The throughput of a possible future fixed wireless access multiple-input multiple-output (MIMO) system operating at high frequencies is investigated. We extend our previous theoretical work on MIMO for line-of-sight (LOS) channels to show that a considerable gain in throughput is achieved compared to single-input single-output transmission for a practical system, which among other things is subject to antenna array size constraints. In our investigation we apply a propagation model applicable for high frequencies, where often LOS is required for sufficient coverage, and where weather phenomena like rain have considerable impact on the quality of the radio link. A state of the art transmission scheme is utilized with eigenmode transmission, low density parity check coded modulation, power control, and bit loading. The performance is evaluated both with respect to throughput and Shannon capacity.