Commission F: Wave Propagation and Remote Sensing

A fixed wireless access (FWA) system enables to provide a broadband wireless access service with a user bit-rate of more than 10Mbps. Propagation studies have been carried out to clarify the multipath characteristics in several environments and frequency bands for developing that system. A 5-GHz band is expected to be available for wireless access systems and a residential area is an important service area. A new delay profile model for estimating multipath characteristics in a residential area was proposed [Kita, et al., 2001a]. It enables to calculate the delay spread considering three different wave components; the front, the primary scattering, and the secondary scattering wave components. Experimental studies using 2GHz/5GHz-dual band antenna show new propagation models for path loss and height gain in residential area [Kita et al., 2000; Kita et al., 2001b; Kita et al., 2001c]. These studies make possible to evaluate the influence of the multipath interference in a region of antenna height from a few meters to around 10m. Urban street area is also a service area for high-speed wireless access services with over 10Mbps-transmission speed. Delay spread measurements in such areas were carried out at 5-GHz band and a relation between median value and the 90% value of the cumulative probability of the delay spread is formulated [Kita, et al., 1999]. In addition to UHF and SHF, quasi-millimeter band has been available for a point-to-multipoint wireless access system. In an urban area, reflected and scattered waves from buildings cause a multipath interference. A study of delay characteristics in such an environment reports the dependency of the delay profile on the height of the base station antenna [Izuka, et al., 2001]. For calculating the delay profile, the propagation path visibility is used for taking account of building parameters. The foliage attenuation affects radio transmission characteristics as a degradation factor in a high frequency region such as above quasi-millimeter band. Experimental studies of the foliage attenuation show some compared results between 5GHz and 29GHz [Kajiwara 2000]. It is also shown that swaying foliage in wind causes a significant fading at 29GHz, ranging over 10dB, while the fading depth at 5GHz is approximately 2dB. The rain attenuation still has been an important parameter for a design of wireless systems and its prediction method has been improved for higher accuracy. For extending a local estimation method to a worldwide use, a new prediction method, which considers the thunderstorm ratio, is …