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Double-decker: Productive Backscatter Communication Using a Single Commodity Receiver

Qiwei Wang, Wei Gong

TL;DR

The paper addresses the challenge of backscatter systems requiring dual receivers by introducing double-decker, which partitions ambient carrier symbols into pilot and data chips, enabling tag data to be decoded with a single receiver using pilot references. It extends FreeRider's codeword-translation approach and demonstrates a practical FPGA-based prototype that supports multiple ambient protocols (802.11b/g, ZigBee, BLE). Across LOS and NLOS deployments, it achieves aggregated throughputs up to 73.2 kbps (38 kbps productive and 35.2 kbps tag) and ranges up to 28 m, while offering mode-based trade-offs between tag and productive data. The contributions include a universal modulation framework, concrete data-chip mode configurations, and extensive experimental validation, highlighting the potential for widespread deployment of productive backscatter with commodity radios.

Abstract

Backscatter communication has attracted significant attention for Internet-of-Things applications due to its ultra-low-power consumption. The state-of-the-art backscatter systems no longer require dedicated carrier generators and leverage ambient signals as carriers. However, there is an emerging challenge: most prior systems need dual receivers to capture the original and backscattered signals at the same time for tag data demodulation. This is not conducive to the widespread deployment of backscatter communication. To address this problem, we present double-decker, a novel backscatter system that only requires a single commercial device for backscatter communication. The key technology of double-decker is to divide the carrier OFDM symbols into two parts, which are pilot symbols and data symbols. Pilot symbols can be used as reference signals for tag data demodulation, thus getting rid of the dependence on the dual receiver structure. We have built an FPGA prototype and conducted extensive experiments. Empirical results show that when the excitation signal is 802.11g, double-decker achieves a tag data rate of 35.2kbps and a productive data rate of 38kbps, respectively. The communication range of double-decker is up to 28m in LOS deployment and 24m in NLOS deployment.

Double-decker: Productive Backscatter Communication Using a Single Commodity Receiver

TL;DR

The paper addresses the challenge of backscatter systems requiring dual receivers by introducing double-decker, which partitions ambient carrier symbols into pilot and data chips, enabling tag data to be decoded with a single receiver using pilot references. It extends FreeRider's codeword-translation approach and demonstrates a practical FPGA-based prototype that supports multiple ambient protocols (802.11b/g, ZigBee, BLE). Across LOS and NLOS deployments, it achieves aggregated throughputs up to 73.2 kbps (38 kbps productive and 35.2 kbps tag) and ranges up to 28 m, while offering mode-based trade-offs between tag and productive data. The contributions include a universal modulation framework, concrete data-chip mode configurations, and extensive experimental validation, highlighting the potential for widespread deployment of productive backscatter with commodity radios.

Abstract

Backscatter communication has attracted significant attention for Internet-of-Things applications due to its ultra-low-power consumption. The state-of-the-art backscatter systems no longer require dedicated carrier generators and leverage ambient signals as carriers. However, there is an emerging challenge: most prior systems need dual receivers to capture the original and backscattered signals at the same time for tag data demodulation. This is not conducive to the widespread deployment of backscatter communication. To address this problem, we present double-decker, a novel backscatter system that only requires a single commercial device for backscatter communication. The key technology of double-decker is to divide the carrier OFDM symbols into two parts, which are pilot symbols and data symbols. Pilot symbols can be used as reference signals for tag data demodulation, thus getting rid of the dependence on the dual receiver structure. We have built an FPGA prototype and conducted extensive experiments. Empirical results show that when the excitation signal is 802.11g, double-decker achieves a tag data rate of 35.2kbps and a productive data rate of 38kbps, respectively. The communication range of double-decker is up to 28m in LOS deployment and 24m in NLOS deployment.
Paper Structure (17 sections, 3 equations, 12 figures)

This paper contains 17 sections, 3 equations, 12 figures.

Table of Contents

  1. Introduction
  2. Double-decker Design
  3. Primer for FreeRider
  4. Double-Decker
  5. Backscatter via 802.11b WiFi
  6. Backscatter via 802.11g WiFi
  7. Backscatter via ZigBee
  8. Backscatter via Bluetooth
  9. Configuration of Data Chip Mode
  10. Experimental Evaluation
  11. Double-decker's Performance
  12. Backscatter with 802.11b WiFi
  13. Backscatter with 802.11g WiFi
  14. Backscatter with Bluetooth
  15. Backscatter with ZigBee
  16. ...and 2 more sections

Figures (12)

  • Figure 1: Double-decker sets some areas in the carrier that cannot be modulated to retain the necessary information of productive data, which can be used as a reference for tag data decoding.
  • Figure 2: Comparison of double-decker and state-of-the-art backscatter systems.
  • Figure 3: Double-decker modulation mechanism: The carrier is divided into many data chips, each data chip is composed of pilot symbols for carrying productive data and data symbols for carrying modulated data. The productive data can be recovered directly from pilot symbols. By XORing the pilot symbols with data symbols, double-decker can decode the tag data.
  • Figure 4: Double-decker uses a decoding window to stand for the pilot (or data) symbol as it contains all 0s when unmodulated and all 1s when modulated for decoding.
  • Figure 5: The results of modulated ZigBee symbols are not deterministic, but we can still decode the tag data by increasing the size of data chip.
  • ...and 7 more figures