Unique Word-Based Frame Design for Bistatic Integrated Sensing and Communication

TL;DR

This paper introduces two novel word-based frame designs for bistatic integrated sensing and communication, replacing cyclic prefix with Zadoff-Chu sequences, enabling efficient radar sensing without data symbol knowledge and improving data rates.

Contribution

It proposes UW-based frame designs that enhance radar sensing and data rate in bistatic ISAC systems, with new receiver algorithms and theoretical performance bounds.

Findings

UW frames achieve similar radar performance to pilot-symbol methods.

UW frames provide 16.67% higher data rate in tested scenarios.

FFT-based receivers enable efficient multi-target delay-Doppler estimation.

Abstract

Integrated sensing and communication (ISAC) aims at enhancing the network functionalities and enabling new applications in the upcoming communications networks. In this paper, we propose two unique word (UW)-based frame designs for bistatic ISAC. The approach consists of replacing the cyclic prefix (CP) with a Zadoff-Chu (ZC)-based sequence. With this approach, the radar receiver does not need to know the data symbols to perform sensing and the data rate is not compromised by the addition of extra pilots. The sensing performance of the UW-based frames is compared with that of orthogonal frequency division multiplexing (OFDM) as well as the pilot-symbol (PS) based radar processing. We derive the Cram\'er-Rao bound (CRB) considering a band-limited system with raised-cosine filtering. Furthermore, we provide low-complexity fast Fourier transform (FFT)-based radar receivers that perform integer and fine grid multi-target delay-Doppler (DD) estimations. For the integer FFT-based receiver, an upper bound for the outlier probability is derived when the true DD falls outside the integer grid. The results demonstrate that the UW frames exhibit competitive radar performance with PS while having a 16.67% higher data rate for the cases investigated.