Statistical Evaluation of Delay and Doppler Spread in 60 GHz Vehicle-to-Vehicle Channels During Overtaking

Millimeter waves experience much higher maximum Doppler shifts than their centimeter wave counterparts. We measured the wireless channel of 36 different overtaking vehicles to obtain delay and Doppler spread values based on ensemble averages. Our TX antenna is a horn with an 18 degree half power beam width. Spatial filtering by this narrow beam decreases the delay and Doppler spread values. We observe that the RMS Doppler spread is effectively below one-tenth of the maximum Doppler shift. For example, at 60 GHz a relative speed of 30 km/h yields a maximum Doppler shift of approximately 3.3 kHz and a median RMS Doppler spread of 220 Hz at the utmost. The largest median RMS delay spread observed is 5.3 ns.