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Bistatic ISAC: Practical Challenges and Solutions

Lucas Giroto, Marcus Henninger, Alexander Felix, Maximilian Bauhofer, Taewon Jeong, Umut Utku Erdem, Stephan ten Brink, Thomas Zwick, Benjamin Nuss, Silvio Mandelli

TL;DR

This work analyzes practical challenges of bistatic ISAC in 6G using OFDM, focusing on transmitter–receiver synchronization, limited transmit data at the receiver, and hardware impairments that bias sensing performance. It presents a system-design and signal-processing framework that combines coarse-to-fine synchronization, full-frame or pilot-based periodogram generation, and angular-domain reconstruction with multi-target tracking to achieve unbiased range–Doppler–DoD–DoA parameter estimation. The paper derives and discusses a bistatic range upper bound $\rho_p^{\mathrm max}$ under hardware impairments and demonstrates via FR2-compliant simulations how impairments (PA nonlinearity, PN, quantization, SJ) reduce sensing performance and detectable range, while CPE compensation and clutter removal can mitigate some degradation. It also highlights open challenges such as geometry calibration, TDD pattern handling, and robust fusion under uncertain deployments, underscoring the practical viability and remaining hurdles for 6G bistatic ISAC.

Abstract

This article presents and discusses challenges and solutions for practical issues in bistatic integrated sensing and communication (ISAC) in 6G networks. Considering orthogonal frequency-division multiplexing as the adopted waveform, a discussion on system design aiming to achieve both a desired sensing key performance indicators and limit the impact of hardware impairments is presented. In addition, signal processing techniques to enable over-the-air synchronization and generation of periodograms with range, Doppler shift, and angular information are discussed. Simulation results are then presented for a cellular-based ISAC scenario considering system parameterization compliant to current 5G and, finally, a discussion on open challenges for future deployments is presented.

Bistatic ISAC: Practical Challenges and Solutions

TL;DR

This work analyzes practical challenges of bistatic ISAC in 6G using OFDM, focusing on transmitter–receiver synchronization, limited transmit data at the receiver, and hardware impairments that bias sensing performance. It presents a system-design and signal-processing framework that combines coarse-to-fine synchronization, full-frame or pilot-based periodogram generation, and angular-domain reconstruction with multi-target tracking to achieve unbiased range–Doppler–DoD–DoA parameter estimation. The paper derives and discusses a bistatic range upper bound under hardware impairments and demonstrates via FR2-compliant simulations how impairments (PA nonlinearity, PN, quantization, SJ) reduce sensing performance and detectable range, while CPE compensation and clutter removal can mitigate some degradation. It also highlights open challenges such as geometry calibration, TDD pattern handling, and robust fusion under uncertain deployments, underscoring the practical viability and remaining hurdles for 6G bistatic ISAC.

Abstract

This article presents and discusses challenges and solutions for practical issues in bistatic integrated sensing and communication (ISAC) in 6G networks. Considering orthogonal frequency-division multiplexing as the adopted waveform, a discussion on system design aiming to achieve both a desired sensing key performance indicators and limit the impact of hardware impairments is presented. In addition, signal processing techniques to enable over-the-air synchronization and generation of periodograms with range, Doppler shift, and angular information are discussed. Simulation results are then presented for a cellular-based ISAC scenario considering system parameterization compliant to current 5G and, finally, a discussion on open challenges for future deployments is presented.
Paper Structure (23 sections, 6 equations, 3 figures, 3 tables)

This paper contains 23 sections, 6 equations, 3 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Notation and Link Budget
  3. System Design
  4. Bistatic sensing KPIs
  5. Effects of hardware impairments
  6. Antenna/array non-idealities
  7. Amplifier non-linear distortion
  8. Mixer non-idealities
  9. Oscillator phase noise
  10. DAC/ADC quantization
  11. DAC/ADC clipping
  12. DAC/ADC sampling jitter
  13. Signal Processing
  14. Synchronization
  15. Coarse time and frequency synchronization
  16. ...and 8 more sections

Figures (3)

  • Figure 1: Bistatic ISAC system model. In this example, a static reference path labeled as $p=0$ and a path $p=1$ associated with a radar target are shown.
  • Figure 2: Bistatic OFDM-based ISAC receiver processing chain based on full-frame approach to obtain a range-Doppler shift periodogram.
  • Figure 3: Power in periodogram accounting for antenna and processing gains as a function of the range parameter $\rho_p=\sqrt{R^\mathrm{Tx-T}_p R^\mathrm{T-Rx}_p}$. Results are shown for a drone (), a pedestrian (), and a car (). In addition, the power of the LoS path peak in the periodogram (), its associated mean () and maximum () impairment-induced interference levels, and the AWGN () level are shown. Finally, the power levels () yielding $17dB$SNR against AWGN, $17dB$SINR against AWGN and mean interference, and $17dB$SINR against AWGN and interference-induced artifacts are marked as A, B, and C, respectively.