Aircraft-to-Aircraft Channel Measurements in the VHF/UHF Band: Analysis of the Line-of-Sight and Lake-Reflected Channel Components

This paper presents a statistical analysis of the main components of the aircraft-to-aircraft channel based on the wideband channel measurements conducted between two aircraft in the VHF/UHF band at 250 MHz. We consider multiple flight segments where the aircraft flew at diverse altitudes and used different antennas for transmission and for reception, alternating between a top and a bottom antenna. In each scenario of interest, we analyse the power and the small-scale fading of the envelope of the direct line-of-sight component and of the specular reflection component off a lake. For both components, we compare the measured average power with the theoretical free-space path loss, and the measured small-scale fading with multiple well-known statistical distributions. The results show that the envelope of both components is strongly affected by the geometry, the location of the antennas, and by the aircraft fuselage itself. The different scenarios yield significant variations in the average power and in the distribution of the small-scale fading. A Rician distribution shows the best fit for the line-of-sight component envelope. The component reflected off the lake can be modeled by a Rician distribution when it is not obstructed or strongly affected by the aircraft fuselage, and by a Nakagami distribution otherwise. The parameters of the best-fitting distributions, including the Rician K-factor, are provided for the different scenarios.