Capacity Maximization for Movable Antenna Enabled MIMO Communication

In this paper, we propose a new multiple-input multiple-output (MIMO) communication system with movable antennas (MAs) to exploit more degrees of freedom (DoFs) in the spatial domain for enhancing the capacity. Different from conventional MIMO systems with fixed-position antennas (FPAs), the proposed system can flexibly change the positions of MAs, such that the MIMO channel between the transmit and receive antennas is reconfigured for achieving higher capacity. We aim to achieve the maximum capacity of MA-enabled point-to-point MIMO communication systems, by jointly optimizing the positions of the receive MAs and the covariance of the transmit signals. We develop an efficient alternating optimization algorithm to find a locally optimal solution by iteratively optimizing the transmit covariance matrix and the position of each MA with the other variables being fixed. Numerical results show that our proposed scheme substantially improves the MIMO capacity compared to traditional FPA systems.