  Movable antenna (MA) is a promising technology to exploit the spatial
variation of wireless channel for performance enhancement, by dynamically
varying the antenna position within a certain region. However, for
multi-antenna communication systems, moving each antenna independently not only
requires prohibitive complexity to find the optimal antenna positions, but also
incurs sophisticated movement control in practice. To address this issue, this
letter proposes a new MA architecture termed group MA (GMA), enabling the group
movement of all elements collectively in a continuous manner, and
simultaneously achieving flexible array architecture by antenna selection (AS).
In this letter, we focus on the uniform sparse array based GMA, where equally
spaced antenna elements are selected to achieve desired array sparsity. The
array position and sparsity level are jointly optimized to maximize the sum
rate of the multi-user communication system. Numerical results verify the
necessity to optimize the position and sparsity of GMA, and considerable
performance gain is achieved as compared to the conventional fixed-position
antenna (FPA).
