Characterising Sleep Mode Energy Savings for Integrated Optical-Wireless Access Network Infrastructure
The convergence of optical and wireless access networks has increased the importance of improving energy efficiency in broadband infrastructure. This paper characterises the energy savings achieved through sleep mode implementation in integrated Gigabit Passive Optical Network (GPON)–Worldwide Interoperability for Microwave Access (WiMAX) and GPON–Long-Term Evolution (LTE) access networks. Power shedding for Optical Network Units (ONUs) and idle mode procedures for Femtocell Base Stations (FBSs) are implemented based on user traffic profiles collected from the Gadong broadband access area in Brunei Darussalam. A measurement-based ONU power consumption model, developed and validated using experimental data collected from a live GPON network at access data rates up to 1 Gbps, is employed to evaluate network power consumption under realistic operating conditions. The analysis considers different fractions of active Integrated Optical Base Stations (IOBs) during lowtraffic periods to assess the impact of sleep mode operation. Results show that sleep mode implementation achieves power savings of up to 19.88% for GPON-WiMAX and 18.48% for GPON-LTE when only 30% of IOBs remain active. The findings demonstrate the effectiveness of coordinated sleep mode strategies in reducing power consumption while maintaining network operation during off-peak traffic periods. This work provides practical insights into the design of more energy-efficient integrated optical-wireless access networks and supports the development of sustainable broadband infrastructure.