PassiveBLE: Towards Fully Commodity-Compatible BLE Backscatter

TL;DR

PassiveBLE tackles the challenge of making BLE backscatter fully commodity-compatible by introducing a high-accuracy, low-latency synchronization circuit, a distributed RF coding scheme, and an excitation-source–driven BLE connection scheduler. By offloading dynamic BLE parameters and channel coding to the excitation source and performing XOR-based encoding on RF signals, PassiveBLE enables standard BLE packet generation on passive tags without local decoding. The system demonstrates commodity-compatible operation with high reliability (>99.9% connection establishment) and substantial throughput gains (up to 974 kbps on LE 2M, 532 kbps on LE 1M), outperforming prior BLE backscatter by over an order of magnitude. These contributions enable practical, battery-free BLE backscatter for short-range IoT, smart infrastructure, and wearable applications, while highlighting future paths toward longer range and tighter security.

Abstract

Bluetooth Low Energy (BLE) backscatter is a promising candidate for battery-free Internet of Things (IoT) applications. Unlike existing commodity-level BLE backscatter systems that only enable one-shot communication through BLE advertising packets, we propose PassiveBLE, a backscatter system that can establish authentic and fully compatible BLE connections on data channels. The key enabling techniques include (i) a synchronization circuit that can wake up tags and activate backscatter communications with symbol-level accuracy to facilitate BLE data packet generation; (ii) a distributed coding scheme that offloads the major encoding and processing burdens from tags to the excitation source while achieving high throughput; (iii) a BLE connection scheduler to enable fully compatible BLE connection interactions, including connection establishment, maintenance and termination for multiple backscatter tags. We prototype PassiveBLE tags with off-the-shelf components and also convert the circuits and control logic into ASIC design sketch, whose power consumptions are 491 uW and 9.9 uW, respectively. Experimental results demonstrate that PassiveBLE achieves a success rate of over 99.9% in establishing commodity BLE connections. PassiveBLE also achieves commodity-compatible BLE communication with a high goodput of up to 974 kbps in LE 2M PHY mode and 532 kbps in LE 1M PHY mode, which is about 63.3 times higher than the previous commodity-level BLE backscatter system in the same mode.

Figures (32)

• Figure 1: A PassiveBLE tag achieves commodity-compatible BLE connections with both data and advertising packets. In contrast, the traditional commodity-compatible tag zhang2021commodity only employs BLE advertising packets to realize one-shot communication.
• Figure 2: Reuse the structure of BLE data packets to achieve commodity-compatible.
• Figure 3: Architecture of active BLE and PassiveBLE.
• Figure 4: Overview of PassiveBLE system.
• Figure 5: The high-level synchronization circuit schematic of PassiveBLE.