Measured Diversity Gains from MIMO Antenna Selection

We investigate the diversity gain of MIMO systems with antenna selection in measured propagation channels for wireless personal area networks. We measure both the communication from an access point to a laptop, and between two handheld devices. Both the transmitter and receiver use antenna selection for diversity transmission and reception. We consider a closed-loop system where the transmitter has full channel state information, and analyze a number of different antenna selection algorithms and signal combining methods. We find that line of sight (LOS) and non-line of sight (NLOS) situations have fairly similar behavior, and that different polarizations result in similar SNR gains. We also find that RF-preprocessing of the signals is less effective for the hand held devices scenario than for the access point and laptop scenario. Finally, we compare bulk selection (same antenna subset is used for all frequency sub-channels) to per-tone selection (different antenna subsets can be used for each frequency sub-channel) for a wideband channel.