A new antenna arrangement design of Massive MIMO in LOS environment for further capacity enhancement

Massive MIMO has two key problems: the low-transmission efficiency caused by channel state information (CSI) feedback overhead and huge computational complexity. Authors have proposed a practical application of Massive MIMO, that is, Massive Antenna System for Wireless Entrance links (MAS-WE), and the performance of the proposed systems have been verified by computer simulations and a propagation experiment. Assuming line of sight (LOS) environment, which provides stable transmission paths, MAS-WE can avoid the two key problems of Massive MIMO. However, the conventional antenna arrangement; e.g. square or circular array degrades the system capacity of MAS-WE due to the mutual coupling of antenna elements or channel spatial correlation; the difficulty is the inter-element spacing of antennas. In this paper, we propose a new antenna arrangement that reduces channel spatial correlation directly without additional mutual coupling. Simulation results show that the proposed arrangement can reduce channel spatial correlation at CDF=50% value by 80% compared to the circular array and 75% compared to the square array.