  Full-duplex (FD) transmission has already been regarded and developed as a
promising method to improve the utilization efficiency of the limited spectrum
resource, as transmitting and receiving are allowed to simultaneously occur on
the same frequency band. Nowadays, benefiting from the recent development of
intelligent reflecting surface (IRS), some unique electromagnetic (EM)
functionalities, like wavefront shaping, focusing, anomalous reflection,
absorption, frequency shifting, and nonreciprocity can be realized by
soft-controlled elements at the IRS, showing the capability of reconfiguring
the wireless propagation environment with no hardware cost and nearly zero
energy consumption. To jointly exploit the virtues of both FD transmission and
IRS, in this article we first introduce several EM functionalities of IRS that
are profitable for FD transmission; then, some designs of FD-enabled IRS
systems are proposed and discussed, followed by numerical results to
demonstrate the obtained benefits. Finally, the challenges and open problems of
realizing FD-enabled IRS systems are outlined and elaborated upon.
