Faster Together: The Case for the Integration of Critical MTC and HTC

We investigate a future cellular network scenario where many human and machine terminals respectively need broadband connectivity (eMBB— enhanced mobile broadband—service), and low latency and high reliability in data transfer (cMTC— critical machine type communications— service). Following an unconventional approach not yet supported by standards, we propose (a) sharing resources between eMBB and cMTC uplink services and (b) letting machine traffic use eMBB services when and where not otherwise needed by human traffic. We study the system by means of a novel analytical model that characterizes throughput, failure probability and latency distributions for uplink human and machine traffic types. We use simulations to validate our model. In particular, we unveil the impact of redundancy in cMTC transmissions, which makes it possible to serve, in a single cell, a few hundred machine terminals with high reliability (up to “six nines”), with very low latency (tens of ms) and with negligible impact on human terminal traffic. Our results show that our unconventional service architecture is able to self-adjust to traffic conditions and, while in principle it can be enhanced with load-based optimization in the allocation of resources, it could work near-optimally in a traffic-load-oblivious management framework.