Wireless cellular networks feature two emerging technological trends. The
first is the direct Device-to-Device (D2D) communications, which enables direct
links between the wireless devices that reutilize the cellular spectrum and
radio interface. The second is that of Machine-Type Communications (MTC), where
the objective is to attach a large number of low-rate low-power devices, termed
Machine-Type Devices (MTDs) to the cellular network. MTDs pose new challenges
to the cellular network, one if which is that the low transmission power can
lead to outage problems for the cell-edge devices. Another issue imminent to
MTC is the \emph{massive access} that can lead to overload of the radio
interface. In this paper we explore the opportunity opened by D2D links for
supporting MTDs, since it can be desirable to carry the MTC traffic not through
direct links to a Base Station, but through a nearby relay. MTC is modeled as a
fixed-rate traffic with an outage requirement. We propose two network-assisted
D2D schemes that enable the cooperation between MTDs and standard cellular
devices, thereby meeting the MTC outage requirements while maximizing the rate
of the broadband services for the other devices. The proposed schemes apply the
principles Opportunistic Interference Cancellation and the Cognitive Radio's
underlaying. We show through analysis and numerical results the gains of the
proposed schemes.

本文论述了利用设备到设备通信解决无线蜂窝网络中大量低速、低功率设备接入和偏远设备断开的问题，并提出了两种网络协助的设备到设备方案，以实现低速、低功率设备的联网并提高宽带服务的速度。