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A high-resolution channel sounding technique has been used to investigate the cross-polarization of electromagnetic waves in the 5-6 GHz band. Experiments were performed in two non-line-of-sight indoor locations, and it was found that there is a strong dependency of the cross-polarization of multipath components on the elevation angle-of-arrival. For a vertically polarized transmitting antenna, clusters of co-polarized multipath components were confined predominantly to the region around the horizontal plane that contains the virtual line-of-sight between transmitter and receiver. In contrast, cross-polarized signals were detected for a variety of elevation angles with considerable power levels. The surroundings of the receiver were identified as the principal source of depolarized signals. In addition, time dispersion analysis of the multipath signals led to the determination of the AoAs where there is a strong correspondence between co- and cross-polarized signals as a consequence of the partial depolarization of MPCs. This work supports the exploitation of the joint space and polarization diversities in indoor propagation scenarios to improve the system performance. Index Terms--Electric field measurement, indoor propagation, multipath channels, polarization.

The performance of multiple-input multiple-output (MIMO) systems using beam selection is investigated in this paper. Based on the results of a channel sounding campaign carried out at the University of Manitoba for line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios, it was possible to contrast the results of transmitter, receiver and joint beam selection in rich scattering environments. The channel was characterized in the 1-2.4 GHz frequency band with a multipath delay resolution better than 5.8 ns. The beam selection was performed by exhaustive search method. The results led us to important conclusions regarding the beam selection procedure and its potential to improve the indoor channel capacity. In LOS, the single input single output (SISO) system that favours the maximum power direction of arrival (DOA) maximizes the capacity. Capacity improvements are observed by increasing the number of receiver beams (RBs) only at high signal-to-noise ratios (SNRs) for omnidirectional transmission. The best performance in transmitter beam selection in LOS is observed by increasing the number of transmitter beams (TBs) for high SNRs. In the case of NLOS, the capacity performance is improved when more than a single beam is used in either, transmitter or receiver side. The joint transmitter-receiver beam selection exhibits best capacity performance only for large SNRs in LOS while the SISO systems outperforms any joint beam selection alternative for low SNRs. In contrast, in NLOS environments, the use of joint beam selection shows a constant capacity performance improvement starting from lower SNR than in the LOS case. Index Terms--Information rate, multiple-input multiple-output (MIMO) systems, multibeam antennas, multipath channels, time-domain measurements.