To generalize characteristics of a received signal level distribution from narrow- to wide-bands in a mobile radio channel, a new propagation parameter called equivalent received bandwidth (2ΔfΔLmax) has been proposed. The distributions are discussed mainly with computer simulation results. The simulation results shows the level distribution depends on 2ΔfΔLmax and power ratio a of direct to indirect waves, and the value of 2ΔfΔLmax classifies the radio channel as narrow- or wide-bands transmission. To confirm these simulated results, a field test was performed with a 3.35 GHz radio wave. This paper describes that the field test demonstrated the simulation results. It is concluded that the equation representing received signal level in the computer simulation is valid. And the fading depth depends directly on 2ΔfΔLmax, and the 2ΔfΔLmax is effective for generalizing the received signal level distribution. Furthermore, a method for calculating the power ratio was found to be better for a peak level model.

Theoretical and experimental evaluations of the horizontal rotating and tilting of the base station antenna beam show that these techniques are effective in reducing delay spread. Result show good agreement between predicted and measured values.

This paper introduces recent propagation studies on land mobile in Japan. Land mobile communications in Japan are offering various type of services, such as paging, automobile and portable telephones, and cordless phones. These services are rapidly progressing in both capacity and quality at the present time. First, this paper describes the progress of propagation studies supporting the growth of these services. Land mobile radio communications in Japan are now moving in the direction of high capacity, portability and digitalization. In accordance with the progress, this paper describes propagation studies on () high capacity, including radio wave trapping by beam tilting and low height base station antenna, anti-cochannel interference receiving techniques by diversity, and improved prediction accuracy by environmental structure correction factor, () portability, including measurements and prediction results of propagation loss in indoor and outdoor, () digitalization, including multipath delay characteristics in urban and suburban areas, and propagation model to estimate the delay spread. Secondarily, this paper describes propagation study subjects and future propagation approaches to support the expected remarkable expansion of land mobile communications. Propagation studies on land mobile satellite communications systems are also touched upon.

In a multiple-user MIMO system in which numerous users simultaneously communicate in a cell, the channel matrix properties depend on the parameters of the individual users in such a way that they can be modeled as points randomly moving within the cell. Although these properties can be simulated by computer, they need to be expressed analytically to develop MIMO systems with diversity. Given a small area with an equivalent multi-path, we assume that a user u is at a certain “user point” $P^u(lambda _p^u,xi _p^u)$ in a cell, or (radius $lambda _p^u$ from origin, angle $xi _p^u)$ and that the user moves with movement $M^u(f_{max}^u, xi_v^u)$ around that point, or (Doppler frequency $f_{max}^u$, direction $xi_v^u$). The MU-MIMO channel model consists of a multipath environment, user parameters, and antenna configuration. A general formula of the correlation $ ho_{i - j,i' - j'}^{u - u'} (bm)$ between the channel matrix elements of users u and u' and one for given multipath conditions are derived. As a feature of the MU-MIMO channel, the movement factor $F^{u - u'}(gamma^u,xi_n ,xi_v^u)$, which means a fall coefficient of the spatial correlation calculated from only the user points of u and u', is also derived. As the difference in speed or direction between u and u' increases, $F^{u - u'}(gamma^u,xi_n ,xi_v^u)$ becomes smaller. Consequently, even if the path is LOS, $ ho_{i - j,i' - j'}^{u - u'} (bm)$ becomes low enough owing to the movement factor, even though the correlation in the single-user MIMO channel is high. If the parameters of u and u' are the same, the factor equals 1, and the channels correspond to the users' own channels and work like SU-MIMO channel. These analytical findings are verified by computer simulation.