Freshness-aware Energy Saving in Cellular Systems with Cooperative Information Updates

Energy saving in cellular systems has attracted the extensive attention of various studies due to ever-deteriorating global warming. In addition to network greenness, various emerging mobile applications (e.g., mixed reality and automated vehicles) further necessitate timely service provision. Recently, the age of information (AoI) has been regarded as a promising performance metric for quantifying the freshness (i.e., timeliness) of information updates in communication systems. Despite the existing works devoted to energy saving in cellular systems, how to leverage information freshness to ensure timely information updates while achieving network greenness is rarely investigated. In this paper, we investigate the problem of freshness-aware energy saving in cellular systems, where active base stations (BSs) can cooperatively update information to target devices (TDs). To address this problem, we formulate a mixed-integer nonlinear program (MINLP) to minimize average power consumption. Due to its intractability, we propose decomposing the MINLP into two subproblems by means of constraint reinterpretation and spatiotemporal decoupling. Then, we propose a two-stage solution that leverages LP techniques to sequentially determine update scheduling and BS activeness. Our simulation results show that the proposed solution can adequately perform update scheduling and BS activeness control, thereby effectively saving energy for cellular systems under various parameter settings.