Impact of directive handset antennas on the performance of outdoor-to-indoor MIMO systems

Multiple-input multiple-output (MIMO) wireless systems are typically associated with high scattering and isotropic propagation. The ability of omnidirectional antennas to capture multi-path components coming from all directions has made them a logical choice for MIMO applications. Recently, it has been argued that in some MIMO wireless propagation environments with limited angular spread, directive antennas may actually be beneficial if the power gain of these antennas can compensate the loss of perceived multi-path content. In this work, performance of a compact four-element prototype handset with directive patch antennas is studied in an outdoor-to-indoor 4×4 MIMO wireless system. Measurements confirm that directivity may be used to achieve significant capacity gains if combined with intelligent beam-steering.