Fine-Grained Coordinated OFDMA With Fiber Backhaul Enabled by openwifi and White Rabbit

TL;DR

This paper demonstrates a Wi-Fi 6 compliant fine-grained Co-OFDMA system using fiber backhaul, achieving precise synchronization and improved signal quality, enabling advanced multi-AP coordination beyond standard wireless capabilities.

Contribution

It presents the first realization of Wi-Fi 6 compliant fine-grained Co-OFDMA with fiber backhaul, utilizing open-source platforms to enhance synchronization and performance.

Findings

Carrier frequency offset pre-compensation exceeds standard requirements

Time synchronization between APs is highly accurate

Received constellation quality surpasses individual AP frames

Abstract

Proper coordination is needed to guarantee the performance of wireless networks in dense deployments. Contention-based systems suffer badly in terms of latency when multiple devices compete for the same resources. Coordinated Orthogonal Frequency Division Multiple Access (Co-OFDMA) is proposed for Wi-Fi 8 to remedy this, as it enables multiple Access Points (APs) to share spectrum more efficiently. However, fine-grained resource allocation, namely within 20MHz bandwidth, is argued to be impractical due to the over-the-air scheduling overhead and complexity in terms of physical layer signaling. A wired backhaul mitigates the need for over-the-air scheduling and synchronization, and it allows for coordination even if APs are not in each others' range. Furthermore, it forms the basis for more advanced multi-AP coordination schemes like coordinated beamforming and joint transmission. In this work we demonstrate the realization of Wi-Fi 6 compliant fine-grained Co-OFDMA using a fiber backhaul, enabled by the open-source platforms openwifi and White Rabbit. We show that the performance in terms of carrier frequency offset pre-compensation and time synchronization between two APs exceeds related wireless standard requirements. Furthermore, the quality of the received constellation of the Co-OFDMA frame as reported by a wireless connectivity tester is better than individual frames sent by the APs.