IRCI Free MIMO OFDM SAR Using Circularly Shifted Zadoff-Chu Sequences

TL;DR

This paper introduces a novel IRCI-free MIMO-OFDM SAR system that uses circularly shifted Zadoff-Chu sequences, enabling single-pulse range profiling with full spatial diversity and efficient swath imaging.

Contribution

It proposes a new CP-based MIMO-OFDM SAR system utilizing circularly shifted Zadoff-Chu sequences for efficient, single-pulse range profiling without IRCI.

Findings

IRCI-free range reconstruction achieved

Full spatial diversity collected with distributed antennas

Single OFDM pulse sufficient for swath imaging

Abstract

Cyclic prefix (CP) based MIMO-OFDM radar has been recently proposed for distributed transmit antennas, where there is no inter-range-cell interference (IRCI). It can collect full spatial diversity and each transmitter transmits signals with the same frequency band, i.e., the range resolution is not reduced. However, it needs to transmit multiple OFDM pulses consecutively to obtain range profiles for a single swath, which may be too long in time for a reasonable swath width. In this letter, we propose a CP based MIMO-OFDM synthetic aperture radar (SAR) system, where each transmitter transmits only a single OFDM pulse to obtain range profiles for a swath and has the same frequency band, thus the range resolution is not reduced. It is IRCI free and can collect the full spatial diversity if the transmit antennas are distributed. Our main idea is to use circularly shifted Zadoff-Chu sequences as the weighting coefficients in the OFDM pulses for different transmit antennas and apply spatial filters with multiple receive antennas to divide the whole swath into multiple subswaths, and then each subswath is reconstructed/imaged using our proposed IRCI free range reconstruction method.