Abstract
Air-to-ground (AG) communications have attracted much attention for future advanced wireless communications. Unmanned aerial vehicle, as a critical enabler in AG communications, can be operated in various environments, such as over-water, hilly, and built-up environments. A better understanding of radio channels in various scenarios can immensely facilitate the deployment and design of wireless systems. Thus, in this letter, wideband characterizations of AG channels are performed based on the multienvironment channel measurements, where the center frequency is set to 6.5 GHz with the bandwidth of 500 MHz, which provides high delay resolution to capture significant multipath. Two key channel parameters, Rician K -factor and root-mean-square (rms) delay spread, are used as metrics to characterize AG channels. The positive Rician K -factor indicates the line-of-sight (LOS)-dominated characteristic of the AG channel. The discrepancy of the rms delay spread shows the obvious influence of multipaths from building on channel delay characteristics.