  This paper studies radio propagation mechanisms that impact handoffs, air
interface design, beam steering, and MIMO for 5G mobile communication systems.
Knife edge diffraction (KED) and a creeping wave linear model are shown to
predict diffraction loss around typical building objects from 10 to 26 GHz, and
human blockage measurements at 73 GHz are shown to fit a double knife-edge
diffraction (DKED) model which incorporates antenna gains. Small-scale spatial
fading of millimeter wave received signal voltage amplitude is generally
Ricean-distributed for both omnidirectional and directional receive antenna
patterns under both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions
in most cases, although the log-normal distribution fits measured data better
for the omnidirectional receive antenna pattern in the NLOS environment.
Small-scale spatial autocorrelations of received voltage amplitudes are shown
to fit sinusoidal exponential and exponential functions for LOS and NLOS
environments, respectively, with small decorrelation distances of 0.27 cm to
13.6 cm (smaller than the size of a handset) that are favorable for spatial
multiplexing. Local area measurements using cluster and route scenarios show
how the received signal changes as the mobile moves and transitions from LOS to
NLOS locations, with reasonably stationary signal levels within clusters.
Wideband mmWave power levels are shown to fade from 0.4 dB/ms to 40 dB/s,
depending on travel speed and surroundings.
