Atmospheric phase perturbation estimation for distributed feeder links

Multiple-Input multiple-output (MIMO) feeder links offer a promising solution for addressing the challenges faced by the ground system of Low Earth Orbit (LEO) constellations. To effectively implement the precoding in a MIMO system, channel estimation is crucial to mitigate atmospheric phase perturbation. This paper proposes a downlink-based phase estimation technique for an N×M MIMO feeder link. To ensure compliance with radio regulation requirements and avoid interference with neighboring systems, a spread spectrum approach is implemented for the downlink signal. Carrier-To-interference plus noise ratio (CINR) results demonstrate that the performance of the proposed system closely approaches the ideal scenario even in the presence of strong phase impairments and low downlink transmission power.