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ISAC-Fi: Enabling Full-fledged Monostatic Sensing over Wi-Fi Communication

Zhe Chen, Chao Hu, Tianyue Zheng, Hangcheng Cao, Yanbing Yang, Yen Chu, Hongbo Jiang, Jun Luo

TL;DR

This article proposes, design, and implements ISAC-Fi as an ISAC-ready Wi-Fi prototype, and presents a novel self-interference cancellation scheme, in order to extract reflected signals for sensing purpose in the face of transmissions.

Abstract

Whereas Wi-Fi communications have been exploited for sensing purpose for over a decade, the bistatic or multistatic nature of Wi-Fi still poses multiple challenges, hampering real-life deployment of integrated sensing and communication (ISAC) within Wi-Fi framework. In this paper, we aim to re-design WiFi so that monostatic sensing (mimicking radar) can be achieved over the multistatic communication infrastructure. Specifically, we propose, design, and implement ISAC-Fi as an ISAC-ready Wi-Fi prototype. We first present a novel self-interference cancellation scheme, in order to extract reflected (radio frequency) signals for sensing purpose in the face of transmissions. We then subtly revise existing Wi-Fi framework so as to seamlessly operate monostatic sensing under Wi-Fi communication standard. Finally, we offer two ISAC-Fi designs: while a USRP-based one emulates a totally re-designed ISAC-Fi device, another plug-andplay design allows for backward compatibility by attaching an extra module to an arbitrary Wi-Fi device. We perform extensive experiments to validate the efficacy of ISAC-Fi and also to demonstrate its superiority over existing Wi-Fi sensing proposals.

ISAC-Fi: Enabling Full-fledged Monostatic Sensing over Wi-Fi Communication

TL;DR

This article proposes, design, and implements ISAC-Fi as an ISAC-ready Wi-Fi prototype, and presents a novel self-interference cancellation scheme, in order to extract reflected signals for sensing purpose in the face of transmissions.

Abstract

Whereas Wi-Fi communications have been exploited for sensing purpose for over a decade, the bistatic or multistatic nature of Wi-Fi still poses multiple challenges, hampering real-life deployment of integrated sensing and communication (ISAC) within Wi-Fi framework. In this paper, we aim to re-design WiFi so that monostatic sensing (mimicking radar) can be achieved over the multistatic communication infrastructure. Specifically, we propose, design, and implement ISAC-Fi as an ISAC-ready Wi-Fi prototype. We first present a novel self-interference cancellation scheme, in order to extract reflected (radio frequency) signals for sensing purpose in the face of transmissions. We then subtly revise existing Wi-Fi framework so as to seamlessly operate monostatic sensing under Wi-Fi communication standard. Finally, we offer two ISAC-Fi designs: while a USRP-based one emulates a totally re-designed ISAC-Fi device, another plug-andplay design allows for backward compatibility by attaching an extra module to an arbitrary Wi-Fi device. We perform extensive experiments to validate the efficacy of ISAC-Fi and also to demonstrate its superiority over existing Wi-Fi sensing proposals.
Paper Structure (29 sections, 9 equations, 22 figures)

This paper contains 29 sections, 9 equations, 22 figures.

Table of Contents

  1. Introduction
  2. Analysis and Motivations
  3. Uncertainties in Temporal Features
  4. Modelling Offsets
  5. Bistatic vs. Monostatic Sensing.
  6. Dominating Interference from LoS Path
  7. Ambiguity in Motion Sensing
  8. ISAC-Fi: Making Wi-Fi ISAC-Ready
  9. System Overview
  10. Tx-Rx Separator Design
  11. Analog Cancellator
  12. Digital Cancellator
  13. Self-Adapted Tx-Rx Separation
  14. Co-existing with Wi-Fi Framework
  15. Monostatic Channel Feature Estimation
  16. ...and 14 more sections

Figures (22)

  • Figure 1: Wi-Fi (a) vs ISAC-Fi (b) sensing. The thin arrows represent RF propagation originated from different Tx's or along distinct paths, while the thick (double-side and colored) arrows denote the directions of sensed subject motions.
  • Figure 2: Architectures of Wi-Fi (a), full ISAC-Fi (b), and partial ISAC-Fi (c). The hardware novelties mainly lie in replacing the Tx-Rx Switch with a Separator to enable concurrency and in revising the Baseband for enhancing the quality of reflected Rx signals.
  • Figure 3: The unwrapped CSI phases of 52 subcarriers and across consecutive symbols (marked with different colors) under bistatic (a) and monostatic (b) modes.
  • Figure 4: The phase variations induced by human (target) breath at two different Rx-target ranges under bistatic (a) and monostatic (b) modes.
  • Figure 5: Sensing motion effect under bistatic mode: conceptual illustration and experiment settings.
  • ...and 17 more figures