An Efficient Contention Resolution Scheme for Massive IoT Devices in Random Access to LTE-A Networks

Long-Term Evolution-Advanced (LTE-A) networks have been regarded as having great potential to support the Internet of Things (IoT). However, the high probability of preamble collisions when massive numbers of IoT devices try to access the network within a short period has become a significant problem. In this paper, we propose a new scheme to efficiently handle the initial access contention for massive numbers of IoT devices in LTE-A networks. The proposed scheme divides an entire preamble set into $k$ subgroups; then, contention resolution is performed in each subgroup independently in a parallel and pipelined manner. Simulation results show that our scheme leads to considerable improvement in terms of average access delay and standard deviation of access delays without increasing blocking probability. Moreover, utilization of preamble resources is greatly improved by reducing the number of random access slots, where only a few devices participate in preamble selection.