Understanding QoS and Energy Saving Performance in FiWi Access Network with Sleep Mode Enabled ONUs

Due to the stupendous demand for ubiquitous and high-speed Internet access, Fiber-wireless (FiWi) access networks are gaining a lot of traction. A FiWi is a network structure combination of Passive Optical Network (PON) as the backend (backhaul) and Wireless networks (e.g. Wireless Local Area Network (WLAN)) at the network's frontend side. With the rise of Internet coverage as well as high bandwidth and low-latency demanding applications, the energy consumption of network equipment is rising unprecedentedly, especially in the network access segment. One of the promising solutions for energy conservation in the network access segment is sleep mode, in which network equipment move into a low-power state periodically. However, the sleep mode mechanism brings a trade-off relationship between energy consumption and network traffic performance. In this paper, we study how the medium access types of IEEE 802.11 based WLAN and sleep mode in the PON segment of a FiWi influence overall delay, throughput and energy-saving performance in the network. Results obtained through the OPNET simulator reveal that the medium access type of WLAN has a noticeable influence on energy-saving performance of the PON segment. Additionally, our findings impart that the sleep mode in a PON segment has a significant influence on traffic performance at the users' terminals connected with the WLAN, regardless of the medium access types applied.