A Survey on Fairness Optimization Techniques in RSMA Networks

Rate-Splitting Multiple Access (RSMA) is an important technology for next-generation networks, especially after 5G, due to its ability to handle imperfect channel state information (CSI). Unlike conventional orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA), RSMA provides greater flexibility by controlling power allocation between common and private data streams, leading to better performance in diverse wireless networks. The robustness of RSMA is particularly useful in challenging environments such as non-terrestrial networks where perfect CSI is difficult to achieve due to rapid channel changes. In such scenarios, RSMA effectively manages interference and maintains stable communication by splitting each user's data into common and private messages, encoding and transmitting them over multiple antennas. This allows each user to reliably decode the intended data even with imperfect CSI. In this paper, we present techniques that optimize user fairness in RSMA environments.