Space diversity measurements for DECT in indoor and outdoor microcells

Diversity measurements have been performed in microcellular environments where DECT typically might be implemented. The intention has been to investigate how well different implementations of antenna space diversity can combat the problems DECT experiences in multipath environments. Diversity with 2 antennas and selection/switching based on signal level and on delay spread has been investigated, and the effect on the delay spread statistics has been studied. Measurements have been performed in three different types of scenarios; both radio base station (RES) and portable part (PP) indoors (indoor case), RES outdoors and PP indoors (outdoor to indoor case) and both RES and PP outdoors (outdoor case). For the indoor case the delay spread values were small. The most severe time dispersion was observed in the outdoor to indoor case, where delay spread values exceeded 100 ns in almost 50% of the cases. In the outdoor scenario delay spread values above 100 ns were observed for approximately 10% of the cases. It seemed that for both the outdoor, and outdoor to indoor cases, where the time dispersion may cause problems for DECT performance, the diversity algorithm should be based on some other selection/switching criterion than signal level, preferably BER or some other quality criterion. In the indoor environment, signal level as a selection/switching criterion should be sufficient. The work presented in this paper is part of an investigation of DECT performance in environments which DECT has not been originally designed for, to possibly extend the usage of DECT for RLL applications and as a public access system.