Finding MIMO

Availability of multiple antennas enables increased capacity or increased resilience for modern radios. This advantage depends on the deployment of the antennas at the sender and receiver. But there is a performance gap between most simulated results and the actual performance obtained in practice. This is due to the rank of the channel obtained in deployments, which depends on local propagation conditions, and on the placement of the senders and receivers. Using implementation on top of USRP platform, and mobile antennas, we show that it is possible to find ´good´ antenna positions within a search space of a few carrier wavelengths. This opens the possibility for adaptive methods in antenna position and coding/modulation techniques to feed back to each other to reduce the gap between theoretical and practical MIMO performance.