Impact of terminal multi-antenna spacing on spatial variation of performance in distributed antenna systems

This paper investigates the impact of multi-antenna spacing at each terminal on the performance of the distributed antenna system in outdoor environments in higher frequency bands (above 6 GHz), where the line-of-sight propagation plays the most important role. We choose the channel matrix condition number as the evaluation criterion of performance and focus on it in simulations and practical tests. The simulation results show that the larger the antenna spacing (normalized to the carrier wavelength) is, the more drastically the channel condition number varies with the terminal moving. It is also found that a small channel condition number can be obtained even when multiple antennas of a terminal are located very close to each other. In addition, outdoor experimental results are provided to support our analysis. These contribute to the design of terminals´ multi-antenna.