Empowering full-duplex wireless communication by exploiting directional diversity

TLDR

Directional antennas in wireless networks are used to reduce interference and improve power efficiency. The study aims to extend the range of full‑duplex wireless communication by exploiting directional antennas. The authors characterize full‑duplex performance by having a base station transmit to one device while receiving from another, using directional antennas to provide passive self‑interference suppression. The characterization shows that at 10 m with 12 dBm transmit power, full‑duplex gains range from 60 % to 90 % when the base‑station antennas are separated by at least 45°, and at 15 m the gains remain at least 40 % for 90° separations, demonstrating that directional passive suppression yields substantial performance improvements without additional RF cancellation hardware.

Abstract

The use of directional antennas in wireless networks has been widely studied with two main motivations: 1) decreasing interference between devices and 2) improving power efficiency. We identify a third motivation for utilizing directional antennas: pushing the range limitations of full-duplex wireless communication. A characterization of full-duplex performance in the context of a base station transmitting to one device while receiving from another is presented. In this scenario, the base station can exploit "directional diversity" by using directional antennas to achieve additional passive suppression of the self-interference. The characterization shows that at 10 m distance and with 12 dBm transmit power the gains over half-duplex are as high as 90% and no lower than 60% as long as the directional antennas at the base station are separated by 45° or more. At 15 m distance the gains are no lower than 40% for separations of 90° and larger. Passive suppression via directional antennas also allows full-duplex to achieve significant gains over half-duplex even without resorting to the use of extra hardware for performing RF cancellation as has been required in the previous work.