Bistatic OFDM-based ISAC with Over-the-Air Synchronization: System Concept and Performance Analysis

TL;DR

This paper proposes a bistatic OFDM-based ISAC system with over-the-air synchronization, analyzing its performance and limitations through theoretical analysis and proof-of-concept measurements, highlighting its potential for 6G applications.

Contribution

It introduces a novel bistatic ISAC framework with over-the-air synchronization and evaluates its performance using both pilot-only and full-frame processing methods.

Findings

Over-the-air synchronization effectively aligns transmitter and receiver.

Full OFDM frame processing improves radar and communication performance.

Residual synchronization errors impact system performance, as analyzed.

Abstract

Integrated sensing and communication (ISAC) has been defined as one goal for 6G mobile communication systems. In this context, this article introduces a bistatic ISAC system based on orthogonal frequency-division multiplexing (OFDM). While the bistatic architecture brings advantages such as not demanding full duplex operation with respect to the monostatic one, the need for synchronizing transmitter and receiver is imposed. In this context, this article introuces a bistatic ISAC signal processing framework where an incoming OFDM-based ISAC signal undergoes over-the-air synchronization based on preamble symbols and pilots. Afterwards, bistatic radar processing is performed using either only pilot subcarriers or the full OFDM frame. The latter approach requires estimation of the originally transmitted frame based on communication processing and therefore error-free communication, which can be achieved via appropriate channel coding. The performance and limitations of the introduced system based on both aforementioned approaches are assessed via an analysis of the impact of residual synchronization mismatches and data decoding failures on both communication and radar performances. Finally, the performed analyses are validated by proof-of-concept measurement results.