  This paper reviews the multiple access techniques for machine-to-machine
(M2M) communications in future wireless cellular networks. M2M communications
aims at providing te communication infrastructure for the emerging Internet of
Things (IoT), which will revolutionize the way we interact with our surrounding
physical environment. We provide an overview of the multiple access strategies
and explain their limitations when used for M2M communications. We show the
throughput efficiency of different multiple access techniques when used in
coordinated and uncoordinated scenarios. Non-orthogonal multiple access is also
shown to support a larger number of devices compared to orthogonal multiple
access techniques, especially in uncoordinated scenarios. We also detail the
issues and challenges of different multiple access techniques to be used for
M2M applications in cellular networks.
