Abstract: A system and method for Machine-to-Machine (M2M) communication over a transmission medium, including a novel random access protocol that is easy to implement, energy efficient, scalable and compatible with the limited-power and low complexity requirements of IoT devices. The proposed protocol utilizes a form of multiple hypothesis testing at the IoT gateway to determine the number of active IoT devices operating in the transmission medium to optimize the power levels of a Successive Interference Cancellation (SIC) receiver in order to distinguish between signals transmitted from different IoT devices on the same time and frequency. The use of beamforming exploits the power and spatial domains without excessively increasing the SIC power levels and address channel access delay problems by reducing the probability of collision and consequently lowering the average back-off delay.