Movable antenna (MA) is an emerging technology that utilizes localized antenna movement to pursue better channel conditions for enhancing communication performance. In this paper, we study the MA-enhanced multicast transmission from a base station equipped with multiple MAs to multiple groups of single-MA users. Our goal is to maximize the minimum weighted signal-to-interference-plus-noise ratio (SINR) among all the users by jointly optimizing the position of each transmit/receive MA and the transmit beamforming. To tackle this challenging problem, we first consider the single-group scenario and propose an efficient algorithm based on the techniques of alternating optimization and successive convex approximation. Particularly, when optimizing transmit or receive MA positions, we construct a concave lower bound for the signal-to-noise ratio (SNR) of each user by applying only the second-order Taylor expansion, which is more effective than existing works utilizing two-step approximations. The proposed design is then extended to the general multi-group scenario. Simulation results demonstrate that significant performance gains in terms of achievable max-min SNR/SINR can be obtained by our proposed algorithm over benchmark schemes. Additionally, the proposed algorithm can notably reduce the required amount of transmit power or antennas for achieving a target level of max-min SNR/SINR performance compared to benchmark schemes.
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