A Synchronization Technique for Frequency-Domain Feedback Interference Canceller in OFDM-Based Full Duplex Relays

In a Decode and Forward (DF) type of an OFDM-based Full Duplex Relay (FDR), the frequency-domain approach is more efficient than the time-domain approach for feedback interference cancellation. However, an Inter-Symbol Interference (ISI) and an Inter-Carrier Interference (ICI) may occur due to a timing mismatch between the feedback interference signal and the desired signal from the Base Station (BS) when feedback interference cancellation is performed in the frequency domain. In this paper, the effects of a timing mismatch on synchronous types and asynchronous types of OFDM-based FDRs are investigated in uplink and downlink cases. A synchronization procedure and techniques for minimizing ISI and ICI in OFDM-based FDRs with a frequency-domain feedback interference canceller are proposed.