  Multi-group multicast (MGM) is an increasingly important form of multi-user
wireless communications with several potential applications, such as video
streaming, federated learning, safety-critical vehicular communications, etc.
Rate-Splitting Multiple Access (RSMA) is a powerful interference management
technique that can, in principle, achieve higher data rates and greater
fairness for all types of multi-user wireless communications, including MGM.
This paper presents the first-ever experimental evaluation of RSMA-based MGM,
as well as the first-ever three-way comparison of RSMA-based, Space Divison
Multiple Access (SDMA)-based and Non-Orthogonal Multiple Access (NOMA)-based
MGM. Using a measurement setup involving a two-antenna transmitter and two
groups of two single-antenna users per group, we consider the problem of
realizing throughput (max-min) fairness across groups for each of three
multiple access schemes, over nine experimental cases in a line-of-sight
environment capturing varying levels of pathloss difference and channel
correlation across the groups. Over these cases, we observe that RSMA-based MGM
achieves fairness at a higher throughput for each group than SDMA- and
NOMA-based MGM. These findings validate RSMA-based MGM's promised gains from
the theoretical literature.
