WiLE-Audio: Wide-Coverage Low-Energy Audio via WiFi-BLE Cross-Technology Communication

Bluetooth audio, as a common application in our daily life, faces a major challenge due to its limited transmission range in meeting users' demands. Traditional solutions, such as using high-power Bluetooth transmitters, require hardware upgrades that are neither cost-effective nor energy-efficient. This work introduces WiLE-Audio, a novel approach that extends Low Energy Audio (LE Audio) coverage through physical-layer cross-technology communication (CTC) from WiFi to Bluetooth Low Energy (BLE). We first present a novel symbol mapping technique from WiFi DQPSK to BLE GFSK symbols, which enables all-channel and reliable CTC to support Bluetooth channel hopping. Then, to implement CTC to commodity WiFi Network Interface Card (NIC), we present a real-time reverse scrambling method that dynamically calculates the payload of WiFi packets at the NIC driver. Finally, to align with the strict time window requirements of the BLE receiver, we design a precise timing strategy and a priority scheduling mechanism at the WiFi transmitter, effectively mitigating timing offsets due to Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) and queue management. These systematic innovations allow WiLE-Audio to be easily implemented into existing commercial WiFi and BLE devices with only a simple software upgrade on the WiFi side. Furthermore, using existing WiFi infrastructures, WiLE-Audio enables the relaying of Bluetooth Low Energy Audio (LE-Audio) and the roaming of BLE receiver at any WiFi-covered location. We implement WiLE-Audio on commercial WiFi and BLE devices, and conduct extensive evaluations across various scenarios. Experimental results demonstrate that WiLE-Audio extends the transmission distance of LE Audio by 2× in single-hop mode and at least 2.6× in two-hop roaming mode. This work provides a cost-effective and scalable solution for enhancing Bluetooth audio coverage, providing a promising prospect for whole-house or even whole-building LE Audio listening.