Non-WSSUS vehicular channel characterization at 5.2 GHz-spectral divergence and time-variant coherence parameters

The scattering environment in vehicle-to-vehicle communication channels at 5.2 GHz changes rapidly. Hence the wide-sense stationary (WSS) uncorrelated scattering (US) assumption for the fading process is valid for short time intervals only. We characterize the spectral divergence of the local scattering function (LSF) sequence in order to assess the non-WSSUS characteristics in different scenarios. We find that the vehicle-to-vehicle channels violate the wide-sense stationarity much stronger than the US assumption. Additionally, we use the LSF to quantify the time dependence of the channel coherence time and bandwidth. Both parameters vary strongly over time depending on the chosen scenario. Furthermore the effect of the antenna radiation pattern on the fading process is quantified, which can cause the strength of a multipath component to change by more than 40 dB in drive-by experiments.