The Module Switching Mechanism for Power-Constrained Devices in LTE and NB-IoT Interworking Networks

The dual mode technology has been adopted to support smart devices to connect to both the NB-IoT and the LTE simultaneously. How to reduce the power consumption of a smart device with limited battery capacity has been treated as an important issue. In this paper, we propose the Module Switching Mechanism (MSM) that consists of the PS scheme and the AWU scheme to reduce the power consumption for dual-mode smart devices. In the PS scheme, the NB-IoT module (i.e., UE $_N$ ) is always on, and the LTE transceiver module on/off is controlled by two proposed timers, $T_L$ and $T_R$ , to reduce unnecessary power consumption. In the AWU scheme, the LTE transceiver module can be turned on through NB-IoT module to lower the call dropping probability. We propose the analytical models and conduct simulation experiments to study the performances of MSM in terms of the power saving ratio ( $R_S$ ) and the call dropping probability ( $P_B$ ).