Ulf Forssen

Base station polarization diversity reception in macrocellular systems at 1800 MHz

Measurements of the signal envelopes in two-branch base station polarization and space diversity reception have been performed in macrocellular urban and suburban non-line-of-sight environments at 1800 MHz. The ratio of the median power in the horizontally polarized signal to the median power in the vertically polarized signal was in the range -1 to -7 dB for a hand-held mobile and -7 to -13 dB for a vertical antenna mounted on the roof of a measurement van. The cross-correlation between polarization diversity branches was less than 0.2 for most of the measurement routes. Using the average signal levels and the cross-correlation coefficients the diversity gain in a noise-limited GSM system was estimated. The gain is normally smaller with polarization diversity than with space diversity, but for many of the environments the difference is only about 1 dB in a GSM system. A statistical model for the horizontal-to-vertical power ratio is also presented.

Adaptive antennas for GSM and TDMA systems

Adaptive antennas have generated great interest in previous years, and at present several manufacturers and operators are separately or jointly performing field tests to gain more detailed knowledge of the potential of the technology. This article summarizes many of the experiences that have been collected since 1996 during field trials carried out for both GSM and TDMA (IS-136) by Ericsson in cooperation with two major network operators, Mannesmann Mobilfunk and AT&T Wireless Services.

Antenna arrays for TDMA personal communication systems

This paper summarizes some of the antenna array work at Ericsson. Systems and receiver/transmitter structures are described and simulations are presented for TDMA systems.