  In this article, we propose a space spreading-assisted framework that
leverages either time or frequency diversity or both to reduce interference and
signal loss owing to channel impairments and facilitate the efficient operation
of large-scale dense Internet-of-Things (IoT). Our approach employs dispersion
of data-streams transmitted from individual IoT devices over indexed space-time
(ST), space-frequency (SF) or space-time-frequency (STF) blocks. As a result,
no two devices transmit on the same block; only one is activated while the rest
of the devices in the network is silent, thereby minimizing possibility of
interference on the transmit side. On the receive side, multiple-antenna array
ameliorates performance in presence of channel impairments while exploiting
array-processing gain. As interference due to superposition of multiple
data-streams is killed at its root, no extra energy is wasted in fighting
interference and other impairments, thereby enabling energy-efficient
transmission from multiple devices over multiple access channel (MAC). To
validate the proposed concept, we simulate the performance of the framework
against dense IoT networks deployed in generalized indoor and outdoor scenarios
in terms of probability of signal outage. Results demonstrate that our
conceptualized framework benefits from interference-free transmission as well
as enhancement in overall system performance.
