Near-Field Line-of-Sight Communication with Massive Movable Antennas

The proliferation of the sixth generation (6G) networks demands innovative antenna technologies to fully unlock spatial degrees of freedom. Large-scale position-reconfigurable antenna (PRA) arrays have emerged as a promising solution, while existing antenna position design approaches often suffer from high computational complexity and neglect the near-field effect. In this paper, we propose efficient methods to determine the antenna positions for near-field line-of-sight communication. Specifically, by transforming the antenna positions into the angular domain, we reformulate the achievable rate maximization problem as a Vandermonde matrix determinant maximization problem, which is known as a weighted Fekete problem, whose optimal solution can be obtained by off-the-shelf solvers. To further reduce the computational complexity, we propose a greedy algorithm to find the asymptotically optimal antenna positions accommodating practical physical constraints. Simulation results demonstrate that the proposed scheme yields a considerable achievable rate gain compared to the conventional uniform linear array scheme in the near-field region with up to 35× reduction in design complexity.