Block Error Rate Analysis of Short-Packet NOMA Communications with Imperfect SIC

In this paper, we study the cellular internet of things (IoT) with multi-user short-packet communications. To achieve low-latency as well as a high spectral efficiency, non-orthogonal multiple access (NOMA) technique is adopted. Considering the practical scenario with imperfect successive interference cancellation, this paper provides a detailed analysis of the average block error rate (BLER) of NOMA systems. Exact approximated expressions are derived for the BLER of an arbitrary user. In addition, to gain further insights, simplified BLER expressions of the worst and best users are obtained in the high signal to noise ratio regime. It was shown that the best user can achieve full diversity order while the worst user can only achieve unit diversity order. Extensive simulation results are provided to validate the analytical results.