GBSB Model for MIMO Channel Using Leaky Coaxial Cables in Tunnel

Abstract

In this paper, a geometrically-based single-bounce multiple-input-multiple-output (GBSB- MIMO) channel model is proposed for the long term evolution-metro (LTE-M) system in tunnel scenarios. The periodic slots of leaky coaxial cable (LCX) are equivalent to a series of magnetic dipoles. Based on the electric field distribution of the LCX, the theoretical model for line-of-sight (LOS) and non-line-of-sight (NLOS) propagation paths in the tunnel environment are derived. The measurement and simulation results are compared in terms of condition number (CN), channel capacity, and channel correlation function (CF), which verifies the feasibility and rationality of the new proposed model. The simulation results demonstrate, under such circumstances when the Ricean K-factor is smaller, the LCX spacing has a little influence on the channel capacity and CN due to a large number of the NLOS propagation paths in the tunnel, while as Ricean K-factor increases, the LCX spacing has more influence on the channel capacity and CN. By comparison of the measurement and simulation results, it was found that the capacity and CN of the LCX-MIMO is better than the dipole MIMO with different Ricean K-factor values, and under such conditions when the spacing between LCXs and the dipole antennas is increased. Therefore, this paper delivers an optimal system design for channel capacity based on the LCX deployment in the tunnel environment.