Joint access class barring and timing advance model for machine-type communications

The existing wireless cellular networks can provide machine-to-machine (M2M) service to machine-type communication (MTC) devices deployed in large coverage areas. However, the current Long Term Evolution (LTE) cellular networks designed for human users may not be able to handle a large number of bursty random access requests from MTC devices. In this paper, we propose to jointly use access class barring (ACB) and timing advance (TA) command to reduce the random access overload. In our proposed scheme, the expected number of MTC devices served in one random access slot is determined by the coverage of the base station, total number of devices to be served, the number of preambles, and ACB parameter. By choosing the optimal ACB parameter, we can maximize the number of MTC devices being served in each random access slot. The total number of random access slots required by an LTE base station to serve all MTC devices can be minimized. Simulation results show that in typical LTE cellular networks, our proposed scheme can reduce at least a half of the total slots required by the base station to serve all MTC devices.