An Enhanced MIMO Hardware Demonstrator - Polarization Diversity in Adaptive OFDM Systems

The performance of multiple-input multiple-output (MIMO) systems is affected by the spatial correlation properties, which depend on the array configuration and the channel characteristics. The configuration can be influenced by manipulating the radiation patterns of the antennas, the antenna spacing and the array geometry. To decrease the spatial correlation effects, e.g., the antenna spacing can be increased, which is usually undesirable in mobile devices. Here, the utilization of polarization diversity techniques comes into consideration. This paper deals with the application and comparison of different polarized transmit/receive array setups in indoor environments using a multiple antenna demonstrator in uncoded adaptive MIMO-OFDM scenarios. Measurement results indicate a decreased correlation of the spatial subchannels, a higher MIMO capacity for cross-polarized antenna arrays and lower bit error rates with bit and power loading algorithms.