Dynamic access class barring for M2M communications in LTE networks

When incorporating machine-to-machine (M2M) communications into Long Term Evolution (LTE) networks, one of the challenges is the traffic overload due to a large number of machine type communications (MTC) devices with bursty traffic. One approach to tackle this problem is to use the access class barring (ACB) mechanism to regulate the opportunity of MTC devices to transmit request packets. In this paper, we first present an analytical model to determine the expected total access delay of all the MTC devices. For the ideal case that the LTE base station (eNodeB) knows the number of backlogged users, we determine the optimal value of the ACB factor, which can best reduce the congestion and access delay. For the practical scenario, we propose a heuristic algorithm to adaptively change the ACB factor without the knowledge of the number of backlogged users. Results show that the proposed heuristic algorithm achieves near optimal performance in reducing access delay.