Modelling Wireless Propagation for Indoor Localization
This paper presents a ray-tracing technique to model the multi-path fading effect in indoor spaces. Random set P of points on all surfaces inside a given hypothetical indoor space are chosen. Each pi ∈ P is considered to be a point from which the transmitted signal reflects just before reaching the receiver. The received signal is the vector sum of various reflections that arrive at the receiver. The received signal strength (RSS) is then computed from the signal envelope. This technique provides RSS statistics that are similar to the models of signal propagation developed after extensive measurements in multi-path environments. In addition, this technique captures the spatial correlation of signal impairment. For example, path loss computed with this technique shows that co-moving receivers experience correlated signal fades while those moving in different spaces see un-correlated fading. The technique presented here is a low cost, first principle approach to simulate channel impairments due to multi-path effect and interference. It benefits any wireless simulation study that needs the signal-space mapping and context such as indoor localization. This randomized ray-tracing technique does not compete with or replace other, more accurate ray-tracing techniques that use either brute force or geometric optics to obtain site-specific signal-to-space mapping.