Multi-Step Ahead Grant Prediction for Dynamic Power Management in Cellular Modems

Reducing the energy consumption is an important objective in the development of cellular modems for LTE and 5G standards. In addition to hardware optimizations, Dynamic Power Management (DPM) techniques that aim at powering down idle system components are crucial for achieving this goal. However, most DPM techniques proposed so far for mobile devices are purely reactive. More promising are recently proposed proactive approaches that predict whether communication with the cellular base station will occur in the next time-slot or not. Due to transition times between power states, however, such single-step approaches may not exploit deeper power-saving states of components. As a remedy, this paper proposes multi-step ahead prediction techniques that forecast periods of no communication lasting multiple time-slots. In this context, we define a formal fine-grained power model and introduce novel predictive power management policies. Furthermore, we explore the impact of the forecast period–the number of predicted time-slots–in terms of false negative error rate as well as achievable energy savings compared to a standard LTE-compliant reactive DPM. Finally, it is shown that this overall energy saving potential of the proposed multi-step predictive approach may be higher by up to a factor of 3 compared to a single-step predictive approach without incurring a higher false negative error rate. Alternatively, the multi-step approach may allow a reduction of the false negative error rate by a factor of 4.1 compared to the single-step approach without reduction of expectable energy savings. In fact, the observed low false negative error rate of 0.0083 may facilitate a realization in future modem solutions.