Underlay of low-rate machine-type D2D links on downlink cellular links

Wireless cellular networks feature two emerging technological trends: direct Device-to-Device (D2D) communications and Machine-Type Communications (MTC). MTC devices (MTDs) pose new challenges to the cellular network, such as low transmission power and massive access that can lead to overload of the radio interface. In this paper we explore the opportunity opened by D2D links for supporting Low-rate Low-power MTDs that are connected to a nearby device, such as an on-body MTD connected to a mobile phone that acts as a relay towards the Base Station (BS). The low-rate requirement for this D2D connection allows underlay operation with Successive Interference Cancellation (SIC) during the cellular downlink transmissions. We consider different ways to use SIC and investigate the trade-off between, on one hand, the achieved rate for the downlink cellular users and, on the other hand, the outage probability for the MTC link. The results show that SIC is an important enabler of low-power underlay D2D transmission for low-rate machine-type traffic; however, it may incur a significant rate penalty for the cellular users when trying to meet the outage requirements of the MTC link.