Energy-efficient discovery process for mMTC applications

Reducing energy consumption is fundamental to address the requirements of Massive Machine-Type Communication (mMTC) applications. In this sense, D2D relaying could play an important role in some scenarios. D2D discovery process is a key phase of D2D relaying since in this phase the MTC device (MTD) has to select an optimal relay. This process should ensure low energy consumption and low complexity while taking into account the specific constraints of the MTDs. In this paper, we analyze the total (i.e., during the discovery phase and the data transmission phase) energy consumed by the MTD when it uses a D2D relaying mechanism. We propose a simple distributed discovery protocol, which allows reducing the MTD energy consumption. Our numerical and simulation results confirm that when using the proposed discovery mechanism, the total MTD energy consumption can be significantly reduced depending on the data packet size and the location of the MTD with respect to the base station.