An annulus-based access class barring scheme for stationary machine-type communications devices

The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) cellular network is a promising system for machine-type communications (MTC). However, random access overload becomes a severe issue with the emerging massive number of MTC devices (MTCDs) in LTE network. To solve the problem, access class barring (ACB) and timing advance (TA) command comparison are two effective schemes by limiting the number of random access requests. In this paper, we propose an annulus-based ACB (AB-ACB) scheme and combine it with TA command comparison in stationary MTCDs scenario. Aiming to exploit the devices distribution potential in stationary scenario, AB-ACB divides cell coverage into some annuluses with equal width and adjusts ACB parameters based on the distribution of MTCDs in these annuluses. In the combined scheme, the optimal number of annuluses and ACB parameters are adaptively configured according to LTE cell deployment, so as to maximize the expected number of MTCDs served in a random access slot (RAS). Simulation results show that, comparing to the scheme jointly using ordinary ACB and TA command comparison, our proposed combined scheme outperforms in random access efficiency.