A Robust and Low-Complexity Walsh-Hadamard Modulation for Doubly-Dispersive Channels

Roberto Bomfin (1) , Ahmad Nimr (1) , Marwa Chafii (2) , Gerhard Fettweis (1)

1 TU Dresden - Technische Universität Dresden = Dresden University of Technology
2 ETIS - UMR 8051 - Equipes Traitement de l'Information et Systèmes

In this letter, we present a generic modulation framework for robust wireless communications over doubly dispersive channels. This robustness is achieved by spreading the symbols over time and frequency such that they experience the same channel gain. Interestingly, we show that our modulation framework is a generalization of the recently proposed orthogonal time frequency space modulation (OTFS). By exploiting an additional degree of freedom enabled by the generic framework, we propose in this paper a low-complex waveform based on the sparse Walsh-Hadamard transform (WHT). We show that the proposed sparse WHT modulation exhibits the same frame error rate performance as OTFS, while significantly reducing the implementation complexity due to the multiplication-free smallsize WHT compared with the discrete Fourier transform used by symplectic finite Fourier transform (SFFT) of OTFS.

Mots clés: Walsh-Hadamard; MMSE-PIC; doubly dispersive channel; OTFS; OFDM

Domaines: Réseaux et télécommunications [cs.NI]

Roberto Bomfin, Ahmad Nimr, Marwa Chafii, Gerhard Fettweis. A Robust and Low-Complexity Walsh-Hadamard Modulation for Doubly-Dispersive Channels. IEEE Communications Letters, inPress. ⟨hal-03146370⟩