Impact of Frequency Selective Channels on a Line-of-Sight MIMO Microwave Radio Link

Two line-of-sight (LoS) multiple-input multiple-output (MIMO) systems for point-to-point microwave radio links are simulated and analyzed. Both 2 × 2 spatially-separated, single-polarized and 4 × 4 spatially-separated, dual-polarized systems are considered in the presence of a frequency selective and time varying channel. Time dependence is introduced by moving the antennas during the simulation and thereby introducing the need for an adaptive space-time-equalizer (STE). Our results indicate that a time-varying frequency selective LoS MIMO channel puts higher requirements on the STE and introduces a higher SNR penalty compared to a single-input single-output (SISO) system.