Unsourced Multiple Access for Heterogeneous Traffic Requirements

We investigate the coexistence of critical and massive Internet of Things (IoT) services in the context of the unsourced multiple access (UMA) framework, introduced by Polyanskiy (2017). We consider the standard UMA setup in which all users employ a common codebook and the receiver returns an unordered list of codewords. To model the critical IoT service, we assume that the users can also communicate a common alarm message. We further assume that the number of active users in each transmission attempt is random and unknown. We derive a random-coding bound for the Gaussian multiple access channel and demonstrate that orthogonal network slicing enables the two traffic types to coexist with high energy efficiency.