Breaking Through the Full-Duplex Wi-Fi Capacity Gain

TL;DR

This paper proposes a new 1:N design guideline for full-duplex Wi-Fi MAC protocols, enabling capacity gains exceeding 2x by leveraging multiple orthogonal PHY channels, overcoming previous limitations.

Contribution

Introducing the 1:N design guideline that allows full-duplex Wi-Fi protocols to surpass 2x capacity gains by utilizing multiple orthogonal PHY channels.

Findings

The 1:N design can achieve more than 2x capacity gain at the MAC layer.

The 1:N approach leverages channel orthogonality and denser modulation.

Experimental results validate the theoretical advantages of 1:N design.

Abstract

In this work we identify a seminal design guideline that prevents current Full-Duplex (FD) MAC protocols to scale the FD capacity gain (i.e. 2x the half-duplex throughput) in single-cell Wi-Fi networks. Under such guideline (referred to as 1:1), a MAC protocol attempts to initiate up to two simultaneous transmissions in the FD bandwidth. Since in single-cell Wi-Fi networks MAC performance is bounded by the PHY layer capacity, this implies gains strictly less than 2x over half-duplex at the MAC layer. To face this limitation, we argue for the 1:N design guideline. Under 1:N, FD MAC protocols 'see' the FD bandwidth through N>1 orthogonal narrow-channel PHY layers. Based on theoretical results and software defined radio experiments, we show the 1:N design can leverage the Wi-Fi capacity gain more than 2x at and below the MAC layer. This translates the denser modulation scheme incurred by channel narrowing and the increase in the spatial reuse offer enabled by channel orthogonality. With these results, we believe our design guideline can inspire a new generation of Wi-Fi MAC protocols that fully embody and scale the FD capacity gain.