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Continuous-Aperture Array-Based ISAC Over Fading Channels

Boqun Zhao, Chongjun Ouyang, Xingqi Zhang, Yuanwei Liu

Abstract

A framework of continuous-aperture array (CAPA)-based integrated sensing and communications (ISAC) under a fading communication channel is proposed. A continuous operator-based signal model is developed, and the statistics of the communication channel gain are characterized via Landau's eigenvalue theorem. On this basis, the performance of the CAPA-based ISAC system is analyzed by considering three continuous beamforming designs: i) the sensing-centric (S-C) design that optimizes sensing performance, ii) the communication-centric (C-C) design that optimizes communication performance, and iii) the Pareto-optimal design that balances the sensing-communication trade-off. For the S-C and C-C design, closed-form expressions for the sensing rate (SR), ergodic communication rate (CR), and outage probability are derived, and high-signal-to-noise ratio asymptotic analysis is conducted to obtain the multiplexing and diversity gains. For the Pareto-optimal design, the Pareto-optimal beamformer achieving the Pareto boundary is derived, and the achievable SR-CR region is characterized. Numerical results demonstrate that the proposed CAPA-ISAC scheme outperforms both conventional spatially discrete arrays-based ISAC and CAPA-based frequency-division sensing and communications.

Continuous-Aperture Array-Based ISAC Over Fading Channels

Abstract

A framework of continuous-aperture array (CAPA)-based integrated sensing and communications (ISAC) under a fading communication channel is proposed. A continuous operator-based signal model is developed, and the statistics of the communication channel gain are characterized via Landau's eigenvalue theorem. On this basis, the performance of the CAPA-based ISAC system is analyzed by considering three continuous beamforming designs: i) the sensing-centric (S-C) design that optimizes sensing performance, ii) the communication-centric (C-C) design that optimizes communication performance, and iii) the Pareto-optimal design that balances the sensing-communication trade-off. For the S-C and C-C design, closed-form expressions for the sensing rate (SR), ergodic communication rate (CR), and outage probability are derived, and high-signal-to-noise ratio asymptotic analysis is conducted to obtain the multiplexing and diversity gains. For the Pareto-optimal design, the Pareto-optimal beamformer achieving the Pareto boundary is derived, and the achievable SR-CR region is characterized. Numerical results demonstrate that the proposed CAPA-ISAC scheme outperforms both conventional spatially discrete arrays-based ISAC and CAPA-based frequency-division sensing and communications.
Paper Structure (30 sections, 20 theorems, 111 equations, 7 figures, 1 table)

This paper contains 30 sections, 20 theorems, 111 equations, 7 figures, 1 table.

Key Result

Lemma 1

The autocorrelation function of $\hat{h}_{\rm{c}}( z )$ is given by

Figures (7)

  • Figure 1: Illustration of CAPA-based ISAC.
  • Figure 2: Illustration of the eigenvalues of $K(z,z')$.
  • Figure 3: ECR versus transmit SNR.
  • Figure 4: OP versus transmit SNR.
  • Figure 5: SR versus transmit SNR.
  • ...and 2 more figures

Theorems & Definitions (23)

  • Lemma 1
  • Lemma 2
  • Corollary 1
  • Remark 1
  • Lemma 3
  • Theorem 1
  • Corollary 2
  • Theorem 2
  • Corollary 3
  • Theorem 3
  • ...and 13 more