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Interference Detection and Exploitation for Multi-User Radar Sensing

Laurits Randers, Martin Voigt Vejling, Petar Popovski

TL;DR

The paper addresses mutual interference in multi-user radar sensing within spectrally interleaved OFDM ISAC systems. It introduces a statistically rigorous interference detector that enforces the familywise error rate $P(V \ge 1) \le \delta$ and an estimation pipeline that uses interfered resources for angle estimation and non-interfered resources for delay estimation, plus data association. A tailored Fisher information analysis yields a CRLB establishing how interfered resources primarily contribute to estimating the angle to the interferer, and numerical results show RMSEs approaching the CRLB and near-oracle performance. The method offers practical gains for mmWave ISAC in shared-spectrum scenarios and suggests extensions to multi-user tracking and joint communications.

Abstract

Integrated sensing and communication is a key feature in next-generation wireless networks, enabling joint data transmission and environmental radar sensing on shared spectrum. In multi-user scenarios, simultaneous transmissions cause mutual interference on overlapping frequencies, leading to spurious target detections and degraded sensing accuracy. This paper proposes an interference detection and exploitation algorithm for sensing using spectrally interleaved orthogonal frequency division multiplexing. A statistically rigorous procedure is introduced to detect interference while controlling the familywise error rate. We propose an algorithm that estimates the angle by exploiting interference, while estimating the delay by avoiding the interference. Numerical experiments demonstrate that the proposed method reliably detects interference, and that the delay and angle estimation error approaches the Cramér-Rao lower bound.

Interference Detection and Exploitation for Multi-User Radar Sensing

TL;DR

The paper addresses mutual interference in multi-user radar sensing within spectrally interleaved OFDM ISAC systems. It introduces a statistically rigorous interference detector that enforces the familywise error rate and an estimation pipeline that uses interfered resources for angle estimation and non-interfered resources for delay estimation, plus data association. A tailored Fisher information analysis yields a CRLB establishing how interfered resources primarily contribute to estimating the angle to the interferer, and numerical results show RMSEs approaching the CRLB and near-oracle performance. The method offers practical gains for mmWave ISAC in shared-spectrum scenarios and suggests extensions to multi-user tracking and joint communications.

Abstract

Integrated sensing and communication is a key feature in next-generation wireless networks, enabling joint data transmission and environmental radar sensing on shared spectrum. In multi-user scenarios, simultaneous transmissions cause mutual interference on overlapping frequencies, leading to spurious target detections and degraded sensing accuracy. This paper proposes an interference detection and exploitation algorithm for sensing using spectrally interleaved orthogonal frequency division multiplexing. A statistically rigorous procedure is introduced to detect interference while controlling the familywise error rate. We propose an algorithm that estimates the angle by exploiting interference, while estimating the delay by avoiding the interference. Numerical experiments demonstrate that the proposed method reliably detects interference, and that the delay and angle estimation error approaches the Cramér-Rao lower bound.
Paper Structure (11 sections, 2 theorems, 20 equations, 5 figures, 1 table)

This paper contains 11 sections, 2 theorems, 20 equations, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. System model
  3. Interference detection and exploitation
  4. Interference detection procedure
  5. Theoretical justification
  6. Delay and angle estimation
  7. Cramér-Rao lower bound
  8. Numerical experiments
  9. Conclusion
  10. Channel parameters
  11. Proofs of Proposition 1

Key Result

Proposition 1

Let $\gamma_1,\dots,\gamma_n \stackrel{{\rm iid}}{\sim} {\rm Gamma}(\varrho, \varsigma^2)$ with order statistics $\gamma_{(1)}\leq \cdots \leq \gamma_{(n)}$. Then, $\mathbb{P}(\gamma_{(n)} > \gamma_{(1)}\beta)$ does not depend on $\varsigma^2$.

Figures (5)

  • Figure 1: Illustration of the scenario. The orange and green lines depict signal paths of the iUE and rUE, respectively, with solid lines for signals impinging on the sensor. An OFDM resource block display how the iUE and rUE occupy distinct parts of the spectrum with overlap at some subcarriers.
  • Figure 2: under the global null for varying $\beta$. The solid blue line and the dashed red line is the theoretical and empirical , respectively.
  • Figure 3: when $\kappa=1$ and $\delta\in\{10^{-1},10^{-2}\}$ for varying number of overlapping subcarriers.
  • Figure 4: True detection rate when $\kappa=1$, $\delta\in\{10^{-1},10^{-2},10^{-3}\}$, and $E_0=0.05$ for varying interference powers, $E_1$.
  • Figure 5: (a),(c) Comparison for varying transmission powers, $E_0$, when the number of overlapping subcarriers are 8. (b),(d) Comparison for varying number of overlapping subcarriers, when the transmission power is $E_0=0.1$. Settings: $\kappa=1$, $\delta=10^{-3}$, and $E_1=0.05$.

Theorems & Definitions (5)

  • Proposition 1
  • proof
  • Lemma 1
  • proof : Proof of Lemma 1
  • proof : Proof of Proposition 1