Uplink Coverage of Machine-Type Communications in Ultra-Dense Networks

Extended coverage is an essential requirement of the successful deployment of Machine-Type Communication (MTC) in harsh scenarios. This would require the MTC nodes to transmit their measurement reports with a high transmit power. At the same time, it is desirable to minimize the transmit power of the MTC nodes for the sake of a longer battery lifetime. These contradicting targets make the uplink coverage one of the main limiting factors to the fruition of MTC applications. In this paper, we analyze the uplink coverage of MTC considering the distinguishing features of a dense network including the high density of cells and the short distances between the cells and the MTC nodes. We model the path loss as a stretched exponential path-loss (SEPL) to capture the short link distances. In addition, a truncated channel inversion power control is considered to satisfy the strict requirements on the power consumption of MTC nodes. The accurate and tractable results unveiled the impact of the system parameters on the network performance. Particularly, the uplink coverage significantly improved at moderate cell density, reasonable bandwidth, and low transmission power. Interestingly, our results reveal that the maximum transmit power has no impact on the uplink coverage in the considered scenario. Fortunately, this allows for a longer lifetime for the battery-powered devices of future IoT applications.