Rail transportation industry has drawn a growing interest on the use of Radio Access Technology for critical and non-critical services to improve safety/reliability, performance, and passenger experience. During the past two decades the theory and practice of the MIMO communications has solidified to the point where MIMO is now the main infrastructure for several legacy and emerging radio access standards.
In this paper, the impact of subway tunnels’ curvatures on the MIMO channel capacity is explored. A heuristic approach is proposed which provides an efficient and low complexity solution for the MIMO channel capacity in curved subway tunnels for both the C-MIMO and the D-MIMO paradigms. The suggested approach is quite versatile and can be swiftly expanded to the case of multi-segment inhomogeneous tunnels.