Measurements and analysis of the directional antenna bottom area in high speed rail

This paper indicates the presence of a big area with poor wireless coverage at the bottom of the directional antenna in high speed rail suburban environment, based on a set of 930 MHz narrowband measurements taken in three different high speed rail cells of China. The critical location of the directional antenna bottom area is calculated, using the height difference of the antennas, and the angle between transmitter antenna and the base station tower. An empirical path loss model is proposed for this directional antenna bottom area. The results help to ensure the safety of high speed rail wireless communications.