Delay-Doppler Multiplexing With Global Filtering

TL;DR

This paper introduces GF-OTFS, a new modulation method combining SC-FDMA and UFMC to improve spectral containment and Doppler interference mitigation in dynamic channels.

Contribution

It presents a novel GF-OTFS modulation technique integrating delay-Doppler representation with universal filtering, enhancing spectral containment and interference mitigation.

Findings

GF-OTFS achieves comparable BER to existing methods.

Significantly reduces out-of-band emissions.

Improves Doppler spread reduction in dynamic channels.

Abstract

This paper proposes a novel modulation technique called globally filtered orthogonal time frequency space (GF-OTFS) which integrates single-carrier frequency division multiple access (SC-FDMA)-based delay-Doppler representation with universal filtered multi-carrier (UFMC) modulation. Our proposed technique first arranges the frequency-Doppler bins of an orthogonal time frequency space (OTFS) frame in adjacency using SC-FDMA and then applies universal filtering to the neighboring signals to mitigate inter-Doppler interference (IDI). By employing this approach, GF-OTFS achieves superior spectral containment and effectively mitigates interference caused by Doppler shifts in dynamic, time-varying channels. This paper also presents a detailed mathematical formulation of the proposed modulation technique. Furthermore, a comprehensive performance evaluation is conducted, comparing our GF-OTFS approach to state-of-the-art techniques, including Doppler-resilient UFMC (DR-UFMC) and receiver windowed OTFS (RW-OTFS). Key performance metrics, such as bit error rate (BER) and out-of-band (OOB) emissions, as well as the Doppler spread reduction are analyzed to assess the effectiveness of each approach. The results indicate that our proposed technique achieves comparable BER performance while significantly improving spectral containment.