Digital Channel Feature Map Assisted Airborne MIMO Communications

Due to the mobility of air platform (AP), the channel estimation (CE) and beamforming matrix update in airborne multiple-input multiple-output (MIMO) communication systems will result in significant consumption in pilot, power and computation resources, especially when the numbers of AP’s antennas and users are large. In this work, we present a digital channel feature (DCF) map assisted airborne MIMO transmission framework. DCF map is a database on local or online servers, which contains the site-specific channel features labeled by positions of AP and users. By exploiting the DCF map, we propose a CE-free beamforming scheme under max-min fairness for efficient downlink air-to-ground transmission. The resulting beamforming problem is solved efficiently by exploiting the inverse problem for power minimization. Simulation results show that the CE-free scheme can retain most of the average achieve rate achieved by perfect CSI based scheme. Since the proposed scheme relies only on the offline DCF, the results of this work can be further exploited in other high-level optimizations, e.g., AP deployment and network planning.