Adaptive Self-Interference Cancellation in Full -Duplex Radio

Abstract

Full-duplex transmission is a scheme where the transmitter and the receiver of a transceiver can transmit and receive simultaneously using same carrier frequency. Full-duplex transmission theoretically doubles the spectral efficiency and avoids using the separate frequency bands for transmitted and received signal. Full duplex transmission suffers from the self-interference because of the powerful transmit signal coupling back to its own receiver chain. This self-interference signal should be mitigated for the efficient operation of the full duplex radio. This thesis work includes the experiment on the cancellation of self-interference signal induced during the full duplex transmission. LMS algorithm has been adopted for the channel estimation of self-interference channel and the self-interference cancellation has been carried out at the baseband level. Rician channel has been used as a self-interference channel with a high power in the line of sight direction. Effect of K parameter of Rician channel and LMS algorithm on self-interference cancellation has been studied in this thesis work. The simulation work has been carried in a LabVIEW™ environment. Different level of attenuation has been observed by varying the number of samples for estimation/cancellation, step size and the length of estimation filter. In this thesis, the used figure of merit is the output power of self-interference digital canceller (error signal).