Path loss measurement and modeling for low-altitude UAV scenarios towards 3GPP ISAC standadization

With the advancement of the low-altitude economy and the widespread application of unmanned aerial vehicle (UAV), regulatory challenges for UAV flights have significantly increased. Integrated sensing and communication (ISAC) technology is expected to solve the above problems. For this reason, the 3rd Generation Partnership Project (3GPP) had identified low-altitude UAV as one of the important application scenarios of ISAC technology. However, the fast flight speed, small size and high altitude of UAV could adversely affect the strength and quality of the received sensing signals. Consequently, there was an urgent need to investigate the path loss characteristics of the UAV sensing channel and develop effective model. Mono-static sensing channel measurements for UAV at frequencies of 15 GHz and 28 GHz were conducted. The impact of horizontal distance, vertical altitude differences, and the radar cross section (RCS) of the target on path loss were examined. The findings revealed low-coupling characteristics between the target and background channels. Subsequently, the path loss and distance model for the UAV sensing target channel was established, contributing to the ongoing progress of 3GPP standardization.