Joint Optimization of Geometric and Probabilistic Constellation Shaping for OFDM-ISAC Systems

Fuente: arXiv
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Autores principales: Geiger, Benedikt, Liu, Fan, Lu, Shihang, Rode, Andrej, Schmalen, Laurent
Formato: Preprint
Publicado: 2025
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author Geiger, Benedikt
Liu, Fan
Lu, Shihang
Rode, Andrej
Schmalen, Laurent
author_facet Geiger, Benedikt
Liu, Fan
Lu, Shihang
Rode, Andrej
Schmalen, Laurent
contents 6G communications systems are expected to integrate radar-like sensing capabilities enabling novel use cases. However, integrated sensing and communications (ISAC) introduces a trade-off between communications and sensing performance because the optimal constellations for each task differ. In this paper, we compare geometric, probabilistic and joint constellation shaping for orthogonal frequency division multiplexing (OFDM)-ISAC systems using an autoencoder (AE) framework. We first derive the constellation-dependent detection probability and propose a novel loss function to include the sensing performance in the AE framework. Our simulation results demonstrate that constellation shaping enables a dynamic trade-off between communications and sensing. Depending on whether sensing or communications performance is prioritized, geometric or probabilistic constellation shaping is preferred. Joint constellation shaping combines the advantages of geometric and probabilistic shaping, significantly outperforming legacy modulation formats.
format Preprint
id arxiv_https___arxiv_org_abs_2501_11583
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Joint Optimization of Geometric and Probabilistic Constellation Shaping for OFDM-ISAC Systems
Geiger, Benedikt
Liu, Fan
Lu, Shihang
Rode, Andrej
Schmalen, Laurent
Signal Processing
6G communications systems are expected to integrate radar-like sensing capabilities enabling novel use cases. However, integrated sensing and communications (ISAC) introduces a trade-off between communications and sensing performance because the optimal constellations for each task differ. In this paper, we compare geometric, probabilistic and joint constellation shaping for orthogonal frequency division multiplexing (OFDM)-ISAC systems using an autoencoder (AE) framework. We first derive the constellation-dependent detection probability and propose a novel loss function to include the sensing performance in the AE framework. Our simulation results demonstrate that constellation shaping enables a dynamic trade-off between communications and sensing. Depending on whether sensing or communications performance is prioritized, geometric or probabilistic constellation shaping is preferred. Joint constellation shaping combines the advantages of geometric and probabilistic shaping, significantly outperforming legacy modulation formats.
title Joint Optimization of Geometric and Probabilistic Constellation Shaping for OFDM-ISAC Systems
topic Signal Processing
url https://arxiv.org/abs/2501.11583