  We propose an enhanced random access (RA) with preamble-assisted short-packet
transmissions to support cellular Internet-of-things (IoT) communications. A
key feature of the proposed scheme is that the base station (e.g., eNodeB in
LTE networks) utilizes the RA preambles as uplink reference signals to estimate
uplink channel state information of IoT devices, which subsequently provides
additional opportunities to transmit short-packets during the RA procedure
without extra signaling (e.g., connection and scheduling requests). Through
simulations, we evaluate the performance of the proposed scheme in terms of a
channel estimation mean squared error, a bit error rate, a preamble collision
probability, and a success probability of short-packet transmissions. The
results show that the proposed scheme can support reliable and low-latency
featured short-packet transmissions during the RA procedure by efficiently
incorporating both multiple antenna and detection techniques.
