A Novel Post-Coded Time-Domain Channel Estimation for Chirp-Based Multicarrier Waveforms
IEEE Transactions on Vehicular Technology, cilt.75, sa.6, ss.10933-10948, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 75 Sayı: 6
- Basım Tarihi: 2026
- Doi Numarası: 10.1109/tvt.2025.3648496
- Dergi Adı: IEEE Transactions on Vehicular Technology
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Compendex, INSPEC, Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Sayfa Sayıları: ss.10933-10948
- Anahtar Kelimeler: AFDM, channel estimation, delay-Doppler coupling, doubly dispersive channel, OCDM, post-coded time-domain
- İstanbul Medipol Üniversitesi Adresli: Evet
Özet
Chirp-based multicarrier waveforms, notably the generalized version, affine frequency division multiplexing (AFDM) have garnered increased attention recently. Particularly, due to its unique channel representation, the channel estimation (CE) in the affine domain raises major challenges. Therefore, this paper introduces a novel, low-complexity CE technique that exploits the properties of chirp carriers in the post-coded time-domain (PCTD). Initially, based on the explicit input-output relationship in doubly selective channels, the inherent properties of AFDM and their dependency on the refining coefficients are analyzed, revealing the limitations of existing guard-based CE techniques. As such, a comprehensive representation of single and multiple chirp carriers in the PCTD is provided both pre- and post-channel transmission, with a focus on interpreting the effects of delay and Doppler shifts. Building on this analysis, a two-stage CE method is proposed, leveraging the zero-padded PCTD (ZP-PCTD) received signal, effectively decoupling delay and Doppler components with scalable resolution. This method effectively compensates for phase selectivity across carriers while maintaining adaptability through scenario-based frame structures with optimized pilot-to-data ratios. The proposed approach significantly reduces the computational complexity and improves spectral efficiency (SE) by minimizing pilot overhead. Simulation results reflect the superiority of the proposed method over the existing iterative schemes, highlighting its ability to improve the performance of AFDM in practical propagation channels.