Power efficient stochastic modeling for Narrowband Internet of Things devices in 5G networks

Narrowband Internet of Things (NB-IoT) embodies the vision of connecting virtually anything with everything and aims to support a massive number of devices for small data transmission. However, an efficient power-saving model for battery-operated NB-IoT devices is the need of the hour. In addition to the legacy discontinuous reception (DRX) scheme, efficient beamforming helps in saving device power. Moreover, the extended discontinuous reception (eDRX) mode and Power Saving Mode (PSM) in Radio Resource Control (RRC) idle mode enhances the effect of sleep while no data is available for the device to serve. In this work, power-saving techniques for NB-IoT devices are studied via stochastic modeling. This work proposes a semi-Markov model (SMM) for beam measurement and beamforming-based DRX mechanism, in RRC modes. The steady-state probabilities for the SMM are calculated using the two-stage method. The numerical results show the effective contribution of efficient beamforming, eDRX state and PSM state in enhancing the power saving of NB-IoT devices.