node by a simple power-aware algorithm using only local information as input and requiring no rerouting. Results show that the savings obtained by adopting sleep modes are significant, even if power efficiency (W/Gbps) is increased. Moreover, we show that networks using MLR always consume less energy than SLR-based networks when the power-aware algorithm is applied to the considered scenarios.

Network Resilience Requirements and Algorithms for Multicasting and Broadcasting Digital TV

In this paper we give an overview of the network architecture and of the resilience requirements for both, metro and core networks.

Cost evaluation of the integration of IP/MPLS and WDM elements

Multi-layer integration is an important trend in the telecom industry as a cost-efficient alternative. From an incremental CapEx analysis, we aim to quantify the maximum cost savings that could be achieved by such integration.

On local CAC schemes for scalability of high-speed networks

Next generation networks are required to provide bandwidth on-demand for fine granularity sessions. In this sense, centralized CAC (connection admission control) approaches could suffer from scalability problems if the number of requests for connections were very high. In this paper we investigate local CAC schemes where the decisions are performed at the network edges, based on pre-calculated admission quotas.