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Dense Multipath Component Characteristics in 11-GHz-Band Indoor Environments

In the next-generation mobile communication system, the higher frequency bands from C-band to V-band are expected to be utilized because it has the potential to improve network capacity drastically by the available wideband spectrum. Since the characteristics of reflected and scattered radio waves from surrounding environments in those bands are thought to be quite different than at lower frequencies, the clarification of its influence on the multiple-input multiple-output (MIMO) transmission performance is a critical issue. In this paper, we focused on the characteristics of diffuse scattering in X-band, and conducted the MIMO channel measurements in indoor environments in the 11-GHz band. The frequency, angular, and polarization domain dense multipath component (DMC) propagation parameters were jointly estimated by using the RiMAX-based estimator. The measurement result showed the existence of significant DMC, which is thought to have originated from the floor, the ceiling as well as the walls. The angular spreads of the DMC tended to increase, and their decay factor tended to decrease as the room size decreased. It is also shown that the existence of DMC significantly affected the eigenvalue structure of the MIMO channel, which defines the MIMO transmission performance. The result is expected to be utilized for novel MIMO channel modeling in X-band that includes the DMC contribution.