  Integrated sensing and communication (ISAC) capability is envisioned as one
key feature for future cellular networks. Classical half-duplex (HD) radar
sensing is conducted in a "first-emit-then-listen" manner. One challenge to
realize HD ISAC lies in the discrepancy of the two systems' time scheduling for
transmitting and receiving. This difficulty can be overcome by full-duplex (FD)
transceivers. Besides, ISAC generally has to comprise its communication rate
due to realizing sensing functionality. This loss can be compensated by the
emerging reconfigurable intelligent surface (RIS) technology. This paper
considers the joint design of beamforming, power allocation and signal
processing in a FD uplink communication system aided by RIS, which is a highly
nonconvex problem. To resolve this challenge, via leveraging the
cutting-the-edge majorization-minimization (MM) and penalty-dual-decomposition
(PDD) methods, we develop an iterative solution that optimizes all variables
via using convex optimization techniques. Besides, by wisely exploiting
alternative direction method of multipliers (ADMM) and optimality analysis, we
further develop a low complexity solution that updates all variables
analytically and runs highly efficiently. Numerical results are provided to
verify the effectiveness and efficiency of our proposed algorithms and
demonstrate the significant performance boosting by employing RIS in the FD
ISAC system.
