Overload control of massive random access for machine-type communications.

•We show that random access retransmissions can lead to performance degradation.•A Markov model is proposed to evaluate the performance of LTE random access.•There is an optimal number of retransmissions for massive random access.•Random access resources are separated into two subsets for MTC overload control.•Conventional and proposed schemes can be used adaptively depending on traffic load.