Radio Wave Diffusion and Cell Splitting Indoors

Diffusion theory is found to provide a simple yet accurate expression for the average received radio power loss indoors in non-Line-of-Sight. Effective specific absorption is the sole parameter. Agreement with extensive indoor power measurements is found at all ranges. Extending the model to account for variation in scatterer density provides a stochastic mechanism explaining the log-normal nature of observed average power variations, usually termed "shadow fading". The standard deviation of power variation is found to increase with range (as r1/2 at short ranges), in agreement with measurements and unlike accepted models. Resulting propagation loss has a large impact on the Signal-to-Interference-and Noise behavior, materially affecting conclusions on the value of cell splitting as a method of increasing wireless network capacity.