Abstract
This paper proposes an intelligent reflecting surface
(IRS) assisted integrated sensing and communication (ISAC)
system operating in the millimeter-wave band. Specifically, the
ISAC system consists of a radar subsystem and a communication
subsystem to detect multiple targets and communicate with the
users simultaneously. The IRS is used to configure the radio
propagation environment by changing the phase of the radio
signal to enhance the communication transmission rate. In the
proposed scheme, we first derive a closed-form solution for the
radar signal covariance matrix to generate a radar beampattern
in the angle of interest. Then, we jointly optimize the beamforming vector of the communication subsystem and the IRS
phase shifts to enhance the communication transmission rate. To
decouple the multiple variables to be optimized, the alternating
optimization and quadratic transformation methods are applied
to determine the communication beamforming vector and the IRS
phase shifts. Specifically, we utilize the majorization minimization
and the complex circle manifold methods to compute the IRS
phase shifts. Simulation results verify the effectiveness of the
proposed algorithm and demonstrate that an IRS can improve
the performance of ISAC systems.