Single Packet, Single Channel, Switched Antenna Array for RF Localization

Link to the paper: https://dl.acm.org/doi/10.1145/3596263 📄

Abstract

Cost-effective and accurate means of localizing radio transmitters has the potential to enable a wide range of applications in the consumer electronics, IoT, and healthcare domains. However, existing multi-antenna localization methods require high-cost synchronized receivers, long integration times, and/or specialized packet structures. This paper proposes using a high-speed RF mux that sequentially connects antennas to a single 2MHz radio receiver and sub-packet switching to determine the Angle of Arrival of individual packets. Importantly, this approach does not need synchronization between the mux and the receiver, reducing cost and system complexity. Our signal processing pipeline recovers both switch timing and the antenna number from the received RF signal. The sub-packet waveforms are used to generate a synthetic reference packet, and our customized Multi-Resolution Beaming and MUSIC algorithms are used to determine the Angle of Arrival. Results show that our real-time system is highly accurate even when the target is moving, with a mean AoA accuracy of 3.4 degrees and a 2D localization accuracy of 36.4 cm. Furthermore, the system is capable of tracking multiple users carrying smartphones in either their hands or pockets. Ultimately this approach enables a single low-cost, low bandwidth commodity RF receiver to be used to create an N-element phased array receiver.

Note

Generating the ideal waveform as a always-on, fake, virtual reference antenna was THE big brain move and I'm so proud I came up with that. I was playing with the idea in a Matlab function called playground_v3, but I couldn't get it to work because I had a bit flipped when generating the ideal waveform. Prof. Euiseok Hwang came to the rescue and fixed the error to make everything happen, huge thanks to Euiseok!