Adaptive Hopping for Bluetooth Backscatter using Commodity Edges

TL;DR

ChannelDance is a BLE backscatter system that uses a low-latency edge server and adaptive hopping techniques to improve channel switching speed, accuracy, and connection success in busy radio environments.

Contribution

It introduces a novel adaptive hopping scheme with a centralized low-latency architecture, enabling fast, accurate channel switching and improved BLE backscatter performance.

Findings

Achieves 93% success rate in channel mapping

Realizes 3.5x goodput gain through channel optimization

Successfully establishes BLE connections with adaptive hopping

Abstract

Channel hopping is essential to BLE backscatter as commodity BLE switches channels frequently during transmission to overcome interferences in busy radio environments. Existing Bluetooth backscatter systems, however, suffer from slow responses to excitation change and poor control of the target channel. To address these issues, this paper presents ChannelDance, a BLE backscatter system that utilizes a low-latency edge server to achieve fast and accurate hopping. Specifically, we show that the backscattered channel relies on the excitation channel and tag toggling frequency. By identifying excitation frequency, the tag can achieve accurate hopping with a dynamically configured clock. Further, we introduce a low-latency architecture, which is centralized, asynchronous, and equipped with high-speed interfaces. This architecture supports the tag to respond to excitation changes fastly. We prototype the ChannelDance tag with FPGA and build the low latency edge server with commodity MCU and off-the-shelf BLE and WiFi radios. Experimental results show that ChannelDance can realize 40 to 40 channel mapping with a median success rate of 93% and achieve 3.5x goodput gain with channel optimization. Moreover, with adaptive hopping, the ChannelDance tag successfully establishes a connection with commodity BLE.