  In a cellular Internet of Things, burst transmissions from millions of
machine type communications (MTC) devices can result in channel congestion. The
main bottleneck in such scenario is inefficient random access channel (RACH)
mechanism that is used to attach MTC devices to a base station (BS). To address
this issue of congestion in RACH mechanism, 3GPP has proposed an extended
access barring (3GPP-EAB) mechanism. However, several works indicate that the
performance of the 3GPP-EAB mechanism can be further improved. In this work, a
successive interference cancellation (SIC) based RACH mechanism is considered
to significantly increase the success rate and reduce congestion. In the
proposed mechanism, the devices are allowed to transmit repeatedly for a finite
number of times in a given cycle, and thereafter, the success rate is improved
by applying back-and-forth SIC at the BS. A novel probabilistic approach of the
proposed mechanism is presented with all transition and steady-state
probabilities. Further, the probability of SIC for a given slot is derived.
Through extensive numerical results, it is shown that the proposed mechanism
significantly outperforms the existing ones in terms of the success rate.
Moreover, to obtain the maximum success rate, the optimum number of devices to
be entered in a cycle is also calculated.
