Photonics-Assisted Simultaneous RF Channelization and Self-Interference Cancellation

Both RF channelization and self-interference cancellation are urgently required for modern in-band full-duplex systems. A photonics-assisted RF receiver for simultaneous wideband channelization and self-interference cancellation is proposed and demonstrated. The key is the implementation of dual optical frequency combs (OFCs) followed by microwave photonic image-reject mixers (IRMs) using a dual-output Hartley structure. The received RF signal and the reference signal are modulated to a pair of signal OFCs with orthogonal polarization states, respectively. The microwave photonic IRM is applied on each polarization state, respectively. For each local OFC comb line, two components will be sliced and downconverted from each copy of the optically-carried received RF signal. Meanwhile, another two components will be sliced and downconverted from the optically-carried reference signal. After combining the outputs of the IRMs, the components from the image signal and the self-interference signal will be eliminated simultaneously. Two channels of the signal of interest will be obtained for each local OFC comb line. Experimental results show that an RF signal with an instantaneous bandwidth of 6 GHz (from 7 to 13 GHz) is channelized into 6 channels, each of which has a 1–GHz bandwidth. The isolation of larger than 28 dB between the channels is realized, and the simultaneous self-interference cancellation and image-rejection are achieved.