This work considers an analytical approach to
evaluate the outage behavior of the device-to-device (D2D)
communication, that is underlaid with cellular networks, as an
enabling technology for Internet-of-Things (IoTs). In such an
architecture, a group of IoT devices (IoTDs) communicate with
an IoT gateway (GW) by reusing the resources of cellular users
(CUEs) to enhance the spectral efficiency of the fifth-generation
(5G) networks. Two interference management schemes are widely
used in the literature for the sharing of D2D spectrum, namely
the fixed-power margin (FPM) and the cooperative pairing
(CooP) schemes. We investigate and compare the performance
of the two schemes from the perspective of outage probability
(OP). While satisfying the minimal performance of the system,
the OP of an arbitrary pair (i.e., one IoTD and one CUE)
under both the interference management schemes are derived
in closed form in terms of hyper-geometric functions via the
Mellin transform technique. Moreover, for the CooP scheme,
an iterative alternating Dinkelbach (IAD) algorithm is proposed
as an outage-optimal power allocation scheme. Analytical and
simulation results reveal that the CooP scheme is the outage-
optimum for the high SNR regime while the FPM scheme is
the optimal one for the low SNR regime. Simulation results also
show that the suitable power margin of the FPM scheme lies in
between 2 and 3 dB. Under these two interference management
schemes, the accuracy of the analytical results is verified through
numerical simulation and it turns out that they are well matched.