Bridge: Enabling BLE Direction Finding Feature Compatible with All Bluetooth Devices

Abstract

Bluetooth 5.1 introduced Angle of Arrival (AoA) direction finding, enabling sub-meter indoor localization. However, this feature requires both transmitter and receiver to support the BLE v5.1 standard — legacy devices cannot participate, severely limiting deployability.

BRIDGE closes this gap with a software-only approach that enables BLE direction finding to work with all Bluetooth devices, including those that predate v5.1. By exploiting signal structure at the physical layer, BRIDGE retrofits AoA capability onto legacy hardware without any firmware changes, enabling large-scale indoor localization deployments today.

Key Contributions

• Backward compatibility of BLE v5.1 direction finding with all legacy BLE devices.
• No firmware or hardware modifications required on the transmitter side.
• Enables large-scale AoA-based indoor localization without device upgrade costs.

BibTeX

@inproceedings{zhang2025bridge,
  title     = {Bridge: Enabling BLE Direction Finding Feature Compatible with All Bluetooth Devices},
  author    = {Zhang, Runting and Li, Yijie and Ding, Dian and Chen, Yi-Chao and Wang, Yida and Chen, Dongyao and Wang, Jingxian and Yu, Jiadi and Ma, Ling and Xue, Guangtao},
  booktitle = {Proceedings of the 31st Annual International Conference on Mobile Computing and Networking (MobiCom)},
  year      = {2025},
  publisher = {ACM}
}