Better than Rician: modelling millimetre wave channels as two-wave with diffuse power

Erich Zöchmann,Christoph F Mecklenbräuker,Sebastian Caban,Martin Lerch,Stefan Schwarz,Markus Rupp,Stefan Pratschner

doi:10.1186/s13638-018-1336-6

Abstract

This contribution provides experimental evidence for the two-wave with diffuse power (TWDP) fading model. We have conducted two indoor millimetre wave measurement campaigns with directive horn antennas at both link ends. One horn antenna is mounted in a corner of our laboratory, while the other is steerable and scans azimuth and elevation. Our first measurement campaign is based on scalar network analysis with 7 GHz of bandwidth. Our second measurement campaign obtains magnitude and phase information; it is additionally sampled directionally at several positions in space. We apply Akaike’s information criterion to decide whether Rician fading sufficiently explains the data or the generalised TWDP fading model is necessary. Our results indicate that the TWDP fading hypothesis is favoured over Rician fading in situations where the steerable antenna is pointing towards reflecting objects or is slightly misaligned at line-of-sight. We demonstrate TWDP fading in several different domains, namely, frequency, space, and time.

Highlights

Accurate modelling of wireless propagation effects is a fundamental prerequisite for a proper communication system design
7 Second measurement campaign (MC2): Time-gated fading results To confirm that our observations are not artefacts of our measurement set-up, for example back-lobes of the horn antenna, we study the wireless channel in the time domain
We evaluated the fading statistic in space for φ = 160◦ at the channel tap corresponding to approximately 2.5 m excess distance

Summary

Introduction

Accurate modelling of wireless propagation effects is a fundamental prerequisite for a proper communication system design. The authors of [27] analysed fading at 28 GHz with high gain horn antennas on both link ends They observe high Rician K-factors even at non-line-of-sight (NLOS). Given the maximum-likelihood fitted parameter tuple (K , ˆ ) of TWDP fading and Rician fading, we calculate the sample size-corrected AIC [49, p. Different phases of the impinging MPCs are realised by changing the TX frequency over a bandwidth of 7 GHz. Thereby, we implicitly rely on frequency translations to estimate the parameters of the spatial fading process. 5.3 Fading distributions To obtain different spatial realisations, with the horn antenna pointing into the same direction, the coordinate of the apparent phase centre is moved to (x, y, z) positions uniformly distributed within a cube of side length 2.8λ (see Fig. 11).

MC2: Efficient computation of the spatial correlation

Conclusion