Predictions of uplink space-diversity gain in the cellular and personal communications systems (PCS) bands (near 850 MHz and 1.9 GHz, respectively), suffer from incomplete modeling of multipath angular spread /spl sigma/. Using previously published measurements to reduce the gap, we show that /spl sigma//spl sim/[distance]/sup -1/2/ and that diversity gains are about 2 dB higher for PCS than for cellular.

Using a soft limiter of the error function type, the authors have applied the time domain Fourier expansion method to analyze intermodulation in multiplexing of CDMA signals. The individual three-tone third-order intermodulation component, normalized with respect to the signal in CDMA, has the same magnitude as that in FDMA except for the reduction by the processing gain. The intermodulation components in FDMA are distributed among all the frequency channels, whereas all the intermodulation components fall on each CDMA channel in a radio carrier band. In practical cases the intermodulation to signal ratio in CDMA is only slightly lower than that in FDMA. However, a CDMA system with digital coding protection and RAKE receiver is expected to need less signal power.

A metropolitan-area radio system that, from a centrally located base station, provides continuously 360 degrees coverage over a large service region is proposed. The base station blankets the service region with a raster of very narrow pencil beams that can be rapidly scanned to any position in synchronism with the switching sequences of a time-division-multiple-access (TDMA) assignment. By deploying multiple scanning spot beams, the allocated spectrum can be reused many times. A centralized network controller, executing an efficient TDMA assignment algorithm, dynamically allocates the resources of a small transceiver pool among the far larger number of beam positions in response to real-time requests for service. By varying the dwell time at each beam position in response to the traffic intensity of the position, highly efficient resource utilization is provided. The high antenna gain of the base station antenna provides adequate arain fade margin to permit operation in the uncongested portion of the ratio spectrum above 20 GHz. The system is particularly well suited to emerging, direct-to-end-user wideband digital service offerings.>

A simple semi-empirical relation is proposed to predict depolarization statistics on earth-space paths from rain-attenuation data for any given polarization and elevation angle, and for frequencies from 10 to 30 GHz. This formula is first justified by theoretical calculations, and then by extensive comparisons to measured data which show good agreement. In contrast to the CCIR approximate formula, the frequency dependence has been revised to be 20 log (f), and predictions of unrealistically large cross-polarization discriminations have been avoided by using a two-tier Ganssian distribution of the raindrop canting angle.

The excitation of extremely low frequency (ELF) waves by a horizontal electric dipole in the earth-ionosphere waveguide can be obtained by a heuristic approach based upon the observation of a relationship between a horizontal electric dipole and a horizontal magnetic dipole. Then multiple imaging takes into account the effect of the ionosphere. This approximate derivation preserves the physical picture which is obscured by complex mathematics in rigorous analysis.