Energy-Constrained NOMA with Packet Diversity for Slotted Aloha Systems

Random access algorithms are fundamental mechanisms for managing multiple uncoordinated transmissions towards a common receiver. For such a scenario, which includes satellite and cellular systems, several Non-Orthogonal Multiple Access (NOMA) techniques and different repetition-based strategies have been separately developed. However, few studies jointly analyze the two solutions and propose combined schemes. Purpose of this paper is to fairly compare the actual performance of the two approaches by imposing suitable energy and complexity constraints. The final aim is to explore the benefits provided by the joint adoption of power and packet diversity in a slotted Aloha scheme implementing interference cancellation, focusing on the impact of the energy levels and of the number of packet replicas.