An investigation on wideband signal fluctuation characteristics in CDMA mobile radio using path and spatial diversity combination

In wideband transmission systems such as mobile CDMA, path diversity is an effective measure to reduce the degree of signal variation due to rapid fluctuation (multipath fading). In order to evaluate the path diversity effect quantitatively, this paper analyzes the characteristics of signal fluctuation width under the RAKE combination scheme based on the measured multipath delay profiles, and compares it with the results obtained from the wideband propagation model we have developed for evaluation of wideband transmission characteristics. Moreover the performance of a hybrid diversity, which is a combined diversity scheme of path and spatial diversities, is also investigated using the experimental results. It is made clear that the hybrid diversity configuration using four antenna branches can offer larger channel capacity without power control for the multipath fading, compared with a single antenna system requesting precise power control ideally followed to the multipath fading, compared with a single antenna system requesting precise power control ideally followed to the multipath fading