Distance Dependent Model for the Delay Power Spectrum of In-room Radio Channels

A model based on experimental observations of the delay power spectrum in closed rooms is proposed.
The model includes the distance between the transmitter and the receiver as a parameter which makes it suitable for range based radio localization.
The experimental observations motivate the proposed model of the delay power spectrum with a primary (early) component and a reverberant component (tail). The primary component is modeled as a Dirac delta function weighted according to an inverse distance power law (d^-n). The reverberant component is an exponentially decaying function with onset equal to the propagation time between transmitter and receiver. Its power decays exponentially with distance. The proposed model allows for the prediction of e.g. the path loss, mean delay, root mean squared (rms) delay spread, and kurtosis versus the distance. The model predictions are validated by measurements: they show good agreement with respect to distance dependent trends.