On the Performance of Zero-forcing Beamforming in a Real I2V Scenario at Millimiter Wave

It is proved that in a rich scattering environment, where the channel can be approximated as a zero-mean circularly symmetric complex Gaussian, Zero-Forcing Beamforming (ZFBF) performs as a sub-optimal spatial multiplexing solution that asymptotically approaches the optimal capacity. In fact, it may benefit from multi-user diversity and spatial multiplexing to increase the sum-rate capacity. However, its efficiency at millimeter wave (mmW), where the propagation suffers from high path loss and blockage, is still an open issue. In this work, we analyze ZFBF performance in a real Infrastructure-to-Vehicles (I2V) scenario at mmW. Our numerical results show that the environment's geometry significantly affects the propagation pattern and thereby reduces the efficiency of ZFBF in terms of multiplexing. On the other hand, it still takes advantage of multi-user diversity to improve capacity.