Performance Comparison of Time-Domain and Frequency-Domain RF Self-Interference Cancellation in Full-Duplex Wireless Systems

Full-Duplex is a wireless communication paradigm which potentially provides a 2x improvement in the data-rate by a more efficient usage of available spectrum. A critical bottle neck in FD operation is the powerful Self-Interference (SI) on top of the desired received signal which lies in the same frequency range, potentially desensitizing the receive chain and thereby corrupting reception. To achieve FD operation, the SI has to be suppressed below the RX noise floor through different stages of cancellation as frequency selective filtering is not possible. Wide-band SI cancellation (SIC) requires a cancellation network which accurately emulates the frequency response of the SI channel over the desired bandwidth. This work examines two ways of achieving wide-band SIC, one from a frequency domain perspective by using a bank of RF filters and another from a time domain perspective by using finite impulse response (FIR) filters. Using data from measurements, we compare the two aforementioned approaches and discuss challenges involved in implementing these networks.