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RIS-Enabled Transmitter Design for Joint Radar and Communication

Emanuele Grossi, Marco Lops, Luca Venturino

TL;DR

This work addresses the challenge of efficient transmit beampattern control for integrated sensing and communication (ISAC) using a RIS-enabled DFRC transmitter illuminated by a small number of active sources. It formulates a joint optimization of source waveforms and RIS phase shifts to match a target space frequency beampattern under a total power constraint, leveraging a least-squares criterion. The approach yields a beampattern match where the amplitude beampattern is B(f; theta, phi) ≈ | v^H(f; theta, phi) diag(x) Q(f; theta, phi) s |, and evaluates radar detection probability Pd and communication rate R under realistic channel and antenna models. Numerical results show two-beam formation with manageable sidelobes and a clear tradeoff between Pd and R, demonstrating that RIS-based DFRC can achieve competitive performance with far fewer active elements compared to fully digital MIMO, highlighting scalability and energy efficiency for practical ISAC deployments.

Abstract

Achieving efficient and cost-effective transmit beampattern control for integrated sensing and communication (ISAC) systems is a significant challenge. This paper addresses this by proposing a dual-function radar communication (DFRC) transmitter based on a reconfigurable intelligent surface (RIS) illuminated by a limited number of active sources. We formulate and solve the joint design of source waveforms and RIS phase shifts to match a desired space-frequency radiation pattern, and we evaluate the resulting ISAC system's performance in terms of radar detection probability and data transmission rate. Numerical results demonstrate the promising capabilities of this RIS-enabled transmitter for ISAC applications.

RIS-Enabled Transmitter Design for Joint Radar and Communication

TL;DR

This work addresses the challenge of efficient transmit beampattern control for integrated sensing and communication (ISAC) using a RIS-enabled DFRC transmitter illuminated by a small number of active sources. It formulates a joint optimization of source waveforms and RIS phase shifts to match a target space frequency beampattern under a total power constraint, leveraging a least-squares criterion. The approach yields a beampattern match where the amplitude beampattern is B(f; theta, phi) ≈ | v^H(f; theta, phi) diag(x) Q(f; theta, phi) s |, and evaluates radar detection probability Pd and communication rate R under realistic channel and antenna models. Numerical results show two-beam formation with manageable sidelobes and a clear tradeoff between Pd and R, demonstrating that RIS-based DFRC can achieve competitive performance with far fewer active elements compared to fully digital MIMO, highlighting scalability and energy efficiency for practical ISAC deployments.

Abstract

Achieving efficient and cost-effective transmit beampattern control for integrated sensing and communication (ISAC) systems is a significant challenge. This paper addresses this by proposing a dual-function radar communication (DFRC) transmitter based on a reconfigurable intelligent surface (RIS) illuminated by a limited number of active sources. We formulate and solve the joint design of source waveforms and RIS phase shifts to match a desired space-frequency radiation pattern, and we evaluate the resulting ISAC system's performance in terms of radar detection probability and data transmission rate. Numerical results demonstrate the promising capabilities of this RIS-enabled transmitter for ISAC applications.

Paper Structure

This paper contains 5 sections, 14 equations, 3 figures.

Table of Contents

  1. Introduction
  2. System model
  3. System design and Performance analysis
  4. Numerical results
  5. Conclusion

Figures (3)

  • Figure 1: Considered DFRC transmit architecture, composed of an illuminator with $J$ sources and a passive RIS with $M$ elements used to form multiple beams for radar sensing and communication. The RIS can either be reflecting (as in this figure) or transmitting (in this case, the illuminator is placed behind the surface).
  • Figure 2: Normalized power beampattern (synthesized with the RIS-based DFRC system) as a function of elevation and azimuth for two frequency cuts when $\eta=0.5$.
  • Figure 3: Average detection probability vs the average data transmission rate for the RIS-based and MIMO DFRC systems and for different values of the nominal SNR at the user and radar sides ($\overline{\text{SNR}}=5,10,15,20,30$ dB).