  In this paper, we aim to improve the connectivity, scalability, and energy
efficiency of machine-type communication (MTC) networks with different types of
MTC devices (MTCDs), namely Type-I and Type-II MTCDs, which have different
communication purposes. To this end, we propose two transmission schemes called
connectivity-oriented machine-type communication (CoM) and quality-oriented
machine-type communication (QoM), which take into account the stochastic
geometry-based deployment and the random active/inactive status of MTCDs.
Specifically, in the proposed schemes, the active Type-I MTCDs operate using a
novel Bernoulli random process-based simultaneous wireless information and
power transfer (SWIPT) architecture. Next, utilizing multi-user power-domain
non-orthogonal multiple access (PD-NOMA), each active Type-I MTCD can
simultaneously communicate with another Type-I MTCD and a scalable number of
Type-II MTCDs. In the performance analysis of the proposed schemes, we prove
that the true distribution of the received power at a Type-II MTCD in the QoM
scheme can be approximated by the Singh-Maddala distribution. Exploiting this
unique statistical finding, we derive approximate closed-form expressions for
the outage probability (OP) and sum-throughput of massive MTC (mMTC) networks.
Through numerical results, we show that the proposed schemes provide a
considerable sum-throughput gain over conventional mMTC networks.
