No abstract

This paper proposes a novel centralized beamforming scheme for Radio-over-Fiber (RoF) systems with fixed wavelength allocation. The proposed scheme offers more wavelength utilization efficiency than the conventional beamforming methods that control wavelength allocation, and can control beam direction without explicit control by the base stations (BSs). Moreover, the scheme makes information about optical fiber length unnecessary, and supports systems that use high radio frequency (RF) signals or long optical fiber. Simulations evaluate and confirm the feasibility of the scheme for a system that uses 60 GHz RF signals, 10 km optical fiber, and 8-element linear array antennas.

No abstract

Massive MIMO is a promising wireless communication technology that realizes large capacity. However, it has the problem that circuit mounting becomes difficult due to the narrow antenna spacing and increased loss and phase deviation of connectors and wiring, especially in the millimeter-wave band. To solve these problems, we propose a novel Massive MIMO device configuration using a stacked Butler matrix and a staircase array antenna. From the simulation results, the radiation patterns are the same between the proposed and conventional antenna at stairs up to about 0.1λ.