A NEW PATH-GAIN DELAY-SPREAD PROPAGATION MODEL FOR DIGITAL CELLULAR CHANNELS/

We derive a statistical model for the distribution of rms delay spread (tau(rms)) within a cellular environment, including the effects of ba se-to-mobile distance, environment type (urban, suburban, rural, and m ountainous areas), and the correlation between delay spread and shadow fading, We begin with intuitive arguments that tau(rms) should be log normally distributed at any given distance d; that the median of this distribution should grow as some (weak) power of d and that the variat ion about the median should be negatively correlated with shadow fadin g gain. We then present empirical evidence, drawn from a wide array of published reports, which gives strong support to these conjectures. F inally, we combine our findings with the widely used model for path ga in in a cellular environment, The result is a compact statistical mode l for the joint distribution of path gain and delay spread. The model lends itself readily to Monte Carlo simulation and is useful for perfo rmance studies of cellular systems with bandwidths up to tens of kiloh ertz.