Adaptive Transmit Antenna Selection Based on PCA for Millimeter Wave LOS MIMO Channel

Uniform rectangular antenna array (URA) is a commonly used antenna array in multiple-input multiple-output (MIMO) system. However, the existing works rarely concentrate on URA in millimeter-wave (mmWave) line-of-sight (LOS) MIMO channels. In this paper, we conduct research on the point-to-point mmWave LOS MIMO channel based on URA. We derive the optimal antenna deployment for URA to obtain the maximum multiplexing gain in mmWave LOS MIMO channel. For the URA with fixed parameters, as the distance between transmitter and receiver increases, some singular values of the channel matrix tend to be 0. In this case, it is not necessary to use all of the transmit antennas. Therefore, according to the two kinds of channel-state information feedback schemes, we propose two adaptive transmit antenna selection (ATAS) schemes based on the principal component analysis for this mmWave LOS MIMO channel. The computational complexity for the proposed algorithm is also derived. Numerical results show that the channel capacity of this proposed ATAS system can approach or even surpass that of the full transmit antenna system with equal power allocation in mmWave LOS MIMO channel. Compared with transmit antenna selection based on greedy search and exhaustive search algorithm, when the distance is longer, the proposed algorithm can achieve the near-optimal performance with much lower computational complexity.