MIMO receiver using an RF-adaptive array antenna with a novel control method

An RF-adaptive array antenna (RF-AAA) is useful for improving the signal-to-interference plus noise ratio (SINR) on each branch in a multiple-input multiple-output (MIMO) receiver. A weight-control method for the RF-AAA, however, has been a major challenge towards its practical use because only one output signal can be observed at the RF-AAA. In this paper, we propose a novel control method that can estimate each channel impulse response (CIR) for each antenna element and calculate optimum weights for the RF-AAA, the same principle as that of the digital-processing type AAA. The proposed control method is implemented with a frame format based on the IEEE 802.11a standard. Bit error rate performance shows that the proposed control method estimates the CIR and calculates the global optimum weights to maximize the output SINR. Consequently, the RF-AAA suppresses the interference and provides a BER close to that without interference.