Applying Sleep Modes in Legacy LTE Networks: An Energy-Efficient Study Based on Operator Data

This paper presents the design and evaluation of three practical sleep-mode mechanisms for improving the energy efficiency of legacy LTE Radio Access Networks (RANs).Motivated by empirical observations of persistent energy waste during low-traffic periods, and informed by site-level hardware constraints and intercomponent dependencies, the proposed modes are tailored to operate within the limitations of existing infrastructure.Their design is based on power consumption data collected from a live operator network and builds upon an earlier optimization framework that identified the minimum number of active eNBs required to maintain full-service coverage.Using real PRB utilization traces from a commercial deployment, we simulate each sleep mode's impact on power savings and quality of service.Results show that substantial energy reductions of up to 18.2 kWh per site per day can be achieved without compromising connectivity, offering operators a flexible and realistic approach to energy-aware RAN operation.