On-Grid 3D Dynamic Channel Tracking for Space-Air Communications with Multiple UAVs

The space-air-ground integrated network (SAGIN) has drawn increasing attention for its potential to support ubiquitous wireless communications. As one of the link segments, it is non-trivial to track the 3D dynamic channel information in space-air links with multiple unmanned aerial vehicles (UAVs) and Ka-band orbiting low earth orbit (LEO) satellite. In this paper, we proposed a multi-dimensional Markov model (MD-MM) which investigates spatial and temporal probabilistic relationships of multi-user (MU) hidden support vector, single-user (SU) joint hidden support vector, and SU hidden value vector to represent the 3D dynamic channel. Moreover, we developed a novel multidimensional dynamic turbo approximate message passing (MD-DTAMP) algorithm to track the 3D dynamic on-grid channel with multiple UAVs in the system. Numerical results prove that the proposed algorithm shows superior channel tracking performance with smaller pilot overheads.