Analog Self-Interference Cancellation with Automatic Gain Control for Full-Duplex Transceivers

The main challenge in full-duplex transceiver design is the self-interference (SI). Analog SI isolation is performed at radio frequency (RF) by using an antenna design based on the characteristic modes theory and using active cancelation principle. Two different structures based on using a vector down-converter and a complex multiplier are used for analog baseband SI cancellation. Cancellers are tuned using a automatic gain control (AGC) enhanced variable-step steepest descent algorithm while transmitting a data signal to a distant node in half-duplex mode. Simulations show that the inclusion of AGC into the tuning process speeds up the convergence significantly.