Body-to-Body Channel Characterization and Modeling Inside an Underground Mine

In this article, the use of circularly polarized multiple-input-multiple-output (MIMO) antenna systems is proposed as a new solution for future body-to-body (B2B) applications. Four B2B channels have been characterized inside a mine. The statistical parameters of the B2B channels using co-positioned (CP) and 90° rotated (90R) antennas have been determined. Path loss (PL) exponent values varied between 2.33 and 1.26. The time dispersion parameters and channel capacities are computed for both CP and 90R scenarios. Moreover, channel correlation matrices and the Rician K-factor have been determined and discussed in terms of their effect on capacity and root mean square (rms) delay spread. Overall, the circularly polarized setup exhibits the best performance in terms of PL, rms delay spread, and channel capacity. The nonline-of-sight (NLOS) situation caused a significant drop in channel capacity due to the significant increase in PL, and an increase in the rms delay spread due to the multipath richness. The MIMO-NLOS scenario exhibits the highest throughput gain of 1.752 (at an SNR of 20 dB), due to its low branch correlation. A model of the B2B impulse response has been created based on a statistical-empirical approach to determine the optimal path amplitudes and time of arrival.