  In this paper, we study compressive random access (CRA) with two stages for
machine-type communication (MTC) in cellular Internet-of-Things (IoT). In
particular, we consider the case that each user (IoT device or sensor) has only
one short message (of the same length) when it is activated to send data in IoT
applications. Two different CRA-based random access schemes are discussed (one
is conventional and the other is new based on a simplified handshaking
process). Based on the throughput analysis, we show that the CRA-based random
access scheme with simplified handshaking process can outperform as its length
of payload is adaptively decided depending on the number of active users.
Simulation results confirm that the derived throughput expressions agree with
them and can be used to design a random access system for MTC with each active
device or sensor that has one short message.
