Stationarity evaluation of high-mobility sub-6 GHz and mmWave non-WSSUS channels

Analysis and modeling of wireless communication systemsare dependent on the validity of the wide-sense stationar-ity uncorrelated scattering (WSSUS) assumption. However,in high-mobility scenarios, the WSSUS assumption is ap-proximately fulfilled just over a short time period. This pa-per focuses on the stationarity evaluation of high-mobilitymulti-band channels. We evaluate the stationarity time, thetime over which WSSUS is fulfilled approximately. The in-vestigation is performed over real, measured high-mobilitychannels for two frequency bands, 2.55 and 25.5 GHz. Fur-thermore, we demonstrate the influence of the user veloc-ity on the stationarity time. We show that the stationar-ity time decreases with increased relative velocity betweenthe transmitter and the receiver. Furthermore, we show thesimilarity of the stationarity regions between sub-6 GHzand mmWave channels. Finally, we demonstrate that thesub-6 GHz channels are characterized by longer stationar-ity time.