  Rate-Splitting Multiple Access (RSMA) is an emerging flexible, robust and
powerful multiple access scheme for downlink multi-antenna wireless networks.
RSMA relies on multi-antenna Rate-Splitting (RS) strategies at the transmitter
and Successive Interference Cancellation (SIC) at the receivers, and has the
unique ability to partially decode interference and partially treat
interference as noise so as to softly bridge the two extremes of fully decoding
interference (as in Non-Orthogonal Multiple Access, NOMA) and treating
interference as noise (as in Space Division Multiple Access, SDMA or Multi-User
Multiple-Input Multiple-Output, MU-MIMO). RSMA has been shown to provide
significant room for spectral efficiency, energy efficiency, Quality-of-Service
enhancements, robustness to Channel State Information (CSI) imperfections, as
well as feedback overhead and complexity reduction, in a wide range of network
loads (underloaded and overloaded regimes) and user deployments (with a
diversity of channel directions, channel strengths and qualities). RSMA is also
deeply rooted and motivated by recent advances in understanding the fundamental
limits of multi-antenna networks with imperfect CSI at the Transmitter (CSIT).
In this work, we leverage recent results on the optimization of RSMA and design
for the first time its physical layer, accounting for modulation, coding (using
polar codes), message split, adaptive modulation and coding, and SIC receiver.
Link-level evaluations confirm the significant throughput benefits of RSMA over
various baselines as SDMA and NOMA.
