The Internet of things (IoT), which is the network of physical devices embedded with sensors, actuators, and connec- tivity, is being accelerated into the mainstream by the emergence of 5G wireless networking. This paper presents an uncoordinated non-orthogonal random access protocol, an enhancement to the recently introduced Aloha-NOMA protocol, which provides high throughput, while being matched to the low complexity requirements and the sporadic traffic pattern of IoT devices. Under ideal conditions it has been shown that Aloha-NOMA, using power-domain orthogonality, can significantly increase the throughput using SIC (Successive Interference Cancellation) to enable correct reception of multiple simultaneous transmitted signals. For this ideal performance, the enhanced Aloha-NOMA receiver adaptively learns the number of active devices (which is not known a priori) using a form of multi-hypothesis testing. For small numbers of simultaneous transmissions, it is shown that there can be substantial throughput gain of 6.9 dB relative to pure Aloha for 0.25 probability of transmission and up to 3 active transmitters.