Small-Scale, Local Area, and Transitional Millimeter Wave Propagation for 5G Communications

TL;DR

This paper investigates millimeter wave propagation mechanisms relevant to 5G, including diffraction, blockage, and small-scale fading, providing models and measurements that inform system design and performance in various environments.

Contribution

It introduces new models for diffraction loss and human blockage at mmWave frequencies, and characterizes small-scale fading and autocorrelation properties for 5G system planning.

Findings

Diffraction models accurately predict loss around buildings from 10 to 26 GHz.

Human blockage at 73 GHz fits a double knife-edge diffraction model with antenna gains.

Small-scale fading is mostly Ricean-distributed, with autocorrelation distances suitable for spatial multiplexing.

Abstract

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.