  This article investigates the exploitation of semantic communications in
multi-user networks. We propose a novel heterogeneous semantic and bit
multi-user framework for providing flawless, customized, and intelligent
information transmission. We discuss both orthogonal multiple access (OMA) and
non-orthogonal multiple access (NOMA) for the proposed heterogeneous framework,
with an emphasis on investigating the attractive interplay between semantic
communications and NOMA, namely NOMA enabled semantic communications and
semantic communications enhanced NOMA. 1) For NOMA enabled semantic
communications, we propose a semi-NOMA scheme for efficiently facilitating the
heterogeneous semantic and bit multi-user communication, which unifies
conventional NOMA and OMA schemes. The fundamental performance limit, namely
semantic-versus-bit rate region, is characterized, which shows the superiority
of the proposed semi-NOMA. 2) For semantic communications enhanced NOMA, we
propose an opportunistic semantic and bit communication approach to alleviate
the early-late rate disparity issue in NOMA. Numerical case studies demonstrate
that significant performance gain can be achieved for NOMA by employing
semantic communications than bit communications. Finally, several open research
directions are highlighted.
