Comparison of Capacity Between Two Beam Coverage Modes in Satellite MIMO Downlink with LOS Channels

In this paper, a GEO satellite MIMO downlink with line of sight channels is considered, the capacity performance of two beam coverage modes is analyzed and compared, which are adjacent coverage and overlapping coverage. First, under the assumption of the same total coverage area, the relationship between transmit antenna gains in the two modes is analyzed and obtained. Next, the closed-form expressions of signal-to-noise ratios in two modes are obtained in a single-user scenario, and it is proved analytically that a larger capacity can be obtained in adjacent coverage. Finally, multiple uniformly distributed users are considered and it is proved through numerical simulations that the system sum capacity of adjacent coverage is greater under different transmit power, precoding methods, and the number of beams (users).