Felipe Jiménez

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.

Protection in optical transport networks with fixed and flexible grid: Cost and energy efficiency evaluation

The ever-increasing Internet traffic demand introduces new challenges for telecommunications carriers. Telecom networks will have to be upgraded to cope with the new capacity requirements. However, deploying enough capacity is not the only requirement for network operators. The impact of new technologies in terms of capital investment and energy consumption becomes a key issue. There is a special interest in investigating new mechanisms and technologies to improve the energy efficiency of future networks, while maintaining the high reliability and service availability of current optical transport networks. This article evaluates the energy- and cost-efficiency of an innovative flexible-grid orthogonal-frequency-division-multiplexing (OFDM) -based network and compares them with those for conventional wavelength-division-multiplexing (WDM) networks. Due to the importance of resilience in optical transport networks, the study considers and evaluates different protection schemes. The results demonstrate the potential energy efficiency improvements that can be achieved by an elastic OFDM-based technology, especially when a shared protection scheme is adopted, and give an insight into the potential cost benefits that such a novel technology can offer to telecommunication carriers.

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.

TREND big picture on energy-efficient backbone networks

The ICT (Information and Communication Technology) sector has recently been identified as a growing contributor to worldwide greenhouse gases emissions and power consumption. This has triggered interest for more energy efficient ways to design and operate telecommunication networks. We present an overview of the solutions proposed within the European network of excellence TREND focusing on core and metro networks including data centers. Potential savings are presented and discussed with respect to their impact and applicability within the global picture.

Amplifier placements optimization for enhanced energy efficiency in optical transport networks

We propose an optimization on the amplifier placement to enhance the energy efficiency of the future optical transport networks based on WDM with mixed line rate transmissions. Simulation results show significant energy efficiency per GHz improvements of up to 74% thanks to the deployment of additional amplifiers, allowing for the utilization of more energy and spectral efficient modulation formats.

Increased energy-efficiency and capacity for mixed-line-rate WDM networks with hybrid Raman-EDFA amplification

The selective placement of additional Hybrid Raman-EDFA amplification provides an effective mechanism to improve the energy and spectral efficiency of mixed-line-rate WDM networks. The energy efficiency per GHz is increased up to 50% and the network capacity is doubled.