  In this paper, we investigate a movable antenna (MA)-aided integrated sensing
and communication (ISAC) system, where a reconfigurable intelligent surface
(RIS) is employed to enhance wireless communication and sensing performance in
dead zones. Specifically, this paper aims to maximize the minimum beampattern
gain at the RIS by jointly optimizing beamforming matrix at the base station
(BS), the reflecting coefficients at the RIS and the positions of the MAs,
subject to signal-to-interference-plus-noise ratio (SINR) constraint for the
users and maximum transmit power at the BS. To tackle this non-convex
optimization problem, we propose an alternating optimization (AO) algorithm and
employ semidefinite relaxation (SDR), sequential rank-one constraint relaxation
(SRCR) and successive convex approximation (SCA) techniques. Numerical results
indicate that the MA and RIS-aided ISAC system outperforms conventional fixed
position antenna (FPA) and RIS-aided systems. In addition, the application of
MAs can reduce the similarity of user channels and enhance channel gain in the
ISAC system.
