Interference detection using wireless LAN based MIMO transmission

This paper proposes an interference detection method in MIMO transmission, which utilizes periodical preamble signals in a frequency domain. The signals are mapped in only several subcarriers in short preamble signals of IEEE802.11 based OFDM signals and the signal in a frequency domain is transformed by IFFT at the transmitter. We assume the collision due to multiple short preamble signals. In the propose method, second antenna receives the preamble signals while first antenna transmits the preamble signals. The interference can be detected by subtracting the short preamble signal which is multiplied by the estimated channel response from the received signal after the FFT processing. Moreover, we utilize the dual polarization to reduce the mutual coupling between the transmitter and receiver. By a computer simulation, it is shown that proposed method can successfully detect interference in OFDM signal when the interfering power is greater than the noise power.