Simulation of the urban radio propagation channel in the presence of distant reflectors

A simulation package for predicting the impulse response of the digital mobile radio propagation channel has been modified to take into account reflection and scattering of the transmitted signals by distant objects such as hills, mountains, and city skylines. For each distant reflector the round trip path loss is calculated using a model derived from the available information in the literature. Impulse response profiles with excess delays of up to 200 μs were then generated by repeatedly calling the original simulation package, scaling the resulting subprofiles properly, and combining them by vector addition of all the multipath components. The final model indicates that retarded echoes with magnitudes comparable to the line-of-sight path are possible under favorable propagation conditions from base to mobile through the reflected path, and unfavorable propagation conditions through the direct path