System Applications for Wireless Indoor Communications

Buildings present a hostile environment for radio communications, with in-building radio propagation difficult to predict and continuously changing. Problems include multipath and shadow fading, which reduces the coverage region, and dispersion due to decay spread, which limits the maximum data rate. Furthermore, in buildings with multiple users, interference between users can be a serious problem, and the available spectrum can be much less than that required to handle all potential users. In this paper we describe various antenna diversity techniques, including selection, maximal ratio and optimum combining, and show how diversity, in combination with other techniques, can be used to overcome these problems.