Delay spread profiles and receiver performance in a dense multipath environment

The design and performance of indoor communication systems are strongly dependent on the delay spread in the impulse response of the channel. The delay spread is due to the abundance of the multipath reflections in the indoor environment. Judicious system design can derive benefit from the availability of the multipath signal to improve the system performance. Such potential improvement is due mainly to the fact that the various multipath components are very weakly dependent on each other, while fading, and a natural temporal diversity situation occurs. For system performance evaluation it is desirable to have an estimate of how the delay spread varies while the received power decreases with increasing transmitter-receiver distance. The simplest possible model that retains the essentials of a dense multipath environment is proposed and analyzed. It assumes that the direct path is blocked and that only scattered signals are received. A small ellipse of focal distance r_min about the transmitter and receiver is assumed to be free of scatterers. The scatterers are assumed to be Lambertian uncorrelated point-scatterers, uniformly distributed in 2-dimensional space. Secondary reflections are neglected and primary reflections are assumed not to be hampered by the presence of the other point scatterers. This is basically the wide sense stationary uncorrelated scatterers (WSSUS) model often used in communications analysis