IEEE Communications Magazine • November 2016 166 0163-6804/16/$25.00 © 2016 IEEE ABSTRACT The IoT has been emerging as the next big leap in the information and communication technology sector. Providing a unified commu- nication platform to support billions of smart connected devices seamlessly alongside existing voice and Internet services is vitally challenging. This article leverages converged fiber-wireless (FiWi) access networks to design a shared com- munication infrastructure for supporting both IoT applications and traditional services. Given the paramount importance of energy efficiency in both IoT and access networks, the article discuss- es the possibilities and potential challenges of designing and implementing power-saving mech- anisms to prolong battery life of IoT devices while reducing energy consumption of the optical backhaul network. In-depth technical guidelines are provided through end-to-end power-saving solutions proposed for typical IoT deployment scenarios. INTRODUCTION While the wired and mobile Internet revolution- ized the telecommunication paradigm by con- necting people “anywhere” at “any time,” the emerging Internet of Things (IoT) is creating another paradigm in which “anything” can be remotely accessed and/or controlled, allowing for more direct integration between the physical world and machine-based systems. Unlike the traditional Internet for delivering human-centric services (e.g., file sharing, voice telephony, video streams), the IoT relies on machine-to-machine (M2M) communications with a focus on smart devices such as sensors, actuators, wearables, and metering devices. The IoT has its application in numerous and diversified fields, from connected vehicles to smart grids, spanning industries of utilities, healthcare, and transportation, just to name a few [1]. Therefore, the IoT is expected to become a new driving force of the information, communications, and technology (ICT) indus- try with about 50 billion devices connected to the Internet in 5 years [2]. Recent research has revealed that the IoT will potentially bring an economic impact of around 11 percent of the world economy in 2025 [3]. Despite enormous opportunities, the advent of the IoT alongside its integration with existing wired and mobile Internet creates huge challeng- es in designing a unified communication platform to fully support a wide range of IoT applications with diverse requirements and human-centric services at the same time [4]. Figure 1 presents key challenges of the paradigm of converged Internet technologies including network inte- gration, energy efficiency, coexistence, diversity, and scalability. Network integration deals with the efficient merging of various types of net- works, for example, converged wired and wire- less access networks and collaboration among different network operators. Another important challenge is to handle the coexistence of conven- tional human-to-human (H2H) traffic, such as triple-play (voice, video, and data), and emerg- ing machine-to-machine (M2M) traffic in order to ensure that high-priority traffic is not jeopar- dized. Note that coexistence is an inherent issue due to the integration of IoT devices into existing access network infrastructure. The tremendous growth of mobile data traf- fic together with the increasing integration of radio access technologies (RATs) and the cell densification paving the way to 5G networks gradually shifts the bottleneck from the radio interface toward the backhaul segment. With the emerging IoT, the backhaul bottleneck is expected to become even more critical. However, until recently, existing studies on IoT connectiv- ity largely focused on enhancements of RATs without looking into the backhaul segment [5]. Meanwhile, economic considerations may play an important role in the successful rollout of IoT, as experienced in smart grids [6]. To address the backhaul bottleneck in a cost-efficient way, a prominent solution is to share the already wide- ly deployed high-capacity and reliable optical access network (OAN) infrastructure, which was originally for fixed broadband access [7]. This can be facilitated by converged fiber-wireless (FiWi) access networks that are able to seamless- ly integrate an OAN and a multi-RAT front-end network in support of both human-centric and IoT applications on the same infrastructure. The integration of IoT and FiWi networks gives rise to so-called IoT over FiWi networks. Power-Saving Methods for Internet of Things over Converged Fiber-Wireless Access Networks Dung Pham Van, Bhaskar Prasad Rimal, Jiajia Chen, Paolo Monti, Lena Wosinska, and Martin Maier GREEN COMMUNICATIONS AND COMPUTING NETWORKS The authors leverage converged fiber-wireless (FiWi) access networks to design a shared com- munication infrastructure for supporting both IoT applications and tradi- tional services. Given the paramount importance of energy efficiency in both IoT and access net- works, they discuss the possibilities and potential challenges of designing and implementing pow- er-saving mechanisms to prolong battery life of IoT devices while reducing energy consumption of the optical backhaul network. Dung Pham Van, Jiajia Chen, Paolo Monti, and Lena Wosinska are with KTH Royal Institute of Technology; Bhaskar Prasad Rimal and Martin Maier are with INRS. The work of D. Pham Van was partially supported by the EIT Dig- ital project EXAM (Energy-Efficient Xhaul and M2M) and the Göran Gustafssons Stiftelse Foundation. The work of B. P. Rimal was sup- ported by the Fonds de recherche du Québec — Nature et Technol- ogies (FRQNT) MERIT Doctoral Research Scholarship Program. Digital Object Identifier: 10.1109/MCOM.2016.1500635CM