Characteristics of the Hexapolarized MIMO Channel over Free-Space and Three Non-Free-Space Scenarios

Abstract

The eigenvalues and channel capacity of the hexapolarized MIMO system in free-space (FS) and three non-FS scenarios are investigated, based on the exact determinant electromagnetic field expressions. Computation results show that there are generally 6 nonzero eigenvalues in all the four scenarios. However, the values of the eigenvalues are affected strongly by the link distance, the antenna position and the scattering condition, thus some of the eigenvalues are too small to contribute to the overall channel capacity. Interestingly, the smallest two eigenvalues and the corresponding hexapolarized MIMO channel capacity can be increased obviously with the increasing of the number of scattering planes, especially in the far field. Furthermore, more scattering can increase the robustness of the multipolarized MIMO system over the location of the array. However, in those non-FS channels, a threefold increase of the capacity over that in the FS channel is not obtained, and the maximum capacity gain is 2.15. Fortunately, a threefold capacity gain of using the tri-polarized electric dipoles over the one-polarized electric dipole can be obtained in most cases of the three-mirror (3M) channel. Finally, some numerical simulations were conducted, the theoretical predicted hexapolarized MIMO capacities agree well with that obtained from the simulations.