Pushing the limits of Full-duplex: Design and Real-time Implementation

TL;DR

This paper presents a real-time full-duplex OFDM physical layer and a MAC protocol, achieving significant self-interference suppression and throughput gains in practical wireless scenarios.

Contribution

It introduces a novel real-time 64-subcarrier full-duplex OFDM physical layer and a MAC protocol with new mechanisms for discovering and exploiting full-duplex opportunities.

Findings

Self-interference suppressed up to 80dB, 10dB better than prior work

Achieved over 70% throughput gains in real-world tests

Demonstrated synchronous and asynchronous full-duplex modes

Abstract

Recent work has shown the feasibility of single-channel full-duplex wireless physical layer, allowing nodes to send and receive in the same frequency band at the same time. In this report, we first design and implement a real-time 64-subcarrier 10 MHz full-duplex OFDM physical layer, FD-PHY. The proposed FD-PHY not only allows synchronous full-duplex transmissions but also selective asynchronous full-duplex modes. Further, we show that in over-the-air experiments using optimal antenna placement on actual devices, the self-interference can be suppressed upto 80dB, which is 10dB more than prior reported results. Then we propose a full-duplex MAC protocol, FD-MAC, which builds on IEEE 802.11 with three new mechanisms -- shared random backoff, header snooping and virtual backoffs. The new mechanisms allow FD-MAC to discover and exploit full-duplex opportunities in a distributed manner. Our over-the-air tests show over 70% throughput gains from using full-duplex over half-duplex in realistically used cases.