Simple analog beamforming method for short range MIMO transmission

In the short range MIMO transmission, an optimal element spacing, which maximizes the channel capacity, exists, when the transmit distance between the transmitter and receiver is given. We focus on that the weight by a zero forcing (ZF) at the optimal element spacing can be realized by using 90-degree phase shifters and dividers because the matrix of weight by the ZF at the optimal element spacing can be expressed as the unitary matrix. In this paper, we propose the simple decoding method for short range MIMO transmission by using analog devices. Moreover, it is shown that the proposed method is effective by the evaluation via Bit Error Rate.