Energy-Efficient Topology Reconfiguration in Green Fiber-Wireless (FiWi) Access Network

As a promising access technique, Fiber-Wireless (FiWi) network not only enables the cost-effective broadband access, but also provides more opportunities for energy savings. Previous works mostly focused on energy savings in the optical back-end of FiWi. Generally, they extend the Optical Network Unit (ONU) sleep mechanisms initially designed for Passive Optical Network (PON) to FiWi by combining with the wireless rerouting. Most of these works, however, remain untouched energy savings in the wireless front-end. In fact, when one or more ONUs in the network is/are sleeping, many wireless components remain idle or underutilized which cause a lot of energy waste. In this paper, we propose a new energy-efficient Wireless-Optical Topology Reconfiguration (WOTR) scheme for the integrated energy savings in FiWi. Aiming to reduce energy consumption over the whole network, WOTR reconfigures the optical topology by using ONU sleep as well as the wireless topology by using Radio Interface (RI) standby. By means of topology reconfiguration, the network components will be utilized more efficiently, thus saving more energy. Simulation results show that WOTR can reduce the energy consumption significantly with just a little performance degradation in network throughput.