A Low-Complexity Range Estimation with Adjusted Affine Frequency Division Multiplexing Waveform

TL;DR

This paper introduces a low-complexity range estimation method for AFDM waveforms in radar systems, optimizing parameters for near-ideal ambiguity functions and demonstrating high-resolution target detection with minimal computational effort.

Contribution

It identifies an AFDM waveform parameter setting with near-optimal ambiguity properties and proposes a low-complexity matched filtering algorithm for high-resolution range estimation.

Findings

Achieves near-optimal range estimation performance.

Maintains same BER as OTFS with simpler processing.

Validates effectiveness through simulations.

Abstract

Affine frequency division multiplexing (AFDM) is a recently proposed communication waveform for time-varying channel scenarios. As a chirp-based multicarrier modulation technique it can not only satisfy the needs of multiple scenarios in future mobile communication networks but also achieve good performance in radar sensing by adjusting the built-in parameters, making it a promising air interface waveform in integrated sensing and communication (ISAC) applications. In this paper, we investigate an AFDM-based radar system and analyze the radar ambiguity function of AFDM with different built-in parameters, based on which we find an AFDM waveform with the specific parameter c2 owns the near-optimal time-domain ambiguity function. Then a low-complexity algorithm based on matched filtering for high-resolution target range estimation is proposed for this specific AFDM waveform. Through simulation and analysis, the specific AFDM waveform has near-optimal range estimation performance with the proposed low-complexity algorithm while having the same bit error rate (BER) performance as orthogonal time frequency space (OTFS) using simple linear minimum mean square error (LMMSE) equalizer.