Q-Learning Algorithm for VoLTE Closed-Loop Power Control in Indoor Small Cells

We propose a closed-loop power control algorithm for the downlink of the voice over LTE (VoLTE) radio bearer for an indoor environment served by small cells. The main contributions of our paper are: 1) proposing closed-loop power control for downlink VoLTE (or any packetized voice bearer), 2) deriving an upper bound of the loss in VoLTE downlink signal to noise plus interference ratio which the closed-loop power control has to overcome, 3) employing reinforcement learning to perform closed-loop power control, and 4) showing that this closed-loop power control method can improve the quality of VoLTE in a realistic network setup. Our simulation results have shown that our proposed algorithm significantly improved both voice retainability and mean opinion score as a result of maintaining the effective downlink signal to interference plus noise ratio against adverse network operational issues and faults.