Performance of orthogonal delay-doppler division multiplexing modulation with imperfect channel estimation

TL;DR

This paper evaluates the performance of orthogonal delay-Doppler division multiplexing (ODDM) with imperfect channel estimation, proposing improved detection algorithms and analyzing their bit error rate performance under realistic conditions.

Contribution

It introduces new detection schemes for ODDM with imperfect CSI and provides a comprehensive analysis of their BER performance compared to existing methods.

Findings

Soft SIC-MMSE outperforms other detectors in BER.

MRC-SD reduces BER effectively with minimal complexity increase.

MPA has an error floor and is sensitive to CSI imperfections.

Abstract

The orthogonal delay-Doppler division multiplexing (ODDM) modulation is a recently proposed multi-carrier modulation that features a realizable pulse orthogonal with respect to the delay-Doppler (DD) plane's fine resolutions. In this paper, we investigate the performance of ODDM systems with imperfect channel estimation considering three detectors, namely the message passing algorithm (MPA) detector, iterative maximum-ratio combining (MRC) detector, and successive interference cancellation with minimum mean square error (SIC-MMSE) detector. We derive the post-equalization signal-to-interference-plus-noise ratio (SINR) for MRC and SIC-MMSE and analyze their bit error rate (BER) performance. Based on this analysis, we propose the MRC with subtractive dither (MRC-SD) and soft SIC-MMSE initialized MRC (SSMI-MRC) detector to improve the BER of iterative MRC. Our results demonstrate that soft SIC-MMSE consistently outperforms the other detectors in BER performance under perfect and imperfect CSI. While MRC exhibits a BER floor above $10^{-5}$, MRC-SD effectively lowers the BER with a negligible increase in detection complexity. SSMI-MRC achieves better BER than hard SIC-MMSE with the same detection complexity order. Additionally, we show that MPA has an error floor and is sensitive to imperfect CSI.