THE INDOOR RADIO PROPAGATION CHANNEL

In this tutorial-survey paper the principles of radio propagation in indoor environments are reviewed. Modeling the channel as a linear time-varying filter at each location in the three-dimensional space, properties of the filter's impulse response are described. Theoretical distributions of the sequences of arrival times, amplitudes and phases are presented. Other relevant concepts such as spatial and temporal variations of the channel, large scale path losses, mean excess delay and RMS delay spread are explored. Propagation characteristics of the indoor and outdoor channels are compared and their major differences are outlined. Previous measurement and modeling efforts are surveyed and areas for future research are suggested