On Self-interference Suppression Methods for Low-complexity Full-duplex MIMO

Full-duplex wireless communication offers improved spectral efficiency, as well as more efficient relaying and medium access, but requires suppression of self-interference. In this paper we analyze the existing methods for active RF suppression and use the ”Rice architecture” for its low complexity and favorable scaling when applied to multi-antenna systems. We analyze the effects of the different sources of self-interference and quantify the potential for further suppression (genie-aided suppression). Our single-chain implementation using a circulator achieves −48 dB of active RF suppression, but only −66 dB of total suppression in the analog domain. On the other hand, our single-chain implementation using separate antennae reaches −85 dB of total analog suppression, thus reducing the self-interference to the noise floor. Extending these setups, we present a low complexity implementation of a 2 × 2 full-duplex MIMO node, which achieves even higher suppression than the single-chain counterparts.