Distributed MIMO System Design and Channel Capacity Analysis Based on Polar Orbit LEO Constellation

This article aims at the future application of MIMO technology on low Earth orbit (LEO) satellites. The MIMO system based on LEO satellites will have better performance than GEO satellites due to smaller delay and attenuation. However, the formation of a distributed MIMO system requires cooperation of LEO satellites, which needs the design of corresponding satellite constellations. The article constructs a system achieving full MIMO coverage based on a polar orbit satellite constellation, derives the time varying channel capacity of the LEO-based MIMO system, and analyzes the performance of edge and central users. The results show that the amplitude and fluctuation of the channel capacity of the central user are larger than those of the edge users, and, as the coverage area moves, the channel capacity shows a trend of first-increasing-and-then-decreasing. The effect of user antenna spacing on channel capacity has also verified, which show that the channel capacity changes periodically as the ground antenna spacing increases, and the period value is positively correlated with the user transmission distance.