Coverage analysis of a DS spread spectrum system over 900 MHz and 60 GHz indoor channels

This paper deals with the performance evaluation of a direct sequence spread-spectrum (DS-SS) system in a real indoor channel, at both 900 MHz and 60 GHz. The aim is to provide some coverage criteria for the design of an indoor wireless system. Exploiting some analytical results presented by the authors in a previous paper, the system performance is investigated accounting for the effect of multipath on the DLL tracking circuit as well. We observe that the presence of a code tracking offset due to delayed paths cannot a priori be neglected or considered as a disadvantage: this is true especially at EHF, given the peculiar indoor propagation characteristics of such high frequencies. Moreover, the effects on the system performance of a different choice of the chip period has been highlighted and explained on the basis of the channel impulse response characteristics. The area considered in this work is the upper floor of the Villa Griffone, Guglieimo Marconi´s house near Bologna, Italy, from where the first radio signal was launched. The building can be considered a quite representative example of a medium size office. The channel has been described by means of a set of 1680 impulse responses, obtained by resorting to a fully 3-D ray-tracing program that provides accurate predictions, so avoiding expensive sounding campaigns. Numerical results show the spatial distribution of the attenuation of the received energy per bit at the output of the despreader, due to the indoor propagation. Three-dimensional plots provide an effective visual indication of the attenuations involved in the coverage area