Wideband Communications Aided by Movable Antenna

In this paper, we investigate the movable antenna (MA)-aided wideband communications employing orthogonal frequency division multiplexing (OFDM) transmissions. Under the general multi-tap field-response channel model, the wireless chan-nel variations in both space and frequency are characterized with different positions of the MAs at the transmitter (Tx) and receiver (Rx) sides. We reveal that the MA positioning can balance between the amplitude and phase over different channel taps. Then, an upper bound on the OFDM achievable rate is derived in closed form when the size of the TxlRx region for antenna movement can be arbitrarily large. Furthermore, we develop a parallel greedy ascent (PGA) algorithm to obtain locally optimal solutions to the MAs' positions for OFDM rate maximization subject to finite-size TxlRx regions. Simulation results demonstrate that the proposed algorithm closely approaches the OFDM rate upper bound with the increase of TxlRx region sizes and outperforms the conventional system with fixed-position antennas (FPAs).