Channel Characteristics of Dynamic Off-Body Communications at 60 GHz Under Line-of-Sight (LOS) and Non-LOS Conditions

Seong Ki Yoo,Simon L Cotton,Young Jin Chun,Gareth A Conway,Wiliam G Scanlon

doi:10.1109/lawp.2017.2650863

Seong Ki Yoo, Simon L Cotton + Show 3 more

Open Access

https://doi.org/10.1109/lawp.2017.2650863

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Abstract

This letter investigates the first-order characteristics of dynamic off-body communications channels at 60 GHz. In particular, we have studied signal propagation from a chest-worn millimeter-wave transmitter as an adult male walked toward and then away from a hypothetical base station. The mobile line-of-sight (LOS) and non-LOS (NLOS) channel measurements have been conducted in a diverse range of environments, including a hallway, an open office, an anechoic chamber, and an outdoor car park. In this study, we have decomposed the received signal into its path loss, large-scale, and small-scale fading components. The large-scale fading has been modeled using the gamma distribution, while the Rice and Nakagami-$m$ distributions have been employed to describe the small-scale fading observed in the LOS and NLOS channel conditions, respectively. The results have shown that the estimated path loss exponents for the anechoic chamber and car park environments were greater than those obtained for the hallway and open office environments for both the LOS and NLOS walking scenarios. Across all environments, it was found that the gamma distribution provided an adequate fit to the large-scale fading. Additionally, the Rice and Nakagami-$m$ distributions were found to well describe the small-scale fading for the LOS and NLOS walking scenarios, respectively.

Highlights

R ECENTLY, much interest has been generated toward the use of millimeter-wave technologies for bodycentric and wearable systems [1]–[6]
The parameter estimates for P0 and n over all of the considered environments are given in Table I along with the body shadowing factor (BSF) that is defined as the difference between P0 for the LOS and NLOS scenarios
When comparing the corresponding BSF for all environments, the body shadowing effects were more predominant in the anechoic chamber and car park environments than those observed in the hallway and open office environments

Summary

INTRODUCTION

R ECENTLY, much interest has been generated toward the use of millimeter-wave (mm-wave) technologies for bodycentric and wearable systems [1]–[6]. In [6], the path gain was considered for varying angular orientations of a human subject while maintaining a fixed separation distance between the transmitter (TX) and receiver (RX) These studies have made important contributions to our understanding of the mmwave on- and off-body communications channels, they have only considered scenarios where the person has been stationary or made dynamic movements at a particular location. We investigate the first-order statistical characteristics of off-body communication channels operating at 60 GHz when a hypothetical user walks toward and away from a base station These truly mobile measurements allow us to simultaneously record the path loss, large-scale, and small-scale fading to provide a detailed description of the channel. We employ well-known fading models to characterize the signal fluctuation in line-of-sight (LOS) and non-LOS (NLOS) conditions that allow the channels presented here to be readily reproduced

MEASUREMENT SYSTEM AND EXPERIMENTS

DATA ANALYSIS

Path Loss

Large-Scale Fading

Small-Scale Fading

CONCLUSION