A reconfigurable multiple-input multiple-output communication system

We present a theoretical analysis on the gains offered by a reconfigurable multiple-input multiple-output (MIMO) system using orthogonal space-time block codes (OSTBCs) and reconfigurable antennas at the receiver only. The proposed system using reconfigurable antennas selects the optimal radiation state of the receive antennas in which the receive signal-to-noise ratio (SNR) is maximized. The theoretical findings show that under certain channel propagation conditions and using an appropriate codification and power allocation of the transmitted signal, the diversity order of the proposed reconfigurable MIMO system is given by the product of transmit and receive antennas as well as the number of reconfigurable radiation states of the receive antennas. The impact of correlated radiation states and imperfect channel estimation are also considered. The geometrical and physical constraints of reconfigurable antennas are also taken into account through the concept of antenna group. Assuming an ideally scattered non-line-of-sight (NLOS) flat Rayleigh channel, the antenna design criteria is given. Finally, we evaluate the theoretical findings through simulations on the array gain, bit error rate and ergodic capacity, where the detrimental impact of channel estimation is observed.