Enhanced Extended Access Barring Mechanism for Massive Machine-Type Communications in 5G Context

The random-access procedure used to support Machine to Machine (M2M) or Machine-Type Communications (MTC), does not provide efficient support for high user loads. This is due to the Slotted ALOHA used as an access protocol for the transmission of preambles and the use of random back-offs in case of Random Access Channel (RACH) failure. With the expected explosion of the number of devices in the coming years, the need for an efficient design to manage the access to the network becomes an urgent key issue especially with the reduced number of preambles available to perform the RACH procedure. To this end, the Third Generation Partnership Project (3GPP) proposed the Extended Access Barring (EAB) mechanism as a solution to control overload for MTC devices. In this paper, we propose an enhancement of the 3GPP EAB mechanism by expanding the contention space statically and dynamically with the aim to reduce collisions and to increase the success probability and therefore to fulfill constraints in terms of delay and energy consumption. An analytical approach along with simulations are provided in this paper to show the impact of this contention space expansion on the performance of the existing 3GPP EAB mechanism.