Digital Fairness in Satellite IoT Systems Based on NOMA With Nonideal SIC

Achieving digital fairness through nonorthogonal multiple access (NOMA) is a critical challenge in modern 5G/6G wireless systems, particularly for satellite uplinks supporting the Internet of Things (IoT) devices across wide coverage areas. The variation in link budgets across space and time increases the risk of unequal access, allowing only a subset of users to achieve sufficiently high transmission rates. This work examines a coordinated uplink NOMA systems to equalize IoT user rates. It also incorporates the impact of imperfect successive interference cancellation (SIC) to reflect practical scenarios. For single-slot NOMA, the optimal SIC ordering to maximize the minimum user rate is determined. For multislot NOMA, relevant to satellite scenarios, a user rate equalization algorithm is proposed and analyzed numerically, assessing the tradeoff between user rates and receiver complexity. The proposed algorithm addresses multislot scheduling constraints with SIC limitations--a critical aspect of fairness in practical systems--by leveraging temporal dynamics to achieve fair resource allocation.