A 40.2 bps/Hz Single Polarization 4x4 Line-of-Sight MIMO Link With Unsynchronized Oscillators.

Line-of-sight MIMO (LOS-MIMO) has the potential to greatly improve the capacity and spectral efficiency of microwave links in backhaul networks. In this paper we present results from an outdoor experiment with a single polarization LOS-MIMO system with four spatial streams in a single channel and unsynchronized oscillators, with which we achieve an uncoded spectral efficiency of 40.2 bps/Hz for a 14 MHz channel with $6.6\cdot 10^{-3}$ bit error ratio. We also discuss the performance limitations of the system.