Stochastic Multipath Model for the In-Room Radio Channel based on Room Electromagnetics

TL;DR

This paper introduces a stochastic multipath model for in-room radio channels with directive antennas, accurately capturing the transition from specular to diffused signals and matching detailed electromagnetic predictions.

Contribution

The paper presents a novel stochastic model based on Poisson processes that closely aligns with electromagnetic theory for in-room multipath propagation.

Findings

Model accurately predicts power delay spectrum

Model matches kurtosis delay spectrum and order statistics

Outperforms constant rate models like Saleh-Valenzuela

Abstract

We propose a stochastic multipath model for the received signal for the case where the transmitter and receiver, both with directive antennas, are situated in the same rectangular room. This scenario is known to produce channel impulse responses with a gradual specular-to-diffused transition in delay. Mirror source theory predicts the arrival rate to be quadratic in delay, inversely proportional to room volume and proportional to the product of the antenna beam coverage fractions. We approximate the mirror source positions by a homogeneous spatial Poisson point process and their gain as complex random variables with the same second moment. The multipath delays in the resulting model form an inhomogeneous Poisson point process which enables derivation of the characteristic functional, power/kurtosis delay spectra, and the distribution of order statistics of the arrival delays in closed form. We find that the proposed model matches the mirror source model well in terms of power delay spectrum, kurtosis delay spectrum, order statistics, and prediction of mean delay and rms delay spread. The constant rate model, assumed in e.g. the Saleh-Valenzuela model, is unable to reproduce the same effects.