Energy efficiency in the extended-reach fiber-wireless access networks

Telecommunication networks call for novel energy-efficient design and management schemes as a result of the increasing contribution of the ICT sector to electricity consumption and greenhouse gas emissions. Access networks, being one of the significant contributors in the last mile, require power saving protocols and architectures. As one of the emerging access network solutions, convergence of PONs and wireless access networks, also named as FiWi, offer to combine the robustness and high capacity of optical networks with the mobility and ubiquity of wireless networks. In this article, we present an overview and a brief comparison of energy-efficient protocols and design approaches in FiWi networks. We further propose an energy-efficient bandwidth allocation mechanism in FiWi networks that adopts an optical burst switching (OBS)-like report generation mechanism in LREPON. Through simulations, we show that the proposed scheme leads to significant energy savings in the long-reach FiWi network while overcoming the delay penalty of the ONU-BS sleep modes.