This paper proposes a new propagation model to accurately predict outdoor-to-indoor propagation loss. Account is taken of the structural openings along the paths; it is assumed that outdoor-to-indoor paths are possible only through wall openings such as doors and windows. Introducing the angle dependency of the losses with the paths that penetrate the indoor area makes it possible to accurately predict outdoor-to-indoor propagation loss. Measurements in a microcellular environment show that the proposed model can predict outdoor-to-indoor propagation loss more accurately than the COST231 model.

Investigates the effects of antenna radiation patterns at the base station or the remote terminal on the multipath propagation characteristics for the design of millimeter-wave indoor communication systems. These effects were investigated by indoor multipath propagation and BPSK transmission measurements at 60 GHz conducted in a modern office room. Multipath channel characteristics were estimated from impulse responses measured for three types of base-station antennas and for two types of directive terminal antennas with different beam widths. The effects of multipath propagation characteristics on high-speed digital transmission channels were also investigated for almost simultaneously measured bit-error performances at transmission rates of 64, 128, and 256 Mbps. From the results of measurements, the use of directive antennas at the remote terminal and also the use of base station antennas with appropriate radiation patterns were found to be effective for reducing the effect of multipath. It is also found that the reduction of multipath is achieved by the use of circular polarization instead of linear polarization. We also examined the effectiveness of several propagation parameters obtained from multipath propagation measurements for the estimation of the indoor digital transmission characteristics such as bit-error performance.

In millimeter-wave indoor communications systems, the radiation patterns and polarizations of the antennas at base stations and remote terminals have a significant influence on channel characteristics. The work reported in this paper investigated the effects of the radiation patterns of the antennas at remote terminals on multipath propagation characteristics. These effects were investigated by indoor propagation measurements at 60 GHz conducted in a modern office room and by ray-tracing simulations based on geometrical optics. Multipath channel characteristics are compared in terms of impulse responses and their root-mean-square (rms) delay spreads for an omnidirectional antenna and for three directive antennas with different beam widths. From the results of measurements and ray-tracing simulations, the use of a directive antenna at the remote terminal is demonstrated to be an effective method of reducing the effects of multipath propagation. Further reduction in the multipath effects is found to be achieved by the use of circular polarization instead of linear polarization with the directive antennas.