Spatial Capacity Optimization for Indoor MIMO Los Channels Applying Methods of High-Rank Transfer Matrix Construction

The indoor MIMO line-of-sight (LOS) channel in theory strongly depends on the geometrical arrangement and spacing of the antennas at both, the transmitter as well as the receiver. Recently, theoretical directives have been presented [1] which enable the user to achieve high-rank LOS channels for linear antenna arrays which are oriented broadside to each other. The authors focus on proper phase angle relations within the entries of the channel transfer matrix, while neglecting the channel path loss in a first approach, and they consider the antenna spacings as the major degree of freedom for optimization. Contrarily, in practical indoor scenarios we consider the antenna array spacings to be fixed at the base station as well as the mobile unit and therefore they can be optimized for one particular transmitter-receiver distance at most. Furthermore, the free space path loss has to be taken into account as it causes huge SNR variations across an indoor environment. Thus, in this paper we try to apply the results in [1] to an exemplary real-world scenario observing the spatial capacity distribution as well as their variation. This way, we endorse the results in [1] by further design hints for practical MIMO systems using linear antenna arrays of arbitrary positioning.