On Spectrum-Efficient Green Optical Backbone Networks

We propose an orthogonal frequency division multiplexing (OFDM) based backbone optical network design. We focus on minimizing the total energy consumption of the network i.e., to make the network green. OFDM is a promising technology for next-generation optical networks with per-wavelength capacities higher than or equal to 100 Gbps. In addition, it can support heterogeneity in network traffic by having flexible bandwidth allocation per wavelength. The flexibility comes through the multiple subcarriers in an OFDM signal which can be modulated with the client data signals. Another paradigm for supporting traffic heterogeneity and high bandwidth demands is mixed-line-rate (MLR) networks where wavelengths can have discrete capacities of 10/40/100 Gbps which are single carrier based. In this study, we compare the energy efficiency of an OFDM-based network versus a MLR network. Our results show that OFDM outperforms MLR in terms of energy efficiency.

I. Introduction

Traffic in today's telecom networks is becoming heterogeneous due to a variety of applications with varied bandwidth needs. There is also an urgency to have energy-efficient (i.e., green) networks. A cost-efficient and energy-efficient network requires flexible bandwidth assignment in its links. Having bandwidth pipes with “elastic” capacity will enable efficient packing of data traffic and provide spectral efficiency as well as energy efficiency [1].