# Moving Target Detection via Multi-IRS-Aided OFDM Radar

## TL;DR

This paper introduces a joint design method for IRS phase-shifts and OFDM signals in multi-IRS-aided radar to enhance target detection accuracy, demonstrating improved performance over conventional methods.

## Contribution

It is the first to jointly optimize IRS phase-shifts and OFDM signals for radar detection, using an alternating optimization approach and a novel unimodular bi-quadratic programming formulation.

## Key findings

- Joint design improves detection accuracy compared to conventional OFDM radar.
- Proposed algorithm is computationally efficient and effective.
- Numerical results confirm enhanced target detection performance.

## Abstract

An intelligent reflecting surface (IRS) consists of passive reflective elements capable of altering impinging waveforms. The IRS-aided radar systems have recently been shown to improve detection and estimation performance by exploiting the target information collected via non-line-of-sight paths. However, the waveform design problem for an IRS-aided radar has remained relatively unexplored. In this paper, we consider a multi-IRS-aided orthogonal frequency-division multiplexing (OFDM) radar and study the theoretically achievable accuracy of target detection. In addition, we jointly design the OFDM signal and IRS phase-shifts to optimize the target detection performance via an alternating optimization approach. To this end, we formulate the IRS phase-shift design problem as a unimodular bi-quadratic program which is tackled by a computationally cost-effective approach based on power-method-like iterations. Numerical experiments illustrate that our proposed joint design of IRS phase-shifts and the OFDM code improves the detection performance in comparison with conventional OFDM radar.