Max-Min Fairness Based on Cooperative-NOMA Clustering for Ultra-Reliable and Low-Latency Communications

In this paper, the performance of a cooperative relaying technique in a non-orthogonal multiple access (NOMA) system, briefly named cooperative NOMA (C-NOMA), is considered in short packet communications with finite blocklength (FBL) codes. We examine the performance of a decode-and-forward (DF) relaying along with selection combining (SC) and maximum ratio combining (MRC) strategies at the receiver. Our goal is user clustering based on C-NOMA to maximize fair throughput in a DL-NOMA scenario. In each cluster, the user with a stronger channel (strong user) acts as a relay for the other one (weak user), and optimal power and blocklength are allocated to achieve max-min throughput.