Predicting the Line-of-Sight Existence Using Radio Channel Properties and Relative Antenna Locations

Existence of the line-of-sight (LoS) in a radio link is an important feature determining radio link and localization performance. This study explores relationship between multidimensional nature of radio channel properties such as delay and angular spreads and link pathloss with the LoS existence along with the relative antenna geometry of the two communicating devices in an attempt to predict the LoS existence. A nonlinear classification method of the decision tree is trained by extensive wideband double-directional channel sounding data in a microcellular environment. It was found that the BS-MS link distance and link pathloss were most influential features in predicting the LOS existence. While the use of less influential features of delay and angular spreads led to 75 % accuracy due to not being able to find the exact pattern across different MS routes. We thereby demonstrate the usefulness of incorporating geometrical knowledge of the link to predict the LoS state, despite not using a map of the cellular site, in addition to using channel parameters.