Radio propagation modeling in indoor stairwell: A K-means clustering approach

The propagation characteristics in indoor stairwell differ from those of the conventional indoor signal propagation across different floors and hence, deserve independent scrutiny. In this work, the propagation characteristics in four indoor stairwells have been examined by means of extensive field measurements at two frequency bands - 2.4 and 5.8 GHz respectively. It has been found the values of the path loss exponent n for stairwell are higher than those for other indoor environments. More importantly, the standard deviation of the n-values are high, leading to less accurate propagation models. This paper proposes the use of K-means clustering for the path loss data and values of path loss exponent n of stairwells are subsequently computed. The newly-computed path loss exponents n are lowered and their standard deviation values are significantly reduced. The path loss characteristics are useful for understanding radio propagation in pico- or femto-cells that have great potential in increasing the capacity and reducing the operational cost for wireless communications systems.