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International Journal of Antennas and Propagation
Volume 2017 (2017), Article ID 1513038, 15 pages
Research Article

Channel Measurements and Modeling at 6 GHz in the Tunnel Environments for 5G Wireless Systems

1College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu 210003, China
2National Key Laboratory of Electromagnetic Environment, China Research Institute of Radio Wave Propagation, Qingdao, Shandong 266107, China

Correspondence should be addressed to Shuang-de Li

Received 14 May 2017; Revised 8 August 2017; Accepted 8 October 2017; Published 10 December 2017

Academic Editor: Larbi Talbi

Copyright © 2017 Shuang-de Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Propagation measurements of wireless channels performed in the tunnel environments at 6 GHz are presented in this paper. Propagation characteristics are simulated and analyzed based on the method of shooting and bouncing ray tracing/image (SBR/IM). A good agreement is achieved between the measured results and simulated results, so the correctness of SBR/IM method has been validated. The measured results and simulated results are analyzed in terms of path loss models, received power, root mean square (RMS) delay spread, Ricean K-factor, and angle of arrival (AOA). The omnidirectional path loss models are characterized based on close-in (CI) free-space reference distance model and the alpha-beta-gamma (ABG) model. Path loss exponents (PLEs) are 1.50–1.74 in line-of-sight (LOS) scenarios and 2.18–2.20 in non-line-of-sight (NLOS) scenarios. Results show that CI model with the reference distance of 1 m provides more accuracy and stability in tunnel scenarios. The RMS delay spread values vary between 2.77 ns and 18.76 ns. Specially, the Poisson distribution best fits the measured data of RMS delay spreads for LOS scenarios and the Gaussian distribution best fits the measured data of RMS delay spreads for NLOS scenarios. Moreover, the normal distribution provides good fits to the Ricean K-factor. The analysis of the abovementioned results from channel measurements and simulations may be utilized for the design of wireless communications of future 5G radio systems at 6 GHz.