Dependency of MIMO Channel Capacity on XPR Around Mobile Terminals for Multi-Band Multi-Antenna

In this paper, we investigate the influence of the cross polarization ratio (XPR) of the waves arriving at a mobile terminal on the Multi-Input Multi-Output (MIMO) channel capacity in multi-band and multi-antenna configurations. We assume that the propagation environment around a mobile terminal will be extremely diverse in future mobile communication systems. This is because it is desirable to support flexibly indoor areas as well as outdoor areas using the same air interface, and diverse antenna configurations will be employed for the base station such as space diversity configurations and polarization diversity configurations. This paper is aimed at evaluating the channel capacity for multi- frequency bands under the conditions of free space and in the data mode. We employ an actual handheld device as a mobile terminal and we mount onto the handheld device unique antennas for MIMO transmission designed for multi-band operation. Furthermore, we quantitatively analyze the dependency of channel capacities on the XPR using detailed parameters including the mean effective gain (MEG), the correlation coefficient between antennas, and the eigenvalue of the correlation matrix based on the measured radiation patterns. As a result, we show that a low absolute XPR of the arriving waves increases the channel capacity for all frequency bands due to the dual-polarized properties of the antennas mounted on the handheld device.