Full-Duplex Wireless Communication Using Transmitter Output Based Echo Cancellation

In this paper, we present a duplexing method for wireless communication that allows both transmission and reception to occur at the same frequency band and time slot simultaneously. The self-interference caused by coupling between the transmit and receive signals is cancelled to allow the detection of the desired receive signal. This scheme can increase the capacity of wireless communication systems since only one channel instead of two is needed for duplexing. Furthermore it also opens up the possibility of using new MAC layer wireless protocols that make use of simultaneous transmission and reception to boost the overall throughput of wireless network. In this work we use a baseband transmitter output based echo cancellation approach with a 2-stage iterative echo canceller at the receiver and the reference samples are obtained from the output of the transmit power amplifier. Implementation issues are considered, including system imperfections and RF impairments such as phase noise. The system performance is evaluated by computer simulation based on IEEE 802.11a/g system parameters. It is shown that the output SINR is sufficient to support full-duplex communication, and the overall channel capacity can be increased by a factor of up to 1.8.