Two-stage radio access for group-based machine type communication in LTE-A

In Long Term Evolution-Advanced (LTE-A) network, Machine Type Communication (MTC) provides random access-based communication for automation applications. In MTC, one of the most critical issues is the emergence of large number of MTC devices which may send requests to the base station at the same time, such that severe collision occurs. When collision occurs, the message delay accumulates, and the data delivery fails. In this paper, we propose a two-stage radio access scheme to alleviate collision for MTC. MTC devices are divided into several groups, where random access in each group (as the first stage) is controlled by a device called MTC gateway. Collision of random access to the base station (as the second stage) is then effectively alleviated. To observe the effect of numbers and sizes of groups, we propose analytical model and simulation model to investigate the performance in terms of utilization of random access slots, access success probability and average message delay. Simulation results show that, by sacrificing a little message delay, the proposed scheme significantly improves access success probability.